A prediction method for coalbed methane development sweet spots based on hierarchical analysis and grey fixed-weight clustering: taking Shizhuangbei block as an example

Abstract

With the development of the coalbed methane industry and the requirements for the integration of unconventional resource exploration and development, the current exploration of coalbed methane is gradually advancing from the favorable area stage to the sweet spot stage. However, limited by the stage of exploration and development or the degree of data possession, most of the current area selection evaluation systems do not take into account the fracability of coal reservoir and the recoverability of coalbed methane. Evaluation results are not effective in guiding development well location selection or infill wells. Based on the data of more than 100 coalbed methane parameter wells and development wells, this paper analyzes the resource conditions, reservoir fracturing improvement and coalbed methane recoverability of the No.3 coalbed methane development in Shizhuangbei Block, Qinshui Basin. An evaluation model was built with the gray fixed weight clustering method, and the sweet spot of ​​the coalbed methane project was evaluated, in an effort to provide a basis for the deployment of new wells and infill wells in the block. It was used coal seam gas content and coal thickness to reflect coal bed methane resource conditions; it was comprehensively considered the in-situ stress environment and rock mechanical properties to construct the reservoir fracability parameter, and then evaluates reservoir fracturing improvement; it was used the proportion of original structure coal and fragmented coal , temporary-reservoir ratio and original reservoir permeability to reflect the recoverability of coalbed methane. Each parameter is graded by the word clustering method, and the comprehensive goodness of each point (each well) is calculated and sorted, and finally the sweet spot for coalbed methane development is divided. The evaluation results show that the central part with the comprehensive goodness value >65 is the sweet spot for further development in the study area.

Keywords

• coalbed methane
• shizhuangbei block
• evaluation system
• analytic hierarchy process
• grey fixed-weight clustering
• sweet spot for cbm development