A General Model of Estimating Permeability from Mercury Injection Capillary Pressure (MICP) in Low Permeability Sandstones

摘要

Permeability is a very important input parameter for reservoir evaluation and productivity prediction. It's a great challenge for permeability prediction due to the heterogeneity at present, especially in low permeability sandstones. Flow unit method can be used to classify core samples into six types to establish permeability estimation formulae, but how to calculate flow zone indicator (FZI) is a difficulty. In this paper, based on the analysis of the mercury injection capillary pressure (MICP) data, which are drilled from three different of basins, the linear function between the Swanson parameter and the pore structure index (√K/Φ) is found to be ubiquitous, and a general linear model is established to estimate air permeability. This model is usable not only in low permeability reservoirs, but also in any conventional formations. We also compare the relationship between the Swanson parameter with the air permeability directly, and the conclusion is that with the pore structure index brought in, the accuracy of permeability estimation is great improved.