Abstract

Extremely viscous fracture fluids have provided a new tool for stimulation of wells provided a new tool for stimulation of wells which previously have not been considered good candidates for conventional fracturing techniques. Soft sands and more permeable formations are the primary targets for the super thick fluids, but they have also performed well in retreatments and other performed well in retreatments and other applications.

Super thick fluids function by creating wider fractures and providing better prop penetration of the reservoir. The extremely penetration of the reservoir. The extremely high injection rates and large volumes of present treatments are not required. present treatments are not required. This paper will discuss the various oil-base and water-base fluids currently available. A theoretical comparison of fracture area, conductivity increase, and productivity increase obtained by conventional and super thick fluids under similar conditions is presented. Comparative field results of conventional and super thick fluids are also shown.

Introduction

A brief history of hydraulic fracturing fluids since the inception of fracturing in the early 1950's might be summarized as follows:

  1. High-viscosity gelled oils and emulsions

  2. Refined oils

  3. Lease ails, water and low-viscosity, gelled oils

  4. Gelled water

In the early days of fracturing, viscosity was required to achieve fracturing efficiency. Pump rates were low and friction pressures were high. pressures were high. With the introduction of early day fluid loss additives, less viscous refined oils were successfully used. Pump rates were still limited by high friction pressures and pumping equipment. pumping equipment. Improved fluid-loss additives and pumping equipment led to an era of fracturing pumping equipment led to an era of fracturing with even lower viscosity fluids, such as lease oils, water and low-viscosity gelled oils. Pump rates increased because of the lower friction pressures.

The introduction of gelled water systems, with the natural properties for friction reduction and fluid-loss control started another era continuing even to date. The gelling materials, guar gum, cellulose derivatives or snythetic polymers have almost completely replaced treatments with oil-base fluids.

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