页岩储层微观孔隙、流体测定方法及吸附—解吸实验——以鄂尔多斯榆林地区盒8段储层为例  

Determining methods of micro-pore and liquids and adsorption-desorption experiment for shale reservoir:Taking Member He-8 reservoir in Ordos Yulin area as an example

作　　者：周凯 陈西泮[2] 屈兴勃[1] ZHOU Kai;CHEN Xipan;QU Xingbo(The Earth Sciences and Resources College of Chang'an University,Xi'an 710054,China;Yanchang Oilfield Co Ltd,Yan'an 716000,China)

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]延长油田股份有限公司,陕西延安716000

出　　处：《大庆石油地质与开发》2022年第2期139-146,共8页Petroleum Geology & Oilfield Development in Daqing

基　　金：国家科技重大专项“鄂尔多斯盆地大型低渗透岩性地层油气藏开发示范工程”(2016ZX05050)。

摘　　要：微观孔隙结构是影响页岩储层吸附和解吸能力的重要因素。基于核磁共振测试原理,采用离心实验与热处理相结合方法,测定了页岩微观孔隙结构特征,定量识别了多种类型孔隙流体,并从微观孔隙尺度研究了吸附解吸过程中多态甲烷赋存量与压力的关系。结果表明:页岩中不可采出流体、可动流体的T;截止值分别为0.18~0.32 ms、0.67~1.07 ms,不可采出流体和可动流体的饱和度分别为7.39%~15.61%、36.25%~56.86%;吸附态甲烷赋存于驰豫时间小于3.42 ms的孔隙,游离态甲烷赋存于驰豫时间为3.42~121.44 ms的孔隙;吸附过程中甲烷首先赋存于基质和小孔,其次逐步进入大、中孔隙,而解吸过程中则是先由裂缝、大孔隙到中、小孔隙,再到微孔隙;吸附态甲烷赋存量与压力呈非线性关系,当压力小于7.25 MPa时出现解吸滞后现象,且滞后程度随压力的降低而增大,游离态甲烷临界解吸滞后压力为1.17 MPa。研究成果可为鄂尔多斯盆地页岩气的高效开发提供技术支持。Micro-pore structure is an important factor affecting adsorption and desorption capacities of shale reservoir.On the basis of testing principle of nuclear magnetic resonance(NMR)and with the help of combined centrifugal test and heat treatment,the micro-pore structure characteristics of shale are determined.Several kinds of pore fluids are quantitatively identified,and relationship between polymorphic methane quantity and pressure in the process of adsorption and desorption are studied at micro-pore scale.The results show that T;cut-off values of non-recoverable fluid and movable fluid in the shale are 0.18~0.32 ms and 0.67~1.07 ms respectively,with corresponding saturation values of 7.39%~15.61%and 36.25%~56.86%respectively.Adsorbed methane occurs in the pores with diameter less than 3.42 ms,and free methane distributes in the pores with diameter of 3.42 ms~121.44 ms.In adsorption process,methane preferentially exists in matrix and pores,and then gradually enters into macropores and meso-pores;while in desorption process,it is from fractures,macropores to medium and small pores,and then in micropores.There is a non-linear relationship between absorbed methane quantity and pressure.When the pressure is less than 7.25 MPa,desorption hysteresis phenomenon appears,and the degree of hysteresis increases with the decrease of pressure;the critical desorption hysteresis pressure of free methane is 1.17 MPa.The study achievements provide technical support for high-efficiency development of shale gas in Ordos Basin.

关 键 词：页岩气 微观孔隙结构 吸附 解吸 核磁共振 盒8段 榆林地区 

分 类 号：TE132[石油与天然气工程—油气勘探]