Prediction of residual resource distribution of high-order coal based on fracture characteristics

Predicting the distribution of remaining high-order coal resources is an important part of well position adjustment and deployment in the middle and later stage of gas field development. Reasonable selection of well type and spacing can promote the depressurization of the area between well groups and improve gas production effect. However, the key problem in accurately predicting the distribution of remaining resources is how to determine the impact range of the wells that have been developed. In view of this problem, based on the southern block of the Qinshui Basin, the geological parameters, fracturing monitoring date and dynamic data of more than 100 wells were systematically analyzed, and the key factors affecting the production range of coalbed methane wells were analyzed. The results show that the mining influence range of coalbed methane wells is an approximate elliptical distribution controlled by the fracturing fractures in the coal seam; the fractures are greatly affected by the structure, and the type of structure affects the direction of the fracturing fractures, such as monoclinic structure, anticline wing, and direction. The crack direction of single-angle structure, anticline wing and synclinal wing are consistent with the maximum principal stress. The crack direction of the axis of the anticline is consistent with the axial direction, and the crack direction of the axis of the syncline is perpendicular to the axis. The structural curvature has a negative correlation with the main crack length, and the greater the curvature, the shorter the length of the main fracture. Based on the above research results, a method for predicting the distribution of remaining resources was established. The core content of the method is based on the principle of structural similarity, using the clustering statistical method, according to the structural characteristics of the developed wells, inferring the distribution law of mining influence, and determining the distribution of remaining resources. Using this method to implement adjustment in the northern part of Fanzhuang has obvious effect, which provides a basis for the preparation of the adjustment plan for the development of high-order coal in the middle and later stages.