Method for determining wettability index of rock from T2 NMR measurements

摘要

A method for rapid wettability evaluation during exploratory drilling of a hydrocarbon. The method include pre-saturation of the sample by a brine, measuring the bulk brine's T2 NMR relaxation parameter, expelling the brine by oil in the sample, measuring the oil's bulk and pore T2 NMR relaxation parameter, measuring the brine's non-reducible content and T2 NMR relaxation parameter of water in the presence of dominant oil content, expelling the oil by the brine and measuring the T2 NMR relaxation parameter of the irreducible oil content in the dominant brine. The measurements are combined in the index:I=[(T2WB−T2WIOIRR)/T2WB]−[(T2OB−T2OIWIRR)/T2OB],where WB is water bulk, OB is oil bulk, WIOIRR—injected pore water at the irreducible oil content, OIWIRR—injected pore oil at the irreducible water content.