鄂北杭锦旗地区下石盒子组储层形成过程探讨  

Discussion on the formation process of the Lower Shihezi Formation reservoir in the Hangjinqi area,northern Ordos Basin

作　　者：曹桐生[1,2] CAO Tongsheng(North China Oil-Gas Branch of Sinopec,Zhengzhou 450006,China;Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]中国石化华北油气分公司,河南郑州450006 [2]成都理工大学沉积地质研究院,四川成都610059

出　　处：《复杂油气藏》2023年第1期19-25,共7页Complex Hydrocarbon Reservoirs

基　　金：国家科技重大专项“鄂尔多斯盆地北缘低丰度致密低渗气藏开发关键技术”(2016ZX05048002)。

摘　　要：二叠系下石盒子组辫状河道、心滩砂岩是鄂北最重要的致密砂岩储层。基于铸体薄片鉴定、物性分析、包裹体测温,开展了储层表征、成岩作用识别、成岩期次和演化分析,探讨了下石盒子组储层的形成过程。结果表明,复杂的成岩作用形成了以次生孔隙为主的储集岩,平均面孔率5.9%,孔渗相关性较好;持续压实、2、3期硅质胶结和2期方解石胶结是储层致密化的关键因素;2、3期的破裂缝和溶蚀作用优化了储集空间;3期流体充注促进了(盒1段:85~90℃、110~115℃、145~155℃;盒2+3段:70~75℃、105~115℃、120~125℃)砂岩的致密和孔隙调整;储层先致密后成藏,经历快速压实阶段(早成岩A期)、致密化阶段(早成岩B期—中成岩A期)、调整阶段(中成岩A—B期)和致密后阶段(中成岩B期)最终形成了现今的致密砂岩储层。The braided channel and braided bar sandstones of the Lower Shihezi Formation are the most important tight sandstone reservoirs in the northern Ordos Basin.Based on the thin section,physical property,and inclusion analysis,the reservoir characterization,diagenesis identification,diagenetic stage,and evolution analysis were carried out to discuss the formation process of the Lower Shihezi Formation.The results show that secondary reservoir spaces are formed by complex diagenesis,with an average porosity of 5.9%and a good pore-permeability correlation.Continuous compaction,siliceous cementation in stages 2 and 3,and calcite cementation in stage 2 are key factors in reservoir densification.Fracturing and dissolution in stages 2 and 3 optimize the reservoir space.The fluid filling in stage 3(He 1 member:85-90℃,110-115℃,145-155℃;He 2+3 member:70-75℃,105-115℃,120-125℃)promotes sandstone densification and pore adjustment.The reservoir first densifies,and then becomes a reservoir,going through a rapid compaction phase(eodiagenesis A),a densification stage(eodiagenesis B to mesodiagenesis A),an adjustment stage(mesodiagenesis A-B),and a post-compaction stage(mesodiagenesis B),which eventually forms the present tight sandstone reservoir.

关 键 词：致密砂岩 成岩作用 成岩期次 下石盒子组 

分 类 号：TE132[石油与天然气工程—油气勘探]