Modeling Hydraulic Fractures in Unconsolidated Sands

Field data show that traditional models for brittle, linear-elastic rocks do not adequately represent fracturing in poorly consolidated rocks. A model was developed for describing the propagation of "fractures" in unconsolidated sands. The model departs radically from current models in that brittle-rock fracture mechanics is not used. Instead, the propagation of pore pressure is computed, and the porosity and permeability of the sand are specified as functions of the effective stress. This region of enhanced porosity defines a "fracture" in unconsolidated sands. The physics of creation and propagation of this oriented high-permeability zone is modeled.

View a Synopsis of SPE 96246.

This article, written by Technology Editor Dennis Denney, contains highlights of paper SPE 96246, "A New Approach to Modeling Hydraulic Fractures in Unconsolidated Sands," by Z. Zhai, SPE, and M.M. Sharma, SPE, U. of Texas at Austin, prepared for the 2005 SPE Annual Technical Conference and Exhibition, Dallas, 9-12 October. The paper has not been peer reviewed.