Fault Sealing Evaluation Based on Displacement Pressure Contrasts: An Integrated 3D Workflow Applied to the K-Area, Pinghu Slope, Xihu Depression

Summary

Accurate evaluation of fault sealing is essential for understanding trap effectiveness and reducing exploration risk in fault-controlled reservoirs. This study presents a displacement pressure-based 3D fault seal evaluation framework based on displacement pressure contrasts between fault rocks and juxtaposed reservoirs. Using the K area of the Pinghu Slope in the Xihu Depression as a case study, structural modeling and geological property modeling were integrated to construct a fault surface-based framework. Within this framework, key controlling factors, including shale content, burial depth, and stress conditions, were incorporated to estimate the displacement pressures of fault rocks and juxtaposed reservoirs. The resulting displacement pressure contrasts were then used as a direct criterion for evaluating fault sealing potential in both vertical and lateral directions. The results indicate that fault sealing potential in the K-area is markedly heterogeneous both vertically and laterally. Strong vertical sealing is mainly developed in the P3 and P7 intervals, which constitute the principal sealing horizons in the study area, whereas the P5 and P6 intervals represent favorable reservoir intervals under relatively strong sealing conditions. Fault segments located closer to the depocenter generally exhibit stronger sealing potential than those toward the slope margin, and the lower reservoir-seal assemblage shows stronger lateral sealing potential than the upper assemblage, implying more favorable conditions for hydrocarbon preservation in deeper structural sectors. The workflow enables continuous spatial characterization of fault sealing behavior across fault surfaces and provides a practical basis for identifying favorable fault segments and exploration targets in structurally complex regions.