| 1. |
Alireza Safari, Lingping Zeng, Ronald Nguele, Yuichi Sugai, Mohammad Sarmadivaleh, Review on using the depleted gas reservoirs for the underground H2 storage: A case study in Niigata prefecture, Japan, International Journal of Hydrogen Energy (Elsevier), https://doi.org/10.1016/j.ijhydene.2022.12.108, 48, 28, 10579-10602, 2023.04, Underground hydrogen storage (UHS) in depleted hydrocarbon reservoirs is a prospective choice to store enormous volumes of hydrogen (H2). However, these subsurface formations must be able not only to store H2 in an effective and secure manner, but also to produce the required volumes of H2 upon demand. This paper first reviews the critical parameters to be considered for geological analysis and reservoir engineering evaluation of UHS. The formation depth, the interactions of rock-brine-H2, the caprock (seal) and well integrity are the most prominent parameters as far as UHS is concerned. In respect of these critical parameters, tentative H2 storage is screened from the existing gas storage fields in the Niigata prefecture of Japan, and it was revealed that the Sekihara gas field is a suitable candidate for UHS with a storage capacity of 2.06 × 108 m3 and a depth of 1000 m. Then, a series of numerical simulations utilizing CMG software was conducted to find out the extent to which critical parameters alter H2 storage capacity. The results demonstrated that this field, with a recovery factor of 82.7% in the sixth cycle of production is a prospective site for H2 storage.. |
| 2. |
Danielle Poungui, Yuichi Sugai, Kyuro Sasaki, Ronald Nguele, Swelling Mechanisms Assessment of Water-based Drilling Mud by Polyvinyl Alcohol, Proceeding of Society of Petroleum Engineers - SPE/IATMI Asia Pacific Oil and Gas Conference and Exhibition 2022, https://doi.org/10.2118/210694-MS, SPE-210694-MS, 2022.10, Swelling control is an elaborated balancing of solid-liquid ratios in the mud, influencing crucial physio-chemical features. Mechanical swelling control methods showing limitations drove recent researchers to consider chemical agents, including polyvinyl alcohol (PVOH). PVOH is known to have a swelling ability to improve mud rheology. The present study investigates the synergy of PVOH and Bentonite in an aqueous environment by analyzing the effluents samples. Three types of PVOH were selected: a standard PVOH and two modified PVOHs (a non-ionic group PVOH and a cationic group PVOH-3 attached to the carbon backbone. Except for the control sample (sample without polymer), PVOHs were added to different mud samples at ranging concentrations of 0.1 wt.% to 0.5 wt.%; each has a bulk volume of 400 ml. Each mud sample was filtrated at room temperature under an applied pressure of 1.28 MPa for 5 hours. The samples' effluents were then analyzed for polymer adsorption. Preliminary filtration tests revealed further effluent production reduction with increased PVOH concentration. Compared to the control sample, samples containing standards PVOH-1, Non-ionic PVOH-2, and Cationic PVOH-3, respectively, had their mud cake mass increase of 48%, 36%, and 38%, while respectively having filtrate recovery reduction of 21%, 19%, and 43%. Adsorption tests showed mud swelling owes primarily to hydrogen bonding which is counteracted by the presence of a charged group. Mud swelling is, therefore, dependent on the rate of hydrogen bounding in a system.. |
| 3. |
Miu Ito, Yuichi Sugai, Evaluation of the Potential of Foam Producing Microorganism Improving Heterogeneity of Permeability for Novel Microbial Foam EOR, Proceeding of Society of Petroleum Engineers - SPE/IATMI Asia Pacific Oil and Gas Conference and Exhibition 2022, https://doi.org/10.2118/210696-MS, SPE-201696-MS, 2022.10, The foam improves heterogeneity of permeability in oil reservoir and contributes to enhancing oil recovery. Both surfactant and gas are alternatingly injected into oil reservoir in foam EOR, therefore, it has several challenges: high cost of surfactant, formation of precipitation with bivalent cations, adsorption of surfactant on reservoir rock, etc. This study proposes the microbial foam EOR which overcomes those challenges by having microorganism generate foam in-situ. We have found an ability of a microorganism belonging to Pseudomonas aeruginosa to generate foam under anaerobic conditions. This study investigated the source materials constructing the foam and capacity of the foam to improve the heterogeneity of the permeability.
The challenges of our study are the reproducibility of the foam generation and the foam stability. This study therefore examined the source materials of the foam to understand the mechanisms of the foam generation. We focused on protein, which has been suggested as a possible component of the foam in our previous studies, and examined the relationship between the amount of foam generated by P. aeruginosa and the concentration of protein in its culture solution. As a result, a positive correlation was found between them. This result indicates that the foam generated by P. aeruginosa is composed of the protein produced by the microorganism.
Next, the performance of the foam decreasing permeability of high permeability porous media was evaluated through sand pack flooding experiment. P. aeruginosa was injected into a sand pack and cultivated in-situ. The post-flush water was injected into the sand pack after three days’ in-situ cultivation to measure the permeability. As a result, the permeability of the sand pack was successfully decreased to half after the cultivation. The permeability of a sand pack in which P. aeruginosa was injected with culture medium and in-situ cultivated was successfully decreased to half of initial . The efflux of bacterial cells of P. aeruginosa was detected after injecting 1.3 pore volumes of postflush water, which shows that the postflush water flowed through areas other than the area where P. aeruginosa grew and produced the foam. These results indicate that the foam produced in-situ by P. aeruginosa is effective for improving the heterogeneity of permeability in oil reservoir.
This EOR can be operated at low cost without expensive chemicals. Because the foam produced by P. aeruginosa is induced by proteins, the precipitation will not be formed in oil reservoir. The stability of protein-induced foam is higher than that of surfactant-induced foam in the presence of oil or high saline conditions. The microbial foam EOR therefore has high potential improving the heterogeneity of permeability in oil reservoir more effectively than the conventional foam EOR.. |
| 4. |
Theodora Noely Tambaria, Yuichi Sugai, Ferian Anggara, Experimental Measurements of CO2 Adsorption on Indonesian Low-rank Coals under Various Conditions., Journal of Petroleum Exploration and Production Technology (Springer), https://doi.org/10.1007/s13202-022-01569-z, 13, 813-826, 2022.09, In this study, the CO2 adsorption capacity was measured on Indonesian low-rank coals in the raw and dry conditions in powder and block states using different coal sample preparation to estimate CO2 sequestration and storage potential. Coal sample specimens were taken from three different areas in the South Sumatra Basin, Indonesia. The adsorption experiments were performed using the volumetric method at a temperature of 318.15 K and pressure up to 3 MPa. The CO2 excess adsorption capacity of powder coal is always higher than block coal. Moreover, decreasing moisture content by the drying process increases CO2 adsorption capacity on coal. Based on fitted CO2 adsorption experimental data with the Langmuir and Freundlich isotherm model, the adsorption occurs on monolayer and multilayer at various conditions. Langmuir volume capacity and pressure show drying and crushing process increased adsorption capacity. However, the drying process affects more the capability of coal to adsorb CO2 than the powdered sample, especially in low-rank coal. It was also observed adsorption capacity is directly proportional to huminite content in the coal. Due to lower moisture and higher huminite contents, the dried WB coal powder had the highest CO2 adsorption capacity over the other coal samples in similar sample conditions. Altogether, this study may provide a better understanding in CO2 adsorption on low-rank coal with different coal sample preparation resulting in different CO2 adsorption capacity.. |
| 5. |
Nam Nguyen Hai Le, Yuichi Sugai, Ronald Nguele, Enhanced Oil Recovery in Heterogeneous Reservoir by CO2-Colloidal Gas Aphrons Fluid Injection., Proceeding of 83rd EAGE Annual Conference & Exhibition, https://doi.org/10.3997/2214-4609.202210546, 2022, 1-5, 2022.06, Carbon dioxide (CO2) gas injection into depleted oil reservoirs is a promising approach to achieve the goal of a neutral carbon society. However, the heterogeneity of formation generally challenges the oil recovery efficiency. The CO2 gas injection preferably flows in the high permeability zone and leaves behind the remaining oil in the lower permeability region. This study presented a new CO2-Colloidal Gas Aphrons fluid to restrict fluid flow in the high permeability zone, and increase swept volume in the low permeability zone. We conducted dual parallel sandpacks with different permeabilities models to evaluate the plugging ability and oil recovery improvement of CO2-CGAs injection in heterogeneous porous media. The results reveal that CO2-CGAs can block the pore throat in the high permeability sandpack and change the flow direction to the low permeability sandpack. Overall, the sweep efficiency in the low permeability region was increased significantly, which led to an improvement in the total oil recovery factor by 39 %.. |
| 6. |
Nam Nguyen Hai Le, Yuichi Sugai, Hung Vo-Thanh, Ronald Nguele, Ronald Ssebadduka, Ning Wei, Experimental investigation on plugging performance of CO2 microbubbles in porous media, Journal of Petroleum Science and Engineering (Elsevier), https://doi.org/10.1016/j.petrol.2022.110187, 211, 110187, 2022.04, To further improve carbon dioxide enhanced oil recovery CO2-EOR efficiency in heterogeneous reservoirs, the use of CO2 microbubbles as a temporary blocking agent is attracting widespread interest due to their significant stability. This study aims to investigate the plugging performance of CO2 microbubbles in both homogeneous and heterogeneous porous media through a series of sandpack experiments. First of all, CO2 microbubble fluids were generated by stirring CO2 gas diffused into polymer (Xanthan gum (XG)) and surfactant (Sodium dodecyl sulfate (SDS)) solution with different gas: liquid ratios. Then, CO2 microbubbles fluids were injected into single-core and dual-core sandpack systems. The results show that the rheological behaviors of CO2 microbubble fluids in this study were followed the Power-law model at room temperature. The apparent viscosity of CO2 microbubble fluid increased as the gas: liquid ratio increased. CO2 microbubbles could block pore throat due to the “Jamin effect” and increase the resistance in porous media. The blocking ability of CO2 microbubbles reached an optimal value at the gas:liquid ratio of 20% in the homogeneous porous media. Moreover, the selective pugging ability of CO2 microbubbles in dual-core sandpack tests was significant. CO2 microbubbles exhibited a good flow control profile in the high permeability region and flexibility to flow over the pore constrictions in the low permeability region, leading to an ultimate fractional flow proportion (50%:50%) in the dual-core sandpack model with a permeability differential of 1.0:2.0 darcy. The fractional flow ratio was considerable compared with a polymer injection. At the higher heterogeneity of porous media (0.5:2.0 darcy), CO2 microbubble fluid could still establish a good swept performance. This makes CO2 microbubble fluid injection a promising candidate for heterogeneous reservoirs where conventional CO2 flooding processes have limited ability. This finding would be helpful in developing the utilization of CO2 microbubbles in EOR operation by better understanding their plugging mechanism in porous media..  |
| 7. |
Miu Ito, Yuichi Sugai, Fundamental Investigation on a Foam-Generating Microorganism and Its Potential for Mobility Reduction in High-Permeability Flow Channels, Energies (MDPI), https://doi.org/10.3390/en15072344, 15, 7, 1-14, 2022.03, This study proposed a novel foam EOR technique using Pseudomonas aeruginosa to generate the foam and investigated the potential of the microbial foam EOR to modify the permeability of a high-permeability porous system. We investigated oxygen nanobubble, carbon dioxide nanobubble and ferrous sulfate concentrations to discover the optimal levels for activating the foam generation of the microorganism through cultivation experiments. We also clarified the behavior of the microbial foam generation and the bioproducts that contribute to the foam generation. The potential of the foam to decrease the permeability of high-permeability porous systems was evaluated through flooding experiments using sand pack cores. The foam generation became more active with the increase in the number of nanobubbles, while there was an optimal concentration of ferrous sulfate for foam generation. The foam was identified as being induced by the proteins produced by the microorganism, which can be expected to bring about several advantages over surfactant-induced foam. The foam successfully decreased the permeability of high-permeability sand pack cores to half of their initial levels. These results demonstrate that the microbial foam EOR has the potential to decrease the permeability of high-permeability porous systems and improve the permeability heterogeneity in oil reservoirs.. |
| 8. |
Theodora Noely Tambaria, Yuichi Sugai, Ronald Nguele, Adsorption Factors in Enhanced Coal Bed Methane Recovery: A Review, Gases (MDPI), https://doi.org/10.3390/gases2010001, 2, 1, 1-21, 2022.01, Enhanced coal bed methane recovery using gas injection can provide increased methane extraction depending on the characteristics of the coal and the gas that is used. Accurate prediction of the extent of gas adsorption by coal are therefore important. Both experimental methods and modeling have been used to assess gas adsorption and its effects, including volumetric and gravimetric techniques, as well as the Ono–Kondo model and other numerical simulations. Thermodynamic parameters may be used to model adsorption on coal surfaces while adsorption isotherms can be used to predict adsorption on coal pores. In addition, density functional theory and grand canonical Monte Carlo methods may be employed. Complementary analytical techniques include Fourier transform infrared, Raman spectroscopy, XR diffraction, and 13C nuclear magnetic resonance spectroscopy. This review summarizes the cutting-edge research concerning the adsorption of CO2, N2, or mixture gas onto coal surfaces and into coal pores based on both experimental studies and simulations.. |
| 9. |
Muhammad Alfiza Farhan, Yuichi Sugai, Nuhindro Priagung Widodo, Syafrizal, The Development of a Low-Cost Method for Monitoring Methane Leakage from the Subsurface of Natural Gas Fields, Methane (MDPI), https://doi.org/10.3390/methane1010003, 1, 1, 24-37, 2021.12, The leakage of methane from the subsurface on the coalfield or natural gas field invariably becomes an important issue nowadays. In notable addition, materials such as activated carbon, zeolites, and Porapak have been successfully identified as adsorbents. Those adsorbents could adsorb methane at atmospheric pressure and room temperature. Therefore, in this scholarly study, a new method using adsorbents to detect points of methane leakage that can cover a wide-scale area was developed. In the beginning, the most capable adsorbent should be determined by quantifying adsorbed methane amount. Furthermore, checking the possibility of adsorption in the column diffusion and desorption method of adsorbents is equally necessary. The most capable adsorbent was activated carbon (AC), which can adsorb 1.187 × 10−3 mg-CH4/g-AC. Hereinafter, activated carbon successfully can adsorb methane through column diffusion, which simulates the situation of on-site measurement. The specific amount of adsorbed methane when the initial concentrations of CH4 in a bag were 200 ppm, 100 ppm, and 50 ppm was found to be 0.818 × 10−3 mg-CH4/g-AC, 0.397 × 10−3 mg-CH4/g-AC, 0.161 × 10−3 mg-CH4/g-AC, respectively. Desorption of activated carbon analysis shows that methane concentration increases during an hour in the temperature bath under 80 °C. In conclusion, soil methane leakage points can be detected using activated carbon by identifying the observed methane concentration increase.. |
| 10. |
Miu Ito, Yuichi Sugai, Study on Enhanced Oil Recovery Using Microorganism Generating Foam in Presence of Nanobubbles, Proceeding of Society of Petroleum Engineers - SPE/IATMI Asia Pacific Oil and Gas Conference and Exhibition 2021, SPE-205671-MS, 2021.10, This study proposed a novel foam EOR technique using Pseudomonas aeruginosa to generate the foam and investigated the potential of the microbial foam EOR to modify the permeability of a high-permeability porous system. We investigated oxygen nanobubble, carbon dioxide nanobubble and ferrous sulfate concentrations to discover the optimal levels for activating the foam generation of the microorganism through cultivation experiments. We also clarified the behavior of the microbial foam generation and the bioproducts that contribute to the foam generation. The potential of the foam to decrease the permeability of high-permeability porous systems was evaluated through flooding experiments using sand pack cores. The foam generation became more active with the increase in the number of nanobubbles, while there was an optimal concentration of ferrous sulfate for foam generation. The foam was identified as being induced by the proteins produced by the microorganism, which can be expected to bring about several advantages over surfactant-induced foam. The foam successfully decreased the permeability of high-permeability sand pack cores to half of their initial levels. These results demonstrate that the microbial foam EOR has the potential to decrease the permeability of high-permeability porous systems and improve the permeability heterogeneity in oil reservoirs.. |
| 11. |
Nam Nguyen Hai Le, Yuichi Sugai, Ronald Nguele, Tola Sreu, Bubble size distribution and stability of CO2 microbubbles for enhanced oil recovery: effect of polymer, surfactant and salt concentrations, Journal of Dispersion Science and Technology (Taylor & Francis), https://doi.org/10.1080/01932691.2021.1974873, 2021.09, Fluids incorporating carbon dioxide (CO2) microbubbles have been utilized to promote enhanced oil recovery from hydrocarbon reservoirs. The performance of such fluids in porous media is greatly affected by both the bubble size and stability. On this basis, the present study evaluated the effects of varying the concentrations of a xanthan gum (XG) polymer, a surfactant (sodium dodecyl sulfate: SDS) and sodium chloride (NaCl) on both the stability and bubble size distribution (BSD) of CO2 microbubbles. CO2 microbubble dispersions were prepared using a high-speed homogenizer in conjunction with the diffusion of gaseous CO2 through aqueous solutions. The stability of each dispersion was ascertained using a drainage test, while the BSD was determined by optical microscopy and fitted to either normal, log-normal or Weibull functions. The results showed that a Weibull distribution gave the most accurate fit for all experimental data. Increases in either the SDS or XG polymer concentration were found to decrease the microbubble size. However, these same changes increased the microbubble stability as a consequence of structural enhancement. The addition of NaCl up to a concentration of 10 g/L (10 g/1000g) decreased the average bubble size by approximately 2.7%. Stability was also reduced as the NaCl concentration was increased because of the gravitational effect and coalescence. |
| 12. |
Miu Ito, Yuichi Sugai, Nanobubbles activate anaerobic growth and metabolism of Pseudomonas aeruginosa, Scientific Reports (Nature), https://doi.org/10.1038/s41598-021-96503-4, 11, (2021) 11:16858, 1-12, 2021.08, The effect of nanobubbles on anaerobic growth and metabolism of Pseudomonas aeruginosa was investigated. P. aeruginosa grew earlier in the culture medium containing nanobubbles and the bacterial cell concentration in that culture medium was increased a few times higher compared to the medium without nanobubbles under anaerobic condition. Both gas and protein, which are the metabolites of P. aeruginosa, were remarkably produced in the culture medium containing nanobubbles whereas those metabolites were little detected in the medium without nanobubbles, indicating nanobubbles activated anaerobic growth and metabolism of P. aeruginosa. The carbon dioxide nanobubbles came to be positively charged by adsorbing cations and delivered ferrous ions, one of the trace essential elements for bacterial growth, to the microbial cells, which activated the growth and metabolism of P. aeruginosa. The oxygen nanobubbles activated the activities of P. aeruginosa as an oxygen source. |
| 13. |
Hung Vo Thanh, Yuichi Sugai, Kyuro Sasaki, Application of artificial neural network for predicting the performance of CO2 enhanced oil recovery and storage in residual oil zones, Scientific Reports (Nature), https://doi.org/10.1038/s41598-020-73931-2, 10, (2020) 10:18204, 1-16, 2020.10, Residual Oil Zones (ROZs) become potential formations for Carbon Capture, Utilization, and Storage (CCUS). Although the growing attention in ROZs, there is a lack of studies to propose the fast tool for evaluating the performance of a CO2 injection process. In this paper, we introduce the application of artificial neural network (ANN) for predicting the oil recovery and CO2 storage capacity in ROZs. The uncertainties parameters, including the geological factors and well operations, were used for generating the training database. Then, a total of 351 numerical samples were simulated and created the Cumulative oil production, Cumulative CO2 storage, and Cumulative CO2 retained. The results indicated that the developed ANN model had an excellent prediction performance with a high correlation coefficient (R2) was over 0.98 on comparing with objective values, and the total root mean square error of less than 2%. Also, the accuracy and stability of ANN models were validated for five real ROZs in the Permian Basin. The predictive results were an excellent agreement between ANN predictions and field report data. These results indicated that the ANN model could predict the CO2 storage and oil recovery with high accuracy, and it can be applied as a robust tool to determine the feasibility in the early stage of CCUS in ROZs. Finally, the prospective application of the developed ANN model was assessed by optimization CO2-EOR and storage projects. The developed ANN models reduced the computational time for the optimization process in ROZs.. |
| 14. |
Nam Nguyen Hai Le, Yuichi Sugai, Kyuro Sasaki, Investigation of Stability of CO2 Microbubbles—Colloidal Gas Aphrons for Enhanced Oil Recovery Using Definitive Screening Design, Colloids and Interfaces (MDPI), https://doi.org/10.3390/colloids4020026, 4, 2, 1-15, 2020.06, CO2 microbubbles have recently been used in enhanced oil recovery for blocking the high permeability zone in heterogeneous reservoirs. Microbubbles are colloidal gas aphrons stabilized by thick shells of polymer and surfactant. The stability of CO2 microbubbles plays an important role in improving the performance of enhanced oil recovery. In this study, a new class of design of experiment (DOE)—definitive screening design (DSD) was employed to investigate the effect of five quantitative parameters: xanthan gum polymer concentration, sodium dodecyl sulfate surfactant concentration, salinity, stirring time, and stirring rate. This is a three-level design that required only 11 experimental runs. The results suggest that DSD successfully evaluated how various parameters contribute to CO2 microbubble stability. The definitive screening design revealed a polynomial regression model has ability to estimate the main effect factor, two-factor interactions and pure-quadratic effect of factors with high determination coefficients for its smaller number of experiments compared to traditional design of experiment approach. The experimental results showed that the stability depend primarily on xanthan gum polymer concentration. It was also found that the stability of CO2 microbubbles increases at a higher sodium dodecyl sulfate surfactant concentration and stirring rate, but decreases with increasing salinity. In addition, several interactions are presented to be significant including the polymer–salinity interaction, surfactant–salinity interaction and stirring rate–salinity interaction.. |
| 15. |
Yuichi Sugai, Yukihiro Owaki, Kyuro Sasaki, Simulation Study on Reservoir Souring Induced by Injection of Reservoir Brine Containing Sulfate-Reducing Bacteria, Sustainability (MDPI), https://doi.org/10.3390/su12114603, 12, 11, 1-17, 2020.06, This paper examined the reservoir souring induced by the sulfate-reducing bacteria (SRB) inhabiting the reservoir brine of an oilfield in Japan. Although the concentration of sulfate of the reservoir brine was lower than that of seawater, which often was injected into oil reservoir and induced the reservoir souring, the SRB inhabiting the reservoir brine generated hydrogen sulfide (H2S) by using sulfate and an electron donor in the reservoir brine. This paper therefore developed a numerical simulator predicting the reservoir souring in the reservoir into which the reservoir brine was injected. The results of the simulation suggested that severe reservoir souring was not induced by the brine injection; however, the SRB grew and generated H2S around the injection well where temperature was decreased by injected brine whose temperature was lower than that of formation water. In particular, H2S was actively generated in the mixing zone between the injection water and formation water, which contained a high level of the electron donor. Furthermore, the results of numerical simulation suggested that the reservoir souring could be prevented more surely by sterilizing the SRB in the injection brine, heating up the injection brine to 50 °C, or reducing sulfate in the injection brine.. |
| 16. |
Nao Miyazaki, Yuichi Sugai, Kyuro Sasaki, Yoshifumi Okamoto, Satohiro Yanagisawa, Screening of the Effective Additive to Inhibit Surfactin from Forming Precipitation with Divalent Cations for Surfactin Enhanced Oil Recovery, Energies (MDPI), https://doi.org/10.3390/en13102430, 13, 10, 2430-2445, 2020.05, Surfactin, which is an anionic bio-surfactant, can be effective for enhanced oil recovery because it decreases interfacial tension between oil and water. However, it forms precipitation by binding with divalent cations. This study examined the countermeasure to prevent surfactin from forming precipitation for applying it to enhanced oil recovery. Alcohols, chelating agents, a cationic surfactant and an ion capturing substance were selected as the candidates for inhibiting surfactin from forming precipitation. Citric acid and trisodium citrate were selected as promising candidates through the measurements of turbidity of the mixture of the candidate, surfactin and calcium ions. Those chemicals also had a function as a co-surfactant for surfactin. However, the permeability of the Berea sandstone core into which the solution containing surfactin and trisodium citrate was injected was decreased significantly, whereas citric acid could be injected into the core without significant permeability reduction. Citric acid was therefore selected as the best inhibitor and subjected to the core flooding experiments. High enhancement of oil recovery of 9.4% (vs. original oil in place (OOIP)) was obtained and pressure drop was not increased during the injection of surfactin and citric acid. Those results suggest that citric acid has a dual role as the binding inhibitor and co-surfactant for surfactin.. |
| 17. |
Hung Vo Thanh, Yuichi Sugai, Ronald Nguele, Kyuro Sasaki, Robust optimization of CO2 sequestration through a water alternating gas process under geological uncertainties in Cuu Long Basin, Vietnam, Journal of Natural Gas Science and Engineering (Elsevier), 10.1016/j.jngse.2020.103208, 76, 1-15, 2020.04, This study presents a robust optimization workflow to determine the optimal water alternating gas (WAG) process for CO2 sequestration in a heterogeneous fluvial sandstone reservoir. As depicted in this study, WAG injection could enhance CO2 residual and solubility trapping based on an integrated modeling workflow. First, continuous CO2 injection and WAG were compared to demonstrate the efficiency of the WAG process for CO2 trapping enhancement. To achieve this while highlighting the impact of reservoir heterogeneity, 200 geological realizations were generated considering a wide range of plausible geological conditions. The ranking of these realizations was performed by quantifying the CO2 cumulative injection (P10, P50, and P90 realizations) that represent the overall geological uncertainties. Then, an innovative robust workflow was used Artificial Intelligence optimizer to determine the optimal solution for CO2 trapping. For comparison, a nominal optimization workflow of P50 realization was also conducted. The proposed robust optimization workflow resulted in higher CO2 trapping than the nominal optimization workflow. Thus, this study demonstrates a fast and reliable workflow that can accurately represent for optimization the cycle length injection in the WAG process under geological uncertainties.. |
| 18. |
Eric O. Ansah, Hung Vo Thanh, Yuichi Sugai, Ronald Nguele, Kyuro Sasaki, Microbe-induced fluid viscosity variation
field-scale simulation, sensitivity and geological uncertainty, Journal of Petroleum Exploration and Production Technology (Springer), 10.1007/s13202-020-00852-1, 2020.01, This study is intended to expand the scope of microbial enhanced oil recovery (MEOR) simulation studies from 1D to field scale focussing on fluid viscosity variation and heterogeneity that lacks in most MEOR studies. Hence, we developed a model that incorporates: (1) reservoir simulation of microbe-induced oil viscosity reduction and (2) field-scale simulation and robust geological uncertainty workflow considering the influence of well placement. Sequential Gaussian simulation, co-kriging and artificial neural network were used for the petrophysical modelling prior to field-scale modelling. As per this study, the water viscosity increased from 0.5 to 1.72 cP after the microbe growth and increased biomass/biofilm. Also, we investigated the effect of the various component compositions and reaction frequencies on the oil viscosity and possibly oil recovery. For instance, the fraction of the initial CO2 in the oil phase (originally in the reservoir) was varied from 0.000148 to 0.005 to promote the reactions, and more light components were produced. It can be observed that the viscosity of oil reduced considerably after 90 days of MEOR operation from an initial 7.1–7.07 cP and 6.40 cP, respectively. Also, assessing the pre- and post-MEOR oil production rate, we witnessed two main typical MEOR field responses: sweeping effect and radial colonization occurring at the start and tail end of the MEOR process, respectively. MEOR oil recovery factors varied from 28.2 to 44.9% OOIP for the various 200 realizations. Since the well placement was the same for all realizations, the difference in the permeability distribution amongst the realizations affected the microbes’ transport and subsequent interaction with nutrient during injection and transport.. |
| 19. |
Hung Vo Thanh, Yuichi Sugai, Ronald Nguele, Kyuro Sasaki, Integrated workflow in 3D geological model construction for evaluation of CO2 storage capacity of a fractured basement reservoir in Cuu Long Basin, Vietnam, International Journal of Greenhouse Gas Control (Elsevier), 10.1016/j.ijggc.2019.102826, 90, 2019.11, Carbon dioxide (CO2) capture, utilization, and storage (CCUS) have been proposed as a possible technique to mitigate climate change. In this vein, CO2 storage through enhanced oil recovery (EOR) in depleted hydrocarbon reservoirs is touted as a most effective approach because it synergistically increases oil production and enables permanent sequestration into the reservoirs. However, the construction of a reasonable 3D geological model for this storage reservoir is a major challenge. Thus, this study presents an efficient workflow for constructing an accurate geological model for the evaluation of CO2 storage capacity in a fractured basement reservoir in the Cuu Long Basin, Vietnam. Artificial neural network (ANN) has been used to predict porosity and permeability values through seismic attributes and well log data. The predicted values were selected using high correlation factors with well log data. Subsequently, the Sequential Gaussian Simulation and co-kriging methods were applied to generate a 3D static geological model by using azimuth and dip parameters. Finally, drill stem test matching was performed to validate the accuracy of the porosity and permeability models through dynamic simulation. A validation 3D reservoir model, which integrates geophysical, geological, and engineering data from fractured basement formation in Cuu Long Basin, was further constructed to calculate theoretical CO2 storage capacity. As a result, the calculated storage capacity for the fractured basement reservoir ranged from 7.02 to 99.5 million metric tons. These estimated results demonstrate that fractured basement reservoir has a combined potential for CO2 storage and EOR in the Cuu Long Basin.. |
| 20. |
Mochammad Andy Natawijaya, Yuichi Sugai, Ferian Anggara, CO2 microbubble colloidal gas aphrons for EOR application: the generation using porous filter, diameter size analysis and gas blocking impact on sweep efficiency, Journal of Petroleum Exploration and Production Technology (Springer), https://doi.org/10.1007/s13202-019-0680-3, 2019.05, The CO2 is regarded to be an excellent solvent for miscible flooding. However, it is still facing a main problem which is the high mobility. Microbubbles with their unique characters offer some advantages for CO2 EOR application. Different pore throat size filters were used to generate different dominant sizes of microbubbles that were injected into sandpacks under tertiary condition. Microscopic analysis was carried out to visualize the presence, stability and behavior of microbubbles inside the solution and porous media. The microbubbles with a dominant size of 10–50 µm showed additional 26.38% of oil recovery, showing their advantages over a larger dominant size of microbubbles up to 5.28% of oil recovery. The injection with larger microbubbles with a dominant size of 70–150 µm showed 27.5% of higher injection pressure than with a smaller dominant size of microbubbles, showing their advantage in gas blocking ability. In the heterogeneous porous media experiment, the recovery volume ratio between low- and high-permeability sandpacks was increased from 1:57 during water flooding to 1:4 during the CO2 microbubble injection with 74.65% of additional recovery from a low-permeability zone, showing the microbubble gas blocking capability to change the flow pattern inside heterogeneous porous media.. |
| 21. |
San Yee Khaing, Yuichi Sugai, Kyuro Sasaki, Myo Min Tun, Consideration of Influential Factors on Bioleaching of Gold Ore Using Iodide-Oxidizing Bacteria, Minerals (MDPI), https://doi.org/10.3390/min9050274, 9, 5, 274-285, 2019.05, Iodide-oxidizing bacteria (IOB) oxidize iodide into iodine and triiodide which can be utilized for gold dissolution. IOB can be therefore useful for gold leaching. This study examined the impact of incubation conditions such as concentration of the nutrient and iodide, initial bacterial cell number, incubation temperature, and shaking condition on the performance of the gold dissolution through the experiments incubating IOB in the culture medium containing the marine broth, potassium iodide and gold ore. The minimum necessary concentration of marine broth and potassium iodide for the complete gold dissolution were determined to be 18.7 g/L and 10.9 g/L respectively. The initial bacterial cell number had no effect on gold dissolution when it was 1×104 cells/mL or higher. Gold leaching with IOB should be operated under a temperature range of 30–35 °C, which was the optimal temperature range for IOB. The bacterial growth rate under shaking conditions was three times faster than that under static conditions. Shaking incubation effectively shortened the contact time compared to the static incubation. According to the pH and redox potential of the culture solution, the stable gold complex in the culture solution of this study could be designated as gold (I) diiodide.. |
| 22. |
Hung Vo Thanh, Yuichi Sugai, Kyuro Sasaki, Impact of a new geological modelling method on the enhancement of the CO2 storage assessment of E sequence of Nam Vang field, offshore Vietnam, Energy Sources, Part A: Recovery, Utilization, and Environmental Effects (Taylor & Francis), https://doi.org/10.1080/15567036.2019.1604865, 1-15, 2019.04, This study proposed a new geological modelling procedure for CO2 storage assessment in offshore Vietnam by integrating artificial neural networks, cokriging and object-based methods. These methods could solve the limitations of well data that have not been addressed by conventional modelling. Petrel software was used to build a geological model for comparing conventional and new modelling workflows. Moreover, the Eclipse simulator was used for CO2 injection scenarios on the geological model of two workflows. The simulation results of CO2 flow response corroborated that the new modelling workflow by showing better performance than the traditional modelling workflow. Thus, in the selected CO2 storage sites, the new modelling workflow is preferred because it strongly enhances the CO2 storage evaluation.. |
| 23. |
San Yee Khaing, Yuichi Sugai, Kyuro Sasaki, Gold Dissolution from ore with Iodide-oxidising Bacteria, Scientific Reports (Nature), https://doi.org/10.1038/s41598-019-41004-8, 9, (2019) 9:4178, 1-11, 2019.03, Gold leaching from ore using iodide-iodine mixtures is an alternative to gold cyanidation. this study evaluated the ability of iodide-oxidising bacteria to solubilise gold from ore that was mainly composed of gold, pyrite, galena, and chalcopyrite. eight bacterial strains were successfully isolated from brine. Those strains were incubated in a liquid culture medium containing ore with a gold content of 0.26 wt.% and pulp density of 3.3 w/v% to evaluate their abilities to mediate the dissolution of gold. The gold was solubilised completely within 30 days of incubation in the iodine-iodide lixiviant solution generated by three bacterial strains. One strain, in particular, completed the dissolution of gold within 5 days of incubation and was identified as a member of the genus Roseovarius. thus, the possibility of bacterial gold leaching using iodide-oxidising bacteria was successfully demonstrated. Bioleaching gold with iodide would likely be more environmentally sustainable than traditional cyanide leaching. Further research is required to evaluate the techno-economic feasibility of this approach.. |
| 24. |
Eric O. Ansah,Yuichi Sugai,Pierre Ronald Nguele Odou,Kyuro Sasaki, Integrated microbial enhanced oil recovery (MEOR) simulation: Main influencing parameters and uncertainty assessment, Journal of Petroleum Science and Engineering (Elsevier), 10.1016/j.petrol.2018.08.005, 171, 784-793, 2018.12, The present study investigated the ability of a thermophilic anaerobic microbe (herein coded as AR80) for MEOR with the further objective to quantify the uncertainty of production forecast in terms of the cumulative probability distribution. A series of core flood experiments conducted in water-flooded Berea sandstone showed that up to 51% of initial oil-in-place was recovered when the plugs were treated with AR80 and shut-in for 14 days. Mainly, the oil recovery mechanisms were attributed to viscosity enhancement, wettability changes, permeability and flow effects. Matching the laboratory data using artificial intelligence: the optimized cumulative oil recovery could be achieved at an enthalpy of 894.2 J/gmol, Arrhenius frequency of 8.3, residual oil saturation of 20%, log of capillary number at microbe flooding stage of −1.26, and also depicted a history match error less than 3%. Therefrom, a sensitivity analysis conducted on reservoir shut-in period effect on oil recovery revealed that a relatively shorter shut-in period is recommended to warrant early incremental oil recovery effect for economical purposes. In addition, MEOR could enhance the oil recovery significantly if a larger capillary number (between 10−5 and 10−3.5) is attained. Per probabilistic estimation, MEOR could sustain already water-flooded well for a set period of time. This study showed that there is a 20% frequency of increasing the oil recovery by above 20% when a mature water-flooded reservoir is further flooded with AR80 for 2 additional years. Lastly, it was demonstrated herein that increasing the nutrient (yeast extract) concentration (from 0.1 to 1% weight) had less or no significant effect on the oil viscosity and subsequent recovery.. |
| 25. |
Yuichi Sugai,Yukihiro Owaki,Kyuro Sasaki,Fuminori Kaneko,Takuma Sakai, Numerical modelling of the growth of sulfate-reducing bacteria indigenous to an oilfield in Japan, Petroleum Science and Technology (Taylor & Francis), https://doi.org/10.1080/10916466.2018.1496102, 36, 19, 1597-1604, 2018.09, We performed kinetic studies of the growth of sulfate-reducing bacteria (SRB) indigenous to the water in an oilfield in Japan. The SRB growth was most active in injection water supplemented with ethanol; therefore, the SRB inhabiting the injection water of the reservoir were assumed to grow predominantly by assimilating sulfate and ethanol and generating H2S. Based on this mechanism and the results of incubation experiments in the injection water, we derived numerical models that calculate the growth rate and H2S generation of the SRB under three variables (temperature, sulfate concentration, and ethanol concentration).. |
| 26. |
Eric O. Ansah,Yuichi Sugai,Kyuro Sasaki, Geological tectonics and physio-chemical metrics as screening criteria for MEOR applicability in West Africa transform regional oil wells - a review, International Journal of Petroleum Engineering, http://dx.doi.org/10.1504/IJPE.2018.093164, 3, 2, 116-137, 2018.07, Primarily, most oil wells in the West Africa transform region are produced using water or water alternating gas. This is believed to be unsustainable going forward. Also, though the region contributes less to global greenhouse emission, global warming effects in the region cannot be undermined. Microbial enhanced oil recovery (MEOR) has been proven worldwide to be environmentally friendly as well as less costly to develop. Despite the advantages of MEOR over other oil recovery methods, operating companies in the region are yet to apply this bespoke technology. Therefore, this study reviews the potential applicability of MEOR process to West African oil fields comparing the geology and physiochemical properties to major oil fields in South America (where MEOR has been previously applied). Applying MEOR in the region could be a major step towards improving production of new oil wells and enhancing sustainability of old oil wells.. |
| 27. |
Eric O. Ansah,Yuichi Sugai,Kyuro Sasaki, Modeling microbial-induced oil viscosity reduction: Effect of temperature, salinity and nutrient concentration, Petroleum Science and Technology (Taylor & Francis), 10.1080/10916466.2018.1463253, 1-7, 2018.05, This research simulated oil recovery with emphasis on oil viscosity reduction by direct microbe action and metabolites; predicted hydrogeochemical reactions involved with nutrient – brine interaction in reservoirs. PHREEQC was used to simulate reactions between the reservoir brine and nutrient minus microbe. Hitherto, UTCHEM was employed for the enhancement of oil viscosity by assuming production of gases and by the direct microbe action. The model depicted the precipitation of calcite plus dissolution of k-feldspar combined with the evolution of CO2 and CH4 influenced by temperature and pH. Oil recovery was directly proportional to salinity reduction and increasing nutrient concentration.. |
| 28. |
Isty Adhitya Purwasena,Yuichi Sugai, The analysis of bacterial diversity in high thermic-low salinity Oil Reservoirs prior to Microbial Enhanced Oil Recovery field test, Journal of Engineering and Applied Sciences, 10.3923/jeasci.2018.4104.4112, 13, 11, 4104-4112, 2018.01, Nutrition injection in Microbial Enhanced Oil Recovery (MEOR) process might stimulate not only desirable microorganisms but also the undesirable ones. Therefore, studying the properties of bacterial community in reservoir prior to field test is a critical step in MEOR process. In this study, bacterial communities from high thermic and low salinity reservoirs located in Japan, China and Indonesia were characterized by 16S rDNA sequence analysis. Bacterial genomic DNAs were extracted from produced water samples and their sequences were evaluated by genetic fingerprinting based approach. PCR-DGGE analyses showed multiple bands in all produced water samples which indicated high bacterial diversities. Sequences identified in this study were mainly related to only five phyla, i.e., Bacteroidetes, Thermotogae, Defferibacteres, Firmicutes and Proteobacteria, suggesting that phylotype richness is low in oil reservoirs. One sequence of Bacteriodetes-affiliated bacteria which showed 99% similarity with Bacteriodales bacterium 5bM was retrieved from DGGE results of all oilfields. This result showed that, Bacteriodetes can grow well in Indonesia, Japan and China oilfield, making it the best bacterial candidate for MEOR field test. Results showed in this study revealed that finger printing is a considerable technique for microbial screening prior to MEOR field test application.. |
| 29. |
Evan Rosyadi Ogara, Yuichi Sugai, Kyuro Sasaki, Ferian Anggara, The Effect of Coal Characteristics on Adsorption and Desorption Gas at Indonesia Low Rank Coal, International Symposium on Earth Science and Technology 2017, 472-477, 2017.11. |
| 30. |
Yuichi Sugai, Junpei Mikumo, Keita Komatsu, Kyuro Sasaki, Experimental Investigation on the Availability of Yeast Cell Wall as an Interfacial Tension Reducer for Enhanced Oil Recovery, Journal of Petroleum & Environmental Biotechnology, 10.4172/2157-7463.1000329, 8, 3, 1-6, 2017.06, We studied on the availability of residue of squeezed beer yeast whose principal component is yeast cell wall for enhanced oil recovery as an interfacial tension reducer. The cell wall solution was hydrothermally treated in order to elute amphiphilic substances such as phospholipids, proteins, and fatty acids from the cell wall to the solution under different conditions such as concentration of the cell wall, temperature and time of the hydrothermal treatment, and salinity. The cell wall solution which was hydrothermally treated with crude oil was also applied to the measurement of interfacial tension between the solution and crude oil. The interfacial tension was reduced with decrease in salinity and increase in concentration of the cell wall and temperature of the hydrothermal treatment. The time of hydrothermal treatment didn't have much influence on the interfacial tension reduction. The capability of the cell wall solution which had been hydrothermally treated with crude oil to reduce the interfacial tension became larger than that of the cell wall solution which had been hydrothermally treated without crude oil. It was suggested that those interfacial tension reductions were brought by phospholipids and proteins eluted from the cell wall. Core flooding experiments were carried out by injecting the cell wall solution which had been hydrothermally treated with and without crude oil after the water flooding as the primary oil recovery. 2.0% and 1.2% of original oil in place was additionally recovered by injecting the cell wall solution which had been hydrothermally treated with and without crude oil respectively. These results support an advantage of process injecting the cell wall solution without hydrothermal treatment into high temperature oil reservoir. The injection of the cell wall solution can be a promising EOR which has both high cost performance and low environmental load.. |
| 31. |
San Yee Khaing, Sugeng Sapto Surjono, Jarot Setyowiyoto, Yuichi Sugai, Facies and Reservoir Characteristics of the Ngrayong Sandstone in the Rembang Area, Northeast Java (Indonesia), Open Journal of Geology, 10.4236/ojg.2017.75042, 7, 5, 608-620, 2017.05, The Rembang area is a well-known prospective region for oil and gas exploration in Northeast Java, Indonesia. In this study, the reservoir characteristics of the Ngrayong Sandstone were investigated based on outcrops in the Rembang area. Petrological, mineralogical, petrophysical and sedimentological facies analyses were conducted. These sandstones are grain- and matrix supported, and composed of very fine to medium, sub-angular to poorly-rounded, moderately to very well-sorted sand grains. These sandstones are mainly composed of quartz, orthoclase, plagioclase, and micas with minor amounts of clay minerals, and therefore are predominantly classified as sub-lithic arenite and sub-felds pathicarenite. Petrographic observations and grain size data indicate that these sandstones are texturally quite mature, based on their good -sorting and the occurrence of minor amounts of matrix clays. Common clays in the samples include illite, smectite, kaolinite, and gibbsite. The porosity of the Ngrayong sandstones ranges from 25.97% to 40.21%, and the permeability ranges from 94.6 to 3385 millidarcies. Thus, these sandstones exhibit well to excellent reservoir qualities. Eight lithofacies were identified from five measured stratigraphic sections, and are dominated by foreshore and tide-dominated shoreface facies. The Ngrayong sequence shows a single transgressiveregressive cycle. Cross-bedded sandstone and massive sandstone are identified as the most promising potential reservoir facies based on their characteristics in outcrops, their lateral and vertical distributions, their sedimentological characteristics and their petrophysical properties.. |
| 32. |
Minoru Saito,Yuichi Sugai,Kyuro Sasaki,Yoshifumi Okamoto,Chencan Ouyang, Experimental and Numerical Studies on EOR Using a Biosurfactant, the Abu Dhabi International Petroleum Exhibition and Conference 2016, SPE-183496-MS, 2016.11, The EOR potential of a biosurfactant was evaluated through core flooding experiments and numerical simulation in this study. The biosurfactant which was called surfactin was generated by a microorganism belonging to Bacillus species. The EOR potential of surfactins has been already reported by previous papers, however, that of surfactins can be different depending on their making process such as the conditions of incubation, extraction, purification, etc. This study used a surfactin which was made by Kaneka corporation's original techniques.
Core flooding experiments were carried out under ambient temperature and pressure to evaluate the EOR potential of the surfactin. Berea sandstone cores whose permeability was 50 md were used in this study. The surfactin solution was injected into cores after water flooding. 3 experiments were carried out by injecting surfactin solution whose surfactin concentration was 0.3 %, 0.03 % and 0.003 % respectively. An experiments were carried out by injecting the culture solution which had been diluted so that the surfactin concentration was 0.3 %. 4 experiments were carried out by injecting sodium dodecyl sulfate (SDS) solution which had been supplemented with a slight amount of surfactin or the culture solution. An injection was continued until oil was not produced completely.
Higher oil recovery was obtained by injecting higher concentration of surfactin. 13.6 % of original oil in place (OOIP) was recovered by injecting 0.3 % of pure surfactin solution, whereas 6.3 % of OOIP was recovered by injecting 0.3 % of pure SDS solution. 0.27 % of SDS solution which was supplemented with surfactin whose concentration was 0.03 % could recover 14.7 % of OOIP. 23.9 % of OOIP could be recovered by injecting the culture solution which was diluted by 16 times so that the surfactin concentration was 0.3 %. Enhancement of oil recovery which was obtained by injecting SDS solution supplemented with the culture solution was a little lower than that with pure surfactin.
The EOR potential of surfactin is quite higher than that of SDS. It was shown that the surfactin can be useful as a cosurfactant for SDS. Culture solution of the microorganism demonstrated much higher EOR potential than pure surfactin, therefore, it may include effective components other than the surfactin. Utilization of the culture solution is economically advantageous.. |
| 33. |
Yuichi Sugai, Keita Komatsu, Kyuro Sasaki, Estimation of IFT Reduction by a Biomass Material and Potential of Its Utilization for EOR, Society of Petroleum Engineers (SPE) Asia Pacific Oil and Gas Conference and Exhibition, SPE-176490-MS, 2015.10, Surfactant injection is one of the most effective EOR techniques. Chemical surfactants however pose a few problems such as their high cost and low-degradability. We study on the utilization of biomass such as agricultural fertilizer mainly comprising the residue of squeezed beer yeast for EOR as an alternative of chemical surfactants because crude oil can be completely miscible with the fertilizer solution. The fertilizer can be stably supplied at a low cost because it is a waste of beer brewing industry and is only used for an animal feed additive so far. Its retail price is approximately 1 USD/kg in Japan.
We semi-quantitatively estimated the interfacial tension (IFT) between the fertilizer solution and crude oil by the oil displacement test. Concentration of the fertilizer was varied between 10 to 50 g/L. The fertilizer solution to which sodium chloride was added at a concentration of 10 to 40 g/L was hydrothermally treated at 60, 80, 100 or 120 ºC for 10, 20, 30, 45 or 60 minutes respectively before the tests. The fertilizer solution to which crude oil was added at a ratio of 1 % was also hydrothermally treated at 120 ºC for 20 minutes. Solution of surfactin which was a commercial biosurfactant was used as a
standard of the IFT.
The IFT was reduced with the decrease in salinity and increase in concentration of the fertilizer and temperature of the hydrothermal treatment. Time of the hydrothermal treatment was preferably 30 minutes or less for the IFT reduction. The capability of 50 g/L of fertilizer solution to reduce the IFT was almost same as the capability of 0.2 g/L of the surfactin solution. Because the fertilizer solution comes into contact with residual oil under high temperature in oil reservoir, IFT between the solution and crude oil can be expected to be reduced in-situ.
Core flooding experiments were carried out by injecting the fertilizer solution after the water flooding as the primary oil recovery. 1.2 % of original oil in place was additionally recovered by injecting 50 g/L of the fertilizer solution after the water flooding. The fertilizer should be biodegradable because it is a microbially-derived substance. In addition, because the IFT reduction was observed after the hydrothermal treatment of the fertilizer solution, the fertilizer should be effective even in the reservoir whose temperature is high such as 120 ºC at which chemical surfactants may be deactivated. From those results, the injection of the fertilizer solution can be a promising EOR which has both high cost performance, low environmental load and high versatility.. |
| 34. |
Yuichi Sugai, Very Susant, Kyuro Sasaki, Ryo Mori, Spectrophotometric determination of pH change of formation water under high CO2 pressure using a mixed pH indicator, Journal of MMIJ（資源・素材学会）, 131, 8,9, 518-523, 2015.08, In geologic CO2 sequestration, the pH of formation water may be decreased due to CO2 dissolution, which may cause the change of porosity and permeability of reservoir rock. The pH changes of formation water are widely varied depending on CO2 pressure and the content of substances having pH buffering action, therefore, it is important to determine the wide range of pH change of various types of formation water under the various CO2 pressure conditions.
We considered a determination method of pH change of various types of formation water under the various CO2 pressure conditions based on the spectrophotometry using a windowed high-pressure cell and a mixed pH indicator consisting of 4 single pH indicators. The well-defined absorption peaks were found at the wavelength of 614 nm or 444 nm when the pH of the solution was ≥5.6 or We carried out experiments on this method using the real formation water samples which contained bicarbonate ion having pH buffering action with different concentration under various CO2 pressure. The results of the experiments demonstrated that this method is capable of determining the pH change of various types of formation water under various CO2 pressure conditions.
. |
| 35. |
Yuichi Sugai, Keita Komatsu, Kyuro Sasaki, Kristian Mogensen, Martin Vad Bennetzen, Microbial-Induced Oil Viscosity Reduction by Selective Degradation of Long-Chain Alkanes, Abu Dhabi International Petroleum Exhibition and Conference, SPE-171850-MS, 2014.11. |
| 36. |
Isty Adhitya Purwasena, Yuichi Sugai, Kyuro Sasaki, Estimation of the potential of an anaerobic thermophilic oil-degrading bacterium as a candidate for MEOR, Journal of Petroleum Exploration and Production Technology (Springer), 10.1007/s13202-013-0095-5, 4, 2, 189-200, 2014.06, We investigated the decrease in oil viscosity caused by the biodegradation of crude oil by a bacterium (AR80) isolated from an oil reservoir, and estimated the potential for this bacterium for use in microbial enhanced oil recovery (MEOR). AR80 degraded long-chain n-alkanes preferentially, and anaerobically increased the ratio between the short-chain and long-chain n-alkane concentrations in the crude oil. The long-chain n-alkane metabolism by AR80 decreased the oil viscosity. AR80 grew well in a reservoir of brine supplemented with yeast extract, and decreased the oil viscosity to approximately 60% of its original value. Adding a small amount of yeast extract (0.05 g/L) was necessary to stimulate the AR80 activity. MEOR can, therefore, be achieved using AR80 without incurring excessive costs. AR80 can grow at temperatures up to 80 °C, and it grows well at between 50 °C and 70 °C. AR80 can grow at a salinity of up to 90 g/L, and it grows well at a salinity of less than 30 g/L. The AR80 activity was not affected very much by high pressures (such as 6.0 MPa). Core flooding experiments were performed by injecting AR80 (in brine supplemented with yeast extract) into Berea sandstone cores. Gas chromatography analysis of the effluent oil suggested that long-chain n-alkanes in the residual oil were preferentially degraded by the AR80 in the porous rocks. The core flooding experiments showed that the AR80 activity in the porous rocks caused the oil recovery to be enhanced, so AR80 could be a suitable candidate for MEOR.. |
| 37. |
Yuichi Sugai, Yukihiro Owaki, Kyuro Sasaki, Fuminori Kaneko, Takuma Sakai, Numerical Prediction of Reservoir Souring Based on the Growth Kinetics of Sulfate-reducing Bacteria Indigenous to an Oilfield, Society of Petroleum Engineers (SPE) International Oilfield Corrosion Conference and Exhibition, 10.2118/169629-MS, SPE-169629-MS, 2014.05. |
| 38. |
Isty Adhitya Purwasena, Yuichi Sugai, Kyuro Sasaki, Petrotoga japonica sp. nov., a thermophilic, fermentative bacterium isolated from Yabase Oilfield in Japan, Archives of Microbiology (Springer), 10.1007/s00203-014-0972-4, 196, 5, 313-321, 2014.05. |
| 39. |
Yuichi Sugai, Tayfun Babadagli, Kyuro Sasaki, Consideration of an effect of interfacial area between oil and CO2 on oil swelling, Journal of Petroleum Exploration and Production Technology (Springer), 10.1007/s13202-013-0085-7, 4, 105-112, 2014.03, Oil swelling is an important phenomenon in CO2–EOR. According to various studies in the past, the degree of oil swelling depends on the partial pressure of CO2, temperature, and oil composition. However, we expect that other factors, such as oil saturation, capillary pressure, and grain size of reservoir rock must be also considered in evaluating oil swelling because they may influence the interfacial area between oil and CO2, which affects the dissolubility of CO2 in oil. Therefore, we had made clear the effect of the interfacial area on oil swelling in this study.
Oil and CO2 were injected into a small see–through windowed high–pressure cell and oil swelling was observed under a microscope. The swelling factor increased with the increase of the specific interfacial area between oil and CO2. Moreover, oil swelling in porous media was observed by using micro–models which had been made of 2 different diameter glass beads. Swelling factor in fine beads micro–model became larger than that in coarse beads micro–model whose interfacial area between oil and CO2 was smaller than that of fine beads micro–model. Therefore, the swelling factor is expected to be larger with an increase in the interfacial area in porous media. These results suggest that the oil swelling should be expressed as a function of oil saturation, capillary pressure, and grain size of reservoir rock which are related to the interfacial area as well as the partial pressure of CO2, temperature, and oil composition.
. |
| 40. |
Isty A. Purwasena, Yuichi Sugai, Kyuro Sasaki, Utilization of Natural Reservoir Brine in Enrichment Culture Medium: An Alternative Approach for Isolation of Anaerobic Bacteria from an Oil Reservoir, Petroleum Science and Technology (Taylor & Francis), 10.1080/10916466.2011.615365, 32, 7, 783-789, 2014.02, The successful enrichment, isolation, and cultivation of prokaryotes are considerably dictated by the selection of appropriate growth media and incubation conditions. In this study, the utilization of natural reservoir brine to enrich and isolate anaerobic thermophilic bacteria from an oil reservoir was observed. The genetic diversity of the bacterial population present in the brine water was subsequently evaluated using polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). In addition, indigenous bacteria that grew in high CO2 concentrations were isolated for examination. We compared the effects of two sterilization methods (filtration and autoclaving) and three gas combinations (pure N2, CO2/N2 (1:9), and pure CO2) injected into the headspace of the medium solution on the cultures. The result demonstrated that the diverse gas composition of the headspace of enrichment culture medium consisting of filtered brine could be one approach to stimulating the growth of physiologically distinct types of microorganisms.. |
| 41. |
Yuichi Sugai, Kyuro Sasaki, Ryo Wakizono, Yasunori Higuchi, Noriyuki Muraoka, Considerations on the possibility of microbial clogging of re-injection wells of the wastewater generated in a water-dissolved natural gas field, International Biodeterioration & Biodegradation (Elsevier), http://dx.doi.org/10.1016/j.ibiod.2012.10.003, 81, 35-41, 2013.07, Brine produced from water-dissolved natural gas reservoirs should be returned to the reservoirs after the resources are recovered to prevent land subsidence. However, the ability to re-inject the brine gradually decreases and is only rectified by carrying out backwashing treatment of re-injection wells. Because the brine contains high levels of iodine also, it is also recovered from the brine using sulfuric acid and oxidizing agents. These chemicals may stimulate the growth of microorganisms that may cause the clogging. In this study, we used column experiments to investigate the possibility of the microbial clogging.
Significant clogging was observed on the columns that were treated by the brine containing both indigenous microorganisms and dissolved oxygen. In particular, iodide-oxidizing bacteria were detected from the columns and original brine dominantly; therefore, it was assumed to have an important influence on the clogging. Iodine that was produced by iodide-oxidizing bacteria corroded iron in the sand under the presence of dissolved oxygen. Eluted Iron formed ferric hydroxide colloid in the brine and it caused the clogging of the pore spaces.
We also demonstrated that deoxidized brine inhibited the iodide-oxidizing bacteria from becoming dominant and the column from the clogging through the column experiments. From these results, we can suggest removing dissolved oxygen as the most feasible countermeasures for the clogging.. |
| 42. |
Yuichi Sugai, Kyuro Sasaki, Keigo Yoshimura, Toshinori Yukitake, Shigenori Muta, Pilot study on the construction of several temperature-controlled multi-purpose rooms in a disused tunnel, Tunnelling and Underground Space Technology (Elsevier), 10.1016/j.tust.2012.06.009, 32, 180-189, 2012.11, Throughout the world, schemes for putting to use abandoned underground spaces are being pursued. We describe one such pilot scheme involving the utilization of a disused tunnel of an uncompleted railway line that has been revamped as a facility housing temperature-controlled multi-purpose rooms. In all, four rooms were constructed and installed with both indoor and outdoor air conditioning units. Testing of the facility was conducted over a 1-year period to establish operating criteria and to monitor for operating stability. The four rooms were finally maintained at different constant-temperature regimes: cold (5ºC), cool (13ºC), mild (21ºC), and warm (32ºC) with such low power consumption of 0.80 kW because of the nature of the subterranean site. Compared with typical surface facilities, this facility offers an obvious advantage in lower energy consumption. Monitoring of the humidity in the rooms revealed that preventing evaporation from the bare soil surface in the tunnel was the more important factor in controlling humidity in this facility.
The heat transfer analysis of this facility was carried out through the computational analysis using a computational model constructed in this study. Computational analysis showed that the heat insulation property of the tunnel wall was reinforced by prolonged operation and the cost of operating facility became lower with the operation time. In addition, we demonstrated the procedure to estimate the overall heat transmission coefficients of the tunnel wall which was a great help in the design of similar facilities in underground spaces.
The different rooms in the facility are expected to be used for manufacturing fermented foods and drinks depending on temperature and humidity requirements. Not only running costs but also initial costs are expected to be lower than those for surface facilities; for this reason, our system has been demonstrated to be economically viable as well as environment friendly.. |
| 43. |
Ryo Mori, Yuichi Sugai, Kyuro Sasaki, Kazuhiro Fujiwara, Takamichi Nakamura, Experimental and Numerical Studies on the Microbial Restoration of Natural Gas Deposits in Depleted Oil Reservoirs Storing CO2, Society of Petroleum Engineers (SPE) Asia Pacific Oil and Gas Conference and Exhibition, SPE-158875-MS, 2012.10, We investigated the microbial conversion of CO2 into CH4 in depleted oil reservoirs by the interaction between indigenous oil-degrading hydrogen-producing bacteria and indigenous hydrogenotrophic methanogens that have been found in oil reservoirs universally. In this study, we investigated the influence of crude oil, yeast extract, bicarbonate and CO2 on the growth and gas production of those bacteria through the incubation experiments of isolated strains under reservoir conditions. The yeast extract was estimated to be the most influential factor on the growth and gas production of oil-degrading hydrogen-producing bacteria. Methanogen was unaffected by the crude oil, the yeast extract and bicarbonate, however, both CO2 and H2 are assumed to be the influential factors on it because they are the energy sources of methanogen.
In addition, we also investigated their growth kinetics that were needed to construct a numerical simulator of the microbial conversion of CO2 into CH4 in depleted oil reservoirs. The specific growth rate of oil-degrading hydrogen-producing bacteria was increased as the yeast extract concentration increased while that of the methanogen was constant regardless of the yeast extract concentration. These results indicate that the growth of methanogens is unaffected by the yeast extract that is injected into reservoirs to stimulate the growth of ODHPB. The growth yield of HYH-8 and HYH-10 was 5.5x1010 cells/g-(yeast extract) and 3.5x1011 cells/g-(yeast extract) respectively.. |
| 44. |
Yuichi Sugai, Isty A. Purwasena, Kyuro Sasaki, Kazuhiro Fujiwara, Yoshiyuki Hattori, Komei Okatsu, Experimental studies on indigenous hydrocarbon-degrading and hydrogen-producing bacteria in an oilfield for microbial restoration of natural gas deposits with CO2 sequestration, Journal of Natural Gas Science and Engineering (Elsevier), 10.1016/j.jngse.2012.01.011, 5, 31-41, 2012.03, Sequestration of carbon dioxide (CO2) into depleted oil reservoirs may be a method of reducing CO2 emissions. We focus on microbial restoration of natural gas deposits with CO2 sequestration via in situ microbial conversion of CO2 into methane (CH4) by hydrogenotrophic methanogens (HM) that universally inhabit oil reservoirs. The means of supplying HM with H2 for their CH4 production is central to this process. This study considers the potential of this process by evaluating the H2 productivity of hydrocarbon-degrading and hydrogen-producing bacteria (HD–HPB) that inhabit oil reservoirs.
Reservoir brine was extracted from 10 producing wellheads in the Yabase Oilfield of Japan. Indigenous bacteria in the brine samples were incubated with sterile oil under anaerobic conditions with 10%-CO2 (N2 balanced) at 50 °C and 75 °C. Production of H2 and CH4 and consumption of CO2 were observed in almost all the brine at both temperature, especially, larger amount of gases were produced at 50 °C. Those gases production was significantly stimulated with the additional yeast extract, on the other hand, it became lower under high pressure condition.
Nutrient agar inoculated with raw brine was incubated under anaerobic conditions at 50 °C and 75 °C. Microbial single colonies formed in the nutrient agar media after 2 weeks were selected and inoculated into sterile brine including sterile oil. More than 20 isolates were isolated and incubated in the brine media and 14 strains were observed to produce H2 after 3 months incubation. The maximum rate of H2 production by HD–HPB was 0.38 NmL/L-medium/day.
These results suggest that in situ microbial conversion of sequestrated CO2 and H2 generated by HD–HPB into CH4 using HM can be expected in many oilfields universally. Moreover, the most capable HD–HPB isolated in this study can be injected into reservoirs to stimulate the restoration of natural gas deposits with CO2 sequestration.. |
| 45. |
Ryo Wakizono, Yuichi Sugai, Kyuro Sasaki, Yasunori Higuchi, Noriyuki Muraoka, Investigation of Indigenous Bacteria in Water-dissolved Natural Gas Fields for Preventing Microbial Clogging of Injection Wells, Society of Petroleum Engineers (SPE) Asia Pacific Oil and Gas Conference and Exhibition, SPE-145990-MS, 2011.09, The brine that has been produced from water-dissolved natural gas reservoirs should be returned into reservoirs after the resources have been extracted to prevent the subsidence. However, the re-injectivity of the brine declines gradually; therefore, re-injection wells should be maintained by backwashing treatments. Colloidal materials like biofilms can be observed in solid materials that have been produced by the backwashing from the re-injection wells.
Because the brine contains not only dissolved natural gas but also high levels of iodine, the iodine is also extracted from the brine chemically using sulfuric acid and oxidizing agent; therefore, re-injected brine contains sulfate and dissolved oxygen abundantly. These chemicals may stimulate the metabolites of microorganisms that have influences on the clogging; therefore, we considered the influences of these materials on microorganisms that may cause the clogging in this study.
Column experiments were carried out using sand and brine that were collected in the gas field. The columns that the brine including indigenous microorganisms, dissolved oxygen and sulfate was injected into were clogged significantly. Iodide-oxidizing bacteria, iron-oxidizing bacteria and sulfate-reducing bacteria were found specifically in clogged columns, suggesting these microorganisms had influences on the clogging. In particular, Iodide-oxidizing bacteria were also found in original brine; therefore, it was assumed to have an important influence on the clogging.
Iodide-oxidizing bacteria convert iodide into iodine that corrodes iron in the sand under the presence of dissolved oxygen. Iron (II) ion that has been eluted from the sand is oxidized to iron (III) ion by iron-oxidizing bacteria under the presence of dissolved oxygen. Iron (III) ion forms ferric hydroxide colloid in the brine and it causes the clogging of the porous media.
From these mechanisms of the clogging, we can suggest removing dissolved oxygen as the most feasible countermeasures for the clogging.. |
| 46. |
Ryo Mori, Yuichi Sugai, Kyuro Sasaki, Kazuhiro Fujiwara, Evaluation of the Potential of Microbial Restoration of Natural Gas Deposit with CO2 Sequestration by Investigating Indigenous Bacteria in a High CO2 Content Oilfield, Society of Petroleum Engineers (SPE) Asia Pacific Oil and Gas Conference and Exhibition, SPE-145898-MS, 2011.09, We investigated the in situ microbial conversion of CO2 into CH4 by oil-degrading and H2-producing bacteria and hydrogenotrophic methanogens. CO2 is injected into depleted oil reservoirs as a method of carbon capture and storage (CCS). The bacteria involved in CO2 conversions are affected by high CO2 conditions, which cause a reduction in the pH level of the reservoir brine. Therefore, we assessed the efficacy of this microbial conversion process under high partial CO2 pressure by investigating the microbial communities present in high/low CO2 content reservoirs, the pH reduction of brine under high partial pressure of CO2, and the production of H2 and CH4 by indigenous bacteria in high CO2 content reservoirs. Thermotoga sp. and Thermoanaerobacter sp., which have previously been shown to produce hydrogen from crude oil by Fujiwara et al.1), were found to be the dominant species in the high CO2 content reservoir. Moreover, Methanobacterium sp. and Methanothermobacter sp., which are well-known hydrogenotrophic methanogens, were also detected in the reservoir. These results indicate that the microorganisms needed for this microbial conversion process can inhabit reservoirs where CO2 has been injected for CCS.
The pH of brine with bicarbonate levels > 0.1 mol/L was found to be maintained at pH 7.0–8.0, which is a favorable pH for the growth of a variety of microorganisms. Neutral pH levels were maintained even under CO2 partial pressure as high as 5.0 MPa, suggesting that the microbial conversion process could easily be applied in reservoirs whose brine is abundant in bicarbonate.
Enrichment culture experiments in brine were carried out under high CO2 partial pressure (3.0 MPa) at 75°C. Production of both H2 and CH4 was detected in brine with pH buffering action, as well as in brine with significantly reduced pH levels due to high CO2 partial pressure. Therefore, the microbial conversion process may also be expected to occur in normal reservoirs with poor acid neutralizing capacity.. |
| 47. |
Isty A. Purwasena, Yuichi Sugai, Kyuro Sasaki, Estimation of the Potential of an Oil-Viscosity-Reducing Bacterium Petrotoga sp. Isolated from an Oil Field for MEOR, Society of Petroleum Engineers (SPE) Annual Technical Conference and Exhibition, SPE-137568-MS, 2010.09. |
| 48. |
Isty Adhitya Purwasena, Yuichi Sugai, Kyuro Sasaki, Estimation of the Potential of an Oil-Viscosity-Reducing Bacteria, Petrotoga sp., Isolated from an Oilfield for MEOR, Proceedings of International Petroleum Technology Conference 2009 (IPTC2009), IPTC-13861-MS, 2009.12. |
| 49. |
Yuichi Sugai, Toshiya Niimi, Kyuro Sasaki, Yoshiyuki Hattori, Sanae Kano, Tsukasa Mukaidani, Kazuhiro Fujiwara and Komei Okatsu, Screening of Oil-Degrading and Hydrogen-Producing Microorganisms for Microbial Conversion of CO2 into CH4 in Oil Reservoir, Proceedings of CIPC/SPE GTS 2008 Joint Conference, SPE-115009-MS, 2008.06. |
| 50. |
Yuichi Sugai, Hong Chengxie, Tadashi Chida, Heiji Enomoto, Simulation Studies on the Mechanisms and Performances of MEOR using Polymer Producing Microorganism Clostridium sp. TU-15A, Proc. of Society of Petroleum Engineers (SPE) Asia Pacific Oil and Gas Conference and Exhibition, SPE-110173-MS, 2007.10. |
| 51. |
Characteristics of Functional Wall Material Containing a Green Tuff, Yuichi SUGAI, Kyuro SASAKI, Shigeyuki TAKAHATA and Hideo NAKA, Transactions of the Society of Heating, Air-Conditioning and Sanitary Engineers of Japan, No.123, 2007. |
| 52. |
Possibility of the Towada-Stone Dust for the Deodorizer and the Compost Accelerator, Journal of Japan Institute of Aggregate Technology, No.147, pp.153-161, 2005. |
| 53. |
Laboratory Investigation on Profile Modification of Oil Reservoir Fluids by Water-insoluble Polymer Producing Microorganism CJF-002, SUGAI Yuichi, KISHITA Atsushi, YUMOTO Tetsuya, ENOMOTO Heiji, HONG Chengxie, FUJIWARA Kazuhiro and ONO Kenji, Journal of the Japanese Association for Petroleum Technology, Vol.70, No.4 (20050701) pp. 315-327 . |
| 54. |
The Abilities of Hinai-Green Tuff to Adjust pH and Activate Microorganisms, SUGAI Yuichi, SASAKI Kyuro, MATSUBAYA Osamu, NAKA Hideo and TANAKA Fujio, Journal of the Mining and Materials Processing Institute of Japan, Vol.121, No.10 (20051125) pp. 513-520 . |
| 55. |
Numerical Experiments of MEOR with the microbe producing water-soluble polymer, SUGAI Yuichi, HONG Chengxie, CHIDA Tadashi and ENOMOTO Heiji, Journal of the Japanese Association for Petroleum Technology, Vol.69, No.5 (20040901) pp. 563-573 . |
| 56. |
Y.SUGAI, J.FANGMING, H.ENOMOTO and T.MORIYA, Application of Membrane Separation Method to Concentrate Products on the Process Producing Environmentally Adaptable Deicer by means of Wet Oxidation of Organic Wastes, RESOURCES PROCESSING, Vol.51、No.3、148－157, 2004.09. |
| 57. |
Simulation study on the performance and mechanism of MEOR with a water-soluble polymer producing microbe, SUGAI Yuichi, HONG Chengxie, CHIDA Tadashi and ENOMOTO Heiji, Journal of the Japanese Association for Petroleum Technology, Vol.69, No.4 (20040701) pp. 335-347 . |
| 58. |
Numerical model for MEOR with a microbe producing water-soluble polymer, SUGAI Yuichi, HONG Chengxie, CHIDA Tadashi and ENOMOTO Heiji, Journal of the Japanese Association for Petroleum Technology, Vol.69, No.3 (20040501) pp. 262-271 . |
| 59. |
Screening of water-soluble polymer producing microorganisms for MEOR, SUGAI Yuichi, HONG Chengxie, IKEDA Shuichiro, CHIDA Tadashi, ENOMOTO Heiji and YAZAWA Nintoku, Journal of the Japanese Association for Petroleum Technology, Vol.67, No.3 (20020501) pp. 277-286. |
| 60. |
Laboratory investigation on oil recovery with a Water-Soluble Polymer producing microorganism TU-15A, SUGAI Yuichi, HONG Chengxie, CHIDA Tadashi, ENOMOTO Heiji and YAZAWA Nintoku, Journal of the Japanese Association for Petroleum Technology, Vol.67, No.5 (20020901) pp. 491-500
. |
| 61. |
Yuichi Sugai, Atsushi Kishita, Hong Chengxie, Heiji Enomoto, Tadashi Chida, S.C.ZHOU, Laboratory Investigation of Polymer Producer TU-15A for MEOR Field Tests, Proc. of Society of Petroleum Engineers (SPE) Asia Pacific Oil and Gas Conference and Exhibition, SPE-54381-MS, 1999.04. |
