Effects of underbalance on perforation flow

摘要: In a study of perforation flow in standard API test targets, underbalance between 500 and 1,000 psi (3.4 6.9 MPa) was needed to obtain optimum efficiency. Perforation cleanup due transient pressure gradients separated from that caused by postshot, steady-state flow. Perforations with low initial efficiencies could be improved washing, but not levels. The amount rock debris washed the during washing phase correlated directly shooting applied. Tests performed kerosene-saturated, brine-free targets resulted generally lower required higher underbalances