Bacteria-based and enzyme-based mechanisms and products for viscosity reduction breaking of viscoelastic fluids

a technology of viscoelastic fluid and gelled fluid, which is applied in the direction of biological water/sewage treatment, water/sludge/sewage treatment, chemical apparatus and processes, etc., can solve the problems of fluid deformation, complex development of suitable fracturing fluid, and inability to close or heal completely cracks or fractures, etc., to reduce the viscosity of ves-gelled fluid.

US20060281167A1Inactive Publication Date: 2006-12-14BAKER HUGHES INC
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
Publication Date
2006-12-14
Estimated Expiration
Not applicable · inactive patent

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Abstract

It has been discovered that fluids viscosified with viscoelastic surfactants (VESs) may have their viscosities reduced (gels broken) by the direct or indirect action of a biochemical agent, such as bacteria, fungi, and / or enzymes. The biochemical agent may directly attack the VES itself, or some other component in the fluid that produces a by-product that then causes viscosity reduction. The biochemical agent may disaggregate or otherwise attack the micellar structure of the VES-gelled fluid. The biochemical agent may produce an enzyme that reduces viscosity by one of these mechanisms. A single biochemical agent may operate simultaneously by two different mechanisms, such as by degrading the VES directly, as well as another component, such as a glycol, the latter mechanism in turn producing a by-product (e.g. an alcohol) that causes viscosity reduction. Alternatively, two or more different biochemical agents may be used simultaneously. In a specific, non-limiting instance, a brine fluid gelled with an amine oxide surfactant can have its viscosity broken with bacteria such as Enterobacter colacae, Pseudomonas fluorescens, Pseudomonas aeruginosa, and the like.
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Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a divisional application of U.S. Pat. No. 7,052,091 issued May 30, 2006, which in turn claims the benefit of U.S. provisional application No. 60 / 244,804 filed Oct. 31, 2000.FIELD OF THE INVENTION

[0002] The present invention relates to gelled treatment fluids used during hydrocarbon recovery operations, and more particularly relates, in one embodiment, to methods of “breaking” or reducing the viscosity of aqueous treatment fluids containing viscoelastic surfactant gelling agents used during hydrocarbon recovery operations. BACKGROUND OF THE INVENTION

[0003] Hydraulic fracturing is a method of using pump rate and hydraulic pressure to fracture or crack a subterranean formation. Once the crack or cracks are made, high permeability proppant, relative to the formation permeability, is pumped into the fracture to prop open the crack. When the applied pump rates and pressures are reduced or removed from the formation, the c...

Examples

examples 1-3

[0065]FIGS. 1-3 show the results of Examples 1-3, respectively, charting the effects of using the indicated bacteria at 10% by volume concentrations. It may be seen that the SurFRAQ viscosity broke most quickly with Enterobacter colacae, losing most of its viscosity in the first 2-3 hours (Ex. 1, FIG. 1). Viscosity reduction was also more complete in this Example 1. Pseudomonas fluorescens (Ex. 2, FIG. 2) and Pseudomonas aeruginosa (Ex. 3, FIG. 3) gave viscosity reduction as well, but more gradually than Enterobacter colacae. All Examples were run using 2% TAPAO in 3% KCl. Example 1 (FIG. 1) was conducted at 125° F. (52° C.); Examples 2 and 3 (FIGS. 2 and 3, respectively) were conducted at 75° F. (24° C.).

Examples 4 AND 9

[0066]FIGS. 4 and 9 show the results of Examples 4 and 9, respectively. Both Examples use 6.0% bv TAPAO surfactant at 180° F. (82° C.) and 950 psi (6.5 kPa) on a Fann 50 rheometer. Both compositions contained 3% KCl. The order of mixing was: DI water, KCl, NH4NO3, ...

examples 5-8

[0068]FIGS. 5-8 show the results of Examples 5-8, respectively, charting the effects of various bacteria or microbe nutrients on 6% bv TAPAO surfactant at 180° F. (82° C.) and 950 psi (6.5 kPa). It may be seen that proper selection of microbe nutrient is possible that has minimal effects on the TAPAO viscosity.

[0069] All of Examples 5-8 used a Fann 50 rheometer at 180° F. (82° C.) at 400 psi (2.8 kPa). Examples 5-7 used 6% TAPAO, 3% KCl, 30 pptg (3.4 kg / m3) NH4PO3 and NH4NO3 combined, and 20.0 pptg (2.4 kg / m3) TSB. Example 8 used 6% TAPAO and 3% KCl with the indicated additives. EGMBE in Example 6 refers to ethylene glycol monobutyl ether.