西昌盆地流体包裹体及其在油气勘探中的应用

通过对西昌盆地下二叠统碳酸盐岩流体包裹体研究证实,储层成岩演化和烃类生成、运移、聚集的每一阶段均可形成流体包裹体,是储层孔隙形成环境、发育阶段以及油气演化、运移、聚集的直接标志.不同世代胶结物和不同期次孔隙充填矿物中流体包裹体研究结果表明,西昌盆地下二叠统烃源告演化及储层孔隙的发展经历了准同生期、成岩早期和中晚期、表生期、再埋藏早、中、晚期7个演化阶段.其中,表生期岩溶孔洞缝、再埋藏早期深部溶蚀孔洞缝和中晚期构造裂隙构成了区内聚烃期储集空间.石油开始生成和初次运移发生在晚二叠世(再埋藏早期),大量运移聚集发生在三叠纪(再埋藏中期),天然气大量运移聚集发生在侏罗纪及其之后(再埋藏晚期).油气生成、运移和聚集与海西期玄武岩喷发(热)事件、印支-燕山期构造运动及岩浆多期侵入活动紧密相关.

FLUID INCLUSION IN XICHANG BASIN AND ITS APPLICATION TO HYDROCARBON EXPLORATION

According to the research made on fluid inclusions in Lower Permian carbonate rocks in Xichang Basin,the fluid inclusions could form in every stage of reservoir diagenetic evolution,hydrocarbon generation,migration and accumulation.This could be the direct evidence for the formation environment and development stages of reservoir porosity,and for hydrocarbon generation, migration and accumulation.The study on diagenetic cements and pore-filling minerals of fluid inclusions in different stages shows that the evolution of Lower Permian source rocks and reservoir porosity development underwent following seven diagenetic stagesl,namely penecontemporaneous,early diagenetic,mid-late diasenetic,epidiagenetic,early,middle and late reburial stages.The epidiagenetic karst porosity, early reburial deep dissolution porosity and middle-late structural cracks constituted the main oil and gas reservoir spaces in hydrocarbon accumulation period. Hydrocarbon generation and primary migration occurred during LatePermian(i.e.early reburial stage); large amounts of hydrocarbon migrated and accumulated during the Triassic(middle reburial stage) and most of natural gas migration and accumulation took place in Jurassic(late reburial sarge) and thereafter.Hydrocarbon generation,migration and accumulation in the study area were closely related to Hereynian basalt eruption,and the tectonics and magmatic intrusion of indo-China and Yenshanian.