ABSTRACT
The effectiveness of hydraulic fracturing in most applications is directly dependent upon the geometry of fractures created within the layered reservoir[l,2]. Therefore, design of fracturing treatments is generally based on maximizing fracture length and propped width (conductivity) while maintaining fracture height as close to pay zone height as possible [c.f. 3, 4]. In certain situations, such as the proximity of the pay zone to a water aquifer, vertical fracture extension could become critical. Hence, fracture geometry calculations that do not assume a constant fracture height have become necessary requirements for optimum treatment design.
This paper discusses a three-dimensional model, "HYFRAC", and shows its applicability to fracture geometry prediction for a wide variety of conditions. The results of the 3-D fracture analysis can be employed to validate and/or evaluate currently used models and theories of fracture growth. Comparisons will be made with Perkins and Kern predictions of constant height growth [5], with Geertsma-DeKlerk[6] and with methods using downhole pressure variation to determine fracture growth and stability[7]. Results from other current models will also be compared to HYFRAC results. Such studies will help determine the strengths and weaknesses of the available models. This will provide a better understanding of when problems require a fully three-dimensional solution and when a two-dimensional, quasithree-dimensional, or other analysis may suffice.
