Optimization of Well Pattern and Injection-Production Parameters for Hydrocarbon Gas Drive in Tight Oil Reservoirs After Volumetric Fracturing

The gas injection and volumetric fracturing technology of horizontal wells have been widely used in the exploration and development of tight reservoirs. However, gas injection tends to trigger gas channeling and cause futile cycles of injected gas. Therefore, studies on optimization of well pattern parameters and injection parameters for gas drive after volume fracturing in tight reservoirs are needed. In this paper, a numerical simulation model of hydrocarbon gas drive for horizontal well volume fracturing by using CMG is established, which is based on the mechanism of hydrocarbon gas drive and the relevant data of block x233 in the Chang 72 reservoir. A comparative analysis of the mining effect of different well patterns was carried out by this model, and the optimization design of well pattern parameters and injection-production parameters was also carried out for the five-point well pattern. The results of the study show that the five-point well pattern has the best extraction effect and the inverted nine-point well pattern has the worst extraction effect on the block X233 in the Chang 72 reservoir. The 5-point well pattern has the optimal well spacing range of 150–250 m and the optimal row spacing range of 150–250 m. Horizontal wells with long fractures have a high recovery degree in the early stage and a low recovery degree in the later stage, and the optimal range of fracture strips is 7–13. The lower the bottomhole pressure of a production well, the earlier the gas is seen and the higher the degree of recovery, but the rise is increasingly slow. The higher the injection pressure of the injected wells, the earlier the gas is seen and the higher the degree of recovery, but the rise is also increasingly slow. This paper combines horizontal well volume fracturing with hydrocarbon gas flooding, and conducts a study on the optimization of well pattern and injection-production parameters of hydrocarbon gas drive, which has certain significance for the development of gas injection in tight reservoirs.