四川盆地中部合川—潼南地区茅一段泥灰岩储层特征与评价

四川盆地中二叠统茅口组一段（简称茅一段）眼球状灰岩在盆内广泛分布，以“眼球灰岩”与“眼皮灰岩”的快速交替发育为特征。近年来，借鉴非常规天然气勘探思路，四川盆地各地区天然气勘探在茅一段相继取得大的突破，钻采成果表明，泥灰岩（眼皮灰岩）储层含气性较好，具有较大的勘探潜力。但长期以来，茅一段被认为是一套良好的烃源岩，忽视了其作为非常规储层的巨大价值。基于四川盆地中部合川—潼南地区2口最新钻井资料以及对周边野外露头观测，对茅一段泥灰岩储层特征进行了详细分析，结果表明：茅一段泥灰岩储层的储集空间类型丰富，孔隙以中孔为主，孔隙间连通性中等；总有机碳含量相对较高，有机质热成熟度高，生烃条件好，为一套具有自生自储成藏特征的非常规碳酸盐岩储层。在此基础上，建立了泥灰岩储层评价标准，并对泥灰岩储层进行初步评价，认为茅一段泥灰岩普遍满足储层成藏的基本条件，部分满足有利储层形成条件，具有进一步勘探开发价值。

Characteristics and evaluation of muddy limestone reservoir in the first member of Maokou Formation of Hechuan-Tongnan area,central Sichuan Basin

The first member of Maokou Formation (Mao 1 Member) of Middle Permian in Sichuan Basin is characterized by the rapid alternate development of “eye limestone” and “eyelid limestone”, which is widely distributed in the basin. In recent years, using the idea of unconventional natural gas exploration for reference, great breakthroughs have been made in the Mao 1 Member in various regions of Sichuan Basin. Drilling and production results show that the muddy limestone (eyelid limestone) reservoir has good gas content and great exploration potential. However, since it has long been considered as a set of good source rocks, the testing and evaluation of the Mao 1 Member reservoir lacks pertinence. In this study, based on the latest drilling data of two wells in Hechuan-Tongnan area of central Sichuan Basin and the outcrop observation of the surrounding field, the characteristics of the muddy limestone reservoir in the Mao 1 Member are analyzed in detail. The results show that the reservoir space of the muddy limestone reservoir in the Mao 1 Member is mainly clay mineral pores, dissolution pores and organic matter pore,followed by micro-fractures. Pores are dominated by medium pore, mainly in the form of slit pores, followed by micropores and macropores. Pores are dispersed and developed, and the connectivity between pores is medium.The total organic carbon content is relatively high, the organic maturity is high, and the hydrocarbon generation condition is good. It is an unconventional carbonate reservoir with self-generation and self-storage characteristics.On this basis, the author establishes the evaluation criteria of marl reservoir, and makes a preliminary evaluation of muddy limestone reservoir. It is considered that the muddy limestone of the Mao 1 Member generally meets the basic conditions of reservoir accumulation, and partially meets the favorable reservoir formation conditions, which has further exploration and development value.