Reservoir characteristics and forming conditions for the Middle Triassic Leikoupo Formation in the western Sichuan Basin, China

摘要

In the past few years, petroleum exploration in the Leikoupo Formation in the western Sichuan Basin of China has obtained fruitful achievements, but composite research on the carbonate rock reservoir and its control factors are lagging behind, which constrains further exploration in the Leikoupo Formation based on field outcrop, core and logging data, while the laboratory analysis, reservoir characteristics and forming conditions of the Leikoupo Formation in the western Sichuan Basin are systematically summarized. The results show: (1) the Leikoupo Formation reservoir mainly involves algae dolomite, grain dolomite and fine powder crystal dolomite with intergranular, intercrystalline and biotrellis pores, and the reservoir generally has low porosity and low permeability; (2) both sedimentary facies and karstification control the development of the Leikoupo Formation reservoir, in which the sedimentary facies is essential to the reservoir, and penecontemporaneous dolomitization and karstification act as a controlling factor to maintain the pore size and secondary pore development, while supergene karstification at the end of the Middle Triassic improved the pores, and the dissolution of organic acid in the burial stage preserved the pores.