Improvements on 'Application of NMR logs in tight gas reservoirs for formation evaluation: A case study of Sichuan basin in China'

摘要

Man et al. (2012) proposed a method of the synthetic pseudo-capillary pressure (Pr) curves from the NMR logs based on a J function method. This method was verified to be effectively applied in the field with similar formation properties. However, it cannot be applied if the formation properties are different, which results to the different J function from the experimented Pc curves of core samples. To improve the applicability of the method of Xiao et al., 84 core samples, drilled from 4 different basins in China, are supplemented for nuclear magnetic resonance (NMR) and mercury injection capillary pressure (MICP) experimental measurements, and they are classified into three types by using a hydraulic flow unit (HFU) method based on a flow zone indicator (FZI) parameter. For each type of rocks, the properties are similar, and they can be expressed by the same J functions. In this case, Xiao's method is applicative. These 84 core samples are reused to calibrate the involved input parameters in the model of Xiao et al., separately. Several wells from different regions are processed by using the calibrated models. Field applications illustrate that the improved models are much more effective in formation evaluation. (c) 2015 Elsevier B.V. All rights reserved.