摘要
采用宏观和微观相结合的方法 ,对川中地区震旦系灯影组地层研究表明,其储集岩类型主要为溶蚀(假)角砾岩、粉晶白云岩、藻白云岩和砂屑白云岩,储集空间以溶蚀孔洞为主,储集物性较差,为低孔低渗型储层,储层类型以裂缝-孔洞型为主。研究区岩溶储层的发育及演化受到沉积作用、成岩作用以及构造作用的共同控制。相对较强水动力环境形成藻白云岩、粉晶白云岩和颗粒白云岩,发育原生孔隙,为后期强烈岩溶作用提供了良好的物质基础。两幕铜湾运动使灯影组地层抬升,长时间暴露于地表,接受大气淡水、混合水改造,发生表生期岩溶作用。在近地表处形成风化壳,大气淡水、混合水通过风化壳继续溶蚀下覆地层,局部地层溶蚀强烈,垮塌形成岩溶角砾岩,同时在下覆地层中形成大量溶蚀孔洞等次生孔隙。沉积作用和成岩作用为次生孔隙的形成提供了有利条件,改善了储层的储集性能,而后期多期次构造作用产生大量裂缝,大大提高了储集岩渗透率。
Research on Sinian Dengying Formation in central Sichuan by adopting combined macroscopic and microscopic methods shows that the main reservoir rocks are dolarenite, karst breccia, grained dolomite and algae dolomite, the reservoir space is dominated by emposieu and karst caves, and the reservoir is of relatively low quality, appearing as fracture-cavity type with low porosity and low permeability. The reservoir of Dengying Formation in the study area was formed by deposition and diagenesis. Dolarenite, grained dolomite and algae dolomite were deposited in a strong hydropower environment with the development of primary pores, which provided favorable material base for later strong karstification. 2nd member and 4th member were uplifted by Tongwan movement; hence the strata were exposed at the land surface for a long time and received atmospheric water together with mixed water reformation, leading to karstification. Through the weathering crest formed by karstification near the land surface, atmospheric fresh water and mixed water continued seeping into and dissolving the lower part of the formation. Strong karstification could create karstic collapse breccias and a great quantity of dissolution pore-caves in the lower part of the formation. Deposition and diagenesis provided favorable conditions for secondary porosity and improved the properties of reservoir rocks, while tectonic action in the later time formed a lot of cracks, providing the permeability for the reservoir.
出处
《中国地质》
CAS
CSCD
北大核心
2013年第5期1505-1514,共10页
Geology in China
基金
教育部“新世纪优秀人才支持计划”(NECT-04-0911)
四川省重点建设学科建设项目(SZD0414)
关键词
川中
灯影组
储层
白云岩
古岩溶作用
central Sichuan
Dengying Formation
reservoir
dolomite
karstification
