关键词: 煤层气, 排采特征, 产能影响因素, 灰色关联分析, 杨家坡区块

Abstract:

Understanding the characteristics and primary controlling factors of coalbed methane (CBM) well productivity is key to improving utilization rate and achieving economic and efficient development of CBM resources. This paper examines the gas production characteristics, dynamic changes in typical well drainage, and factors affecting CBM well productivity, based on a comprehensive analysis of regional geology and gas well production data from the Yangjiapo block, Eastern Ordos Basin. New parameters, such as gas production per unit decrease in liquid level and the liquid level decrease ratio, were proposed to enhance the rationality and accuracy of evaluating gas well productivity. A grey correlation analysis was used to identify the primary factors controlling the productivity of CBM wells in the Yangjiapo Block. The study results indicate that gas production from CBM wells in the Yangjiapo Block is heterogeneous, with stable rate ranging from 552 to 1744 m³/d. Based on gas production characteristics, the production can be divided into three stages: low production, production increase, and stable production. The primary controlling factors on the production capacity of the CBM wells are geological factors, including the desorption characteristics of coal reservoirs and hydrogeological conditions. A regional CBM enrichment and high-yield model has been proposed, characterized by a high desorption index and weak hydrodynamic conditions. This model suggests that areas with a high desorption index and weak hydrodynamic conditions are more likely to achieve efficient CBM production in the Yangjiapo Block. Understanding these key parameters provide important insights and reference for selecting well locations and efficiently developing resources in this area and potentially other CBM blocks.

Key words: coalbed methane, drainage characteristic, productivity influencing factor, grey correlation analysis, Yangjiapo Block