A Modified Probability-Based Pore Network Model Considering Particle Plugging for Characterizing Velocity-Sensitive Damage

Abstract

Efficient, economical, and environmentally friendly development of oil-gas reservoirs is essential for mitigating the energy crisis. Notably, in oil reservoirs exhibiting pronounced velocity-sensitive characteristics, improper production rates can lead to formation damage through the scouring, transport, and subsequent plugging of rock particles, consequently deteriorating the production performance. However, the characterization of the velocity sensitivity at the pore scale remains inadequately explored. In this paper, based on the pore network model, the force analysis of the particles in each throat is carried out, and the probability distribution function of particle diameters in the throats where particle transport occurs is solved. Then, a probability-based plugging approach is proposed and coupled with a quasi-static single-phase flow and a two-phase flow to obtain the permeability and relative permeability under different pressure gradients (flow rates). Finally, the effects of velocity-sensitive damage caused by different pressure gradients on the pore-throat structure, effective porosity, permeability, and relative permeability curves were analyzed. The results show that the connected pore number, mean coordination number, effective porosity, permeability, and two-phase coflow intervals decreased, while the irreducible water saturation and residual oil saturation increased with the increase in the displacement pressure difference. Additionally, the equal-permeability point on the relative permeability curves progressively shifts downward and to the right. This research significantly advances the characterization of velocity sensitivity at the pore scale, filling a critical gap in the field.