孤北斜坡带煤成气成藏条件分析

孤北斜坡带石炭-二叠系煤系地层分布广泛，煤质优良，演化程度适中，具有形成煤成气藏的物质基础，已有多口井发现了煤成气藏。早期对研究区煤成气资源评价、勘探目标评价的研究取得一些水平较高的成果，但同时也存在一些问题有待深入研究，如煤成气成藏条件、控制因素、下步勘探方向等。文章在系统分析该地区构造特征、气源、储层、盖层条件及成藏控制因素的基础上，阐述了孤北煤成气的成藏条件，指出研究区煤成气成藏的3个主控因素，①储层沉积微相控制储层物性，是获得高产的重要条件；②中生界底部含煤层系控制石炭-二叠系煤成气藏的分布；③构造控制气藏富集。通过总结研究区煤成气的成藏条件和主控因素，指明孤北斜坡带南部是近期煤成气钻探方向，并结合地震资料评价了有利勘探目标。

Analysis of Coal-derived Gas Reservoiring Conditions in Gubei Slope Zone

Permo-Carboniferous coal measure strata with high coal quality and moderate evolution degree are widely developed in Gubei slope zone, thus this area has the material base to form coal-derived gas accumulations, which have been encountered by several wells. Initial assessment of the coal-derived gas resources and evaluation of the exploration targets in the study area have achieved some positive results, however some issues still need to be studied in depth, such as reservoiring conditions of coal-derived gas, controlling factors and future direction of exploration etc. Based on systematic analysis of the structural features, source rocks, reservoir rocks, cap rocks and control factors of reservoiring, this paper discusses the reservoiring conditions of coal-derived gas in Gubei area and presents the three main control factors of coal-derived gas reservoiring in the study area, i.e. the poroperm characteristics of reservoirs are controlled by sedimentary microfacies; the coal-bearing series on the base of Mesozoic control the distribution of Permo-Carboniferous coal-derived gas accumulations and the structures control the enrichment of coal-derived gas accumulations. Based on analysis of the reservoiring conditions and major control factors of coal-derived gas in the study area, the southern part of Gubei slope zone is believed to be the direction of future exploratory drilling and the favorable exploration targets are evaluated in combination with the seismic data.