Improving Fracture Conductivities with a Delayed Breaker System: A Case History

Abstract

A case study has been conducted on over 90 gas wells in West Texas to optimize fracture conductivity and well profitability. This study provides direct comparisons evaluating the effectiveness of treatments incorporating various designs and breaker systems. The wells stimulated with new designs focusing on methods to improve fracture conductivity have shown significant increases in production rates. These same wells have also shown improved clean-up properties, as compared to surrounding wells, by eliminating swabbing time and returning higher volumes of fracturing fluid. Recent laboratory studies have demonstrated that realistic in-situ fracture conductivity values are significantly lower than previously thought. New testing procedures have concluded that proppant permeability values are greatly reduced when exposed to long term tests. Additionally, fluid damage and polymer concentration further impair these permeability numbers. When breaker concentrations are increased to a level to effectively degrade the concentrated polymer the rheology of the fluid will be adversely affected, thus sacrificing the execution of the treatment. New designs have evolved placing emphasis on proper fluid selection, increasing proppant volumes and concentrations, and improved breaker scheduling. Encapsulation techniques have been developed allowing a controlled delay of breaker activation until after the proppant is placed. Extremely high breaker concentrations are now obtainable without adversely effecting the rheological properties of the fracturing fluids.

Application of Guar Gum Degrading Bacteria in Microbial Remediation of Guar-Based Fracturing Fluid Damage

“…The reports of Ayoub et al showed that filter cake is dense and insoluble, which is formed dynamically on the fracturing face through leak-off. The concentration of galactomannan within a filter cake can range from 10 to 25 times of the concentration of fracturing fluids. , Hence, the guar gum degrading bacterial strains have the potential to remediate the fracturing fluid damage caused by filter cake.…”

An Improved Encapsulated Breaker To Decrease Hydrostatic Release and Increase Thermal Stability

“…The material is proven to be effective for improving well productivity when applied properly. 8,9 Previous investigations have identified two precrush release mechanisms: mechanical release and hydrostatic release. 1x10 -2 -m] inner diameter tubing.…”

Enzymatic Breaker System for Nondamaging Removal of Cellulose-Based Blocking Gels

“…1 Breaker systems were applied to the blocking gel using 730 standard static test methods. These breakers were allowed to stand for 12 hours and then tested using Benedict's, Barfoed's, and Anthrone reagent.…”

“…These breakers were allowed to stand for 12 hours and then tested using Benedict's, Barfoed's, and Anthrone reagent. 1 Results of these colormetric tests indicate that an oxidizer such as ammonium persulfate will reduce cellulose to monosaccharides according to the concentration of the oxidizer present. 4 Standard loadings of 0.01 % to 0.4% (by weight) will leave longer chain segments while concentrations above 0.4% tend to reduce the polymer to monosaccharides.…”