Study on the influence of fracture lengths and fracture angles on residual oil distribution based on the slab model

Abstract

After fracturing in the pilot area, channeling occurs at a low fracture angle (15°). Based on the resistance-water saturation relationship, three-dimensional physical simulation methods are used in the laboratory to study the effect of different fracture angles and lengths on the residual oil distribution during the displacement process. Meanwhile, recovery percent, displacement efficiency and expanding sweep coefficient to the improvement of recovery percent are also discussed. The results show that the fracture angle and length are closely related to the oil saturation distribution in these models. As the fracture angle increases, the sweep coefficient decreases (0.2412 → 0.1463), and the recovery percent also increases (46.16 → 56.88%), but the extent of increase has been reduced (7.96 → 2.96%). The extension of the fracture length is more prone to have a cross-flow phenomenon; the sweep coefficient is reduced (0.2412 → 0.1463). Compared to the model with 1/2 oil-water well spacing, the recovery percent is decreased by 14.29%. In different fracture models, the increasable sweep coefficient has a greater impact on oil recovery than the increasable displacement efficiency (71.30 → 28.70%).

Keywords

• Slab model
• Polymer-surfactant flooding
• Electronic resistance
• Displacement efficiency
• Sweep coefficient