Significant gel break problems may exist when using borate crosslinked fluids with resin coated proppants (RCP). A test method was developed which measures proppant settling, fluid breakdown, and flow of broken fluid through the settled proppant pack. Generally, sand settling was nearly complete before the fluid showed significant signs of breaking. The degree of break was determined by measuring the rheological character of broken fluid flow in the proppant pack. This measurement discriminated whether the fluid was fully broken to water-thin or retained base gel character, and whether the proppant pack was partially plugged by broken gel residue.

Guar and HPG borate crosslinked fluids were examined with different breakers, including delayed release oxidizers, enzymes, and acids. Effects of uncoated proppants and resin coated proppants were tested. The dynamics of breaking borate fluids containing curable RCP, which release oxidizer consuming materials, suggests that the release of breaker chemicals must occur at the proper sequence for the polymer breakdown process to work.

The method presented in this paper is useful for observing the process which occurs after a fracturing process is pumped, i.e., proppant settling, fluid breakdown, and flow of fluid through a proppant pack. Concentrations of breaker materials for crosslinked fluids can be determined in the presence of RCP.

You can access this article if you purchase or spend a download.