自渗吸作用下深层页岩裂缝演化及力学特性  

Fracture Evolution and Mechanical Properties of Deep Shales Under Spontaneous Imbibition

作　　者：方正 陈勉[1,2] 李集 韦世明 考佳玮 毛渝 FANG Zheng;CHEN Mian;LI Ji;WEI Shiming;KAO Jiawei;MAO Yu(China University of Petroleum(Beijing),State Key Laboratory of Petroleum Resources and Prospecting,Beijing 102249,China;China University of Petroleum(Beijing),MOE Key Laboratory of Petroleum Engineering,Beijing 102249,China;Research Institute of Engineering Technology,Southwest Oil&Gas Company,Sinopec,Beijing 102249,China)

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]中国石油大学(北京)石油工程教育部重点实验室,北京102249 [3]中国石化西南油气分公司石油工程技术研究院,北京102249

出　　处：《新疆石油地质》2025年第2期208-216,共9页Xinjiang Petroleum Geology

基　　金：国家自然科学基金(52334001);国家自然科学基金青年项目(42407252);中国石油大学(北京)青年拔尖人才项目(ZX20230042)。

摘　　要：针对深层页岩储集层水力压裂后压裂液与储集层发生渗吸,导致裂缝扩展机理不明确及其对储集层力学特性变化不清晰的问题,通过CT扫描、连续划痕测试和覆压孔渗仪测试,结合自渗吸实验,综合评价渗吸前后裂缝扩展规律、岩石力学特性及物性参数变化特性。结果表明:渗吸促使页岩层理与原有微裂纹被激活、扩展并相互贯通,从而形成更为复杂的裂缝网络,提高了储集层孔隙度与渗透率;裂缝发育与层理弱面的相互作用使岩石整体强度与稳定性下降,呈现出提高流体输导能力与降低力学性能的双重效应;在有限裂纹扩展条件下,孔隙度和渗透率增幅有限,而当复杂裂缝网络充分发育时,孔隙度和渗透率大幅提升,力学性能弱化更为显著。在非常规储集层评价与增产改造设计中,应平衡自渗吸诱发的裂缝网络,形成对储集层渗流条件与地层稳定性的影响。The mechanism of fracture propagation and changes in mechanical properties of deep shale reservoirs caused by the imbibition of fracturing fluid after hydraulic fracturing remain unclear.By CT scanning,continuous scratch testing,and overburden pressure porosity-permeability testing,as well as spontaneous imbibition experiments,the fracture propagation patterns,changes in rock mechanics,and vari-ations in physical properties before and after imbibition were comprehensively evaluated.The results show that imbibition promotes the ac-tivation,propagation,and interconnection of shale beddings and pre-existing microcracks,forming a more complex fracture network to en-hance reservoir porosity and permeability.The development of fracture and bedding plane reduce the overall strength and stability of rock,demonstrating a dual effect of improving fluid transport capacity while weakening mechanical performance.Under limited crack propaga-tion conditions,the increase in porosity and permeability is modest.When a complex fracture network is developed,reservoir porosity and permeability significantly improve,and mechanical weakening becomes more pronounced.In the evaluation and stimulation design of un-conventional reservoirs,it is essential to balance the fracture network induced by spontaneous imbibition to account for its impact on reser-voir flow conditions and formation stability.

关 键 词：深层页岩 渗吸作用 裂缝扩展 岩石力学 水力压裂 物性参数 连续划痕测试 CT扫描 

分 类 号：TE357[石油与天然气工程—油气田开发工程]