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黔西比德-三塘盆地上二叠统煤层群具有特殊的煤层气含气系统.基于实测资料分析,根据煤层群垂向层位含气量波动性强弱和含气量梯度大小作为划分研究区煤层群含气系统类型的指标,将研究区划分为3类煤层气系统.研究表明:中部区域波动性最为复杂,含气量梯度中等;东部区域波动性较简单,含气量梯度最大;西部区域含气量梯度最小,波动亦简单,3类系统总体上显示为随层位降低煤层含气量增加.控制含气量波动性变化的主要因素是含煤地层的层序结构,东、西区域灰岩和细砂岩发育,封闭性较弱,含气系统较为简单;中部地区泥质岩发育,封闭性好,存在多套含气系统.钻孔抽水资料佐证了中部地区存在多套含气系统,各系统内部视储层压力随埋深增加而增大,这是煤层群含气量总体随埋深增加而增大的间接控制因素.
The Upper Permian coal seam group in Qianxiibeide-Santang Basin has a special CBM gas system.According to the measured data, according to the vertical and horizontal gas layers in coal seams, The study area is divided into three types of CBM systems. The study shows that the central part of the region is the most complex and the gas content gradient is moderate. The easterly region has the simplest volatility and the largest air content gradient. The western region contains The gas gradient is the smallest and the fluctuation is also simple.These three systems are generally shown as the gas content of the coal seam decreases with the increase of the horizon.The main factors controlling the fluctuation of the gas content are the sequence structure of coal-bearing strata, limestone and fine Sandstone is relatively weak and the gas-bearing system is relatively simple. Argillaceous rocks in the central area are well developed and closed with multiple sets of gas-bearing systems. The borehole pumping data corroborate the existence of multiple sets of gas-bearing systems in the central region, As the reservoir pressure increases with the increase of burial depth, this is an indirect control factor for the overall gas content of coal seams to increase with depth.