The Impact of Fracturing Engineering Parameters on the Propagation of Fractures in Infill Wells and the Evolution of the In Situ Stress Field During Waterflood Processes

This study aims to enhance the development effectiveness of infill wells in the strongly heterogeneous conglomerate reservoir of the Baikouquan Formation in the Bai 21 well area of the Junggar Basin. By optimizing the synergy between fracturing and waterflooding development, it provides a basis for improving the recovery rate of such reservoirs. Integrating geomechanical modeling, fracturing numerical simulation, and reservoir dynamic analysis, the influence mechanisms of fracturing parameters—including pumping rate, pad fluid ratio, and proppant intensity—on fracture propagation, waterflooding response, and stress field evolution were systematically investigated. The results indicate that an optimal parameter combination of a pumping rate of 3.5–4.0 m3/min, a pad fluid ratio of 40–50%, and a proppant intensity of 3.0–4.0 m3/m can create short, wide fractures with half-lengths of 40–45 m, effectively delaying water breakthrough and reducing inter-well interference. Stress field simulations further reveal non-uniform evolution during injection and production: the stress near injection wells initially increases and then decreases, dropping by 9.3% compared to the initial value, while the stress around production wells continuously decreases, with a reduction of up to 37.3%. These findings provide valuable guidance for the synergistic development of fracturing and waterflooding in infill wells in similar strongly heterogeneous conglomerate reservoirs.