Coalbed Methane Enrichment Regulation And Favorable Area Selection In Jixi Mining Area

Jixi Mining Area is rich in coal resources and has high gas content in the coal seam.It has good coalbed methane?CBM?resources potential and exploration and development prospects.This paper takes Jixi mining area as the research object,based on the coalfield exploration data,CBM exploration data and experimental test results in the mining area,carries out coal reservoir characteristics,coal bed methane enrichment patterns,and optimization research of favorable areas for CBM exploration and development.It provides a theoretical basis for the follow-up CBM exploration and development in the mining area.The main research conclusions are as follows:?1?Analyzes the reservoir characteristics such as coal thickness,gas-bearing capacity,adsorption,pore infiltration conditions and reservoir pressure in the main mining seam of the mining area.Coal seam thickness varies widely in the mining area,and the northern depression is larger than the southern depression.The overall gas content of the coal seam is relatively high,and the gas content varies from 1.41 to15.88 m³/t,with an average of 5.73 m³/t,with CH₄ as the major component.The main coal bed has strong adsorption capacity and gas desorption.The average Langerville volume is 12.62m³/t,and the average Langerville pressure is 3.35MPa.Coal reservoir pressure and pressure gradient change greatly,and overall gas saturation is higher.In terms of pore permeability characteristics,the main coal seam in the mining area is dominated by small pores,and the reservoir permeability is relatively good and average permeability is 0.357mD.?2?Summarized the enrichment regulation of CBM,and discussed the control of CBM enrichment from the aspects of structure,sedimentation and hydrology.The enrichment of CBM in the mining area shows the characteristics of the north-south zoning,and the gas content and gas gradient of the northern depression is higher than that of the southern depression.The gas content increases from north to south within each depression;the gas content in the middle of the northern depression is lower than that of the eastern and western regions.The CBM enrichment control factors in the mining area are mainly reflected in the three aspects of structure,sedimentary and hydrogeological conditions:in terms of tectonic gas control,the flattened fractures and secondary structural units that are subjected to compression are conducive to the preservation and enrichment of CBM.In addition,with the increase of the burial depth,the gas content has a significant increase trend;in terms of deposition and gas control,the distribution characteristics of the coal metamorphic degree in the coal mine have a high consistency with the enrichment of CBM,and at the same time,the well-developed regional coal seam The gas is relatively enriched;in terms of hydrology and gas control,the southern depression of the mining area is dominated by water migration,and the northern depression is relatively weak in water migration,and the local area appears as a hydraulic plugging effect.?3?Calculated CBM resources and selected favorable area in key minefields.The result of CBM resource calculation by volumetric method showed the CBM geological resources and recoverable resources of the 12 key mines in the mining area were 200.35×10⁸m³ and 91.31×10⁸m³,and the average recoverable coefficient was45.58%.Using the method of“Fuzzy Comprehensive Evaluation based on Analytic Hierarchy Process”,selected Chengshan minefield,Xinghua minefield and Didao minefield as favorable areas for exploration and development of CBM in mining areas.Taking the areas with relatively simple shallow structures and high resource abundance in each favorable area as the first coal mining methane production area,and give priority to CBM exploration and development.