Structural controls on coalbed methane reservoirs in Faer coal mine, Southwest China

Abstract

Guizhou (贵州) Province, Southwest China, is rich in coalbed methane (CBM) resources, wherein its geological structure is complicated. We discuss the occurrence characteristics of CBM based on CBM borehole test data and geological setting. In combination with the analysis of the regional tectonics, macro- and micro-scopic geological structures and pore size distributions, the structural controls on CBM reservoirs were further discussed from the aspects involving tectonic evolution, structural features, and deformation of coal. The results show that the CBM enrichment was mainly controlled by the regional tectonic subsidence and weak structural deformation on coal reservoirs after coal formation. The Yangmeishu (杨梅树) syncline and topography are the main controlling factors to the current distribution pattern of CBM, which is higher in the north than the south and trending toward the NE direction. Normal faults and fractures can be divided into open, closed, and occluded types. The open type reduces both gas content and methane concentration of nearby coal seams. The closed type causes the decrease of gas content, while methane concentration is still high. The occluded type fail to reduces gas content, and even results in the enrichment of CBM in small areas near fault. Moderate brittle deformation can improve the pore structure and development of structural fracture of coal reservoir. Cataclastic structural coals with well-developed fractures and relatively uniformly distributed pore structures are common in the Faer (发耳) coal mine, which are favorable for the production of CBM.

Keywords

coalbed methane / structure / fault / tectonically deformed coal / Faer coal mine

References

[1] Cao Y X, Davis A, Liu R X, . The Influence of Tectonic Deformation on Some Geochemical Properties of Coals—A Possible Indicator of Outburst Potential. International Journal of Coal Geology, 2003, 53: 69-79.

[2] Dou X Z, Jiang B, Qin Y, . Pattern and Mechanism of Metamorphism of Late Permian Coal in Western Guizhou. Journal of China Coal Society, 2012, 37(3): 424-429.

[3] Gao D, Qin Y, Yi T S. CBM Geology and Exploring-Developing Stratagem in Guizhou Province, China. Procedia Earth and Planetary Science, 2009, 1: 882-887.

[4] Groshong R H, Pashin J C, Mcintyre M R. Structural Controls on Fractured Coal Reservoirs in the Southern Appalachian Black Warrior Foreland Basin. Journal of Structural Geology, 2009, 31: 874-886.

[5] Hotot B B. Coal and Gas Outburst, 1966 Beijing: China Industry Press, 318.

[6] Jiang B, Qu Z H, Wang G X, . Effects of Structural Deformation on Formation of Coalbed Methane Reservoirs in Huaibei Coalfield, China. International Journal of Coal Geology, 2010, 82: 175-183.

[7] Jiang B, Qin Y, Ju Y W, . The Coupling Mechanism of the Evolution of Chemical Structure with the Characteristics of Gas of Tectonic Coals. Earth Science Frontiers, 2009, 16(2): 262-271.

[8] Jiang B, Qu Z H, Wang J L, . Research on Coupling Mechanism of Mine Structure and Gas Occurrence. Procedia Earth and Planetary Science, 2009, 1: 1029-1036.

[9] Ju Y W, Lin H, Li X S, . Tectonic Deformation and Dynamic Metamorphism of Coal. Earth Science Frontiers, 2009, 16(1): 158-166.

[10] Ju Y W, Li X S. New Research Progress on the Ultrastructure of Tectonically Deformed Coals. Progress in Natural Science, 2009, 19: 1455-1466.

[11] Le G S, Zhang S J, Yang W N. Structural Deformation Patterns and Tectonic Stress Field in West-Central Guizhou. Scientia Geologica Sinica, 1994, 29(1): 10-18.

[12] Li H Y, Ogawa Y J. Pore Structure of Sheared Coals and Related Coalbed Methane. Environmental Geology, 2001, 40: 1455-1461.

[13] Li M, Jiang B, Lin S F, . Tectonically Deformed Coal Types and Pore Structures in Puhe and Shanchahe Coal Mines in Western Guizhou. Mining Science and Technology, 2011, 21: 353-357.

[14] Li M, Jiang B, Lin S F, . Response of Coal Seam Deformation to Structural Evolution in Fa’er Coal Mining Area, Western Guizhou. Journal of China Coal Society, 2011, 36(10): 1668-1673.

[15] Li M, Jiang B, Lan F J, . Pore Structures and Structural Control of Coals with Different Degrees of Deformation from Western Guizhou and Eastern Yunnan. Geological Journal of China Universities, 2012, 18(3): 533-538.

[16] Li G Z, Wang H Y, Wu L X, . Theory of Syncline-Controlled Coalbed Methane. Natural Gas Industry, 2005, 25(1): 26-28.

[17] Pashin J C, Groshong R H. Structural Control of Coalbed Methane Production in Alabama. International Journal of Coal Geology, 1998, 38: 89-113.

[18] Qin Y, Jiang B, Wang J Y, . Coupling Control of Tectonic Dynamical Conditions to Coalbed Methane Reservoir Formation in the Qinshui Basin, Shanxi, China. Acta Geologica Sinica, 2008, 82(10): 1355-1362.

[19] Qin Y, Xiong M H, Yi T S, . On Unattached Multiple Superposed Coalbed-Methane System: In a Case of the Shuigonghe Syncline, Zhijin-Nayong Coalfield, Guizhou. Geological Review, 2008, 54(1): 65-70.

[20] Qu Z H, Wang G X, Jiang B, . Experimental Study on the Porous Structure and Compressibility of Tectonized Coals. Energy and Fuels, 2010, 24: 2964-2973.

[21] Tao S, Tang D Z, Qin Y, . Analysis on Thermal History of Coal Strata of Typical Mining Areas in Western Guizhou and Eastern Yunnan. Coal Geology and Exploration, 2010, 38(6): 17-21.

[22] Wang Z T. Structure and Its Evolution of Coalfield in Western Guizhou. Coal Geology of China, 1990, 2(3): 13-17.

[23] Xu B B, He M D. Coal Geology of Guizhou Province, 2003 Xuzhou: China University of Mining and Technology Press

[24] Ye J P, Qin Y, Lin D Y. Coalbed Methane Resources of China, 1998 Xuzhou: China University of Mining and Technology Press

[25] Zhang X M, Zhuang J, Zhang S A. Coalbed Methane Geology and Resources Evaluation in China, 2002 Beijing: Science Press

[26] Zhang H. Genetical Type of Proes in Coal Reservoir and Its Research Significance. Journal of China Coal Society, 2001, 26(1): 40-44.