Study on Gas Loss Characteristics of Shale Based on Gas Diffusion Model

doi:10.11885/j.issn.1674-5086.2021.02.27.02

Abstract

Abstract: The commonly used lost gas calculation models of shale use different assumptions or simplified conditions, and result in the uncertainty of the lost gas content of shale. In this paper, the characteristics and deficiencies of the conventional unipore diffusion model are specified. A modified unipore diffusion model is established considering the time-dependent gas diffusion coefficient and time-dependent gas concentration at core boundary. The analysis indicates that the initial gas concentration, gas diffusion coefficient, gas concentration at core boundary, and core size are the key parameters affecting the shale gas loss process. USBM method may misestimate the lost gas content when the gas diffusion coefficient is too large, or the lost time is too long. Compared with the piecewise linear decline mode, the exponential decline mode of boundary gas concentration may be closer to the actual situation. The decline rate of boundary gas concentration mainly controls the total time of gas diffusion in the core, while the change rate of gas diffusion coefficient mainly affects the characteristics of gas diffusion at the early stage. The modified unipore diffusion model established in this paper can better reveal the gas loss characteristics of shale from the gas diffusion perspective, but the gas flow process under pressure difference should be further integrated into this mathematical method and its key parameters still need to be optimized based on the experimental data, so as to improve the calculation accuracy of lost gas content of shale.

Key words: shale, gas content, lost gas content, unipore diffusion model, key parameter

CLC Number:

TE155

TIAN Zhenhua, ZHOU Shangwen, LI Junqian, CAI Jianchao. Study on Gas Loss Characteristics of Shale Based on Gas Diffusion Model[J]. Journal of Southwest Petroleum University(Science & Technology Edition), 2021, 43(5): 56-65.

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References

[1] BERTARD C, BRUYET B, GUNTHER J. Determination of desorbable gas concentration of coal (direct method)[J]. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 1970, 7(1):43-65. doi:10.1016/0148-9062(70)90027-6
[2] SINGH H, CAI Jianchao. A mechanistic model for multi-scale sorption dynamics in shale[J]. Fuel, 2018, 234:996-1014. doi:10.1016/j.fuel.2018.07.104
[3] ZHAO Wei, CHENG Yuanping, PAN Zhejun, et al. Gas diffusion in coal particles:A review of mathematical models and their applications[J]. Fuel, 2019, 252:77-100. doi:10.1016/j.fuel.2019.04.065
[4] 周伟. 页岩气含气量计算方法研究[D]. 成都:成都理工大学,2019. ZHOU Wei. Study on the calculation method of shale gas content[D]. Chengdu:Chengdu Univerisity of Technology, 2019.
[5] LI Junqian, LU Shuangfang, ZHANG Pengfei, et al. Estimation of gas-in-place content in coal and shale reservoirs:A process analysis method and its preliminary application[J]. Fuel, 2020, 259:116266. doi:10.1016/j.fuel.2019.116266
[6] GOU Qiyang, XU Shang. Quantitative evaluation of free gas and adsorbed gas content of Wufeng-Longmaxi shales in the Jiaoshiba Area, Sichuan Basin, China[J]. Advances in Geo-Energy Research, 2019, 3(3):258-267. doi:10.26804/ager.2019.03.04
[7] YANG Feng, XIE Congjiao, NING Zhengfu, et al. High-pressure methane sorption on dry and moisture-equilibrated shales[J]. Energy & Fuels, 2017, 31(1):482-492. doi:10.1021/acs.energyfuels.6b02999
[8] ZHOU Junping, LIU Muhan, XIAN Xuefu, et al. Measurements and modelling of CH₄ and CO₂ adsorption behaviors on shales:Implication for CO₂ enhanced shale gas recovery[J]. Fuel, 2019, 251:293-306. doi:10.1016/j.fuel.2019.04.041
[9] WANG Sen, FENG Qihong, JAVADPOUR F, et al. Competitive adsorption of methane and ethane in montmorillonite nanopores of shale at supercritical conditions:A grand canonical Monte Carlo simulation study[J]. Chemical Engineering Journal, 2019, 355:76-90. doi:10.1016/j.cej.2018.08.067
[10] 邢雅文,张金川,冯赫青,等. 页岩含气量测试方法改进效果分析[J]. 断块油气田,2015,22(5):579-583. doi:10.6056/dkyqt201505008 XING Yawen, ZHANG Jinchuan, FENG Heqing, et al. Effectiveness analysis of determination method for shale gas content[J]. Fault-Block Oil & Gas Field, 2015, 22(5):579-583. doi:10.6056/dkyqt201505008
[11] 魏强,晏波,肖贤明. 页岩气解吸方法研究进展[J]. 天然气地球科学,2015,26(9):1657-1665. doi:10.11764/j.issn.1672-1926.2015.09.1657 WEI Qiang, YAN Bo, XIAO Xianming. Research progress on the desorption methods of shale gas[J]. Natural Gas Geoscience, 2015, 26(9):1657-1665. doi:10.11764/j.issn.1672-1926.2015.09.1657
[12] KISSELL F N, MCCULLOCH C M, ELDER C H. The direct method of determining methane content of coalbeds for ventilation design[R]. Washington:United States Departemnt of the Interior, 1973.
[13] 郝进,姜振学,邢金艳,等. 一种改进的页岩气损失气含量估算方法[J]. 现代地质,2015,29(6):1475-1482. doi:10.3969/j.issn.1000-8527.2015.06.023 HAO Jin, JIANG Zhenxue, XING Jinyan, et al. An improved method of calculating lost gas content of shale gas[J]. Geoscience, 2015, 29(6):1475-1482. doi:10.3969/j.issn.1000-8527.2015.06.023
[14] SMITH D M, WILLIAMS F L. Direct method of determining the methane content of coal:A modification[J]. Fuel, 1984, 63(3):425-427. doi:10.1016/00162361(84)90024-3
[15] SHTEPANI E, NOLL L A, ELROD L W, et al. A new regression-based method for accurate measurement of coal and shale gas content[J]. SPE Reservoir Evaluation & Engineering, 2010, 13(2):359-364. doi:10.2118/115405-PA
[16] YEE D, SEIDLE J P, HANSON W B. Gas sorption on coal and measurement of gas content:Chapter 9[M]//LAW B E, RICE D D. Hydrocarbons from coal. United States, 1993:203-218.
[17] 周尚文,王红岩,刘浩,等. 基于Arps产量递减模型的页岩损失气量计算方法[J]. 天然气地球科学,2019,30(1):102-110. doi:10.11764/j.issn.1672-1926.2018.10.021 ZHOU Shangwen, WANG Hongyan, LIU Hao, et al. A new calculation method for lost gas content of shale based on Arps production decline analysis model[J]. Natural Gas Geoscience, 2019, 30(1):102-110. doi:10.11764/j.issn.1672-1926.2018.10.021
[18] CRANK J. The mathematics of diffusion[M]. 2nd ed. Oxford:Oxford University Press, 1975.
[19] NANDI S P, WALKER P L. Activated diffusion of methane from coals at elevated pressures[J]. Fuel, 1975, 54(2):81-86. doi:10.1016/0016-2361(75)90061-7
[20] RUCKENSTEIN E, VAIDYANATHAN A S, YOUNGQUIST G R. Sorption by solids with bidisperse pore structures[J]. Chemical Engineering Science, 1971, 26(9):1305-1318. doi:10.1016/0009-2509(71)80051-9
[21] 周尚文,王红岩,薛华庆,等. 页岩含气量现场测试中损失气量的计算方法对比分析[J]. 中国科技论文,2018,13(21):2453-2460. doi:10.3969/j.issn.2095-2783.2018.21.010 ZHOU Shangwen, WANG Hongyan, XUE Huaqing, et al. Comparative analysis of calculation methods for lost gas in the field-test of shale gas content[J]. China Sciencepaper, 2018, 13(21):2453-2460. doi:10.3969/j.issn.2095-2783.2018.21.010
[22] 姚光华,王晓泉,杜宏宇,等. USBM方法在页岩气含气量测试中的适应性[J]. 石油学报,2016,37(6):802-806,814. doi:10.7623/syxb201606011 YAO Guanghua, WANG Xiaoquan, DU Hongyu, et al. Applicability of USBM method in the test on the shale gas content[J]. Acta Petrolei Sinica, 2016, 37(6):802-806, 814. doi:10.7623/syxb201606011
[23] 王志兴,侯吉瑞,李妍,等. 气体在原油中扩散系数影响因素研究进展[J]. 油田化学,2019,36(3):558-563. doi:10.19346/j.cnki.1000-4092.2019.03.032 WANG Zhixing, HOU Jirui, LI Yan, et al. Proceedings of influencing factors of gas diffusion coefficient in crude oil[J]. Oilfield Chemistry, 2019, 36(3):558-563. doi:10.19346/j.cnki.1000-4092.2019.03.032
[24] ZHANG Liehui, SHAN Baochao, ZHAO Yulong, et al. Review of micro seepage mechanisms in shale gas reservoirs[J]. International Journal of Heat and Mass Transfer, 2019, 139:144-179. doi:10.1016/j.ijheatmasstransfer.2019.04.141
[25] ZHANG Tao, SUN Shuyu. A coupled lattice Boltzmann approach to simulate gas flow and transport in shale reservoirs with dynamic sorption[J]. Fuel, 2019, 246:196-203. doi:10.1016/j.fuel.2019.02.117
[26] YUE Gaowei, WANG Zhaofeng, XIE Ce, et al. Time-dependent methane diffusion behavior in coal:Measurement and modeling[J]. Transport in Porous Media, 2017, 116(1):319-333. doi:10.1007/s11242-016-0776-x