Developmental Characteristics of Sandstone Strips and Their Influence on Formation Pressure in Overpressured Shale

ABSTRACT The strong heterogeneity of shale oil reservoirs in continental rift basins of eastern China complicates their efficient development. This study takes the X Block of the Bohai Bay Basin as the research object, with a focus on locally developed, isolated sandstone strips. Using integrated dataset of core, log, thin‐section, and pressure test data, we characterize the macro‐ and micro‐scale features of these sand bodies. Statistical analysis of logging and pressure data identifies key parameters and quantitative thresholds controlling pressure differentials, supported by numerical simulations revealing the underlying mechanisms. Results show the sandstone strips are mainly low‐porosity and low‐permeability lithic arkose. Pressure release is governed by petrophysical properties, diagenesis, and structural factors: Thickness and porosity jointly control transmission capacity, with porosity >3% and thickness ≥1 m typically inducing >5% initial pressure release. Bedding‐fracture density positively correlates with the pressure coefficient, while proximity to major faults reduces pressure. This study clarifies how sandstone strips act as “pressure‐transmission windows” and establishes four pressure‐control models: fault‐controlled, thickness‐controlled, petrophysical‐property‐controlled, and bedding‐fracture‐controlled. The results offer a preliminary quantitative framework for evaluating energy potential in highly heterogeneous continental shale oil reservoirs.