Researches On The Distribution And Occurrence Of Coalbed Methane In Hongyang Coalfield, Southern Shenyang

Based on the coal and coalbed methane (CBM) exploration data in the Hongyang Coalfield, Southern Shenyang, the coalbed methane geology characteristics of Linsheng, Hongling, Hongyang and Xima mining areas are detailedly researched. The coal petrology characteristics, the CBM reservoir physical properties, the CH4 adsorption capacity of coal and the gas content distribution properties are studied based on the sedimentary, coal geology, oil & gas geology etc. The geological controls of gas accumulation are discussed from characteristics of the coal metamorphism, tectonic settings, igneous intrusion, coal thickness, coal burial depth, hydrologic geology and surrounding rocks. The in-place gas resources and resources concentration are estimated based on the gas volume method, at the same time the prospective target for CBM production are evaluated and forecasted using the GIS based fuzzy AHP method. This research may provide guidance for further CBM exploration and development in the Hongyang Coalfield.The pore-fracture system of CBM reservoirs including macro-fracture, cleat, micro-fracture, porosity, pore structure and permeability are summarized based on the analysis of subsurface observation, microscope observation on coal block, mercury injection porosimetry, liquid nitrogen adsorption tests and so on.The CH4 adsorption characteristics of Hongyang coals are studied using an IS-100 isothermal adsorption instrument. Results show that the adsorption capacity of coals are strong correlated to the coal rank, coal maceral and sub-macerals, while are poor correlated to the inorganic constituent of coals such as mineral contents, moisture contents and ash yields. The geological controls of CBM accumulation are analyzed base on the sedimentary history, tectonic evolution history, gas generation history, burial history and thermal evolution history. Results indicate that the CBM concentration is principally related to the tectonics and igneous intrusions, and the next are coal burial depth, coal thickness, hydrologic geology and surrounding rocks.The gas-in-place resources are estimated to be 217.87×108m3, the CBM resources concentration are (0.26-3.56)×108m3/km2 (averagely about 1.54×108m3/km2) base on the volume method with a GIS system.The prospective target area for CBM production are forecasted to be the south of Hongling mine, the south and central of Hongyang mine, and also the south and central of Xima mine using the GIS platform based on the fuzzy AHP CBM evaluation model.