Analysis of Sand Production Sensitivity Factors in Deepwater Low-Permeability Gas Reservoirs

Deepwater, low-permeability, medium- to high-strength sandstone reservoirs are susceptible to pressure depletion and fluid–rock interactions during production. These processes can induce plastic instability and particle migration in the near-wellbore region, ultimately causing sand production. Taking the deepwater L gas field as the study area, this work combines laboratory experiments with numerical simulation to systematically investigate reservoir mechanical properties and the evolution of sand production. The target interval is a low-permeability, fine-grained sandstone reservoir. Quartz is the dominant whole-rock mineral, illite is the dominant clay mineral, and the smectite content is low. The median grain size d50 is mainly 58–139 μm, and the sediments are generally poorly sorted. The uniaxial compressive strength is approximately 43 MPa, indicating a medium- to high-strength sandstone, whereas water immersion causes a pronounced reduction in rock strength. A hydro-mechanically coupled sand-production model was employed in ABAQUS 2026 to incorporate porous-medium fluid seepage, rock mechanical response, and an empirical sand-erosion criterion. The model was used to quantify how reservoir parameters affect near-wellbore plastic deformation and sand production. With progressive reservoir depletion, the equivalent plastic strain increases and sand production remains concentrated in the near-wellbore region. The normalized sensitivity of the maximum equivalent plastic strain decreases in the following order: cohesion, Young’s modulus, ratio of maximum horizontal principal stress to overburden stress, internal friction angle, Poisson’s ratio, and production drawdown. Production forecasts for a development well further show that sand production evolves in three distinct stages: an initial sand-production stage, a rapid sand-production growth stage, and a fluctuating and declining sand-production stage. Numerical simulation results indicate that sand-production risk persists throughout the predicted 15-year production period, highlighting the need to incorporate appropriate sand-control measures into the well completion design and maintain sand-production management throughout the production life cycle. The results provide a basis for sand-production risk assessment and completion and development optimization in comparable deepwater, low-permeability sandstone gas reservoirs.