Effects of Imbibition During Well Shut-In on Ultimate Shale Oil Recovery: A Numerical Study

2021 ◽  
Author(s):  
Nur Wijaya ◽  
James Sheng
Keyword(s):  
Hydraulic Fracturing ◽  
Oil Recovery ◽  
Numerical Study ◽  
Extended Period ◽  
Strong Relationship ◽  
Driving Mechanism ◽  
Shale Oil ◽  
Probabilistic Forecasting ◽  
Reservoir Conditions ◽  
Shale Oil Reservoirs

Abstract Shale wells are often shut-in after hydraulic fracturing is finished. Shut-in often lasts for an extended period in the perceived hope to improve the ultimate oil recovery. However, current literature does not show a strong consensus on whether shut-in will improve the ultimate oil recovery. Because of the delayed production, evaluating the benefits of shut-in in improving the ultimate oil recovery is crucial. Otherwise, shut-in would merely delay the production and harm the economic performance. This paper uses a numerical flow-geomechanical modeling approach to investigate the effect of imbibition on shut-in potentials to improve the ultimate oil recovery. This paper proposes that imbibition is one of the strongly confounding variables that cause the mixed conclusions in the related literature. The investigation methodology involves probabilistic forecasting of three reservoir realization models validated based on the same field production data. Each of the models represents different primary recovery driving mechanism, such as imbibition-dominant and compaction-dominant recovery. A parametric study is conducted to explore and identify the specific reservoir conditions in which shut-in tends to improve the shale oil recovery. Ten reservoir parameters which affect the imbibition strength are studied under different shut-in durations. Comparison among the three models quantitatively demonstrates that shut-in tends to improve the ultimate oil recovery only if the shale reservoir demonstrates imbibition-dominant recovery. A first-pass economic analysis also suggests that when the shale oil reservoirs demonstrate such an imbibition-dominant recovery, shut-in tends to not only improve the ultimate oil recovery, but also the NPV. A correlation among ultimate oil recovery, flowback efficiency, and NPV also shows that there is no strong relationship between flowback efficiency and ultimate oil recovery. This study is one of the first to emphasize the importance of quantifying the imbibition strength and its contribution in helping recover the shale oil for optimum flowback framework and shale well shut-in design after hydraulic fracturing.

Effects of Imbibition and Compaction during Well Shut-In on Ultimate Shale Oil Recovery: A Numerical Study

2021 ◽  
pp. 1-15
Author(s):  
Nur Wijaya ◽  
James Sheng
Keyword(s):  
Hydraulic Fracturing ◽  
Oil Recovery ◽  
Net Present Value ◽  
Numerical Study ◽  
Extended Period ◽  
Strong Relationship ◽  
Shale Oil ◽  
Probabilistic Forecasting ◽  
Driving Mechanisms ◽  
Reservoir Conditions

Summary Shale wells are often shut in after hydraulic fracturing is completed. Shut-in often lasts for an extended period in the perceived hope of improving the ultimate oil recovery. However, current literature does not show a strong consensus on whether shut-in will improve ultimate oil recovery. Because of the delayed production, evaluating the benefits of shut-in in improving the ultimate oil recovery is crucial. Otherwise, shut-in would merely delay the production and harm the economic performance. In this paper, we use a numerical flow-geomechanical modeling approach to investigate the effect of imbibition on shut-in potentials to improve the ultimate oil recovery. We propose that imbibition is one of the strongly confounding variables that causes mixed conclusions in the related literature. The investigation methodology involves probabilistic forecasting of three reservoir realization models validated based on the same field production data. Each of the models represents different primary recovery-driving mechanisms, such as imbibition-dominant and compaction-dominantrecovery. A parametric study is conducted to explore and identify the specific reservoir conditions in which shut-in tends to improve shale oil recovery. Ten reservoir parameters that affect the imbibition strength are studied under different shut-in durations. Comparison among the three models quantitatively demonstrates that shut-in tends to improve both the ultimate oil recovery and net present value (NPV) only if the shale reservoir demonstrates imbibition-dominant recovery. A correlation among ultimate oil recovery, flowback efficiency, and NPV also shows that there is no strong relationship between flowback efficiency and ultimate oil recovery. This study is one of the first to emphasize the importance of quantifying the imbibition strength and its contribution in helping recover the shale oil for optimum flowback and shale well shut-in design after hydraulic fracturing.

Experimental and Numerical Study on CO2 Sweep Volume during CO2 Huff-n-Puff Enhanced Oil Recovery Process in Shale Oil Reservoirs

2019 ◽  
Vol 33 (5) ◽  
pp. 4017-4032 ◽  
Author(s):  
Lei Li ◽  
Yuliang Su ◽  
James J. Sheng ◽  
Yongmao Hao ◽  
Wendong Wang ◽  
...  
Keyword(s):  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Numerical Study ◽  
Recovery Process ◽  
Oil Reservoirs ◽  
Shale Oil ◽  
Shale Oil Reservoirs

scholarly journals Study on mechanism of spontaneous imbibition and pressurized imbibition in shale oil reservoirs

2020 ◽  
Author(s):  
Lanlan Yao ◽  
Zhengming Yang ◽  
Haibo Li ◽  
Bo Cai ◽  
Chunming He ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Spontaneous Imbibition ◽  
Oil Reservoirs ◽  
Recovery Ratio ◽  
Shale Oil ◽  
Fracture System ◽  
Matrix System ◽  
Jianghan Basin ◽  
Shale Oil Reservoirs ◽  
Shale Permeability

AbstractImbibition is one of the important methods of oil recovery in shale oil reservoirs. At present, more in-depth studies have been carried out on the fracture system and matrix system, and there are few studies on the effect of energy enhancement on imbibition in shale oil reservoirs. Therefore, based on the study of pressurized imbibition and spontaneous imbibition of shale oil reservoirs in Qianjiang Sag, Jianghan Basin, nuclear magnetic resonance technology was used to quantitatively characterize the production degree of shale and pore recovery contribution under different imbibition modes, and analyze the imbibition mechanism of shale oil reservoirs under the condition of energy enhancement. The experimental results showed that with the increase in shale permeability, the recovery ratio of pressurized imbibition also increased. The rate of pressurized imbibition was higher than spontaneous imbibition, and pressurized imbibition can increase the recovery ratio of fractured shale. Spontaneous imbibition can improve the ultimate recovery ratio of matrix shale. Pressurized imbibition can increase the recovery contribution of macroporous and mesoporous.

scholarly journals Mechanisms and capacity of high-pressure soaking after hydraulic fracturing in tight/shale oil reservoirs

2020 ◽  
Author(s):  
Jing Wang ◽  
Hui-Qing Liu ◽  
Gen-Bao Qian ◽  
Yong-Can Peng
Keyword(s):  
High Pressure ◽  
Hydraulic Fracturing ◽  
Specific Surface ◽  
Surface Area ◽  
Oil Reservoirs ◽  
Shale Oil ◽  
Oil Viscosity ◽  
Soaking Time ◽  
Matrix Permeability ◽  
Shale Oil Reservoirs

Abstract Huff-n-puff by water has been conducted to enhance oil recovery after hydraulic fracturing in tight/shale oil reservoirs. However, the mechanisms and capacity are still unclear, which significantly limits the application of this technique. In order to figure out the mechanisms, the whole process of pressurizing, high-pressure soaking, and depressurizing was firstly discussed, and a mechanistic model was established. Subsequently, the simulation model was verified and employed to investigate the significances of high-pressure soaking, the contributions of different mechanisms, and the sensitivity analysis in different scenarios. The results show that high-pressure soaking plays an essential role in oil production by both imbibition and elasticity after hydraulic fracturing. The contribution of imbibition increases as the increase in bottom hole pressure (BHP), interfacial tension, and specific surface area, but slightly decreases as the oil viscosity increases. In addition, it first decreases and then slightly increases with the increase in matrix permeability. The optimal soaking time is linear with the increases of both oil viscosity and BHP and logarithmically declines with the increase in matrix permeability and specific surface area. Moreover, it shows a rising tendency as the interficial tension (IFT) increases. Overall, a general model was achieved to calculate the optimal soaking time.

scholarly journals The effects of ion diffusion on imbibition oil recovery in salt-rich shale oil reservoirs

2019 ◽  
Vol 16 (3) ◽  
pp. 525-540 ◽  
Author(s):  
Liu Yang ◽  
Xuhui Zhang ◽  
Tong Zhou ◽  
Xiaobing Lu ◽  
Chuanqing Zhang ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Oil Reservoirs ◽  
Shale Oil ◽  
Ion Diffusion ◽  
Shale Oil Reservoirs
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