Abstract

It has been realized for a number of years that guar gum, the most commonly used polymer for thickening water-based fracturing fluids, has a significant amount of insoluble residue. This material has retained its popularity over the years because it has a high popularity over the years because it has a high viscosity yield per dollar spent compared to other suitable polymers. Repeated laboratory testing on productive cores has also proven that damage to matrix permeability is negligible and confined to the immediate fracture wall.

Attention has recently been focused on the potential damage that can be done to the sand potential damage that can be done to the sand pack or proppant pack by heavy residue guar pack or proppant pack by heavy residue guar gels and the subsequent reduction of fracture conductivity.

Extensive research has been done to develop fluids which retain the yield of high concentration quar gum gels while at the same time reduce the damage done by insoluble residue. Simple gels formed by high concentration synthetic polymers (H.E.C., C.M.C., etc.), while free of residue, are prohibitively expensive.

This paper will discuss a family of gels designed to meet or exceed the viscous yield furnished by guar gum gels that are low or free of residue and can be pumped at a price competitive with the high concentration guar gum gels.

In each case a base gel with a low to moderate polymer loading is crosslinked after sand addition with a consequent increase in viscosity.

Clean fracturing systems will be discussed with emphasis on fluid loss, rheology, and applications. A broad range of case histories will be presented to illustrate the application of these systems in the field under a variety of conditions. Criteria for the selection of individual gel systems to match particular well conditions will be presented.

The use of these moderate polymer concentration crosslinked systems is rapidly displacing the traditional gelled water fracturing systems. Their popularity is due not only to cleaner polymers but to their ability to furnish high viscosity systems without undue polymer loadings. The use of these and polymer loadings. The use of these and similar systems is desirable in all applications where the need for fracture conductivity dictates that damage be reduced to an absolute minimum.

This content is only available via PDF.
You can access this article if you purchase or spend a download.