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

Key words: 
• Leikoupo Formation

Abstract: 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 middle-upper part of member 4 of Leikoupo Formation in Mianzhu. The high energy bank is the results of the environment 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.