Stimulation fluid must have the capability to decrease in viscosity following proppant placement. This decrease is necessary to 1) minimize return of proppant; 2) maximize return of stimulation fluids to the surface. This decrease is achieved using chemicals referred to as gelling agent breakers or gel breakers.
Following are some of the more widely used breakers in sand control-related operations.
SP Breaker - SP breaker is a water soluble oxidizing breaker for aqueous-based gelling agents. It is used at temperatures above 120°F (48.8°C).
ViCon NF Breaker- ViCon NF breaker is an aqueous form of a strong oxidizer breaker. It has been shown to be effective in breaking a variety of oilfield polymer gels. Breaker concentration is determined by downhole temperature, stabilizer concentration, and required break time. Gels containing this breaker retain viscosity and break slowly. In addition, this breaker can be added to batch-mixed gels or run on-the-fly throughout the entire job, including the pad volume.
CAT-OS-1 and CAT-OS-2 - CAT-OS-1 and CAT-OS-2 are catalysts for the ViCon NF internal breaker used with SeaQuest service and Delta FracPac system. CAT-OS-1 can effectively activate ViCon above 170°F. At lower temperatures, a combination of CAT-OS-1 and CAT-OS-2 with ViCon NF internal breaker will provide an accelerated break time.
Oxol II™ Breaker - Oxol II breaker is a delayed release oxidizing breaker for low temperature applications where enzyme breakers may not function. It is effective in the 70 to 140°F (21 to 60°C) temperature range. Combined with CAT-3, it can be used in high concentrations to give performance profiles superior to those of a persulfate breaker.
GBW-40™ Breaker - GBW-40 is a strong oxidizer breaker used primary for Flo-PacSMservice gels at temperatures below 100°F (37.7°C).
HT Breaker - HT Breaker is one of the internal breaker systems recommended for K-Max PlusSM service. HT Breaker can be used at temperatures ranging from 75° to 200°F (24° to 93°C). A relatively small concentration of HT Breaker/Mgal of K-Max Plus service gel can provide break times of approximately 21 hours at 150°F (65°C).