An Integrated Optimization Method for CO2 Pre-Injection during Hydraulic Fracturing in Heavy Oil Reservoirs

CO2 pre-injection during hydraulic fracturing is an important method for the development of medium to deep heavy oil reservoirs. It reduces the interfacial tension and viscosity of crude oil, enhances its flowability, maintains reservoir pressure, and increases reservoir drainage capacity. Taking the Badaowan Formation as an example, in this study a detailed three-dimensional geomechanical model based on static data from well logging interpretations is elaborated, which can take into account both vertical and horizontal geological variations and mechanical characteristics. A comprehensive analysis of the impact of key construction parameters on Pre-CO2 based fracturing (such as cluster spacing and injection volume), is therefore conducted. Thereafter, using optimized construction parameters, a non-structured grid for dynamic development prediction is introduced, and the capacity variations of different production scenarios are assessed. On the basis of the simulation results, reasonable fracturing parameters are finally determined, including cluster spacing, fracturing fluid volume, proppant concentration, and well spacing.