Effect of Pore Structure on Slippage Effect in Unsaturated Tight Formation Using Pore Network Model

The gas slippage phenomenon under dry conditions has been investigated extensively both numerically and experimentally. However, very limited research focused on behavior wet conditions. Unlike conventional formation, the influence of water transport process cannot be neglected in tight formations due to comparable amount thin film attached along rock surface. It is found experimentally that factor positively related saturation if small, while it decreases with larger than a critical value. Most existing models failed capture measured downtrend increasing saturation, which resulted from blocking or trapping phenomenon. In this work, pore-scale network model proposed look at distribution characteristic investigate effect factor. incorporates capillary dominated multiphase fluid distribution, real effect, mechanisms pore scale. On basis our model, structure characteristics including frequency mean radius, size aspect ratio, coordination number are discussed detail. Similar previous experimental observations, simulated shows non-monotonic increase trend saturation; starts decrease high depends factors. increases radius but ratio. We used phase scale for first time. emphasized predominance estimation saturation.