Development and Field Application of a Delayed Breaker System for Use at High Temperatures

Abstract

It can be M1tit to effeet a timely fracturing fluid bx tier a hydradic ticturing titment in resetvok above 190"F. Fracturing fluid systems often are quite stable at ternperatis up to 300"F. At eIevated tempemw the~tment designer is faced with the selection of~cturing fluid breaker @m three main categories: otidizers, acids and enzymes.Typical oxidizing breakers systems, used at temperatures up to 250°F,~@ates ofien encaptiated by a thin fflm of polymer. Encapmkted p-ates ofien "leak" allowing some of the encapsulated b@er to be rapidly released into the fracturing fluid'. EarIy release of oxidizing breaker degrades the ticturing fluid during the fracturing treatment--before the desired time.Acids can be used as breakers but m usually limited to lower temperaws. In additio~the buffering capacity of the formation and the fmcturing fluid can significantly impact the performance of acids and finrdly, acids w usually less cost effective than other b-m.Polymer speeific enzymes, while an eff~ve breaker at elevated t~~do not provide a rapid break in fluids with a high PH.The industry Ms developed an appreciation of minhuizing gel loadings in ficturing fluids because of perceived high insitu polymer concentrations brought about during fracture closure.%3'4.For this reasomit is desimble to use breaker systems that do not prematurely attack fluid viscosity, atlowing use of the *um gel loading that adequately transports proppant.A high tempemture, ticturing fluid br+er system that ciwmvents many of the problems discussed has been developed. The breaker systq instead of relying on a microthin mting on a vw mctive substrate, provides a cliff-t app-h to the problem. The alternative breaker system discussed here utilizes a non-encapfited, otidizing b-er that effwts a delayed break by slowly releasing free radicals in water based fracturing fluids, thus degrading Mcturing fluids in a controlled manner,