WO2019022789A1

WO2019022789A1 - Production of xanthan-degrading enzymes and methods of use

Info

Publication number: WO2019022789A1
Application number: PCT/US2018/000123
Authority: WO
Inventors: Robert Tjon-Joe-Pin; Guy L. MCCLUNG, IV
Original assignee: Tjon Joe Pin Robert; Mcclung Guy L Iv
Priority date: 2017-07-26
Filing date: 2018-07-25
Publication date: 2019-01-31

Abstract

Xanthan-degrading material, e.g. enzymes, produced by a process using fungi and uses for such enzymes, including as a breaker enzyme or in a treatment fluid, and methods of such use.

Description

Production of Xanthan-Degrading Enzymes & Methods Of Use

RELATED APPLICATIONS

This application claims the benefits, including the benefit of priority, of U.S. Application Serial No. 62/604,920, filed July 26, 2017, which application is fully incorporated herein for all purposes.

BACKGROUND OF THF, INVENTION

FIELD OF THE INVENTION

The present invention is directed to: processes for producing a xanthan-degradi ng enzyme from a fungus, e.g., but not limited to, a xanthanase enzyme, a xanthanlyase enzyme, and a xanthan depolymerase enzyme; the thus-produced enzyme; the fungus, e.g., being a filamentous fungus; and methods of using the thus-produced enzyme; e.g. but not limited to, in well fluids, oil and gas operations fluids, well drilling fluids, and in treatment fluids.

RELATED ART

There are known processes for making xanthanase and known methods for using such an enzyme. A typical polysaccharide employed in well fluids is xanthan. Xanthan containing fluids are known to cause damage to the permeability of the near wellbore area due to leakoff and mud or polymer filter-cake buildup on formation faces in the same manner as other polysaccharides, such as celluloses and starches. Xanthan is a biopolymer that may be produced by a bacterial fermentation. SUMMARY OF THE INVENTION

The present invention, in certain aspects and embodiments, discloses xanthan-degrading enzymes, e.g., but not limited to, xanthanase, produced from fungus using a fermentation process. In certain aspects, the fungus is a filamentous fungus. Herein "xanthan-degrading enzyme" and xanthan-degrading enzyme complex" include an enzyme made from a fungus, the enzyme being one of: a xanthanase enzyme, a xanthanlyase enzyme , and a xanthan depolymerase enzyme; and any such enzyme of these three, or possible combination thereof, being used as the enzyme (s) in any xanthanase enzyme complex herein.

In certain aspects, the fungus is a filamentous fungus such as, but not limited to: versicolor; phoenics; Rhizopus stolonifera; microspores; rhizopodiforms ; Trichoderma harzianum, lonibrachiatum, or reesei; and Aspergillus caespitosus, halophilicus , hollandicus, or iizukae; and, e.g., fungi listed on the attached list and methods of cultivation and enzyme production therein. Filamentous fungi include eukaryotic microorganisms that include filamentous forms of the subdivision Eumycotina. The filamentous fungi for processes of the present invention are morphologically, physiologically, and genetically distinct from yeasts. Vegetative growth by filamentous fungi is by hyphal elongation, and carbon catabolism of most filamentous fungi is obligately aerobic. Filamentous fungi as host cells can be from the genera Aspergillus, Trichoderma (e.g., Trichoderma reesei), Humicola, Acremonium, Fusarium, and Penicillium. Filamentous fungi of the phylum (division) Ascomycota, include various Penicillium, Phanerochaete, Agaricus, Neurospora, Humicola, Fusarium, Chaetomium, Magnaporthe, Aspergillus and Trichoderma species

The List of Filamentous Fungi provided in U.S. Patent Application Serial No. 62/604,920 is fully incorporated herein in its entirety for all purposes, including, but not limited to, for purposes of disclosure.

In certain aspects, the present invention discloses methods for degrading xanthan molecules which include contacting the molecules with a xanthanase enzyme complex produced from a fungus in a fermentation process.

The enzymes used in the present method may be any enzyme capable of degrading a xanthan biomaterial, including a material containing xanthan biomaterial, and which enzyme is produced from a fungus. The enzymes may degrade particular linkages found in the backbone of xanthan gum.

In another respect, this invention is a method of treating xanthan-containing formation damage present in a wellbore or a subterranean formation penetrated by the wellbore, including the step of introducing into the wellbore a well treatment fluid including a xanthanase complex produced by a process using a fungus under conditions such that at least a portion of the xanthan-containing formation damage is degraded.

In another respect, this invention provides methods of reducing the viscosity of xanthan-containing fluid by degrading xanthan molecules contained within the xanthan-containing fluid, including the step of combining the xanthan-containing fluid with a xanthanase complex produced by a process using a fungus under conditions such that the viscosity of the xanthan- containing fluid is reduced.

In another respect, this invention is a method for producing a xanthanase enzyme complex, including the step of culturing a fungus, e.g., but not limited to, a filamentous fungus, in a medium under conditions suitable for the growth of the fungus and for the production of xanthanase by the fungus. The method also includes the step of recovering the xanthanase from the medium. Also disclosed herein are methods for treating a subterranean formation using a xanthan-degrading enzyme, e.g., xanthanase, made with a process using fungus to produce the enzyme. In certain aspects, such a method includes first preparing a treatment fluid. The treatment fluid may include, for example, an aqueous fluid, a xanthan biomaterial (e.g. a xanthan gum material), and a xanthan degrading enzyme. Then, the treatment fluid is introduced into the subterranean formation. Optionally, the xanthan degrading enzyme may be added after the fluid is introduced into a formation.

The xanthan biomaterial may be included in the treatment fluid to provide viscosity to the treatment fluid.

As used herein, the term "treatment fluid," refers, inter alia, to any pumpable and/or flowable fluid used at a surface of the earth or used in a subterranean operation in conjunction with a desired function and/or for a desired purpose. In some embodiments, the pumpable and/or flowable treatment fluid may have any suitable viscosity. As used herein, "well treatment fluid" means, but is not limited to, any fluid suitable for introduction into a wellbore during drilling, completion, cementing, workover or remedial operations including, but not to limited to, stimulation fluids (such as acid-containing fluids, condensate treatment fluids, scale removal or inhibitor fluids, asphaltene inhibitor or removal fluids, fracturing fluids with or without proppant, oxidizer-containing fluids, etc.), blocking gels, gravel pack fluids, frac pack fluids, clear fluids, foamed fluids, etc. The treatment fluids used for carrying out the present invention may be provided in any suitable physical form, such as concentrated or dilute aqueous solutions, powders, particulates, or lyophilized powders. The enzyme may be in the treatment fluid in an amount in a range of about 10 ppm to about 5000 ppm, such as about 50 ppm to about 500 ppm or about 100 ppm to about 300 ppm.

The biomaterial may be xanthan and material combinations including xanthan. The biomaterial may be combined with the aqueous fluid in an amount in a range of about 0.1 g/L to about 20 g/L, such as about 1 g/L to about 10 g/L or about 1 g/L to about 5 g/L.

While the treatment fluids of the present disclosure are described herein as having components mentioned herein, it should be understood that the treatment fluids of the present disclosure may optionally include other chemically different materials. In embodiments, the treatment fluid may further have proppants, crosslinking agents, stabilizing agents, chelating agents, surfactants, diverting agents, fibers, fillers, buffers, pH control agents, surfactants, antioxidants, corrosion inhibitors, and/or additives added to promote the stability or the functionality of the treatment fluid.

The treatment fluid may be used to treat subterranean formations that surround any type of wellbore or earth bore, including both oil and gas wellbores, with the treatment fluid being provided, introduced, injected and/or pressure released.

The term "fracturing" refers to breaking down a geological formation and creating a fraclure, such as the rock formation around a wellbore, by pumping a treatment fluid at very high pressures (pressure above the determined closure pressure of the formation) , in order to increase production rates from or injection rates into a hydrocarbon reservoir.

Certain fracturing methods of the present disclosure may include a composition containing a biomaterial, a xanthan- degrading enzyme, e.g., but not limited to, xanthanse enzyme, according to the present invention. DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THE INVENTION

In the practice of certain features of methods according to the present inveiiLion, a polymer^-linkage specific xanthan- degrading enzyme complex according to the present invention, e.g. but not limited to a xanthanase enzyme complex, is used to hydrolyze or otherwise degrade xanthan or xanthan-based polymer materials to non-interfering and/or non-damaging pieces or fragments .

Enzymes are highly specialized proteins produced by cells and living organisms which have the ability to act as catalyst to promote specific reactions. Since, as a catalyst, the conformational structure of an enzyme is often unchanged by a reaction it promotes, it may then initiate another, and so on. Thus, the reactivity of an enzyme may be essentially infinite. In embodiments of the disclosed method, xanthan-containing materials may be combined with or contacted with xanthan- degrading enzyme complex according to the present invention to cause degradation of the xanthan and/or of xanthan-containing materials .

As used herein, the terms "combining", "contacting", and "applying" include any methods suitable for admixing, exposing, or otherwise causing two or more materials, compounds, or components to come together in a manner sufficient to cause at least partial degradation, partial reaction, and/or at least partial mixing to occur between the components.

A "wellbore" may be any type of well, including, a producing well, a non-producing well, an injection well, a fluid disposal well, an experimental well, a geothermal well, a geothermal earth loop bore, an exploratory deep well, and the like. ellbores may be vertical, horizontal, deviated some angle between vertical and horizontal, and combinations thereof, for example a vertical well with a non-vertical component.

In embodiments of the disclosed method and compositions, a culture with fungus is provided. This fungus may be used to produce or elaborate a xanthan-degrading enzyme complex, e.g., xanthanase enzyme complex, which is stable and active at a desired temperature, e.g., but not limited to, temperatures up to and exceeding 250 degrees F. As used herein the "xanthan- degrading enzyme," "xanthan-degrading enzyme complex," and "disclosed enzyme complex" is defined to mean a xanthan- degrading enzyme, e.g. but not limited to, a xanthanase enzyme complex, produced from fungus.

The disclosed enzyme complex is also useful in degrading, breaking, and/or reducing the viscosity of xanthan and xanthan- containing fluids in non-wellbore applications, such as in the surface remediation of well fluids or process fluids at atmospheric pressure and in any other industrial application, particularly those applications involving relatively high temperatures and/or pressures as described above. Although such an enzyme complex is useful at relatively high temperatures and pressures, it will be understood with benefit of this disclosure that benefits of the disclosed method and enzyme compositions may also be realized at lower pressures and temperatures, and under any condition in which it may be suitably applied or introduced to degrade, break or otherwise reduce the viscosity of any type of xanthan and/or xanthan-containing fluids.

The disclosed enzyme complex is defined herein as an enzyme complex capable of degrading xanthan molecules. Without desiring to be bound to any particular theory, based on structural characterization of degradation products, it is believed that at least two, possibly three, enzymes activities are involved: a lyase or a hydrolase that removes terminal pyruvated D-mannose residues and a . beta . - ( 1 , 4 ) -D-glucanase that cleave glucosidic linkages of backbone chain residues bearing side chains. The disclosed xanthan-specific enzyme complex is believed to be specific to degrade or cleave either the .alpha. -1,2 and/or .beta. -1,4 glycosidic linkages of the substituent and the .beta. -1,4 glucosidic linkages of the backbone.

In wellbore related embodiments of the disclosed method, enzyme complexes produced from a method using fungus are introduced into a wellbore to degrade xanthan-based formation damage in the form of filter-cakes, residues, filtrates, is and/or other permeability or productivity inhibiting materials.

In the present disclosure "introduced into a wellbore" means that the disclosed enzyme complex flows into, may be pumped, injected, poured, released, displaced, spotted, circulated or otherwise placed within a well or wellbore using any suitable manner known in the art.

In one embodiment of a disclosed method, a treatment containing an enzyme complex according to the present invention, e.g. but not limited to a xanthanase enzyme according to the present invention, made with a process using a fungus, the enzyme can be used to quickly and substantially degrade, or completely degrade xanthan-based residue found within a filter- cake or rock matrix in a wellbore. In the disclosed method, xanthan-based formation damage is typically treated with an externally applied enzyme treatment fluid. The degraded residue may then be flushed from a formation by formation fluids. Because the disclosed enzyme complex used is highly specific, it does not substantially react or degrade some other materials commonly found within a subterranean formation or used in wellbore operations (such as limestone, iron, resin coated proppants, tubular goods, etc.) .

In addition to addressing formation damage induced during drilling applications by, for example, drilling mud, certain of the disclosed enzymes, processes, methods and compositions may be employed to remove or reduce formation damage induced by other wellbore operations, such as any operation utilizing xanthan material or xanthan-based fluids including, but not limited to, completion fluids, workover fluids, gravel pack fluids, frac pack fluids, blocking gels, and fracturing fluids. Still other applications include using an enzyme according to the present invention made by a process using a fungus for tailoring the viscosity of xanthan fluid suspensions for a particular use, such as thinning suspensions prior to injection into underground oil-bearing formations for assisting secondary or tertiary recovery operations.

Besides xanthan-containing fracturing fluids, the disclosed enzyme complexes may be used to degrade xanthan-containing blocking gels, frac packs, gravel packing fluids and cementing fluids .

The disclosed enzyme complexes may be used to clean out or otherwise remove or degrade xanthan based materials, such as formation damage, prior to a stimulation fluid including, but not limiled to, acid-containing fluids, condensate treatment fluids, scale removal or inhibitor fluids, asphaltene inhibitor or removal fluids, fracturing fluids with or without proppant, oxidizer-containing fluids, or any other type of fluid known to the art suitable for stimulating production from a subterranean reservoir or wellbore.

Drill-in fluids (which are also referred to as "clean" fluids) containing low-residue producing polymers are sometimes employed so that potential for permeability damage is reduced; and categories of drill-in fluids include fluids comprising sized salt, specially sized calcium carbonate, conventional calcium carbonate, mixed-metal hydroxide, and specially formulated oil-based and synthetic fluids.

Certain of the disclosed xanthan-degrading enzyme complexes may also be utilized in degrading xanthan-based materials in non-wellbore applications. For example, it may be utilized in the degradation, breaking, and/or viscosity reduction of xanthan-based materials present in well treatment fluids or other industrial fluids that are present on the surface, rather in a wellbore. For example, these non-wellbore applications include, but are not limited to, treatment to reduce viscosity of fluids containing xanthan-based materials present in surface storage facilities including, but not limited to, containers, drums, mud pits, surface vessels, mud tanks, frac tanks, conventional storage tanks, process vessels, etc. In such cases, the temperature of the xanthan-based fluid may be adjusted to facilitate degradation and/or viscosity reduction. In certain aspects, and without limitation, the temperature of a xanthan- containing fluid may be adjusted to a value in the range of from about 75 degrees F. to about 120 degrees F. , more typically to a value in the range from about 80 degrees F. to about 100 degrees F. Other non-wellbore applications of the disclosed enzyme complex include degradation, breaking, or viscosity reduction of xanthan or xanthan-based fluids used in industrial applications including, but not limited to, xanthan-based clarifying fluids used in high temperature refining operations.

Although particular embodiments of the disclosed method and xanthan-degrading enzyme complex and xanthanase have been described, it will be understood with the benefit of the creative and new concepts of the present disclosure that the disclosed enzyme complexes and xanthanase may be utilized in many ways and combinations, including alone or in simultaneous or sequential combination with other enzymes, enzyme complexes, chemical breakers, treatment fluids (well or process type) or other compositions. In addition, it will be understood that the disclose enzyme complexes and xanthanase may be utilized to degrade and/or remove many xanthan containing fluids, including those fluids containing other polymers in addition to xanthan, wherever such a fluid may be located or flowing.

Fluids according to the present invention including a xanthan-degrading enzyme complex according to the present invention can be used in enhanced oil recovery operations (EOR) . Such a fluid is used in cyclic or continuous heated fluid injection or steam injection into subterranean formations. The fluids according to the present invention are made and stabilized to withstand the temperatures and other conditions associated with such injections.

In one method according to the present invention, a fluid with an enzyme complex according to the present invention, with xanthanase or a xanthan-degrading enzyme produced from a fungus according to the present invention, henceforth "enzymatic fluid," is pumped into a subterranean formation for the enhanced recovery of oil or of other hydrocarbon deposits in the subterranean formation, wherein said deposits are releasable by initially adding the enzymatic fluid directly to a pump for pumping said fluid into said oil formation followed by a period of time allowing said fluid to soak said formation, followed by injection of either water or steam or both into said formation, followed by an additional period of time allowing water, steam, and enzymatic fluid to soak within said formation, followed by recovery of said deposits by pumping or other means. Such a method as in the previous paragraph, or any appropriate method disclosed herein, may include one or two, three, four or some, in any possible combination, of the following :

wherein the fluid is a stabilized aqueous enzyme fluid made thru batch fermentation of fungus, e.g. but not limited to filamentous fungus, and wherein the deposits include crude oil.

wherein the method for injecting the fluid includes a process referred to as cyclic steam stimulation (CSS) or is continuous steam injection.

wherein the fluid is used for pre-treatment and treatment between steam injection cycles or treatment of the subterranean formation during a steam injection cycle wherein said enzymatic fluid is injected as a heated liquid into said formation.

wherein the fluid is heated before injection into a well thereby minimizing heat loss downhole and allowing maximize penetration of injected steam.

wherein the fluid is diluted with water to a working range of 0.5 to 10% percent enzymatic fluid in water prior to pumping downhole.

wherein the fluid is used for pre-treatment or treatment of the formation during enhanced oil recovery such that the fluid is injected and intermixed with water which is sent into the formation and wherein the formation is a well that is subsequently not used for a period of time allowing for soaking of the well prior to another phase of enhanced oil recovery including, but not limited to pumping and use of steam for one or more cycles during said recovery. wherein the fluid reduces wellbore build up during production that occurs at an end of an enhanced oil recovery cycle, wherein the cycle includes a cyclic steam cycle.

wherein the fluid is introduced into cyclic steam operations so that reduction of steamload is accomplished to impart a favorable impact to the steam- to-oil ratio thereby increasing crude oil recovery from a new or existing formation.

wherein the fluid, is introduced into cyclic steam operations so that the same steamload as otherwise would be used during enhanced oil recovery imparts a favorable impact to the steam-to-oil ratio, thereby increasing crude oil recovery from a new or existing formation, wherein the fluid is initially diluted or heated or both prior to adding said fluid to the formation,

wherein adding the fluid after initial steam injection or cycling of said steam is diluted or heated or both prior to adding said fluid to said formation, and wherein adding said fluid after initial steam injection or cycling of said steam is accomplished; and

wherein instead of introduction into a subterranean formation, the fluid is introduced into an apparatus, machine, conduit, vessel, container, tank, pipe, or pipeline to reduce deposits.

All patents and applications identified herein are rporated fully herein for all purposes.

Claims

What is claimed is: Each and every invention described herein and the subject matter of each numbered claim below.

1. A method for degrading xanthan molecules, comprising:

contacting said molecules with a complex comprising a xanthanase enzyme complex produced by a fungus under conditions such that at least a portion of said molecules are degraded.

2. The method of claim 1 wherein the fungus is a filamentous fungus .

3. The method of claim 1, wherein said xanthan molecules are present in a wellbore.

4. The method of claim 1, wherein said xanthan molecules are present in a xa n t h a n-containing aqueous fluid, and wherein a viscosity of said xanthan-containing fluid is reduced during said step of contacting.

5. The method of claim 1, wherein said contacting occurs at a temperature which is one of: up to about 250 degrees F. ; at least about 150 degrees F. ; above 250 degrees F. ; and at a pressure at which said complex is active to degrade said xanthan molecules .

6. The method of claim 1, wherein said method further comprises the steps of:

forming xanthan-containing fluid by combining said xanthan molecules with an aqueous fluid and said complex; and

allowing said complex to degrade at least a portion of said xanthan molecules such that the viscosity of said xanthan- containing fluid is reduced.

7. The method of claim 5, wherein said xanthan-containing fluid is a well treatment fluid, and further comprising the step of:

introducing said xanthan-containing fluid into a wellbore after said step of forming said xanthan-containing fluid.

8. The method of claim 1, further comprising the step of forming xanthan-containing fluid by combining said xanthan molecules with an aqueous fluid, and wherein the step of contacting comprises the steps of:

applying said complex to said xanthan-containing fluid; and allowing said complex to degrade at least a portion of said xanthan molecules contained in said xanthan-containing fluid.

9. The method of claim 8, wherein said contacting occurs within a wellbore.

10. The method of claim 8, wherein said contacting occurs within a refinery process stream or in a conduit or in a machine.

11. The method of claim 8, further comprising the step of

allowing said xanthan-containing fluid to form xanthan- containing filter-cake, xanthan-containing residue, or mixture thereof prior to said step of applying; and wherein said step of applying further comprising the steps of:

applying said complex to said xanthan-containing filter- cake, xanthan-containing residue, or mixture thereof; and

allowing said complex to degrade at least a portion of said xanthan molecules contained in said xanthan-containing filter- cake, xanthan-containing residue, or mixture thereof.

12. The method of claim 11, wherein said filter-cake residue or mixture, is found within a subterranean formation which

surrounds a well bore, and further comprising the steps of:

allowing production fluids to flow from said well bore; reducing the flow of said production fluids from said formation below expected flow rates prior to said step of applying; and

removing the degraded filter-cake from said subterranean formation to the well surface after said step of applying.

13. The method of claim 11, wherein said filter-cake, residue or mixture is found within a wellbore, and further comprising the step of introducing cement into said wellbore after said step of allowing .

14. The method of claim 11, wherein said filter-cake, residue or mixture is found within a wellbore, and further comprising the step of introducing a second well treatment into said wellbore after said step of allowing.

15. The method of claim 14, wherein said second well treatment fluid comprises a stimulation fluid.

16. The method of claim 1, wherein said xanthan molecules have repeating units of glucose linked by .beta. -1-4 glucosidic linkages, and wherein said complex attacks said .beta. -1-4 glucosidic linkaqes.

17. The method of claim 1, wherein said xanthan molecules are present in a fluid containing solid particulate materials stored in a surface storage facility, and further comprising the steps of:

allowing said solid particulate materials to settle in said surface facilities after said step of contacting.

18. The method of claim 17, wherein said fluid is a well

treatment fluid.

19. A method of treating xanthan-containing formation damage present in a wellbore or a subterranean formation penetrated by said wellbore, comprising the step of: introducing into said wellbore a well treatment fluid comprising complex that is a xanthanase enzyme complex produced by a method using a fungus under conditions such that at least a portion of said xanthan-containing formation damage is degraded; said fungus being, optionally, in certain aspects a filamentous fungus .

20. The method of claim 19, wherein at least a portion of said wellbore is openhole, wherein at least a portion of said

formation damage is present in said openhole, and wherein said step of introducing comprises introducing said well treatment fluid into said open hole.

21. The method of claim 19, wherein said step of introducing comprises introducing said well treatment fluid into said wellbore through a string of pipe positioned within said

wellbore .

22. The method of claim 19, wherein at least a portion of said wellbore is horizontal or deviated at an angle from the

vertical .

23. The method of claim 19, wherein said well treatment fluid comprises said complex in an aqueous fluid.

24. The method of claim 19, wherein said xanthan formation damage comprises an xanthan-containing filter-cake or residue, and wherein said step of introducing further comprises the steps of:

injecting said well treatment fluid to a desired location within said wellbore;

allowing said complex to degrade said xanthan formation damage such that said formation damage may be removed from said wellbore or subterranean formation to the well surface.

25. The method of claim 19, further comprising the step of introducing cement into said wellbore after said step of

introducing said well treatment fluid comprising said complex.

26. The method of claim 19, wherein said formation damage exists in an annular area between an interior surface of said wellbore and a string of pipe present in said wellbore; wherein said step of introducing comprises the step of circulating said well treatment fluid through said annular area to remove at least a portion of said formation damage; and further comprising the step of:

introducing cement into said annular area to cement said pipe string in said wellbore.

27. The method of claim 19, further comprising the step of introducing a second well treatment fluid into said wellbore after said step of introducing said xanthanase well treatment fluid into said wellbore.

28. The method of claim 27, wherein said second well treatment fluid comprises a stimulation fluid.

29. A method of reducing a viscosity of an xanthan-containing fluid by degrading xanthan molecules contained within said xanthan-containing fluid, comprising the step of combining said xanthan-containing fluid with a complex, said complex comprising a xanthanase enzyme complex produced by a process using a fungus, under conditions such that said viscosity of said xanthan-containing fluid is reduced.

30. The method of claim 29, wherein said xanthan-containing fluid is present within a surface vessel or earthen mud or reserve pit.

31. The method of claim 29, wherein said step of combining includes the step of formulating said xanthan-containing fluid by combining said complex with an aqueous fluid and an xanthan- containing polymer; and further comprising the steps of:

introducing said xanthan-containing fluid into a wellbore; and allowing said complex to degrade said xanthan-containing polymer .

32. The method of claim 31, wherein said xanthan containing fluid is a well treatment fluid for at least one of hydraulic fracturing or gravel packing.

33. A method of treating a well penetrating a subterranean formation and having a well surface comprising the steps of: formulating a gelable fluid by blending together an aqueous fluid, a xanthan polymer, a suitable cross linking agent to form a xanthan polymer gel, and a complex comprising a xanthanase enzyme complex produced by a process using a fungus;

introducing said xanthan polymer gel into said well; and allowing said complex to degrade said xanthan in said polymer gel, whereby said fluid may be removed from said

subterranean formation to said well surface.

34. The method of claim 33, wherein said gellable fluid is a blocking fluid.

35. The method of claim 33, wherein said gellable fluid is a fracturing fluid.

36. A method for producing a complex, said complex comprising a xanthanase enzyme complex, the method comprising:

culturing a fungus in a medium containing xanthan molecules under conditions suitable for the growth of said fungus and for the production of xanthanase by said fungus; and

recovering said xanthanase from said medium.

37. The method of claim 36 wherein said fungus is a filamentous fungus .

38. A xanthanase contained in, or produced from, a solution comprising a culture of a filamentous fungus.

39. A method for treating a subterranean formation, the method comprising: combining an aqueous fluid, a xanthan biomaterial, and a xanthan-degrading enzyme produced using a fungus.

40. The method according to claim 1 or of any claim herein, further comprising adjusting a viscosity of the treatment fluid to be a viscosity in a range of from about 10 cP to about 5,000 cP before introducing the treatment fluid into the subterranean formation .

41. The method according to claim 41, or of any claim herein, wherein the treatment fluid further comprises a crosslinking agent or a xanthanase enzyme complex is used in the presence of a crosslinking agent.

42. The method of any claim herein wherein a treatment fluid further comprises proppant particles.

43. A method for producing a xanthanase degrading enzyme from a fungus, the enzyme being one of: a xanthanase enzyme, a

xanthanlyase enzyme , and a xanthan dcpolymerase enzyme; and any such enzyme of these three, or possible combination thereof, being used as the enzyme (s) in any xanthanase enzyme complex herein .

44. A method employing a xanthanase degrading enzyme according to the present invention, said method being one of: well fluid preparation and/or use, drilling fluid production and/or use, preparation and/or use of any oil and gas operation fluid, preparation and/or use of any workover fluid, preparation and/or use of any fracturing fluid, and preparation and/or use of any treatment fluid.

45. A method employing a xanthanase degrading enzyme according to the present invention, said method being one of preparation and/or use of a friction reducer, preparation and/or use of cement, preparation and/or use of a slickwater fracturing fluid, preparation and/or use of a gravel pack.

46. A method employing a xanthanase degrading enzyme according to the present invention, said method being one of: a frac packing operation, a secondary and tertiary recovery operation, waterflooding, heated fluid injection, and steam injection.

47. A method employing a xanthanase degrading enzyme according to the present invention, said method being one of: a non- petroleum applications and a clarifying application for use in refining processes.

48. A process for producing an enzyme, the process including producing a xanthanase from a fungus.

49. The process of claim 48 wherein the fungus is a filamentous fungus.

50. A method for degrading xanthan, the method comprising degrading the xanthan with an enzyme made from fungus and/or made by the process of claim 48 or of claim 49.

1. 50 (canceled)

51. A process for making a xanthan-degrading material, the process comprising

making a xanthan-degrading material from a fungus.

52. The process of claim 51 wherein said fungus is a filamentous fungus.

53. The process of claim 52 wherein said filamentous fungus is one of: versicolor; phoenics; Rhizopus stolonifera; microspores;

rhizopodiforms; Trichoderma harzianum, lonibrachiatum, reesei;

Aspergillus caespitosus, halophilicus, hollandicus, or iizukae; fungi that are eukaryotic microorganisms that include filamentous forms of the subdivision Eumycotina; fungi of the genera Aspergillus, Trichoderma, Trichoderma reesei, Humicola, Acremonium, Fusarium, and

Penicillium. fungi of the phylum Ascomycota, including Penicillium, Phanerochaete, Agaricus, Neurospora, Humicola, Fusarium,

Chaetomium, Magnaporthe, Aspergillus and Trichoderma.

54. The process of claim 51 wherein the process is a fermentation process.

55. The process of claim 51 wherein the xanthan-degrading material is an enzyme, the enzyme being one of, or two of, or all three of: a

xanthanase enzyme, a xanthanlyase enzyme , and a xanthan depoiymerase enzyme.

56. The process of claim 51 further comprising

culturing the fungus in a medium containing xanthan molecules under conditions suitable for the growth of said fungus and for the production of said xanthan-degrading material by said fungus, and recovering said xanthan-degrading material from said medium.

57. A xanthan-degrading material made by a process according to the present invention.

58. The xanthan-degrading material of claim 57 comprising a xanthanase enzyme.

59. A method employing a xanthanase degrading enzyme according to the present invention, said method being one of: well fluid preparation and/or use; drilling fluid production and/or use; preparation and/or use of any oil and gas operation fluid; preparation and/or use of any workover fluid; preparation and/or use of any fracturing fluid;

preparation and/or use of any treatment fluid; breaking xanthan molecules in a formation; fraccing a subterranean formation; gravel packing a well; cementing a well; a water-flooding operation; a tertiary recovery operation; a frac packing operation; a secondary recovery operation; a heated fluid injection operation; a steam injection operation; preparation and/or use of a friction reducer; preparation and/or use of cement; preparation and/or use of a slickwater fracturing fluid; preparation and/or use of a gravel pack.