Research and Application of Temporary Plugging Diverting Fracturing in Horizontal Shale Oil Wells of the Sichuan Basin

The shale oil reservoirs in the Sichuan Basin are distinguished by pronounced heterogeneity, with natural fractures locally developed within specific horizontal well intervals. These fractures serve as pivotal conduits for crude oil migration; consequently, maximizing connectivity with these pre-existing discontinuities to enlarge the Stimulated Reservoir Volume (SRV) remains a paramount objective in hydraulic fracturing design. In early-stage field operations, temporary plugging fracturing was routinely implemented in horizontal wells to establish effective linkage with natural fractures. However, critical treatment parameters—including the type of Temporary Plugging Agent (TPA), plugging location, and pumping rate—were predominantly determined via empirical approaches. This heavy reliance on field heuristics often led to suboptimal diversion performance and substantially undermined overall stimulation efficiency. To address these limitations, we employed a three-dimensional dynamic temporary plugging evaluation system equipped with wedge-shaped fracture models of varying apertures (specifically 6 mm, 4 mm, and 2 mm) to systematically screen high-strength TPA combinations. This experimental setup enabled the simulation of realistic fracture geometries under dynamic flow conditions. The screening results revealed a clear inverse correlation between fracture width and plugging efficacy: for any given TPA formulation, the achieved plugging pressure differential decreased progressively as the fracture aperture expanded from 2 mm to 6 mm. Furthermore, under a constant fracture width, the incorporation of smaller-sized TPA particulates into the formulation proved critically effective in substantially elevating the plugging pressure, attributable to the enhanced bridging and packing efficiency within the narrower constrictions. Through this rigorous, width-dependent optimization protocol, the final optimized TPA blend consistently generated a plugging pressure differential exceeding 24 MPa, thereby robustly validating its capacity to induce effective fracture diversion. In parallel with the experimental efforts, a numerical simulation model was developed to systematically optimize the plugging position, injection rate, and target plugging pressure. The proposed workflow was subsequently applied to Well XN1. Post-treatment diagnostic analysis indicated that the temporary plugging operation markedly enhanced the extent of fracture propagation, thus validating the effectiveness of the optimized strategy.