Experimental study on fracture conductivity in high temperature and high pressure tight gas formation: A case of Tarim basin in China

With the increase in demand, deep and ultra-deep gas formations have been gradually explored and developed. As increasing the depth, the temperature and pressure were enhanced accordingly. Hydraulic fracturing is the main method to ensure a tight gas formation acquires high productivity. The fracture conductivity (FC) is a significant parameter to evaluate the flow capacity of fractures in a hydraulic fracturing design. FC was barely studied in the high temperature and high pressure tight gas formation. This study conducted the problem with Keshen formation in the Tarim basin in China. To evaluate FC in deep and high-temperature tight gas formations, we studied the impact of several crucial parameters, which are temperature, effective closure pressure, closure time, proppant type, proppant size, fracturing fluid, fracture roughness, and shear slip. Besides, we also considered the effect of pump proppant methods, static and dynamic pumping proppant on the fracture. Results showed that factors all had negative effects on the FC including higher temperature, higher effective closure pressure, smaller size proppant, lower proppant concentration, fracturing fluid addition, and increased closure time. Rough fracture surface and shear slip had a positive effect at the lower effective closure pressure. Moreover, we also found dynamic pumping proppant was more easily to form channel fracturing. The FC of the dynamic method was less than the static method when the effective closure pressure was larger than 50 MPa. This study provides a new approach to assess the FC in the high-temperature and high-pressure tight gas formation. Additionally, the mechanism of enhancing FC and production has been revealed through several key factors. This work facilitates engineers to optimize the hydraulic fracturing design and enhance the production of tight formations in the world.(c) 2022 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.