Naturally occurring microfractures, called cleats, provide the permeability essential for bulk fluid flow in coalbed reservoirs. The bulk fluid flow, in turn, is controlled by the cleat properties, specifically their orientation, spacing, compressibility, and effective porosity. A two parameter, geologic process-based model for predicting the effective cleat porosity of coalbed reservoirs was developed from an analysis of cleat property data for San Juan Basin Fruitland Formation coal. The cleat property data indicate that thermal maturation and effective stress act in opposite directions on the effective cleat porosity of Fruitland Formation coal. These two variables are the basis for the geologic process-based model for calculating effective cleat porosity values.

You can access this article if you purchase or spend a download.