铁法盆地煤层气资源条件及控气地质因素分析

Analysis of the coal bed methane(CBM) resources condition and gas-controlling geologic factors in Tiara basin

铁法盆地的煤阶为长焰煤,南部地区的煤阶达到了气煤阶段,实测最大渗透率为1.51×10-3m2,平均含气量为5.84cm3/g,煤层气资源量为93.34108m3,煤层气资源条件良好。本文通过对铁法盆地煤层气地质条件和储层条件的深入分析,认为铁法盆地控气的地质因素有三个方面, 构造对煤层的沉积分布、含气量和煤层气资源量具有明显的控制作用;水文地质条件对煤层气具明显的封堵作用;区域浅成岩浆热变质提高了的煤阶、改善了煤储层的渗透性,增大了煤储层的含气量。提出了铁法盆地煤层气勘探开发的首选靶区是西南部的大兴矿一带。

Coal has entered the step of dry coal in the Tiara Basin, while the coal in the south area has already entered gas coal one. The maximal permeability measured on the spot can be as much as 1.51×10-3μm2, and the average gas content is 5.84cm3/g, the total amount of the coal-bed gas can be up to 93.34×108cm3, it is certain that the resources condition of the coal-bed gas is quite good. In this paper, three geology factors which controlled the gas resources have been proposed after the thorough analysis of the geology and the reservoir conditions about the coal-bed gas in Tiara basin. Among which, the structure one had an obvious control over the distribution, the gas content and the total amount of the CBM resources of the coal beds; the hydrological geology one had an apparent blockage effect on the coal-bed gas and the last one,the areal epi thermo-metamorphosis enhanced the coal step and improved the reservoir permeability at the meantime, what抯 more, it had an active part on the increasing of the sum of the gas-content in the reservoirs. By the way, the most beneficial target area for the CBM exploratory development in this basin can be choose near the Daxing mine, which locating at the southwestern of Tiara Basin.