Stimulation mechanism and model application of CO2 pre-pad fracturing for production enhancement in tight glutenite reservoirs

Tight glutenite reservoirs are generally characterized by low porosity， low permeability， high flow resistance， and poor natural productivity， making effective stimulation methods essential to enhance oil recovery. CO2 pre-pad fracturing， as an effective stimulation method for enhanced production and gas storage， has attracted increasing attention in recent years， yet standardized modeling and system parameter optimization remain insufficient. To address this issue， based on the characteristics of tight glutenite reservoirs， a flow and fracturing model for CO2 pre-pad fracturing was developed. By using a combined approach of theoretical analysis and numerical simulation， a systematic study was conducted on fracture propagation patterns， hydrocarbon displacement characteristics， and stimulation performance under different injection conditions. This study employed the embedded discrete fracture model （EDFM） and CO2-driven hydrocarbon experiments to analyze the influence of key parameters on stimulation performance， such as injection volume， rate， and shut-in time. The results indicate that CO2 pre-pad fracturing significantly improves reservoir permeability and fracturing fluid recovery， thereby enhancing oil and gas displacement efficiency. The recommended parameters are an injection volume of 200-300 m3 per stage， an injection rate of approximately 8 m3/min， a cluster spacing of 15-20 m， and a shut-in time not exceeding 40 days.