基于地质因素的煤层气储层压裂产能分类评价

Classification and Evaluation of Post-fracturing Productivity of Coalbed Methane Reservoirs Based on Geological Factors

煤层气储层压裂产能受地质因素和工程因素共同影响。分析不同压裂产能的地质影响因素,综合不同区域地质影响因素进行压裂区优选,建立适用于鄂东缘H区的压裂产能预测分类标准。鄂东缘H区煤体结构主要划分为原生结构煤、碎裂煤、碎粒煤,测井信息与不同煤体结构之间的关系随着煤体结构越破碎,井径扩径越严重,深电阻率逐渐降低;煤层厚度、煤体结构、含气量、地应力、天然裂缝是影响压裂产能的地质主控因素。对21口新井32个煤层气压裂层段进行了压裂产能预测检验,预测符合率达84.4%。

The post-fracturing productivity of coalbed methane(CBM)reservoirs is affected by geological and engineering factors. In this paper, geological factors affecting post-fracturing productivity are analyzed, target fracturing zones are selected based on regional geological factors, and classification criteria are established for predicting post-fracturing productivity in the H area on the eastern edge of Hubei Province. Coal structures in the H area are mainly divided into undeformed coal, fragmented coal and granulated coal. Log data indicate that the more fragmented the coal structure, the more serious the borehole is enlarged, and the lower the deep resistivity. The thickness of coal seam, coal structure, gas content, in-situ stress and natural fractures are controlling geological factors affecting post-fracturing productivity. Tests on 32 fractured coal seams in 21 new wells demonstrate that the productivity prediction is coincident by 84.4%.