Modeling Water-Injection Induced Fractures in Reservoir Simulation

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractWe couple a fracture growth simulator to a standard reservoir simulator using a two-way communication approach. The new approach allows interaction of two stand-alone software packages in order to capture the impact of both, varying reservoir pressure-and stress fields as well as dynamically growing or shrinking fracture shapes.At a given time step during the simulation, the pressure field is calculated by the reservoir simulator. We determine the stress field on the reservoir grid. Both, the pressure-and the stress field are needed to evaluate a fracture propagation criterion that is based on a stress intensity formulation. The fracture shape is determined in balance with the fracture fluid pressure and the in-situ reservoir stress field using an iterative procedure.Currently, the coupled simulator handles fracture growth/shrinkage for horizontally, symmetric fractures with fixed height in a single layer reservoir model. The stress calculations require the reservoir grid blocks to be sufficiently rectangular in shape.We benchmark the new simulator for a number of different test simulations by comparison. The overall comparison with analytical solutions and/or analytical simulations shows a very good fit.

Discrete fracture model for simulating waterflooding processes under fracturing conditions

“…One of the approach is to couple a numerical reservoir simulator with analytical 2‐D and pseudo–three‐dimensional (pseudo–3‐D) fracture solutions. Such models were developed and tested by Hustedt et al and Dikken and Niko . Another approach uses a full numerical representation of fractures and a surrounding porous medium.…”