四川盆地西北部中三叠统雷口坡组滩体及储集性

Characteristic and Reservoir Property of the Leikoupo Formation of Middle Triassic in Northwestern Sichuan Basin

根据四川盆地西北部中三叠统雷口坡组野外剖面及钻井岩心的宏观及微观特征,结合常规物性资料,对区内滩体的类型及特征、储集性能及其影响因素和分布进行了较为详细的研究。认为区内有内碎屑滩、藻粘结颗粒滩、核形石滩和鲕粒滩4类滩体,内碎屑滩和藻粘结颗粒滩广泛分布于中46井—杨家岩一线的雷三段,核形石滩集中于江油观音滩的雷三段下亚段,鲕粒滩集中于绵竹的雷四段中上部。这些高能滩体是局限陆表海和开阔陆缘海环境的产物,受后期成岩作用改造强烈,储集性差异大,雷三段中—上亚段的内碎屑滩和藻粘结颗粒滩在表生期岩溶作用和埋藏期溶蚀作用的共同改造下,储集空间内充填的石膏、石盐和方解石发生溶解,晶间溶孔、粒间溶孔、粒内溶孔、藻粘结"格架"溶孔和小溶洞发育,成为区内最有利的储集体,它们主要分布于中46井—鱼1井区块。

Based on observations on the macro-micro features of outcrop sections and the drilling cores of the Leikoupo Formation of Middle Triassic in the northwest of Sichuan Basin,and combining with the conventional physical property,this paper profoundly studies the types,features,reservoir capacity,influencing factors on bank reservoir property and distribution of the banks within study area. It is considered that there are four types of bank-intraclast bank,algal-bounding grain bank,oncolite bank and oolitic bank ,of which the intraclast bank and algal-bounding grain bank widely distribute in member 3 of Leikoupo from Zhong well 46-Yangjia yan,oncolite bank concentrate in lower submember of member 3 of Leikoupo Formation in Jiangyou Guanyin bank,and oolitic bank concentrate in the middleupper part of member 4 of Leikoupo Formation in Mianzhu. The high energy bank is the results of the envi-ronment of the limited eperic sea and Open shelf sea. By the joint action of krastification of hypergence period and burial dissolution for intraclast bank and algal-bounding grain bank in the middle-upper submember of member 3 of Leikoupo Formation,the gypsum,halite and calcite filled in the reservoir space are dissolved,intercrystalline solution pores,intergranular dissolution pore,intragranular dissolved pore,algae-bounding framework dissolved pore and small cave develop well,and they are of the best reservoir body,which mainly distribute in the Zhong Well 46-Yu Well 1 block.