Abstract: A treatment for wells and/or subterranean formations in which a pre-treatment fluid is introduced prior to a polymer-containing treatment fluid, such as a hydraulic fracturing fluid. The pre-treatment fluid may contain an enzyme and/or oxidative breaker effective to degrade the polymer in the polymer-containing treatment fluid. The enzyme or oxidative breaker of the enzyme pre-treatment fluid enhance degradation of polymer filter cake from the reservoir-side of the filter cake during flow-back of the treatment fluid.

Abstract: Xanthan molecules are degraded using an xanthanase enzyme complex that is stable at temperatures above 250.degree. F., such as those temperatures found in some wellbores and process streams. The xanthanase enzyme complex is produced by a novel soil bacterium. The xanthanase enzyme complex may be used to remove xanthan based formation damage, such as drilling filter-cakes and filtrates, or to remove xanthan based filter-cakes and/or residues present in processing equipment. The xanthanase enzyme complex may also be used to reduce the viscosity of xanthan-containing fluids, such as hydraulic fracturing fluids, blocking gels, drilling muds, and process fluids. The xanthanase enzyme complex may also be used in conjunction with other well or process treatments, such as stimulations and cementing operations, to improve the effectiveness of these treatments.

Abstract: A method is provided for improving the effectiveness of cleaning up wells in a subterranean formation. The treatment is made more effective by first treating the well with a clean-up fluid that enzymatically degrades residual polymeric viscosifiers followed by removing solids contained in drill-in fluids.

Abstract: A method is shown for reducing the viscosity of a cellulose-containing fluid used during workover, fracturing or well completion operations. An enzyme system is used to degrade the polymer, whereby the fluid can be removed from the subterranean formation to the well surface. The enzyme systems are effective over broad pH and temperature ranges.

Abstract: A method of fracturing a subterranean formation in a well bore is shown in which a gellable fracturing fluid is first formed by blending together an aqueous fluid, a hydratable polymer, a suitable cross-linking agent for cross-linking the hydratable polymer to form a polymer gel and an enzyme breaker. The cross-linked polymer gel is pumped into the well bore under sufficient pressure to fracture the surrounding formation. The enzyme breaker is allowed to degrade the cross-linked polymer with time to reduce the viscosity of the fluid so that the fluid can be pumped from the formation back to the well surface. The particular enzyme breaker utilized has an activity in the temperature range from about 60.degree.-300.degree. F. and at a pH range from about 2.0 to 11.0 and is effective to attack only specific linkages in the cross-linked polymer gel.

Abstract: The invention shows a method of degrading damaging material within a subterranean formation of a well bore using an enzyme treatment. Filter cakes and very viscous fluids are such damaging materials. The enzyme treatment degrades polysaccharide-containing filter cakes and damaging fluids which reduces their viscosity. The degraded filter cake and damaging fluid can then be removed from the formation back to the well surface. The particular enzymes utilized are specific to a particular type of polysaccharide and are active at low to moderate temperatures. The enzymes attack only specific linkages in filter cakes and damaging fluids and are active in the pH range of about 2.0 to 10.0.

Abstract: A method of degrading a blocking gel in a subterranean formation of a well bore is shown in which a gellable blocking fluid is first formed by blending together an aqueous fluid, a hydratable polymer, a suitable crosslinking agent for crosslinking the hydratable polymer to form a polymer gel. The polymer gel may contain an enzyme breaker incorporated within. The cross-linked polymer gel is pumped into the well bore. If required, an externally applied enzyme breaker is added prior to gel degradation. The enzyme breaker is allowed to degrade the cross-linked polymer with time to reduce the viscosity of the fluid so that the fluid can be removed from the formation back to the well surface. The particular enzyme breaker utilized has an activity in the pH range from about 1.0 to 8.0 and is effective to attack only specific linkages in the cross-linked polymer gel.

Abstract: A method of fracturing a subterranean formation in a well bore is shown in which a gellable fracturing fluid is first formed by blending together an aqueous fluid, a hydratable polymer, a suitable cross-linking agent for cross-linking the hydratable polymer to form a polymer gel and an enzyme breaker. The cross-linked polymer gel is pumped into the well bore under sufficient pressure to fracture the surrounding formation. The enzyme breaker is allowed to degrade the cross-linked polymer with time to reduce the viscosity of the fluid so that the fluid can be pumped from the formation back to the well surface. The particular enzyme breaker utilized has an activity in the range from about 2.0 to 11.0 and is effective to attack only specific linkages in the cross-linked polymer gel.