页岩柱塞样与碎样孔隙度差异性分析与启示

Analysis and enlightenment of porosity differences between shale plug samples and crushed samples

付永红 蒋裕强 陈虎 周克明 邱峋晰 张海杰 刘雄伟 谷一凡 蒋增政

FU Yonghong JIANG Yuqiang CHEN Hu ZHOU Keming QIU Xunxi ZHANG Haijie LIU Xiongwei GU Yifan JIANG Zengzheng

西南石油大学 地球科学与技术学院, 成都 610500 中国石油非常规油气重点实验室 储层评价实验室, 成都 610500 中国石油 西南油气田公司 开发事业部, 成都 610051 中国石油 西南油气田公司 勘探开发研究院, 成都 610213 四川页岩气勘探开发有限责任公司, 成都 610051 重庆页岩气勘探开发有限责任公司, 重庆 610213 四川杰瑞泰克科技有限公司, 成都 610500

School of Geoscience and Technology, Southwest Petroleum University, Chengdu, Sichuan 610500, China Unconventional Reservoir Evaluation Laboratory, UOGKL, CNPC, Chengdu, Sichuan 610500, China Exploration Department, PetroChina Southwest Oil&Gas Field Company, Chengdu, Sichuan 610051, China Research Institute of Exploration and Development, PetroChina Southwest Oil & Gas Field Company, Chengdu, Sichuan 610213, China Sichuan Shale Gas Exploration and Development Company Limited, Chengdu, Sichuan 610051, China Chongqing Shale Gas Exploration and Development Company Limited, Chongqing 610213, China Sichuan Geoscience and Technology Company Limited, Chengdu, Sichuan 610500, China

页岩孔隙度是评价页岩储层品质和页岩气储量计算的重要参数之一，因此准确测量页岩孔隙度十分重要。测量页岩孔隙度的方法较多，从样品形状上可分为柱塞样和碎屑颗粒样，从测量方法上可分为液体饱和法和氦气饱和法。目前对柱塞样孔隙度和碎样孔隙度测量结果比对研究较少，两者差异更是鲜见报道。首先通过测量典型柱塞样孔隙度，确定不同测量方法的适用范围；然后将柱塞样粉碎后测量其碎样孔隙度及分析影响碎样孔隙度的因素；最后比较柱塞样孔隙度和碎样孔隙度之间的差异。实验结果表明，页岩柱塞样氦孔隙度为页岩连通孔隙度，碎样氦孔隙度为页岩总孔隙度，且后者较前者高0.65%~2.40%，约占总孔隙度的11.21%~44.36%。柱塞样氦孔隙度偏小的原因主要有：（1）测量氦孔隙度的注入压力过低；（2）测量氦孔隙度前未对样品抽真空；（3）柱塞样中大量的不连通孔隙无法被氦气有效饱和。不同矿物组分与柱塞样、碎样孔隙度之间的相关性分析表明，不连通孔隙主要存在于有机质中，少量存在于黏土矿物中。为实现页岩气高效开发，可在压裂液中添加适当的化学剂，改造有机质和黏土矿物结构，释放不连通孔隙中的页岩气，以提高页岩气单井产量和页岩气采收率。

Shale porosity is one of the important parameters for shale reservoir quality evaluation and shale gas reserve calculation, so it is very important to accurately measure shale porosity. There are many methods to measure shale porosity. Liquid saturation and helium saturation methods are applied to core plugs and crushed samples. At present, there are few comparative studies on the measurement results of the porosity of plug samples and crushed samples, and the differences between them are even less reported. Firstly, the porosity of plug samples is measured using different measurement methods. Then, the plug samples are crushed and the porosity of the crushed samples is measured, and the factors affecting porosity are analyzed. Finally, the differences between the porosity of the plug samples and the crushed samples are compared. The experiment results show that the porosity of shale plug samples (helium saturation method) is the connected porosity of shale, and the porosity of crushed samples is the total porosity of shale, and the latter is 0.65%-2.40% higher than the former, which accounts for 11.21%-44.36% of the total porosity. There are several reasons. (1) The injection pressure of helium saturation method is too low. (2) The samples are not evacuated. (3) A large number of unconnected pores in the shale plug samples are not effectively saturated with helium. The correlation between different mineral components and the porosity of plug and crushed samples shows that the unconnected pores mainly exist in organic matter and a small amount in clay minerals. Appropriate chemical reagents can be added in the process of reservoir transformation to effectively modify the structure of organic matter and clay minerals, and release shale gas in these disconnected pores as far as possible, so as to improve shale gas recovery.

国家自然科学基金项目“页岩储层纳米孔隙结构表征及渗流机理研究” 51674044;四川省应用基础研究项目“海相页岩气建产核心区智能评价系统研究（省重）” 2019YJ0340;四川省苗子工程重点项目“基于压裂液返排规律评价页岩气储层压裂效果的方法研究” 2019JDRC0095;高等学校学科创新引智计划（111计划）“深层海相页岩气高校开发学科创新引智基地” D18016

https://doi.org/10.11781/sysydz202002302