A Method for Predicting Mercury Injection Capillary Pressure Curves Based on NMR Echo Data

Abstract

Summary In this paper, a new method for predicting the mercury injection capillary pressure (MICP) curves based on the nuclear magnetic resonance (NMR) echo data is proposed. We calculate multiple characteristic parameters of NMR echo data: porosity (ϕ), the area enclosed by the NMR echo data (S_echo) and the decay time of NMR echo data (t_echo), establish the relationship between the aforementioned parameters of NMR echo data and the mercury saturation (Snw) at each capillary pressure point of the MICP curve, thereby the prediction model of the MICP curves based on the NMR echo data is obtained. We use the established model to predict the MICP curves of 14 tight sandstone core samples and the results show that the method for predicting the MICP curves based on NMR echo data has smaller calculation amount and higher precision. This method can be used to predict the MICP curves continuously with depth of well logging, which lays a foundation for the evaluation of reservoir pore structure.