滇东老厂矿区多层叠置独立含煤层气系统

Multilayer Superimposed CBM-bearing Independent System in Laochang Mine Area, Eastern Yunnan

滇东煤田煤炭资源丰富,主要含煤地层为龙潭组,煤层厚度适中,埋藏适宜,煤层气含量高。从沉积、构造、煤层煤质、煤储层特征等方面对滇东煤田煤炭资源较好的老厂煤矿煤层气赋存地质条件进行分析。研究表明:老厂矿区龙潭组第三段是多层叠置含煤层气独立系统,是沉积—水文—构造条件耦合控气作用的产物。含煤地层的层序格架特点奠定了多层叠置独立含煤层气系统的地质基础,每套独立含煤层气系统分别被限定在对应的二级层序格架内;含煤地层与上覆、下伏含水层之间缺乏水力联系,含煤地层内部不同岩层(组合)之间相互封闭,这些条件构成了多层叠置含气系统的水文地质基础。老厂煤矿煤层气由四个含煤层气系统组成,各系统间相互独立,其岩性分段具备完整的生储盖层,形成了一多层叠置独立含煤层气系统。

The eastern Yunnan coalfield has abundant coal resources, coal-bearing strata belong to the Longtan Formation, coal seam thicknesses are moderate and well buried with high content of CBM. The Laochang coalmine in eastern Yunnan coalfield has better coal resources in the area, thus CBM hosting geological conditions have analyzed from aspects of sedimentation, structure, coal seam, coal quality and coal-reservoir characteristics. The study has demonstrated that the Third Member of Longtan Formation in Laochang mine area is a muhilayer superimposed CBM-bearing independent system, a result of sedimentation-hydrology-structure conditions coupled with methane controlling. Coal-bearing strata sequence framework characteristics have settled the geological basis of the system. Every independent CBM-bearing subsystem is restricted in a corresponding second order sequence framework respectively. There is no hydraulic connection between coal-bearing strata and overlying, underlying aquifers, within the coal-bearing strata, different layers （combinations） are closed each other, these conditions makeup hydrogeological basis of multilayer superimposed CBM- bearing system. CBM-bearing system in Laochang coalmine is composed of 4 subsystems, they are independent mutually, lithology is provided with integrated source-reservoir-cap rock associations, thus the muhilayer superimposed CBM-bearing independent system formed.