贵州省织纳煤田煤层特征及煤层气资源潜力

贵州省中西部织纳煤田煤层气资源丰富，但煤层气的系统评价工作比较薄弱，为全面分析、评价该区煤层气资源状况、赋存条件，以煤田地质钻孔、煤层气参数井获取的原始资料为基础，对织纳煤田煤层气地质条件，特别是储层含气特征及煤层渗透性等方面进行了研究，并采用体积法对煤层气资源进行了计算和评价。结果表明：①该区煤层主要为中-薄层、中等灰分、低挥发分、相对富氢无烟煤，除了煤层气勘探主力煤层6号煤煤体结构较大程度地受到构造破坏外，其余煤层原生结构较完整；②虽然该区煤储层渗透性相对较低，但区内含煤面积大，煤层气资源丰度较高，含气量较高，煤储层厚度较大，可采性好，具备较有利的煤层气勘探地质条件与可采性；③煤层气总资源量为1 852.91×10⁸ m³，其中埋深1 000 m以浅煤层气资源量为1 436.59×10⁸ m³，大于15 m^3/t含气带资源量为1 484.34×10⁸ m³，潜在煤层气可采资源量为747.65×10⁸ m³。结论认为：比德向斜化乐勘探区在煤层气资源丰度、平均含气量和试井渗透率3个方面优势相对明显，可作为煤层气勘探最有利靶区。

Characteristics and CBM potentials of coal seams in the Zhina Coalfield, Guizhou

The Zhina Coalfield in west central Guizhou province of China is rich in CBM resources. However, little work has been performed in respect of systematic evaluation of CBM in this coalfield. In order to fully understand the resource potentials and storage conditions of CBM in the study area, we studied the CBM geological conditions there, especially the gas bearing features and coal seam permeability, by using the available original data from core drilling as well as CBM well parameters. The CBM resource volume was evaluated and estimated by using the volumetric method. The following results were obtained. (1) The coal seams in the study area with moderate and small thickness are dominated by anthracite coals with moderate ash content, low volatile content and relatively rich hydrogen. The original structures of most coal seams are well preserved, except for the pay zone of the No.6 coal seam whose original structure was seriously destroyed by tectonic movement. (2) Although being relatively low in permeability, the coal reservoirs in the study area have the favorable characteristics such as a large area of coal, high CBM abundance, relatively high gas content, great thickness, and good recoverability. (3) The total resource volume of CBM is 185.291 BCM, about 143.659 BCM of which is stored in reservoirs with a burial depth of less than 1000 m. The resource volume in the area with a gas content of over 15 m³/t is 148.434 BCM and the potential recoverable resource volume is 74.765 BCM. It is concluded that the Huale area on the Bide anticline is relatively supreme in the resects of resource abundance, average gas content and well test permeability, thus can be selected as the most favorable target area of CBM exploration in this study area.