鄂尔多斯盆地宜川地区煤层气储层特征及勘探潜力分析

Characteristics of CBM Reservoirs and Exploration Potential in Yichuan Region of Ordos Basin

鄂尔多斯盆地宜川地区发育本溪组、山西组等多套煤层,具备煤层气形成的基本条件。为查明鄂尔多斯盆地宜川地区煤层气的勘探潜力,本文从煤层分布特征、煤岩煤质特征、煤岩演化程度、煤层等温吸附等方面入手,分析了该区煤层气的基本地质特征,并对煤层气的勘探潜力进行了初步分析。结果表明:宜川地区发育山西组3号和本溪组11号两套煤层,煤层分布稳定,单层厚度一般为2m左右,煤层含气量可达25m^3/t。通过与已获得较好煤层气勘探开发先导试验效果的延川南和韩城地区相比,本区具有煤层厚度相近,含气量大,埋深相对较大等特点,下步勘探工作的重点是寻找低地应力、高渗透率,煤层气富集的地区。

There are several series of developed coal seams such as Benxi Formation, Shanxi Formation at the Yichuan area of Ordos Basin, which has favorable conditions for the accumulation of combed methane. In order to evaluate the CBM exploration potential of Yichuan area, the authors analyze the basic geological characteristics of CBM in this area from the aspects of coal seams distribution, coal quality, degree of evolution and isothermal adsorption. The CBM exploration potential is also evaluated. The results show that there are two favorable coal seams in Yichuan area which is No. 3 of Shanxi Formation and No. 11 of Benxi Formation. The coal seams distributed steadily, the thickness of single layer generally is about 2m, and the gas content can be up to 25m^3/t. Based on the comparison of the pilot test results of CBM exploration in Yanchuannan and Hancheng area, the Yichuan area is featured with similar thickness of coal seams, large gas content, deep buried depth, etc. The next step for exploration will be focused on looking for areas with low crustal stress, high permeability and abundant coalbed methane enrichment.