四川盆地西南部震旦系白云岩成岩过程中的孔隙演化  

Evolution of Porosity in the Process of Sinian Dolostone Diagenesis in Southwest Sichuan

作　　者：王兴志[1] 穆曙光[1] 方少仙[1] 黄继祥[1] 侯方浩[1] 

机构地区：[1]西南石油学院,四川南充637001

出　　处：《沉积学报》2000年第4期549-554,共6页Acta Sedimentologica Sinica

基　　金：石油天然气总公司"石油科技中青年创新基金";"油气藏地质及开发工程国家重点实验室开放基金项目"资助的部分研究成果

摘　　要：我国南方 ,特别是西南地区震旦系白云岩具有良好的油气储集潜力。四川盆地西南部震旦系白云岩储层多集中分布在灯影组的中、上部 ,储集空间以次生成因的孔、洞、缝为主。这些孔隙的形成与演化受多种因素的影响 ,其中成岩作用的控制明显 ,压实作用和多期白云岩的胶结作用使原生孔隙基本消失 ,而重结晶作用和溶解作用促进了次生孔隙的形成 ,但多期白云石和硅质的充填作用又导致次生孔隙缩小 ,局部消失。总之 ,震旦系白云岩储层内的孔隙是在长达六亿年左右的地质历史中 ,由各种成岩作用及其它因素相互影响下的最终产物。In South China, especially in Southwest China, Sinian dolostone is widely distributed and with great thickness,which is of favorable potential of oil/gas accumulation. But the formation is very old in geologic age and complicated in diagenesis, which results in the uneven distribution and apparent inhomogeneity of the reservoirs. In the area, the Sinian dolostone reservoirs are dominantly concentrated at the top and middle parts of the Dengying Formation, and pore spaces are completely dominated by pores, vugs and fractures with secondary origination.Study indicates that the formation and evolution of the porosity are controlled by diagenesis.The destructive diagenesis,which is unfavorable for the formation and evolution of porosity,are mainly compression, cementation of primary porosity and filling of chemical prceipitation in secondary porosity, and the constructive diagenesis,which stimulates the formation and resolution of porosity,include recrystallization, dissolution in hypergenesis and in burial diagenesis. Compression is the main factor of closing all the primary porosity in fine dolostone; the primary intergranular porosity in grain dolostone and algae bound dolostone and algae framework porosity were eliminated after cementation of three phase dolosparite with the shapes of fiber, silt fine crystal and coarse crystal, and only a little residual primary porosity was preserved.The chemical fillings in the secondary pores, vugs and fractures are the cause of the porosity being not able to be preserved. There are mainly three phases of chemical fillings.The first phase is characterized by fiber like dolomite with the shapes of grape lace, the second one takes shape of fine to course dolomite, and the third one megacrystal dolomite. They may reduce the secondary porosity by 20%～80%, or up to 100% locally. The cements and chemical fillings precipitated in different diagenesis environments differ from each other not only in shapes of the crystals occurrence and succession of formation,also in geochemic

关 键 词：四川盆地 震旦系 白云岩 成岩作用 孔隙演化 储层地质 

分 类 号：P618.130.2[天文地球—矿床学] P588.245[天文地球—地质学]