A practical method to construct capillary pressure curves of reservoir using NMR logging date

A new method to construct the pseudo-capillary pressure curve using nuclear magnetic resonance (NMR) logging data is established. In this method, the displacement pressure can be predicted using the maximum relaxation time of T2 spectrum of nuclear magnetic resonance (NMR) logging. Next, the effective porosity and density of rock, calculated from logging data, are used to predict the maximum mercury saturation. Then the mercury saturation at displacement pressure point and threshold pressure point can be estimated according to empirical data. Thus, the four important points on the capillary pressure curve can be obtained, namely zero point, displacement pressure, threshold pressure and end point. Then, referring to the 4 pressure points above, the pseudo-capillary pressure curve is constructed in two sections with the dividing point of threshold pressure. The method is convenient especially for the evaluation of deep and complex formations where the coring is difficult. [Received: July 12, 2017; Accepted: December 15, 2017]