Construction and application of gas resource estimation and evaluation method in abandoned coal mines

On the basis of on the exploration and development status of gas resources in abandoned coal mines in China, the idea of “resource estimation + preliminary evaluation” was put forward to reasonably evaluate the gas resources in abandoned coal mines. The estimation and evaluation method of gas resources in abandoned coal mines was established, which has the advantages of less required parameters and strong practicability. According to the gas emission characteristics and abandoned time, the types of abandoned coal mines were divided into two categories: stable and unstable. Unstable coal mines were further divided into early, middle and late stages of unstable coal mines. Furthermore, the evaluation model of abandoned coal mine gas resources was constructed according to the types of abandoned coal mines and gas occurrence characteristics. The abandoned coal mine gas resources were divided into 16 types. The analysis shows that the gas resources in abandoned coal mines are mainly dominated by the gas resources existing in the coal resources, and the gas resources and desorption amount in the residual coal are relatively small. Besides, based on the gas resources and occurrence, the development value was divided into four grades: relatively good, relatively medium, relatively poor and relatively worst. Finally, taking Jiaozuo mining area as an example, the abandoned time of coal mines was counted, the types of abandoned coal mines were divided, and the unstable abandoned coal mines closed since 2006 were emphatically evaluated. It was estimated that the amount of gas resources in abandoned coal mines of mining coal seam is about 26.06×10⁸ m³ in the past 15 years in Jiaozuo mining area. Among them, the amount of gas resources in reserved coal resources is about 20.75×10⁸ m³, and the amount of gas resources in the residual coal is about 5.31×10⁸ m³. The development value is relatively good.