The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform

Baojun Bai - One of the best experts on this subject based on the ideXlab platform.

  • A Critical Review of CO 2 Enhanced Oil Recovery in Tight Oil Reservoirs of North America and China
    Day 1 Tue October 29 2019, 2020
    Co-Authors: Zhaojie Song, Baojun Bai, Yilei Song, Kaoping Song, Jirui Hou, Ajiao Jiang
    Abstract:

    Abstract Primary Oil Recovery remains less than 10% in tight Oil reservoirs, even after expensive multistage horizontal well hydraulic fracturing stimulation. Substantial experiments and pilot tests have been performed to investigate CO2-EOR potential in tight reservoirs; however, some results conflict with each other. The objective of this paper is to diagnose how these conflicting results occurred and to identify a way to narrow the gap between experimental results and field performance through a comprehensive literature review and data analysis. Peer-reviewed journal papers, technical reports, and SPE publications were collected, and three key steps were taken to reach our goal. First, rock and fluid properties of tight reservoirs in North America and China were compared, and their potential effect on tight Oil production was analyzed. Afterward, based on published experimental studies and simulation works, the CO2-EOR mechanisms were discussed, including molecular diffusion, CO2-Oil interaction considering nanopore confinement, and CO2-fluid-rock minerals interaction. Subsequently, pilot projects were examined to understand the gap between laboratory works and field tests, and the challenges faced in China's tight Oil exploitation were rigorously analyzed. Compared with Bakken and Eagle Ford formation, China's tight Oil reservoirs feature higher mud content and Oil viscosity while they have a lower brittleness index and formation pressure, leading to confined stimulated reservoir volume and further limited CO2-Oil contact. The effect of CO2 molecular diffusion was relatively exaggerated in experimental results, which could be attributed to the dual restrictions of exposure time and Oil-CO2 area in field scale. Numerical modeling showed that the improved phase properties in nanopores led to enhanced Oil Recovery. The development of nano-scale chips withholding high pressure/temperature may advance the experimental study on nano-confinement's effect. Oil Recovery can be further enhanced through wettability alteration due to CO2 adsorption on nanopores and reaction with rock minerals. CO2 huff-n-puff operations were more commonly applied in North America than China, and the huff time is in the order of 10 days, but the soaking time is less. Conformance control was essential during CO2 flooding in order to delay gas breakthrough and promote CO2-Oil interaction. There is less than 5% of tight Oil reserve surrounded by CO2 reservoirs in China, limiting the application of CO2-EOR technologies. An economic incentive from the government is necessary to consider the application of CO2 from power plants, refineries, etc. This work provides an explanation of conflicting results from different research methods and pilot tests, and helps researchers and Oil operators understand where and when the CO2-EOR can be best applied in unconventional reservoirs. New directions for future work on CO2-EOR in tight formations are also recommended.

  • A critical review of CO2 enhanced Oil Recovery in tight Oil reservoirs of North America and China
    Fuel, 2020
    Co-Authors: Zhaojie Song, Baojun Bai, Yilei Song, Kaoping Song, Jirui Hou
    Abstract:

    Abstract Primary Oil Recovery remains less than 10% in tight Oil reservoirs, even after expensive multistage horizontal well hydraulic fracturing stimulation. Substantial experiments and simulation works have been performed to investigate CO2 enhanced Oil Recovery (CO2-EOR) potential in tight reservoirs; however, some results conflict with each other. The objectives of this paper are to fully understand the CO2-EOR mechanisms and to figure out the difference between tight Oil exploitation in North America and China through a comprehensive literature review. It is shown that compared with Bakken and Eagle Ford formation, China’s tight Oil reservoirs feature higher mud content and Oil viscosity while they have a lower brittleness index of rock and formation pressure coefficient, leading to confined stimulated reservoir volume and further limited CO2-Oil contact. The effect of CO2 molecular diffusion is relatively exaggerated in experimental results, which can be attributed to the dual restrictions of exposure time and Oil-CO2 area in field scale. Numerical simulation works show that the shifted phase properties in nanopores lead to an Oil Recovery increment. The development of nano-scale chips withholding high pressure/temperature may advance the experimental study on the nanopore confinement effect. CO2-fluid-rock minerals interaction might be more complex due to the large specific surface area of nanopores in tight formations. The geomechanics coupling effect cannot be ignored when examining the CO2-EOR performance in tight reservoirs. And a comprehensive simulation study coupling with technical and economic feasibility is highly recommended before running a field test of CO2-EOR.

  • Miscible Gases Based EOR in Unconventional Liquids Rich Reservoirs: What We Can Learn
    Day 2 Tue December 11 2018, 2018
    Co-Authors: Dheiaa Alfarge, Mingzhen Wei, Mortadha Alsaba, Baojun Bai
    Abstract:

    Abstract Over the last decade, Unconventional Liquids Rich Reservoirs (ULR) have become the main target for Oil and gas investors as conventional formations started to deplete and diminish in numbers. These unconventional plays have a huge Oil reserve; however, the Primary Oil Recovery factor is predicted to be less than 10%. Unconventional Improved Oil Recovery (UIOR) techniques are still a new concept in the Oil industry since there is no commercial project reported for any IOR technique yet. Miscible gas based EOR technique might be the most potential strategy to improve Oil Recovery in such complex plays. In this study, a comprehensive and critical review has been conducted to evaluate the feasibility of miscible gas based EOR technique in ULR. The reports and studies from three different approaches (lab, simulation and pilot tests) were summarized and combined to provide in-depth insights and lessons learned from the applicability of miscible gas based EOR in ULR. Firstly, the main problems in the previous lab and simulation approaches, which were used to investigate the viability of different EOR methods, have been diagnosed. Secondly, the performance of injecting different miscible gases to enhance Oil Recovery in the pilot tests conducted in ULR has been extensively discussed. Thirdly, the physical and chemical reasoning behind the performance gap for the injected gases in the lab scale versus the field scale of ULR been diagnosed. This study reported that most of the previous lab and simulation approaches suffered from significant lacks and drawbacks, which created a clear gap in the performance of the injected gases in the lab scale versus the field scale. This research clearly found that the performance of Natural Gas (NG) injection is significantly better than the performance of CO2 injection in terms of enhancing Oil Recovery in the field pilots. This study also found that the production response of unconventional reservoirs to the injected NGs is much faster than that for the injected CO2. Combining the pilot tests data and simulation studies showed that the number of cycles in huff-n-puff operations has a negative impact on CO2-EOR while it has a positive impact on NGs-EOR. Finally, this research provided deep insights on what the operators can expect from the EOR performance by injecting different miscible gases in the lab scale versus the field scale of ULR.

  • Data analysis for CO2-EOR in shale-Oil reservoirs based on a laboratory database
    Journal of Petroleum Science and Engineering, 2018
    Co-Authors: Dheiaa Alfarge, Mingzhen Wei, Baojun Bai
    Abstract:

    Abstract Unconventional resources have played a significant role in changing Oil industry plans recently. Shale formations in North America such as Bakken, Niobrara, and Eagle Ford have huge Oil in place, 100–900 Billion barrels of recoverable Oil in Bakken only. However, the Primary Oil Recovery is still low as 5–10%. EOR methods are currently considered as a new concept in unconventional reservoirs due to the immature information about these plays. Injecting carbon dioxide (CO2) might be the most potential strategy to improve Oil Recovery in such complex plays (Alfarge et al., 2017a,b). Jin et al. (2016) conducted an experimental study to investigate improving Oil Recovery by CO2 injection in 21 natural preserved core samples from Bakken Petroleum System (BPS). Their experimental results indicated that CO2 injection has a significant potential to improve Oil transportability in these Nano-pores formations. In this study, data analysis for feasibility of CO2-EOR has been conducted on 95 cases of natural preserved cores collected from different formations including 44 cases from Middle Bakken, 26 cases from Lower Bakken, 17 from Upper Bakken, 4 cases from Three Forks, and 4 cases from unknown formation/formations. The relationship between the improved Oil Recovery by the injected CO2 and 6 rock properties including porosity, permeability, mean pore throat radius, total organic carbon content (TOC), water saturation, and Oil saturation has been separately determined and physically discussed. Furthermore, the relationships between the improved Oil Recovery obtained by the injected CO2 and 4 operating parameters including CO2 bath pressure, CO2 bath temperature, and core sample bulk size, and exposing time have been also separately investigated. A Proxy model to associate the functionality of the improved Oil Recovery by CO2 injection and these 10 parameters have been constructed. Moreover, statistical methods for Design of Experiments (DOE) have been used to rank the most important parameters affecting CO2-EOR performance in the microscale level (lab scale) of these unconventional reservoirs. This study provides an important set of lab-based data obtained from natural preserved cores to find out the applicability of CO2-EOR in these unconventional reservoirs. Also, this research demonstrates some key points which could help in understanding CO2-EOR mechanisms in shale plays since they are much complex and very different from conventional formations.

  • Lessons Learned from IOR Pilots in Bakken Formation by Using Numerical Simulation
    Journal of Petroleum Science and Engineering, 2018
    Co-Authors: Dheiaa Alfarge, Mingzhen Wei, Baojun Bai, Mortadha Alsaba
    Abstract:

    Abstract Bakken is the most productive formation among unconventional plays in North America. This formation has about 7.4 billion barrels of recoverable Oil. However, the Primary Oil Recovery is still low as 5–10%. Miscible natural gas and carbon dioxide (CO2) might be the most two potential strategies to improve Oil Recovery in such a complex play. In this study, some of the IOR pilots which have been conducted in Montana, North Dakota, and South Saskatchewan have been presented. The performance results of these pilots in US-Bakken versus Canadian-Bakken have been compared. Moreover, the reasons behind the successful IOR pilots in Canadian-Bakken versus US-Bakken have been discussed. Then, numerical simulation models have been constructed to mimic the results of some pilots. Two different compositional models have been built for Oils of two different formations. Furthermore, two different models, single porosity model and dual permeability model have been created to match the performance of some pilots. Implementation of molecular diffusion mechanism has been conducted in both of single porosity and dual permeability model. Finally, the continuous miscible gases injection versus huff-n-puff protocols have been compared and investigated. The results showed that the performance of natural gases generally over-performed the CO2 injection technique's in Bakken formation. Although the diffusion flow is dominant in these types of reservoirs, the diffusivity of the injected CO2 into formation Oil is slow due to the fact that CO2 has large molecules as compared with the small pore throats of these porous media. Accordingly, miscible CO2-EOR might not be beneficial in huff-n-puff operations as in continuous flooding process. However, the success of natural gases based EOR does not have that strong functionality of molar diffusivity. Therefore, their performance was much better than CO2 performance in the field scale of these tight formations. Furthermore, the numerical simulation of this study concluded that the spacing between the production wells and injection wells should be minimized, for the continuous flooding process of miscible-gases EOR, to enhance their performance. Although the permeability of Canadian-Bakken has a permeability of 1–2 order higher than the permeability of US-Bakken, the pilots' spacing between injectors and producers in Canadian Bakken is interestingly much shorter than that for US-Bakken, which might be the reason behind the EOR success in Canadian Bakken. Finally, the activatiown process of the highly intensive natural fractures might be the key to enhance the diffusivity of CO2-EOR. Otherwise, natural gases are highly recommended to be the most potential EOR in these types of reservoirs. This study explains how the diffusion mechanism affects the performance of different miscible gases to improve Oil Recovery in these plays since they are more complex and very different from conventional formations. Also, it suggests that CO2 flooding process would be a good practice to overcome the limitations of CO2-diffusion rate in these reservoirs if the conformance problems are wisely controlled.

Dheiaa Alfarge - One of the best experts on this subject based on the ideXlab platform.

  • Miscible Gases Based EOR in Unconventional Liquids Rich Reservoirs: What We Can Learn
    Day 2 Tue December 11 2018, 2018
    Co-Authors: Dheiaa Alfarge, Mingzhen Wei, Mortadha Alsaba, Baojun Bai
    Abstract:

    Abstract Over the last decade, Unconventional Liquids Rich Reservoirs (ULR) have become the main target for Oil and gas investors as conventional formations started to deplete and diminish in numbers. These unconventional plays have a huge Oil reserve; however, the Primary Oil Recovery factor is predicted to be less than 10%. Unconventional Improved Oil Recovery (UIOR) techniques are still a new concept in the Oil industry since there is no commercial project reported for any IOR technique yet. Miscible gas based EOR technique might be the most potential strategy to improve Oil Recovery in such complex plays. In this study, a comprehensive and critical review has been conducted to evaluate the feasibility of miscible gas based EOR technique in ULR. The reports and studies from three different approaches (lab, simulation and pilot tests) were summarized and combined to provide in-depth insights and lessons learned from the applicability of miscible gas based EOR in ULR. Firstly, the main problems in the previous lab and simulation approaches, which were used to investigate the viability of different EOR methods, have been diagnosed. Secondly, the performance of injecting different miscible gases to enhance Oil Recovery in the pilot tests conducted in ULR has been extensively discussed. Thirdly, the physical and chemical reasoning behind the performance gap for the injected gases in the lab scale versus the field scale of ULR been diagnosed. This study reported that most of the previous lab and simulation approaches suffered from significant lacks and drawbacks, which created a clear gap in the performance of the injected gases in the lab scale versus the field scale. This research clearly found that the performance of Natural Gas (NG) injection is significantly better than the performance of CO2 injection in terms of enhancing Oil Recovery in the field pilots. This study also found that the production response of unconventional reservoirs to the injected NGs is much faster than that for the injected CO2. Combining the pilot tests data and simulation studies showed that the number of cycles in huff-n-puff operations has a negative impact on CO2-EOR while it has a positive impact on NGs-EOR. Finally, this research provided deep insights on what the operators can expect from the EOR performance by injecting different miscible gases in the lab scale versus the field scale of ULR.

  • Data analysis for CO2-EOR in shale-Oil reservoirs based on a laboratory database
    Journal of Petroleum Science and Engineering, 2018
    Co-Authors: Dheiaa Alfarge, Mingzhen Wei, Baojun Bai
    Abstract:

    Abstract Unconventional resources have played a significant role in changing Oil industry plans recently. Shale formations in North America such as Bakken, Niobrara, and Eagle Ford have huge Oil in place, 100–900 Billion barrels of recoverable Oil in Bakken only. However, the Primary Oil Recovery is still low as 5–10%. EOR methods are currently considered as a new concept in unconventional reservoirs due to the immature information about these plays. Injecting carbon dioxide (CO2) might be the most potential strategy to improve Oil Recovery in such complex plays (Alfarge et al., 2017a,b). Jin et al. (2016) conducted an experimental study to investigate improving Oil Recovery by CO2 injection in 21 natural preserved core samples from Bakken Petroleum System (BPS). Their experimental results indicated that CO2 injection has a significant potential to improve Oil transportability in these Nano-pores formations. In this study, data analysis for feasibility of CO2-EOR has been conducted on 95 cases of natural preserved cores collected from different formations including 44 cases from Middle Bakken, 26 cases from Lower Bakken, 17 from Upper Bakken, 4 cases from Three Forks, and 4 cases from unknown formation/formations. The relationship between the improved Oil Recovery by the injected CO2 and 6 rock properties including porosity, permeability, mean pore throat radius, total organic carbon content (TOC), water saturation, and Oil saturation has been separately determined and physically discussed. Furthermore, the relationships between the improved Oil Recovery obtained by the injected CO2 and 4 operating parameters including CO2 bath pressure, CO2 bath temperature, and core sample bulk size, and exposing time have been also separately investigated. A Proxy model to associate the functionality of the improved Oil Recovery by CO2 injection and these 10 parameters have been constructed. Moreover, statistical methods for Design of Experiments (DOE) have been used to rank the most important parameters affecting CO2-EOR performance in the microscale level (lab scale) of these unconventional reservoirs. This study provides an important set of lab-based data obtained from natural preserved cores to find out the applicability of CO2-EOR in these unconventional reservoirs. Also, this research demonstrates some key points which could help in understanding CO2-EOR mechanisms in shale plays since they are much complex and very different from conventional formations.

  • Lessons Learned from IOR Pilots in Bakken Formation by Using Numerical Simulation
    Journal of Petroleum Science and Engineering, 2018
    Co-Authors: Dheiaa Alfarge, Mingzhen Wei, Baojun Bai, Mortadha Alsaba
    Abstract:

    Abstract Bakken is the most productive formation among unconventional plays in North America. This formation has about 7.4 billion barrels of recoverable Oil. However, the Primary Oil Recovery is still low as 5–10%. Miscible natural gas and carbon dioxide (CO2) might be the most two potential strategies to improve Oil Recovery in such a complex play. In this study, some of the IOR pilots which have been conducted in Montana, North Dakota, and South Saskatchewan have been presented. The performance results of these pilots in US-Bakken versus Canadian-Bakken have been compared. Moreover, the reasons behind the successful IOR pilots in Canadian-Bakken versus US-Bakken have been discussed. Then, numerical simulation models have been constructed to mimic the results of some pilots. Two different compositional models have been built for Oils of two different formations. Furthermore, two different models, single porosity model and dual permeability model have been created to match the performance of some pilots. Implementation of molecular diffusion mechanism has been conducted in both of single porosity and dual permeability model. Finally, the continuous miscible gases injection versus huff-n-puff protocols have been compared and investigated. The results showed that the performance of natural gases generally over-performed the CO2 injection technique's in Bakken formation. Although the diffusion flow is dominant in these types of reservoirs, the diffusivity of the injected CO2 into formation Oil is slow due to the fact that CO2 has large molecules as compared with the small pore throats of these porous media. Accordingly, miscible CO2-EOR might not be beneficial in huff-n-puff operations as in continuous flooding process. However, the success of natural gases based EOR does not have that strong functionality of molar diffusivity. Therefore, their performance was much better than CO2 performance in the field scale of these tight formations. Furthermore, the numerical simulation of this study concluded that the spacing between the production wells and injection wells should be minimized, for the continuous flooding process of miscible-gases EOR, to enhance their performance. Although the permeability of Canadian-Bakken has a permeability of 1–2 order higher than the permeability of US-Bakken, the pilots' spacing between injectors and producers in Canadian Bakken is interestingly much shorter than that for US-Bakken, which might be the reason behind the EOR success in Canadian Bakken. Finally, the activatiown process of the highly intensive natural fractures might be the key to enhance the diffusivity of CO2-EOR. Otherwise, natural gases are highly recommended to be the most potential EOR in these types of reservoirs. This study explains how the diffusion mechanism affects the performance of different miscible gases to improve Oil Recovery in these plays since they are more complex and very different from conventional formations. Also, it suggests that CO2 flooding process would be a good practice to overcome the limitations of CO2-diffusion rate in these reservoirs if the conformance problems are wisely controlled.

  • Analysis of IOR Pilots in Bakken Formation by Using Numerical Simulation
    Day 4 Thu November 16 2017, 2017
    Co-Authors: Dheiaa Alfarge, Mingzhen Wei, Baojun Bai, Mortadha Alsaba
    Abstract:

    Abstract Bakken is the most productive formation among unconventional plays in North America. This formation has 7.4 billion barrels of recoverable Oil. However, the Primary Oil Recovery is still low as 5-10%. Miscible natural gas and carbon dioxide (CO2) might be the most two potential strategies to improve Oil Recovery in such complex play. In this study, some of the IOR pilots which have been conducted in Montana, North Dakota, and South Saskatchewan have been presented. The performance results of these pilots in US-Bakken versus Canadian-Bakken have been compared. Moreover, the reasons beyond the successful IOR pilots in Canadian-Bakken versus US-Bakken have been discussed. Then, numerical simulation models have been constructed to mimic the results of these pilots. Two different compositional models have been built for two different formation-Oils. Furthermore, two different models, single porosity model and dual permeability model have been created to match the performance of some pilot-tests. Implementation of molecular diffusion mechanism has been conducted in both of single porosity and dual permeability model. Finally, continuous miscible gases injection versus huff-n-puff protocols have been compared and investigated. The results showed that the performance of natural gases generally over-performed the CO2 injection technique's in Bakken formation. Although the diffusion flow is dominant, the diffusivity of the injected CO2 into formation Oil is slow due to its large molecules as compared with the small pore throats of these porous media. Accordingly, miscible CO2-EOR might be not beneficial in huff-n-puff as compared to continuous flooding process. However, success of natural gases does not have that strong functionality of molar diffusivity. Therefore, their performance was much better than CO2 performance in the field scale of these tight formations. Furthermore, the numerical simulation of this study concluded that the spacing between the production wells and injection wells should be minimized, for the continuous flooding process of miscible-gases EOR, to enhance their performance. Although the permeability of Canadian-Bakken has permeability of 1-2 order higher than the permeability of US-Bakken, the spacing between injectors and producers in Canadian Bakken is interestingly much shorter than that for US-Bakken, which might be the reason beyond the EOR success in Canadian Bakken. Finally, the activation process for the highly intensive natural fractures might be the key to enhance the diffusivity of CO2-EOR. Otherwise, natural gases are highly recommended to be the most potential EOR in these types of reservoirs. This study explains how diffusion mechanism of miscible gases affects their performance to improve Oil Recovery in these plays since they are more complex and very different from conventional formations. Also, it suggests that CO2 flooding process would be a good practice to overcome the limitations of CO2-diffusion rate in these reservoirs.

  • Factors Affecting CO2-EOR in Shale-Oil Reservoirs: Numerical Simulation Study and Pilot Tests
    Energy & Fuels, 2017
    Co-Authors: Dheiaa Alfarge, Mingzhen Wei, Baojun Bai
    Abstract:

    Shale Oil reservoirs such as Bakken, Niobrara, and Eagle Ford have become the main target for Oil and gas investors as conventional formations started to be depleted and diminished in number. These unconventional plays have a huge Oil potential; however, the predicted Primary Oil Recovery is still low as an average of 7.5%. Injecting carbon dioxide (CO2) to enhance Oil Recovery in these poor-quality formations is still a debatable issue among investigators. In this study, three steps of research have been integrated to investigate the parameters that control the success of CO2 huff-n-puff process in the field scale of shale Oil reservoirs. First, a numerical simulation study was conducted to upscale the reported experimental studies outcomes to the field conditions. The second step was to validate these numerical models with the field data from some of CO2-EOR pilots, which were performed in Bakken formation, in North Dakota and Montana regions. Finally, statistical methods for Design of Experiments (DOE)...

Mingzhen Wei - One of the best experts on this subject based on the ideXlab platform.

  • Miscible Gases Based EOR in Unconventional Liquids Rich Reservoirs: What We Can Learn
    Day 2 Tue December 11 2018, 2018
    Co-Authors: Dheiaa Alfarge, Mingzhen Wei, Mortadha Alsaba, Baojun Bai
    Abstract:

    Abstract Over the last decade, Unconventional Liquids Rich Reservoirs (ULR) have become the main target for Oil and gas investors as conventional formations started to deplete and diminish in numbers. These unconventional plays have a huge Oil reserve; however, the Primary Oil Recovery factor is predicted to be less than 10%. Unconventional Improved Oil Recovery (UIOR) techniques are still a new concept in the Oil industry since there is no commercial project reported for any IOR technique yet. Miscible gas based EOR technique might be the most potential strategy to improve Oil Recovery in such complex plays. In this study, a comprehensive and critical review has been conducted to evaluate the feasibility of miscible gas based EOR technique in ULR. The reports and studies from three different approaches (lab, simulation and pilot tests) were summarized and combined to provide in-depth insights and lessons learned from the applicability of miscible gas based EOR in ULR. Firstly, the main problems in the previous lab and simulation approaches, which were used to investigate the viability of different EOR methods, have been diagnosed. Secondly, the performance of injecting different miscible gases to enhance Oil Recovery in the pilot tests conducted in ULR has been extensively discussed. Thirdly, the physical and chemical reasoning behind the performance gap for the injected gases in the lab scale versus the field scale of ULR been diagnosed. This study reported that most of the previous lab and simulation approaches suffered from significant lacks and drawbacks, which created a clear gap in the performance of the injected gases in the lab scale versus the field scale. This research clearly found that the performance of Natural Gas (NG) injection is significantly better than the performance of CO2 injection in terms of enhancing Oil Recovery in the field pilots. This study also found that the production response of unconventional reservoirs to the injected NGs is much faster than that for the injected CO2. Combining the pilot tests data and simulation studies showed that the number of cycles in huff-n-puff operations has a negative impact on CO2-EOR while it has a positive impact on NGs-EOR. Finally, this research provided deep insights on what the operators can expect from the EOR performance by injecting different miscible gases in the lab scale versus the field scale of ULR.

  • Data analysis for CO2-EOR in shale-Oil reservoirs based on a laboratory database
    Journal of Petroleum Science and Engineering, 2018
    Co-Authors: Dheiaa Alfarge, Mingzhen Wei, Baojun Bai
    Abstract:

    Abstract Unconventional resources have played a significant role in changing Oil industry plans recently. Shale formations in North America such as Bakken, Niobrara, and Eagle Ford have huge Oil in place, 100–900 Billion barrels of recoverable Oil in Bakken only. However, the Primary Oil Recovery is still low as 5–10%. EOR methods are currently considered as a new concept in unconventional reservoirs due to the immature information about these plays. Injecting carbon dioxide (CO2) might be the most potential strategy to improve Oil Recovery in such complex plays (Alfarge et al., 2017a,b). Jin et al. (2016) conducted an experimental study to investigate improving Oil Recovery by CO2 injection in 21 natural preserved core samples from Bakken Petroleum System (BPS). Their experimental results indicated that CO2 injection has a significant potential to improve Oil transportability in these Nano-pores formations. In this study, data analysis for feasibility of CO2-EOR has been conducted on 95 cases of natural preserved cores collected from different formations including 44 cases from Middle Bakken, 26 cases from Lower Bakken, 17 from Upper Bakken, 4 cases from Three Forks, and 4 cases from unknown formation/formations. The relationship between the improved Oil Recovery by the injected CO2 and 6 rock properties including porosity, permeability, mean pore throat radius, total organic carbon content (TOC), water saturation, and Oil saturation has been separately determined and physically discussed. Furthermore, the relationships between the improved Oil Recovery obtained by the injected CO2 and 4 operating parameters including CO2 bath pressure, CO2 bath temperature, and core sample bulk size, and exposing time have been also separately investigated. A Proxy model to associate the functionality of the improved Oil Recovery by CO2 injection and these 10 parameters have been constructed. Moreover, statistical methods for Design of Experiments (DOE) have been used to rank the most important parameters affecting CO2-EOR performance in the microscale level (lab scale) of these unconventional reservoirs. This study provides an important set of lab-based data obtained from natural preserved cores to find out the applicability of CO2-EOR in these unconventional reservoirs. Also, this research demonstrates some key points which could help in understanding CO2-EOR mechanisms in shale plays since they are much complex and very different from conventional formations.

  • Lessons Learned from IOR Pilots in Bakken Formation by Using Numerical Simulation
    Journal of Petroleum Science and Engineering, 2018
    Co-Authors: Dheiaa Alfarge, Mingzhen Wei, Baojun Bai, Mortadha Alsaba
    Abstract:

    Abstract Bakken is the most productive formation among unconventional plays in North America. This formation has about 7.4 billion barrels of recoverable Oil. However, the Primary Oil Recovery is still low as 5–10%. Miscible natural gas and carbon dioxide (CO2) might be the most two potential strategies to improve Oil Recovery in such a complex play. In this study, some of the IOR pilots which have been conducted in Montana, North Dakota, and South Saskatchewan have been presented. The performance results of these pilots in US-Bakken versus Canadian-Bakken have been compared. Moreover, the reasons behind the successful IOR pilots in Canadian-Bakken versus US-Bakken have been discussed. Then, numerical simulation models have been constructed to mimic the results of some pilots. Two different compositional models have been built for Oils of two different formations. Furthermore, two different models, single porosity model and dual permeability model have been created to match the performance of some pilots. Implementation of molecular diffusion mechanism has been conducted in both of single porosity and dual permeability model. Finally, the continuous miscible gases injection versus huff-n-puff protocols have been compared and investigated. The results showed that the performance of natural gases generally over-performed the CO2 injection technique's in Bakken formation. Although the diffusion flow is dominant in these types of reservoirs, the diffusivity of the injected CO2 into formation Oil is slow due to the fact that CO2 has large molecules as compared with the small pore throats of these porous media. Accordingly, miscible CO2-EOR might not be beneficial in huff-n-puff operations as in continuous flooding process. However, the success of natural gases based EOR does not have that strong functionality of molar diffusivity. Therefore, their performance was much better than CO2 performance in the field scale of these tight formations. Furthermore, the numerical simulation of this study concluded that the spacing between the production wells and injection wells should be minimized, for the continuous flooding process of miscible-gases EOR, to enhance their performance. Although the permeability of Canadian-Bakken has a permeability of 1–2 order higher than the permeability of US-Bakken, the pilots' spacing between injectors and producers in Canadian Bakken is interestingly much shorter than that for US-Bakken, which might be the reason behind the EOR success in Canadian Bakken. Finally, the activatiown process of the highly intensive natural fractures might be the key to enhance the diffusivity of CO2-EOR. Otherwise, natural gases are highly recommended to be the most potential EOR in these types of reservoirs. This study explains how the diffusion mechanism affects the performance of different miscible gases to improve Oil Recovery in these plays since they are more complex and very different from conventional formations. Also, it suggests that CO2 flooding process would be a good practice to overcome the limitations of CO2-diffusion rate in these reservoirs if the conformance problems are wisely controlled.

  • Analysis of IOR Pilots in Bakken Formation by Using Numerical Simulation
    Day 4 Thu November 16 2017, 2017
    Co-Authors: Dheiaa Alfarge, Mingzhen Wei, Baojun Bai, Mortadha Alsaba
    Abstract:

    Abstract Bakken is the most productive formation among unconventional plays in North America. This formation has 7.4 billion barrels of recoverable Oil. However, the Primary Oil Recovery is still low as 5-10%. Miscible natural gas and carbon dioxide (CO2) might be the most two potential strategies to improve Oil Recovery in such complex play. In this study, some of the IOR pilots which have been conducted in Montana, North Dakota, and South Saskatchewan have been presented. The performance results of these pilots in US-Bakken versus Canadian-Bakken have been compared. Moreover, the reasons beyond the successful IOR pilots in Canadian-Bakken versus US-Bakken have been discussed. Then, numerical simulation models have been constructed to mimic the results of these pilots. Two different compositional models have been built for two different formation-Oils. Furthermore, two different models, single porosity model and dual permeability model have been created to match the performance of some pilot-tests. Implementation of molecular diffusion mechanism has been conducted in both of single porosity and dual permeability model. Finally, continuous miscible gases injection versus huff-n-puff protocols have been compared and investigated. The results showed that the performance of natural gases generally over-performed the CO2 injection technique's in Bakken formation. Although the diffusion flow is dominant, the diffusivity of the injected CO2 into formation Oil is slow due to its large molecules as compared with the small pore throats of these porous media. Accordingly, miscible CO2-EOR might be not beneficial in huff-n-puff as compared to continuous flooding process. However, success of natural gases does not have that strong functionality of molar diffusivity. Therefore, their performance was much better than CO2 performance in the field scale of these tight formations. Furthermore, the numerical simulation of this study concluded that the spacing between the production wells and injection wells should be minimized, for the continuous flooding process of miscible-gases EOR, to enhance their performance. Although the permeability of Canadian-Bakken has permeability of 1-2 order higher than the permeability of US-Bakken, the spacing between injectors and producers in Canadian Bakken is interestingly much shorter than that for US-Bakken, which might be the reason beyond the EOR success in Canadian Bakken. Finally, the activation process for the highly intensive natural fractures might be the key to enhance the diffusivity of CO2-EOR. Otherwise, natural gases are highly recommended to be the most potential EOR in these types of reservoirs. This study explains how diffusion mechanism of miscible gases affects their performance to improve Oil Recovery in these plays since they are more complex and very different from conventional formations. Also, it suggests that CO2 flooding process would be a good practice to overcome the limitations of CO2-diffusion rate in these reservoirs.

  • Factors Affecting CO2-EOR in Shale-Oil Reservoirs: Numerical Simulation Study and Pilot Tests
    Energy & Fuels, 2017
    Co-Authors: Dheiaa Alfarge, Mingzhen Wei, Baojun Bai
    Abstract:

    Shale Oil reservoirs such as Bakken, Niobrara, and Eagle Ford have become the main target for Oil and gas investors as conventional formations started to be depleted and diminished in number. These unconventional plays have a huge Oil potential; however, the predicted Primary Oil Recovery is still low as an average of 7.5%. Injecting carbon dioxide (CO2) to enhance Oil Recovery in these poor-quality formations is still a debatable issue among investigators. In this study, three steps of research have been integrated to investigate the parameters that control the success of CO2 huff-n-puff process in the field scale of shale Oil reservoirs. First, a numerical simulation study was conducted to upscale the reported experimental studies outcomes to the field conditions. The second step was to validate these numerical models with the field data from some of CO2-EOR pilots, which were performed in Bakken formation, in North Dakota and Montana regions. Finally, statistical methods for Design of Experiments (DOE)...

Deepak Tapriyal - One of the best experts on this subject based on the ideXlab platform.

James J. Sheng - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Fracture Characteristics on Behavior of Fractured Shale-Oil Reservoirs by Cyclic Gas Injection
    SPE Reservoir Evaluation & Engineering, 2016
    Co-Authors: Tao Wan, James J. Sheng, Mohamed Y. Soliman, Y.. Zhang
    Abstract:

    Summary The current technique to produce shale Oil is to use horizontal wells with multistage stimulation. However, the Primary Oil-Recovery factor is only a few percent. The low Oil Recovery and abundance of shale reservoirs provide a huge potential for enhanced Oil-Recovery (EOR) process. Well productivity in shale Oil-and-gas reservoirs primarily depends on the size of fracture network and the stimulated reservoir volume (SRV) that provides highly conductive conduits to communicate the matrix with the wellbore. The fracture complexity is critical to the well-production performance, and it also provides an avenue for injected fluids to displace the trapped Oil. However, the disadvantage of gasflooding in fractured reservoirs is that injected fluids may break through to production wells by means of the fracture network. Therefore, a preferred method is to use cyclic gas injection to overcome this problem. In this paper, we use a numerical-simulation approach to evaluate the EOR potential in fractured shale-Oil reservoirs by cyclic gas injection. Simulation results indicate that the stimulated fracture network contributes significantly to the well productivity by means of its large contact area with the matrix, which prominently enhances the macroscopic sweep efficiency in secondary cyclic gas injection. In our previous simulation work, the EOR potential was evaluated in hydraulic planar-traverse fractures without considering the propagation of a natural-fracture network. In this paper, we examine the effect of fracture networks on shale Oilwell secondary-production performance. The impact of fracture spacing and stress-dependent fracture conductivity on the ultimate Oil Recovery is investigated. The results presented in this paper demonstrate that cyclic gas injection has EOR potential in shale-Oil reservoirs. This paper focuses on evaluating the effect of fracture spacing, the size of the fracture network, fracture connectivity (uniform and nonuniform), and stress-dependent fracture-network conductivity on well-production performance of shale-Oil reservoirs by secondary cyclic gas injection.

  • Surfactant Preflood to Improve Waterflooding Performance in Bakken Shale Formation
    2015
    Co-Authors: Samiha Morsy, James J. Sheng
    Abstract:

    The lower Primary Oil Recovery from shale formations accelerated the application of waterflooding technology as a secondary Recovery mechanism at an earlier time compared with conventional reservoirs. This situation suggests the EOR surfactant technology designed to promote additional Oil Recovery from fractured carbonate formations is a fit for these shale formations that are characterized by complex fractured lithology. The presented study investigates the idea of incorporating appropriate surfactant formulations at a low dosage as a preflood to waterflooding in shale formations. If properly designed, such surfactant in the preflood fluid will penetrate into the high Oil saturation matrix or natural fracture region and accelerate the extraction of the Oil in place by rapid imbibition. This extracted Oil can readily move from the matrix into the propped fracture system, and then be produced. Another benefit of the preflood surfactant is that it is engineered in such a way that it leaves the matrix or natural fracture face water wet to facilitate Oil movement during production. This paper presents a study of a series of surfactant additives developed for extracting additional Oil. Over 10 of these specially customized product blends were evaluated in the laboratory for their effectiveness in increasing Oil Recovery of Bakken formation. Only one surfactant (Stim aid A) was compatible with Bakken formation brine and crude Oil, so it was the only one used for spontaneous imbibition experiments. The average porosity of the used Bakken reservoir samples was 5.8% with an average bulk density of 2.75 g/cc. The Bakken rock samples were pre-treated with different surfactant solutions and then used for water spontaneous imbibition experiments. During the spontaneous imbibition, the maximum Oil Recovery was from the samples that were pre-treated with 2 wt.% of (Stim aid A) surfactant. The measured contact angles on Bakken samples showed an alteration in rock wettability that interpreted the improvement of Bakken higher Recovery factors from spontaneous imbibition in surfactant solutions compared with brine solutions only.

  • Surfactant Preflood to Improve Waterflooding Performance in Shale Formations
    All Days, 2014
    Co-Authors: Samiha Morsy, James J. Sheng
    Abstract:

    Abstract The lower Primary Oil Recovery from shale formations accelerated the application of waterflooding technology as a secondary Recovery mechanism at earlier time compared with conventional reservoirs. This situation suggests the EOR surfactant technology designed to promote additional Oil Recovery from fractured carbonate formations is a fit for these shale formations that are characterized by complex fractured lithology. The presented study investigates the idea to incorporate appropriate surfactant formulations at a low dosage as a preflood to waterflooding in shale formations. If properly designed, such surfactant in the preflood fluid will penetrate into the high Oil saturation matrix or natural fracture region and accelerate the extraction of the Oil in place by rapid imbibition. This extracted Oil can readily move from the matrix, into the propped fracture system, and then is produced. Another benefit of the preflood surfactant is engineered in such that it leaves the matrix or natural fracture face water wet to facilitate Oil movement during production. This paper presents a study of a series of surfactant additives developed for extracting additional Oil. Over 10 of special customized product blends were evaluated in laboratory for their effectiveness in increasing Oil Recovery of Bakken formation. Only one surfactant (Stim aid A) that was compatible with Bakken formation brine and crude Oil, so it was the only one used for spontaneous imbibition experiments. The average porosity of the used Bakken reservoir samples was 5.8% with an average bulk density of 2.75 g/cc. The Bakken rock samples were pre-treated with different surfactant solutions and then used for water spontaneous imbibition experiments. During the spontaneous imbibition, the maximum Oil Recovery was from the samples that were pre-treated with 2 wt% of (Stim aid A) surfactant. The measured contact angles on Bakken samples showed an alteration in rock wettability that interpreted the improvement of Bakken higher Recovery factors from spontaneous imbibition in surfactant solutions compared with brine solutions only.

  • Evaluate EOR Potential in Fractured Shale Oil Reservoirs by Cyclic Gas Injection
    Unconventional Resources Technology Conference Denver Colorado 12-14 August 2013, 2013
    Co-Authors: Tao Wan, James J. Sheng, Mohamed Y. Soliman
    Abstract:

    The current technique to produce shale Oil is to use horizontal wells with multi-stage stimulation. However, the Primary Oil Recovery factor is only a few percent. The low Recovery and the abundance of shale reservoirs provide a huge potential for enhanced Oil Recovery. Well productivity in shale Oil and gas reservoirs primarily depends upon the size of fracture network and the stimulated reservoir volume (SRV) which provides highly conductive conduits to communicate the matrix with the wellbore. The natural fracture complexity is critical to the well production performance and it also provides an avenue for injected fluids to displace the Oils. However, the disadvantage of flooding in fractured reservoirs is that the injected fluids may break through to production wells via the fracture network. Therefore, a preferred method is to use cyclic gas injection to overcome this problem. In this paper, we use a numerical simulation approach to evaluate the EOR potential in fractured shale Oil reservoirs by cyclic gas injection. Simulation results indicate that the stimulated fracture network contributes significantly to the well productivity via its large contact volume with the matrix, which prominently enhances the macroscopic sweep efficiency in secondary cyclic gas injection. In our previous simulation work, the EOR potential was evaluated from planar traverse fractures. In this paper, we examine the EOR potential by including the effect of fracture networks. Therefore, a higher Oil Recovery potential is demonstrated. The impacts of fracture spacing density and stress dependent fracture conductivity on the ultimate Oil Recovery are also investigated. In a case where the fracture network spacing is 100 ft and the fracture network is 100% stimulated, it can achieve more than 60% of incremental Oil Recovery. The results presented in this paper demonstrate an EOR potential by cyclic gas injection in fractured shale Oil reservoirs.