致密储层岩石超低渗测试系统研发与应用进展

DEVELOPMENT AND APPLICATION PROGRESS OF ULTRA-LOW PERMEABILITY TESTING SYSTEM FOR TIGHT RESERVOIR ROCKS

面向深部非常规能源开发领域,自主研制了一套适应于储层特性和深埋环境的超低渗测试系统,旨在解决高地温、高地压、高孔压条件下致密岩石超低渗透率精准测定的难题。该系统由渗流管路和高温高压多通道压力室两部分重要组件构成,经过创新设计和系统优化,能稳定且可靠地模拟150℃高温、150 MPa围压和100 MPa孔压的深部储层环境,并能实现从亚纳达西至毫达西量级岩石样品渗透率的脉冲衰减法测量。基于该系统,开展了花岗岩和页岩在不同加卸载循环、有效应力、孔隙压力和温度条件下的渗透率测试。测试结果表明,加卸载循环次数增加有助于减少取样、制样过程中次生变形或次生微裂隙对测试结果的干扰;孔隙压力的提升抑制了气体滑脱效应,测得的表观渗透率更接近固有渗透率;相同有效应力条件下,页岩单一裂隙渗透率比基质渗透率至少高3个数量级;所建立的裂隙渗透率物理模型精准拟合了单一裂隙渗透率的测试结果,适用于刻画有效应力、孔隙压力和裂隙压缩变形共同影响下的裂隙页岩渗透率变化规律;固定有效应力和孔隙压力条件时,页岩渗透率随温度升高而降低。综上所述,所研发的超低渗测试系统可为致密储层渗透率的评价提供技术支撑,相关测试结果有助于加深对深部储层环境中流体运移机制的理解。

This study focuses on the development of unconventional energy resources in deep subsurface environments,where a specialized ultra-low permeability testing system has been independently developed.The system is tailored to reservoir characteristics and extreme burial conditions,aiming to solve the challenges of accurately determining ultra-low permeability in dense rocks under high geothermal temperatures,high geo-stress,and high pore pressures.The system comprises two key components:a flow pipeline and a high-temperature,high-pressure multi-channel pressure chamber.Through innovative design and system optimization,it reliably simulates deep reservoir environments with temperatures up to 150℃,confining pressures of 150 MPa,and pore pressures of 100 MPa.Additionally,it measures the permeability of rock samples ranging from sub-nanodarcy to millidarcy levels using the pulse decay method.Based on this system,we have conducted permeability tests on granite and shale under various conditions,including different loading and unloading cycles,effective stress,pore pressure,and temperature.The results indicate that increased loading and unloading cycles help reduce the impact of secondary deformation or micro-fractures during sampling and preparation on the test results;increased pore pressure suppresses the gas slippage effect,leading to apparent permeability measurements that more closely reflect the intrinsic permeability.Under identical effective stress conditions,the permeability of a single fracture in shale is at least three orders of magnitude higher than that of the matrix.The developed physical model for fracture permeability accurately fits the experimental results and describes the permeability variations in fractured shale under the combined effects of effective stress,pore pressure,and fracture compression deformation.Furthermore,under fixed conditions of effective stress and pore pressure,shale permeability decreases as temperature increases.In summary,the developed ultra-low permeability testing system provides technical support for permeability evaluation in tight reservoirs,and the relevant test results contribute to a deeper understanding of fluid migration mechanisms in deep reservoir environments.