页岩储层盐离子扩散规律及其在压裂缝网诊断中的应用  

The Diffusion Law of Salt Ions in Shale Reservoirs and Its Application in Hydraulic Fracture Network Diagnostics

作　　者：刘拯君 张衍君 廖婉蓉 杨兵 杨柳[2] 周德胜[1] LIU Zhenjun;ZHANG Yanjun;LIAO Wanrong;YANG Bing;YANG Liu;ZHOU Desheng(College of Petroleum Engineering,Xi'an Shiyou University,Xi'an 710065,Shaanxi,China;China University of Mining and Technology(Beijing),Haidian 100083,Beijing,China)

机构地区：[1]西安石油大学石油工程学院,陕西西安710065 [2]中国矿业大学(北京),北京海淀100083

出　　处：《新疆石油天然气》2025年第1期41-49,共9页Xinjiang Oil & Gas

基　　金：国家自然科学基金联合项目“超深储层水力压裂改造裂缝轨迹延伸机理与控制方法研究”(U23B2089)。

摘　　要：页岩储层具有低孔、低渗、难动用等特点,通常采用长水平井和大规模体积压裂组合技术进行开发。压裂液进入地层后与储层发生一系列物理-化学反应,其中盐离子扩散作用显著,但针对离子扩散机理及其诊断压裂缝网作用的现有研究尚不完善。采用理论分析和现场案例相结合的方法总结了页岩储层中盐离子来源、离子扩散特征、机理及影响因素,给出了基于盐离子扩散机理诊断压裂缝网的实例。页岩储层盐离子来源包括储层孔隙壁面水膜中的溶解盐、生烃排水时的结晶盐、水-岩相互作用的产出盐。离子扩散特征与渗吸过程相似,分为扩散初期、过渡期、后期三个阶段;其中初期离子扩散速率较高,对数时间尺度上呈线性关系,遵循Fick定律和Einstein-Smoluchowski方程;影响盐离子扩散的因素包括储层性质、溶液性质、温度、黏度等;盐离子扩散可用于体积压裂缝网发育程度诊断。盐离子扩散诊断压裂缝网发育程度的方法可为页岩储层压裂设计和缝网评估提供科学指导,有助于实现更加精准和有效的储层改造,推动页岩油气资源的高效开发和利用。Shale reservoirs are characterized by low porosity,low permeability,and difficulty in exploitation,typically requiring the development approach combining long horizontal wells with large-scale volume fracturing techniques.After the fracturing fluid enters the formation,it undergoes a series of physical and chemical reactions with the reservoir,where salt ion diffusion plays a significant role.However,the existing research on the mechanism of ion diffusion and its application to diagnosing hydraulic fracture network is still imperfect.Therefore,this paper combines theoretical analysis with field cases to summarize the sources of salt ions in shale reservoirs,and the characteristics,mechanisms and influencing factors of ion diffusion,and presents an example of diagnosing hydraulic fracture network based on salt ion diffusion.The sources of salt ions in shale reservoirs include dissolved salts in the water film on the pore walls,crystallized salts from hydrocarbon generation and water expulsion,and salts produced by water-rock interactions.The characteristics of ion diffusion are similar to the imbibition process,which is divided into three stages:initial,transitional,and late diffusion.The initial ion diffusion rate is relatively high,exhibits a linear relationship on a logarithmic time scale,and follows Fick's law and the Einstein-Smoluchowski equation.The factors affecting salt ion diffusion include reservoir properties,solution properties,and other factors such as temperature and viscosity.Saltion diffusion can be used for the diagnosis of the development degree of volume fracturing fracture network.The method of diagnosing hydraulic fracture network through salt ion diffusion can provide scientific guidance for shale reservoir fracturing design and fracture network evaluation,help to deliver more accurate and effective reservoir stimulation and promote the efficient development and utilization of shale oil and gas resources.

关 键 词：页岩储层 离子扩散 体积压裂 缝网诊断 返排液 

分 类 号：TE348[石油与天然气工程—油气田开发工程]