四川盆地蓬莱气区沧浪铺组白云石化作用与鲕粒云岩储集性OA

The Canglangpu Formation in the Penglai gas area of the Sichuan Basin plays a crucial role in oil and gas accumulation and is considered an important backup field for risk exploration.This study focuses on three typical wells in the Canglangpu Formation in the Penglai gas area.According to their petrological characteristics,cathodoluminescence and scanning electron microscopy,the influence of fabric selective dolomitization on reservoir property is analyzed and studied.The results show that:(1)Oolitic dolomite is the most common type of grain dolomite in the Canglangpu Formation,while other types being rare.Based on the position and morphology characteristics of the oolitic dolomite,it can be subdivided into oolitic dolomite,cloud pelitic oolitic dolomite,and sparry oolitic limestone dolomite;(2)The reservoir in the Canglangpu Formation is mainly porous,with main types of reservoir spaces including intergranular(dissolved)pores,intragranular(dissolved)pores,intercrystalline(dissolved)pores and a small number of fractures;(3)Diagenetic processes affecting the Canglangpu Formation reservoir mainly include micritization,cementation,dolomitization,recrystallization,hydrocarbon charging and dissolution.It is considered that dolomitization is an important factor in the formation of high-quality reservoirs.Analysis indicates that high-quality reservoirs are more commonly found in cloud pelitic oolitic dolomites,followed by oolitic dolomites,while sparry oolitic limestone dolomites are the least conductive to high-quality reservoir formation.