Numerical Modelling and Experimental Validation of Hydraulic Fracture Propagation in Coal Reservoirs: A Case Study From Guizhou, China

ABSTRACT

Hydraulic fracturing technology plays a crucial role in coalbed methane (CBM) extraction. Utilising data from a CBM development site in western Guizhou, China, this study employed the ABAQUS software and cohesive element approach to establish a numerical model for hydraulic fracturing fracture propagation within thin coal seams. The results of the numerical simulations reveal the following insights: Under constant fracturing fluid displacement, variations in fracturing fluid viscosity directly impact the length and width of hydraulic fractures. Specifically, lower viscosity leads to narrower and longer fractures, tending to produce elongated fracture geometries, whereas higher viscosity results in wider and shorter fractures. For a fixed fluid viscosity, increasing the displacement yields both longer and wider fractures. For reservoir stimulation, it is recommended to use a high‐displacement, low‐viscosity fluid as the pre‐flush (provided that equipment specifications allow), as this promotes rapid fracture propagation and enhances interaction with natural fractures, ultimately forming a complex fracture network. During reservoir reconstruction, it is advisable to utilise fracturing fluids with high displacement and low viscosity as the pre‐flush fluid, provided all equipment specifications are met. This approach facilitates the rapid propagation of hydraulic fractures and their interaction with natural fractures within the reservoir, ultimately forming a complex fracture network. For the fracturing support stage, substituting the pre‐flush fluid with a high‐displacement, high‐viscosity sand‐carrying fluid enhances the fluid's sand‐carrying capacity, increases fracture volume, and further improves the fracturing effectiveness. This study provides valuable guidance for CBM development in China.