古潮湿环境下碳酸盐岩缝洞型油气藏结构模式——以塔里木盆地奥陶系为例

岩溶发育的气候条件是决定碳酸盐岩油气田储集空间和运移通道类型的主要因素,溶缝和溶洞是古潮湿环境下塔里木盆地奥陶系碳酸盐岩岩溶发育的产物。通过对塔里木盆地北缘奥陶系碳酸盐岩古风化壳岩溶发育特征的调查与分析,掌握了溶缝与溶洞的发育分布规律,认为溶洞与裂缝并不是孤立分布的,溶洞与周边有成因联系的影响带(裂缝密集发育带)一起共同组成一个有机的缝洞系统,从而构成了良好的缝洞型储集层。将溶洞与裂缝有机的结合起来,建立了碳酸盐岩风化壳储集体的非均质分布模型—— 缝洞型油气藏结构模式,并提出将裂缝和溶洞比较集中的彼此互相连通的区域作为油元来研究,有利于从宏观上认识缝洞型油气藏的实质。 

STRUCTURE PATTERN OF RIFT-CAVITY OIL-GAS POOL IN CARBONATE ROCK UNDER MOIST PALEO-ENVIRONMENT-A Case Study on the Ordovician in Tarim Basin

Paleo-climate is the major factor that decides the type of reservoir space and the moving pathway in carbonate oil-gas pool.Rift and cavity are the characteristic productions of the Ordovician carbonate rock under the moist paleo-environment in Tarim basin.Based on geologic investigations on corrosion zone in weathered mantle,the fractures are divided into 2 types according to the origin,and four stages according to the structural developing history,as well as three grades according to the scale.And the developing characteristics of the paleo-cavity are illustrated also.It is indicated that rift and cavity don't distribute lonely.Actually,cavity and its surrounding regions constitute an integrated rift-cavity system.So,the heterogeneous karst distribution pattern of carbonate reservoir in fossil weathered mantle,structure pattern of rift-cavity oil-gas pool,is built by combined rift and cavity.At last,oil unit,namely the region where rift and cavity are centralized relatively and connect to each other,is put forward for the research on understanding the substance of the riftcavity oil-gas pool.