Geological controls and coalbed methane production potential evaluation: A case study in Liulin area, eastern Ordos Basin, China

被引：0

作者：

Meng, Yanjun ^{[1
,2
]}

Tang, Dazhen ^{[1
,2
]}

Xu, Hao ^{[1
,2
]}

Li, Chen ^{[3
]}

Li, Ling ^{[1
,2
]}

Meng, Shangzhi ^{[4
]}

机构：

[1] School of Energy Resources, China University of Geosciences (Beijing), Beijing,100083, China

[2] Coal Reservoir Laboratory of National CBM Engineering Center, Beijing,100083, China

[3] Research Institute of Petroleum Exploration and Development, PetroChina, Beijing,100083, China

[4] China United Coalbed Methane Co., Ltd, Beijing,100011, China

来源：

Journal of Natural Gas Science and Engineering | 2014年 / 21卷

基金：

中国国家自然科学基金;

关键词：

Coal bed methane - Flow of gases - Methane - Gas adsorption - Groundwater - Metamorphic rocks - Well testing - Lithology - Hydrogeology - Petroleum reservoir engineering - Coal deposits - Roofs;

D O I：

暂无

中图分类号：

学科分类号：

摘要：

The Liulin area in the eastern Ordos Basin is one of the optimum areas for medium-rank coalbed methane (CBM) exploration and development in China. This work investigated the CBM geology and accumulation characteristics of No.4 coal in the Permian Shanxi Formation in the Liulin area based on data from 29 coal mining wells, 25 CBM wells and 14 coal samples. The results show that coal rank (medium volatile bituminous and low volatile bituminous) varies laterally, with the maximum vitrinite reflectance (Ro, max) ranges from 1.23 to 1.90%. Coals are dominated by vitrinite (47.9-90.5%); followed by inertinite (7.7-50.5%) and liptinite (0-0.6%). Minerals account for only a small proportion (0.4%-16.5%, avg. 4.7%). The results of well tests show that the coal permeability ranges from 0.02 to 3.44mD, and the reservoir pressure ranges from 2.58 to 9.26MPa. Most coal pores are less than 100nm in diameter, and are favorable for gas adsorption but unfavorable for gas flow. Microfractures of coals are characterized by dendritic and step-shaped structures, relatively good connectivity, directionality and infrequent mineralization. The dominated types of microfractures are type C (less than 5μm wide and more than 300μm long) and type D (less than 5μm wide and 300μm long), with a large span of frequency ranging from 18 to 78 per 9cm2. Methane adsorption isothermal measurements reveal that their maximum adsorption capacity (dry ash-free) vary from 21.36 to 26.38m3/t. The in-place gas content is generally 4.93-14.96m3/t. In combination with the geological information, the data reveals that structure properties, coal roof lithology and hydrogeology conditions have important influences on gas accumulation, preservation and enrichment. Furthermore, integrated geographical information system (GIS) and analytical hierarchy fuzzy prediction method (AHP) are used to evaluate the CBM production potential in the Liulin area. The best prospective target area for CBM production is forecasted to be located in the central slope belt (near southern Beilijiyuan and Yangjiayu areas) of the Liulin area. © 2014 Elsevier B.V.

引用

页码：95 / 111