Study on Gas Invasion Behavior of Gas–Liquid Displacement in Fractured Reservoirs

When drilling or exploiting fractured formations, gas fluid displacement and invasion often occur, is very subtle difficult to find. The in the fracture enters wellbore arrives near wellhead with fluid. Improper treatment may lead serious accidents such as lost circulation blowout. In this study, using computational dynamics (CFD) simulation software for modeling grid generation, based on volume of (VOF) method, behavior under different conditions was simulated explore flow process characteristics invasion, effects properties morphology were analyzed. experimental results show that compress gas, making pressure greater than wellbore, thus leading occurrence invasion. viscosity density have process. higher viscosity, smaller possibility However, when gradually increases from 10–50 MPa·s, change rate small, all within 1.0–1.2 m/s. density, more conducive inlet has no obvious effect time fluctuates 0.35 s at 0.5–2.5 MPa. With increase width length, decreases, but there an extreme value height. does not beyond value. height 100–700 mm, height; 700–900 change. These provide a practical effective method enhancing oil recovery, preventing treating gas–liquid flooding.