Shallow gas development: Stimulation fluids

The stimulation treatments for a 40-well Medicine Hat Shallow Gas Project d eveloped by Husky Oil Operations Ltd. are discussed. Field application of t he stimulation designs is pre sented. Laboratory test results of newly deve loped breaker technology are also presented. The new breaker technology is based on encapsulation of an acid source and an enzyme source. These products are specifically designed for use in low-t emperature, borate-crosslinked fracturing fluids. Encapsulation of these br eakers allows controlled release of the substrate compared to the conventio nal breaker package of soluble, catalyzed sodium persulphate. Laboratory data, including rheology and conductivity for fluids containing the new breakers, are compared to fluids containing traditional, low-temper ature breakers. The release-rate profiles for the encapsulated breakers are discussed in relation to the pH requirements of enzyme breakers. In labora tory tests, the new breakers result in improved conductivity compared to a catalyzed, sodium persulphate breaker system.