Study on well pattern density and well spacing of coalbed methane development: taking Hanchengbei Block as an example

Coalbed methane (CBM) well network density and well spacing optimization are important factors affecting CBM production and economic efficiency, and are important components of CBM development programs. At present, most of the researches on well spacing for CBM development only consider productivity factors or economic factors, but there are few comprehensive evaluation studies on them. In order to explore the optimum scheme of well pattern density and well spacing for CBM development, and to comprehensively evaluate the productivity and economic benefits of CBM wells, based on the basic geological conditions of the Hanchengbei block and physical data of coal reservoir, the well pattern and well pattern orientation suitable for CBM development are determined in this paper. Through experience comparison method, single well reasonable control reserve method, economic limit well spacing method, specified single well productivity method and economic limit well pattern density method, the well pattern density and well spacing deployment scheme for CBM development in Hanchengbei block are calculated and discussed. Using numerical simulation software Comet3 of CBM productivity, the productivity under different well spacing development schemes is simulated and evaluated, and the density of well pattern for CBM development is further optimized from the perspective of economic evaluation by discounted cash flow method. The result shows that the suitable well pattern for CBM development in Hanchengbei block is rectangular well pattern. The well pattern orientation is NE49°. The numerical simulation results show that when the well spacing is 200 m×250 m, the stable production period productivity of CBM well is the highest and the cumulative production capacity is the highest. According to economic evaluation and comparison of different well spacing schemes in 1 km², when well pattern density is more than 10 wells/km², the development of CBM in this area has economic benefits, where well pattern density is 20 wells/km² and well spacing is 200 m×250 m scheme is 11.27%, the net present value is 14.37 million yuan, and the payback period of investment is 7.49 years, the economic index is the best. Comprehensive analysis shows that the best development well pattern density of Hanchengbei block is 20 wells / km², and the best well spacing scheme is 200 m×250 m.