准噶尔盆地腹部莫西庄地区三工河组低孔渗砂岩储层成岩与孔隙演化研究  

Diagenesis and Porosity Evolution of the Low-porosity and Low-permeability Sandstones:Evidence from the Lower Jurassic Sangonghe Formation in Moxizhuang Area,Central Junggar Basin

作　　者：胡才志[1] 张立宽[1] 罗晓容[1] 赵洪 杨彬[3] 曹斌风[1] 雷裕红[1] 程明[1] 李超[1] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]中海石油(中国)有限公司上海分公司,上海200030 [3]中国石化胜利油田分公司海洋采油厂,山东东营257237

出　　处：《天然气地球科学》2015年第12期2254-2266,共13页Natural Gas Geoscience

基　　金：国家自然科学基金(编号:41372151);国家重大油气专项(编号:2011ZX05008-004)联合资助

摘　　要：以准噶尔盆地腹部莫西庄地区三工河组（J1S）低孔渗储层为研究对象，通过系统的岩石薄片观察、扫描电镜、阴极发光及烃类荧光显微鉴定，依据成岩产物之间及其与烃类流体（油包裹体和孔隙沥青）之间的赋存关系，建立了储层成岩演化和油气充注的时间序列，恢复了关键油气充注时期的储层古物性，探讨了孔隙演化与油气成藏的匹配关系。结果表明：三工河组储层为低成分成熟度的长石岩屑砂岩和岩屑砂岩，压实作用、碳酸盐和黏土矿物胶结作用是导致储层低孔渗的主要原因，石英颗粒表面覆盖的绿泥石膜难以有效地保持原生孔隙，次生溶蚀孔隙是主要储集空间；储层成岩演化具有显著的差异性，在压实作用下富含软岩屑砂岩中软岩屑强烈塑性变形致使早期致密，而钙质强胶结砂岩因成岩早期的碳酸盐胶结发生致密化，低软岩屑～弱胶结砂岩主要经历了3期有机无机流体作用交替，分别以无荧光炭质沥青、黄色荧光油、蓝白色荧光油等3期烃类流体活动为划分标志；在晚白垩世末关键油气成藏时期（距今100～70Ma），高软岩屑和钙质强胶结砂岩古孔隙度低于8％，早期致密化储层难以发生油气注入；低软岩屑～弱胶结砂岩在晚白垩世末期可保持中高孔渗性，普遍发生了早期油气充注，早期原油注入不能阻止储层深埋过程中物性变差的趋势，但可能改变局部储层的润湿性质，油湿通道网络是晚期成藏阶段（距今62～0Ma）低孔渗储层条件下发生大规模油气注入的主要原因。Diagenetic products and their cross-cutting relationships with hydrocarbons（oil inclusions and bitumen in conventional thin section） of the Lower Jurassic Sangonghe Formation,which contains low-porosity and low-permeability sandstones in Moxizhuang area,central Junggar Basin were examined with an inte grated approach of thin-section petrography, scanning electron microscopy, cathodoluminescence microscopy and ultra-violet fluorescence microscopy. This study aims to establish the relative histories of diagenesis and hydrocarbon charging,estimate paleoporosity during the critical period for hydrocarbon charging, and discuss the dynamic coupling relationship between porosity evolution and hydrocarbon accumulation. The Sangonghe sandstones are feldspathic litharenites and litharenites having a low mineralogical maturity. Compaction,carbonate and clay cementation are major processes deteriorating reservoir quality. Chlorite coats have a less prominent role in preserving primary porosity and secondary dissolution porosity predomi- nates in these sandstones. The three reservoir types identified in the Sangonghe sandstones show big varia- tions in the pathways of diagenetic evolution. Sandstones, rich in ductile rock fragments were compacted strongly and became tight during the early diagenetic stage. Calcareous sands also became tight early by carbonate cementation. Sandstones, poor in ductile rock fragment compaction and cementation, experienced three phases of diagenesis and hydrocarbon charging with black bitumen without fluorescence,and bitumen with yellow and white blue fluorescence respectively. At the end of Late Cretaceous（100-70Ma） when critical hydrocarbon accumulation occurred, it is difficult for the bulk of hydrocarbons to migrate into both tightly compacted sandstone and tightly carbonate cemented sandstones with an estimated paleoporosity value of 8%. However,sandstones,poor in ductile rock fragment compaction and cementation had still had the intermediate-high porosity and permeability. Early hyd

关 键 词：孔隙演化 成岩作用 油气充注 三工河组 莫西庄 

分 类 号：TE122.2[石油与天然气工程—油气勘探]