Effect of Fluid Leakoff on Fracture Geometry Evolution during Fracpack Treatments

Abstract

In recent years, the use of fracpack treatments has gained attention and is becoming increasingly popular because of their dualbenefits of stimulation and sand control. A fracpack is a hydraulic fracturing treatment using a very high proppant concentration that attempts to "pack-off" the mouth of the fracture. Fracpacking is widely used in high-permeability, poorly consolidated to unconsolidated sandstone formations. Accurate estimation of fracture width is important for both fracpacking and hydraulic fracturing to help ensure a successful treatment. With the development of low-leakoff fluid systems, it has become possible to force the fluid through the proppant pack and out through the tip of the fracture without losing all the fluid through the fracture faces in a high-permeability, soft formation. In such scenarios, the effec of fluid leakoff on the fracture width profile for the case of arbitrary pressure distribution developed as a result of flow of non-Newtonian fluid through the proppant pack has been discussed in the literature. In this paper, the work has been further extended to include the effect of fluid leakoff through fracture faces for radial fractures. The fracture face leakoff phenomenon is modeled using a generalized Carter equation, with different leakoff rates being incorporated in the form of fracture face leakoff coefficient values. The effect of fracture face leakoff on the final width profile, net pressure, fracture volume, and pack radius was investigated. It was observed that the width profile is significantly affected when fluid leakoff through the entire fracture face is considered. Controlling fluid leakoff through the fracture faces can result in much wider fractures because of large net pressure developed inside the fracture from fluid squeezing through the proppant pack.