Dowell Schlumberger Incorporated

Harold D Brannon

Vernon G Constien

Richard M Hodge

Milton T King

Janet Gulbis

George W Hawkins

Kevin W England

Method of reducing the viscosity of a fracturing fluid containing a polymer by introducing both delayed breaker and nondelayed breaker into the fracturing fluid. Preferably, the relative amounts of delayed and undelayed breaker are determined by first determining the concentration of polymer in the fracture, determining the relationship of breaker concentration for a polymer concentration to proppant pack permeability, picking a desired proppant pack permeability, calculating the amount of breaker necessary to lessen the viscosity of the polymer concentration in the fracture to the desired permeability. This amount of breaker is X. Next, the minimum viscosity of the fracturing fluid which maintains the proppant in suspension in the fracture is determined. The amount of breaker Y which lessens the viscosity of the fracturing fluid no lower than this minimum viscosity is calculated for the bottom hole static temperature and an interval of time. The amount of delayed breaker Z which upon initial introduction into the fracturing fluid releases Y is calculated. Finally, if X is less than Y, no more than X amount of delayed breaker is introduced into the fracturing fluid; however if Y is less than X, no more than Z amount of delayed breaker is introduced into the fracturing fluid. Additionally, Y amount of nondelayed breaker may be introduced into the fracturing fluid at each of its treatment stages.

Method of optimizing the conductivity of a propped fractured formation

An improved method of mixing a fracturing fluid slurry concentrate comprising a hydrophobic solvent base (e.g., diesel No. 2) and a dispersed hydratable polymer (e.g., hydroxypropyl guar) on a real time basis thus continuously producing a fully hydrated fracturing fluid during the actual fracturing of a subterranean earthen formation. Viscosity rise times of less than 5 minutes are achieved in a continuous operation without the use of large volume storage/hydration tanks, employing primarily conventionally necessary pumps.

Method of hydrating oil based fracturing concentrate and continuous

A fracturing fluid based on quar gum exhibiting good viscosity and stability at temperatures from about 80.degree. C. to at least about 120.degree. C. The fracturing fluid includes a guar gum, a zirconium or hafnium cross-linking agent, and a bicarbonate salt in an aqueous solution at a pH from about 8 to about 10.

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Glenpool, OK, United States of America

Harold D Brannon