Novel oxidizing breaker for high-temperature fracturing

A novel oxidizing breaker system has been developed for fracturing fluids a t high temperatures. Below 200 degrees F, the system is not active, but abo ve 200 degrees F, the oxidizing system aggressively at tacks the polysaccha ride backbone of the fracturing fluids, resulting in a complete break of th e crosslinked fluids. In the presence of; a gel stabilizer, an intermediate , reactive oxidizing species is formed. The result of this formation is a d elayed, soluble, high temperature oxidizing system. Controlled viscosity reduction at 200 to 300 degrees F in crosslinked gelle d fluids with and without gel stabilizer will be demonstrated. Testing incl uded model 50 viscosity profiles, high temperature static break tests, and conductivity testing. Results from all testing showed the effect of oxidant concentration in producing a predictable,, controlled break of the thermal ly stabilized crosslinked systems. Data were-obtained in low-pH and high-pa Zr-crosslinked fluids as well as in borate-crosslinked fluids. The delayed mechanism of the new breaker system provides fluids with excellent crossli nked viscosity properties at early times with predictable, long-term viscos ity reductions. Case histories show that the breaker system can be used thr oughout the treatment in the pad fluid, proppant-laden fluid, and flush. This article provides data that allow significant improvements in job desig n. The operations engineer can obtain predictable, controlled gel degradati on by using the data provided for temperature, gel type, gel stabilizers, a nd breaker concentration. The results are optimized treatment designs with rapid fluid recovery, improved proppant-bed conductivity, and increased wel l productivity.