摘要
页岩气的渗流特性极大地影响着采收率,但对页岩气渗流特性的研究大多是在不同围压条件下开展的,其结果尚不能揭示中间主应力对渗透率的影响。因此,选用涪陵页岩气区块志留系龙马溪组页岩露头立方体岩石试件,采用自主研发的“多功能真三轴流固耦合试验系统”开展了页岩真三轴流固耦合试验,利用Klinkenberg方程拟合试验数据分析不同中间主应力系数对页岩气渗流特性和气体滑脱效应的影响。试验结果表明:①当偏应力较小时,中间主应力对页岩渗透率演化的影响较小,而当偏应力增加时,其影响越大且越不可忽略;②滑脱系数—固有渗透率的关系式与试验数据的拟合结果显示二者具有良好的相关性,可用于对同区块页岩滑脱系数的预测;③当偏应力小于或等于35 MPa时,滑脱效应贡献率保持在65%以上,表明此时滑脱效应主导着页岩中气体的渗流。
Seepage behaviors in shale gas affect the recovery significantly.However,previous studies on the seepage are often done under different confining pressure,and studied findings fail to reveal the intermediate principal stress affecting permeability.So,by employing a self-developed true tri-axial liquid-solid coupling system with multiple functions,many coupling experiments were conducted on the cubic samples from shale outcrop of the Silurian Longmaxi Formation,Fuling shale gas block.Moreover,matching with the Klinkenberg equation,experimental data were adopted to analyze how different intermediate principal stress impacts on both seepage behaviors and slippage effect.Results show that(i)this principal stress has a little influence on permeability evolution at smaller deviatoric stress,while an incremental effect along with the increasing deviatoric stress cannot be ignored;(ii)after fitting the relation of slippage factor to inherent permeability with experimental data,a better correlation is found,which can be used to predict this factor for shale in the same block;and(iii)when the deviatoric stress is less than or equal to 35 MPa,the slippage contribution is above 65%,indicating that the slippage effect dominates gas seepage in shale.
作者
范翔宇
张昕宇
胡小媛
蒋长宝
张千贵
赵鹏斐
陈昱霏
FAN Xiangyu;ZHANG Xinyu;HU Xiaoyuan;JIANG Changbao;ZHANG Qiangui;ZHAO Pengfei;CHEN Yufei(School of Geosciences and Technology,Southwest Petroleum University,Chengdu,Sichuan 610500,China;National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu,Sichuan 610500,China;Chongqing Chuandongnan Survey and Design Institute Co.,Ltd.,Chongqing 400030,China;State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing 400030,China;School of Petroleum Engineering,Southwest Petroleum University,Chengdu,Sichuan 610500,China)
出处
《天然气勘探与开发》
2024年第2期97-103,共7页
Natural Gas Exploration and Development
基金
四川省自然科学基金项目(编号:2023NSFSC0938、2022NSFSC0185、2023NSFSC0921)。
关键词
中间主应力系数
页岩气渗流特性
真三轴
滑脱效应贡献率
偏应力
Intermediate principal stress
Seepage behaviors in shale gas
True triaxial
Slippage Contribution
Deviatoric stress
