Stimulation of tight gas reservoir using coupled hydraulic and CO2 cold-frac technology

Abstract

Conventional hydraulic fracture stimulation technique has been widely used to enhance the production from tight gas reservoirs. Success of this technique, however, substantially depends on fracturing fluids and it responses to fracturing fluid-in the treated formations. This technology predominantly has been used to stimulate the tight sandstone reservoir. There are very limited applications for low permeable tight carbonate reservoirs due to complexities associated with the physical and mechanical properties of carbonate rocks and its interaction with fracturing fluid. This study has been focused on the development of a new fracture stimulation technique especially for tight carbonate reservoir, where the fracture will be created by hydraulic pressure and cold CO2. This paper presents a numerical model that has been developed to simulate the stimulated fracture created by proposed technology with an emphasis on the evaluation of the relative permeability of supercritical CO2, brine/liquid CO2, created achieved fracture porosity and permeability; and the prediction of the production performance of stimulated fractures. Numerical simulation employing the development model has been conducted to: understand the science; investigate the thermo-hydro-fluid-mechanical behaviour; and identify the key parameters influencing the production performance for tight carbonate reservoirs using representative field data. The potential field application of the proposed technique for other formations such as tight sand and shale plays including adsorption effects on the shale and displacement efficiency of CO2 and advantages of this technique are also elaborated in this paper.