成都凹陷中侏罗统沙溪庙组储层特征与控制因素

Characteristics and Controlling Factors of Reservoirs of Middle Jurassic Shaximiao Formation in Chengdu Depression

利用钻井、薄片及测试分析等相关资料对成都凹陷中侏罗统沙溪庙组储层发育特征及控制因素进行研究,结果表明:研究区沙溪庙组储层岩性以岩屑砂岩、岩屑石英砂岩为主,受不同物源的影响,储层在平面上表现出差异性,自西向东表现为长石含量增加、岩屑含量减少.其中:西部崇州-温江地区为近物源区,主要受龙门山近物源的影响,发育辫状河三角洲沉积体系,长石含量较低(10.8%),岩屑含量较高(29.96%);东部马井-什邡地区为远物源区,主要受龙门山北段、米仓山-大巴山远物源的影响,发育曲流河三角洲沉积体系,长石含量较高(32.09%),岩屑含量较低(20.84%).储层物性在平面上也存在差异性,西部近物源区的崇州-温江地区物性较差,孔隙度平均值为4.6%,渗透率平均值为0.13×10^(-3)μm^(2);东部远物源区的马井-什邡地区物性较好,孔隙度平均值为13.07%,渗透率平均值为0.96×10^(-3)μm^(2).研究区储层孔隙度总平均值为8.96%,渗透率总平均值为0.73×10^(-3)μm^(2),总体上属于中-低孔、低渗类型.压实作用是造成本区储层物性变差的最主要因素,胶结作用次之,而溶蚀作用可能是改善本区储层物性的最主要因素.

The reservoir development characteristics and main controlling factors of Shaximiao formation of middle Jurassic in Chengdu Depression were studied by using a series of relevant data,such as drilling,thin section and test analysis.The results show that the reservoir lithology of Shaximiao formation in the study area is dominated by lithic sandstone and lithic quartz sand⁃stone.Due to the influence of different sources,the reservoirs are different in plane.The content of feldspar is increasing,and the debris is decreasing from west to east.The west areas,such as Chongzhou-Wenjiang are called near source areas,which are main⁃ly affected by the proximal source of Longmen Mountain.These areas have developed into braided river delta sedimentary sys⁃tems,and the content of feldspar is low(10.8%),the content of debris is high(29.96%).The east areas,such as Majing-Shifang,are remote source areas,which are mainly influenced by the north section of Longmen Mountain and Micang-Daba Mountain.These areas have developed into meandering river delta sedimentary system,and the content of feldspar is high(32.09%),the con⁃tent of debris is low(20.84%).The reservoir properties are also different on the plane.The physical properties are poor in near source areas as Chongzhou-Wenjiang in the west,their average porosity is 4.6%,and average permeability is 0.13×10^(-3)μm^(2);the physical properties are good in remote source areas as Majing-Shifang in the east,their average porosity is 13.07%,and aver⁃age permeability is 0.96×10^(-3)μm^(2).The total average value of reservoir porosity in the study area is 8.96%,and the total average permeability is 0.73×10^(-3)μm^(2),which is the medium-low pore and low-permeability type in general.In this area,compaction is the main factor causing the deterioration of reservoir physical properties,followed by cementation.And dissolution may be the main factor for reforming the reservoir physical property.