Study On Geological Conditions Of CBM Development And Productivity Evaluation In Liulin Area

Geological condition is the basis of CBM development, which directly affects the implementation of CBM development project and the potential of gas well production, and it is also related to the success of CBM exploration and development. CBM resources in Liulin area is abundant, it is one of the hotspots of CBM exploration and development in China, and it has initially realized the CBM commercial development. In this paper, based on the analysis of geological background of CBM in Liulin area, we Identified CBM geological conditions and reservoir characteristics in the study area, and specified the CBM development target layer is 3+4,5 and 8+9 coal seam; Combined with the previous CBM development project in this area, and for drilling engineering, fracturing stimulation engineering and drainage engineering, analyzed the problems in project implementation, Proposed separated layer pressure control and multi-hydraulic fracturing layers drainage operating recommendations for CBM wells.Based on the analysis of the geological conditions and reservoir conditions, studied the main geological factors that affect the production capacity of vertical wells in Liulin block, and obtained that the high-yield wells formed under the combined effect of a variety of favorable geological factors;Through the analysis of the drainage curve characteristics of CBM wells, we summarized three types of gas production curve of CBM wells, that is single peak, peak-stabilized and low-peak-peak-stabilized, It is pointed out that peak-Stable gas production curve represents favorable geological conditions.Combined with the studied of geological factors that affect the productivity of CBM well, we selected two drainage wells in this area, and put them into history fitting according to the production curve, fixed the main reservoir parameters such as permeability and porosity, the corrected coal seam permeability is 3.78～4.38×10-3μm2, and the porosity is 1.7%～2.0%; on the basis of historical fitting, we predict and evaluate the productivity of CBM exploration and development in the area, it is pointed out that the development potential of CBM development in this area is larger, and the northern area is better than the southern area.