D.J. White & John Thompson, Dowell Schlumberger
This paper discusses case histories of load recovery and production data from wells that were fracture treated with aqueous polymeric fracturing fluids utilizing encapsulated breaker in West Texas and Southeast New Mexico. The basic fracture treatment, design of these wells and their actual load recovery and production history will be compared to results obtained from offset, wells prior to the introduction of encapsulated breaker. The case study will focus on 15 oil and gas wells in the Permian basin that were hydraulically fracture treated with proppant, placed using gelled-water-based fracturing fluids containing encapsulated breaker. The encapsulated breaker was used to maximize the clean up and minimize the damage caused by polymer in the proppant, pack of the fracture. Recent studies have documented this damage to be more severe as the polymer concentrates with leak-off of the aqueous component, of the fluid than previously suspected. This damage occurs during both the fracturing and fracture closure processes. Conventional breakers used at, concentration levels needed to degrade this damage would result in fluid viscosity reduction when exposed to time and temperature during pumping operations. This viscosity reduction would result in job failure. Proper fracturing treatment, design combined with the correct utilization of the encapsulated breaker has been very successful in the aspects of fracture treatment operations and post treatment production results.