致密砂岩气储层孔缝特征及控储作用——以鄂尔多斯盆地东北部下石盒子组为例  

Characteristics of pores and fractures in tight gas sandstone reservoirs and the role of reservoir control:A case study of Lower Permian Shihezi Formation in northeastern Ordos Basin

作　　者：尹帅 卢明德[3] 许广军 侯亚龙 刘思宏 陈朝兵 YIN Shuai;LU Mingde;XU Guangjun;HOU Yalong;LIU Sihong;CHEN Chaobing(School of Earth Science and Engineering,Xi’an Shiyou University,Xi’an 710065,China;Shaanxi Key Laboratory of Petroleum Accumulation Geology,Xi’an Shiyou University,Xi’an 710065,China;E&D Research Institute of PetroChina Liaohe Oilfield Company,Panjin 124010,China;No.2 Gas Production Plant,PetroChina Chang Qing Oilfield Company,Xi’an 710200,China)

机构地区：[1]西安石油大学地球科学与工程学院,西安710065 [2]西安石油大学陕西省油气成藏地质学重点实验室,西安710065 [3]中国石油辽河油田勘探开发研究院,辽宁盘锦124010 [4]中国石油长庆油田分公司第二采气厂,西安710200

出　　处：《成都理工大学学报（自然科学版）》2024年第5期758-771,共14页Journal of Chengdu University of Technology: Science & Technology Edition

基　　金：陕西省自然科学基础研究计划项目(2023-JC-QN-0355);国家科技重大专项(2011ZX05044);中石化科技攻关项目(P14150)。

摘　　要：加强致密气砂岩储层孔缝特征及影响因素研究有助于提高非常规储层甜点预测效果。采用宏观结合微观尺度定量观测方法,对鄂尔多斯盆地东北部S地区上古生界下石盒子组致密气砂岩储层孔缝特征进行了综合研究。目的层孔隙类型包括残余粒间孔、粒间溶蚀孔、粒内溶蚀孔、晶间孔和微裂缝。镜下观察到两期石英加大边,其提高了骨架承载能力。石英加大边经历了碱性溶蚀作用。致密气砂岩储层在碱性及酸性叠加溶蚀作用下,物性得到显著改善。目的层致密气砂岩中发育孔隙及不同尺度裂缝,孔隙周边容易发生应力集中而破裂,发育大量孔隙相关微裂缝。微裂缝主要包括粒内缝及粒缘缝,粒缘缝通常具有较好的方向性,而粒内缝的方向性则较差。致密砂岩气储层裂缝发育程度与累积砂体厚度、孔隙度及渗透率均有一定正相关性,其与含气饱和度的之间无明显相关性。统计显示,随着裂缝密度从0.6条/m增加到1.2条/m过程中,致密气储层孔隙度约增长1.2%,而渗透率约增长0.14×10^(-3)μm^(2),增幅较为明显,局部剪切破裂作用显著改善了致密储层的物性条件。此外,裂缝发育程度与储能系数(Esc)之间具有良好的正相关性。研究认为,致密砂岩气储层的孔隙与裂缝密切关联,发育程度明显受颗粒粒度及分选等因素的影响,对储层物性有较为显著的改善作用。Research on the characteristics of pore fractures in tight gas sandstone reservoirs and the factors influencing them can help to improve predictions of sweet spots in unconventional reservoirs.This study comprehensively investigates the pore-fracture characteristics of dense gas sandstone reservoirs in the Lower Shihezi Formation from the Upper Paleozoic,in the S area of the northeastern Ordos Basin,using a combination of macroscopic and microscopic observations.The target layer was found to contain residual intergranular pores,intergranular and intragranular dissolution pores,and intercrystalline pores and microcracks.Microscopic observations of the samples revealed that the increasing edge of quartz in the two stages improved the stress bearing capacity of the skeleton.The enlarged edge of quartz was found to have undergone alkaline dissolution.The physical properties of the tight gas sandstone reservoirs improved significantly under the action of alkaline and acid-superimposed dissolution.Furthermore,its physical properties improved with the increase in the quartz content.Pores and fractures at different scales developed in the tight sandstone of the target layer,which more easily led to fractures due to the concentration of stress around them,such that a large number of microcracks related to the pores were formed,including intragrae and edge microfractures.The edge microfractures usually had good directivity while the intragrae microfractures had poor directivity.The degree of fracture development was positively correlated with the cumulative thickness,porosity,and permeability of the sand body.When the density of fractures increased from 0.6 to 1.2 fractures/m,the porosity of the tight gas reservoir increased by approximately 1.2%,while its permeability prominently increased by about 0.14×10^(-3)μm^(2).Local shear rupture significantly improved the physical properties of the tight gas reservoir,while a sound positive correlation was observed between the degree of fracture development and the coefficient o

关 键 词：鄂尔多斯盆地 孔隙结构 致密砂岩 物性 孔隙结构 裂缝 

分 类 号：P624.6[天文地球—地质矿产勘探]