成岩作用对储层致密化的影响差异及定量表述——以苏里格气田苏77区块致密砂岩为例  

Different Influences and Quantitative Description of Effect of Diagenesis on Reservoir Densification:Case study of tight sandstone in Su77 block,Sulige gas field

作　　者：宫雪 胡新友[3] 李文厚 沈武显[1,2] GONG Xue;HU XinYou;LI WenHou;SHEN WuXian(School of Earth Sciences and Engineering,Xi’an Shiyou University,Xi’an 710065,China;Key Laboratory of Shaanxi Province for Petroleum Accumulation Geology,Xi’an Shiyou University,Xi’an 710065,China;eesearch Institute of Exploration and Development,PetroChina Changqing Oilfield Company,Xi’an 710018,China;State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi’an 710069,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]中国石油长庆油田公司勘探开发研究院,西安710018 [4]西北大学地质学系,大陆动力学国家重点实验室,西安710069

出　　处：《沉积学报》2020年第6期1338-1348,共11页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(41372148);陕西省教育厅重点实验室科研计划项目(16JS089)。

摘　　要：苏里格气田苏77区块二叠系下统山西组二段发育自北向南的曲流河,各气层组沉积特征比较一致。但是山西组二段山12、山22亚段气层组比山32亚段气层组储层经历了更强的压实、胶结作用,残余粒间孔所剩无几,加之后期扩容性成岩作用程度不够,次生孔隙发育有限,使得山12、山22气层组成为平均孔隙度不足7%,平均渗透率小于0.3×10^-3μm^2的致密储层,与平均孔隙度为7.7%、平均渗透率为1.74×10^-3μm^2的山32气层组相比储层渗流能力较差。为了衡量成岩作用程度的强弱,利用视压实率、视胶结率和视溶蚀率的方法来定量分析孔隙度的变化。综合分析认为,研究区山12、山22气层组储层处于中等压实、较强胶结和强溶蚀水平,与山32气层组相比这两个气层组压实、胶结作用丧失的孔隙度远远大于溶蚀、破裂增加的孔隙度,其现今孔隙度只保留到5.48%,成为储集性能较差的致密储层。Meandering rivers developed from north to south formed the second member of the lower Permian Shanxi formation(P1s2)in Su77 block,Sulige gas field.The sedimentary characteristics of each gas-bearing member were consistent.The first and second members are tight sandstone reservoirs with low levels of residual intergranular and secondary pores due to intense compaction and cementation,with an average porosity less than 7%and average permeability less than 0.3×10^-3μm^2.These members are less permeable than the third gas-bearing member of P1s2(average porosity 7.7%;average permeability 1.74×10^-3μm^2).The change in porosity was quantitatively analyzed in the present study as functions of the apparent rates of compaction,cementation and dissolution in order to measure the degree of diagenesis.The calculations indicate that the first and second gas-bearing members of P1s2 suffered medium compaction,less intense cementation,and intense dissolution.Compared to the third gas-bearing member of P1s2,the reduction in porosity caused by compaction and cementation was much greater than the increase by dissolution and rupturing in the other members,which are poor reservoirs,currently with a porosity of only 5.48%.

关 键 词：孔隙组合 成岩作用 致密储层 苏77区块 

分 类 号：P618.13[天文地球—矿床学]