Delaying of Bottom-Water-Coning Oriented Hydraulic Fracturing Design and Optimization: Numerical Simulation and Field Case Study

Abstract

ABSTRACT Is usually used hydraulic fracturing to enhance the productivity of tight gas sandstone formations. If basal water layers were connected to the upper gas formation via hydraulic fractures, the gas productivity of the stimulated wells would be reduced drastically. It is crucial to postpone the bottom-water-coning effect by meticulous hydraulic fracturing design and operation parameters optimization. Temporary plugging could be a potential solution for controlling hydraulic fracture extension in the vertical direction. This paper proposed a basal water-avoiding hydraulic fracturing design and optimization methodology and procedures to solve this problem. The geological and geo-mechanical models were built based on the characteristics of the gas layer, natural fracture, and basal water layer analysis. Hydraulic fracture propagation simulation conducted pump rate, Hydraulic fracture propagation simulation considered pump rate, frac-fluid volume, frac-fluid viscosity, temporary plugging material volume, proppant concentration, and proppant volume. Hydraulic fracture vertical height and distance to the basal water layer were used as the primary indicators to optimize the frac-fluid volume, pump rate, and temporary plugging material volume. Then simulated fracture area and fracture propped area were used as significant parameters to identify the optimal frac-fluid viscosity, proppant concentration, and proppant volume. KS field is an ultra-deep tight gas sandstone formation with basal aquafers. The fracture propagation model of the KS-X well was established to delay bottom-water-coning-oriented hydraulic fracturing design and optimization. Results showed that the optimal frac-fluid volume, pump displacement, and temporary plugging material quality are 950 m3, 4.5 m3/min, and 300 kg, respectively. The optimal proppant volumes of 70/140 mesh, 40/70 mesh, and 30/50 mesh ceramic proppant are 6 m3, 38 m3, and 9 m3, respectively. After hydraulic fracturing, the gas production rate of the KS-X well is as high as 290,000 m3/day without any water production for one month, indicating the effectiveness of the proposed basal water-avoiding hydraulic fracturing design and optimization methodology. The proposed design and optimization procedures can be further used in other basal aquifer gas fields.