Study of hydraulic fracturing for gas drainage in a coal mine in Iran

Abstract

Hydraulic fracturing (HF) is one of the methods for making the coal mining operation safer and more economical. The most important parameters affecting the HF process of a coal seam are dip, thickness, uniformity, roof and floor conditions, reserve and strength. This paper presents the development and application of a fuzzy model for predicting the efficiency of HF, considering the aforementioned factors. In the developed model, the efficiency of HF of coal seams is calculated as a dimensionless numerical index within the range 0–100. The suggested numerical scale categorises the efficiency of HF of seams to very low, low, medium, high and very high, each one being specified by a numerical range as a subset of the mentioned range (0–100). The model is used to study the potential of HF in Parvadeh 4 coal mine in Iran. The mine consists of five different seams C1, C2, B1, B2 and D. The results show that seams C1 and B2, with predicted 94·6 and 81·2% efficiency, have high potential for gas drainage. The B1 seam, with 31·8% efficiency, has low potential for gas drainage by HF. HF would not be appropriate for both C2 and D seams, with 7·5% efficiency.