Abstract
Abstract This paper reviewed many conventional capillary pressure (Pc) models, which is the foundation of estimating permeability through Pc curves. The infeasibility of Brooks-Corey Pc model for heterogeneous rocks caused poor prediction accuracy of the existing permeability model. An advanced Pc model was derived through fractal theory in which the cylindrical capillary tube was regarded as the pore unit of the fractal object. In addition, a novel permeability model was developed by substituting the integral item in Nakornthap-Evans model with the advanced Pc model expression. The permeability model established a power law relationship with the rock physical properties and characteristic parameters of Pc curves. The calibration and validation analysis were then conducted with a dataset of 210 rock samples. The fractal based Pc model can fit the Pc points measured in laboratory well, and estimate the characteristic parameters for each Pc curve through fitting work. The prediction permeability closely matches the measured permeability, which was verified by the high regression Coefficient of Determination. With the fractal dimension increasing, the absolute permeability decreases monotonically. The advanced Pc model and novel permeability model should have great application prospects in the field of Pc curve characterization and physical property analysis.
Published Version
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