Fluid Loss During the Fracturing of Naturally Fractured Reservoirs

Abstract

There are several different types of reservoirs that have a high degree of natural fracturing. In these reservoirs, the fluid loss mechanisms are more complicated than those found in more coherent formations. The loss of fluid to intersecting fractures is especially important in the fracturing of coalbeds, Devonian type shales, limestones and naturally fractured sandstones. In many cases, the reservoir permeability is often such that the fluid loss to these fractures is the primary fluid-loss mechanism. Little is known "about how to handle this type of fluid loss in fracture simulation calculations, or the effects of this fluid-loss mechanism on pressure drop in the fracture. While the loss of fluid to intersecting fractures is not the only fluid-loss mechanism in naturally fractured sandstone reservoirs, it can dominate the fluid loss to the reservoir under some conditions. Examination of the problem from both a computer based modeling and laboratory standpoint is clearly warranted.Flow of fluid down a fracture in a sandstone reservoir is modified by the continual loss of fluid to the reservoir through the permeability of the rock. In a naturally fractured reservoir, fluid loss occurs mainly at points where the fracture intersects an existing fracture in the rock. ThisReferences and illustrations at end of paper.