淮南煤田构造演化与煤系天然气成藏

Tectonic Evolution and Coal Measures Natural Gas Reservoiring in Huainan Coalfield

针对淮南煤田复杂的煤系天然气地质条件,以区域构造演化为主线,结合盆地模拟和最新钻探成果(潘气1井),深入探讨了淮南煤田构造演化阶段以及构造控制下的煤系天然气成藏过程和赋存特征。结果表明:淮南煤田晚古生代成煤期以来经历了稳定沉降(C2-T2)、构造形变(T3-J3)、伸展隆升(K-E)和坳陷沉积(N-Q)四个构造演化阶段;在经历了晚石炭-中三叠世的沉降埋藏之后,淮南煤田煤系有机质热演化在三叠纪末期达到最大值,生成大量的热成因气,在侏罗纪-古近纪持续隆升剥蚀和新近纪以来的坳陷沉积后,潘气1井现今煤系最大埋深超过了2 000 m;淮南煤田总体表现为压性构造特征,对煤系天然气资源保存有利,内部发育的小型正断层,一定程度上改善了煤系储层物性,其中潘集煤矿外围地区是淮南煤田最为有利的煤系天然气勘查开发区域。

In allusion to complex coal measures natural gas geological condition in the Huainan coalfield,focused on regional tectonic evolution,combined with basin simulation and recent drilling data( well PQ-1) discussed coalfield tectonic evolution stage,coal measures natural gas reservoiring process and hosting features under tectonic control in detail. The result has shown that since late Paleozoic coal-forming stage the coalfield has experienced four tectonic evolution stages of stable subsidence( C2-T2),structural deformation( T3-J3),extensional uplift( K-E) and depressed sedimentation( N-Q). After the late Carboniferous-middle Triassic subsidence and sedimentation,the organic matter thermal evolution has been maximized at the end of Triassic and formed large amount thermogenic gas. After the Jurassic-Paleogene sustained uplift denudation and Neogene depressed sedimentation,the maximum buried depth of coal measures in the well PQ-1 is 2000 m more at present. As a whole,the coalfield presents compressive structural features,thus propitious to coal measures natural gas resources preservation,the internal developed minor normal faults have improved coal reservoir physical property in a certain degree,in which,the periphery Panji coalmine is most advantageous area for coal measures natural gas exploration and exploitation in the coalfield.