Research and application of sand-flushing with foam fluid for horizontal wells

Sand-flushing with foam fluid can effectively reduce leakage of flushing fluid in horizontal wells with low pressure. Sand carrying ability of foam fluid is studied by experiment and numerical simulation. When foam quality is 0.85, the maxmum of viscosity of foam fluid is 1.14 Pa·s. Falling velocity of sand with diameter 0.5 mm is from 10-4 m/s to 10-3 m/s. The sand could nearly suspend in foam fluid. In the annular pipeline closing to horizontal well, sand carrying ability of foam fluid is much better than that of aerated water and water, and it is especially suitable for sand cleanout of horizontal well. It can be seen from site applications that sand cleanout with foam fluid could prevent formation from leakage, and set up circulation between casing and tubing effectively. Oil production can be recovered soon after sand cleanout operation, and oil production rate can be improved. Sand cleanout with foam fluid is an effective method to remove bottom-hole produced sand of horizontal wells.