It can be difficult to cause a timely fracturing-fluid break after hydraulic-fracturing treatment in reservoirs where the temperature is greater than 190℉. Fracturing-fluid systems often are quite stable at temperatures up to 300℉. The fracturing industry has developed chemical breaker systems that degrade fracturing-fluid viscosity For elevated temperatures, the hydraulic-fracturing treatment designer must select a fracturing-fluid breaker from three main categories: oxidizers, acids, and enzymes. Persulfates encapsulated by a thin film of polymer are the oxidizing breakers typically used at temperatures higher than 130℉. As temperatures approach or exceed 200℉, addition of encapsulated persulfates in any appreciable amount, especially to low-polymer-concentration gels, becomes difficult.
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