Methods and compositions for sealing pipe and forming barriers in well bores

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to methods and compositions for forming barriers in well bores such as barriers in the annulus between a casing, liner or screen and the walls of a well bore.

[0003] 2. Description of the Prior Art

[0004] In the completion of well bores penetrating subterranean producing zones, casings or liners are often sealed therein to prevent the inflow or outflow of fluids. The sealing composition utilized has generally been a cement composition having a relatively high density. The high density requires the use of special cement composition pumping equipment which is costly to obtain and use to pump the cement composition into the annulus between the casing or liner and the walls of the well bore. Also, the high density of the cement composition increases the well head pressure during pumping which can and often does form undesirable fractures in the walls of the well bore.

[0005] A well completion operation often conducted in the portion of a well bore penetrating a subterranean producing zone is gravel packing. In gravel packing operations, particles referred to in the art as gravel are carried to the subterranean producing zone in which a gravel pack is to be placed by hydrocarbon or water carrying fluids. Prior to placing the gravel particles in the subterranean zone, a screen is often placed in the subterranean zone for retaining the gravel particles in the zone. After the screen is placed in the zone, the gravel particles are pumped into the zone between the walls of the well bore and the screen therein. Once the particles are placed in the zone, the treating fluid leaks off into the zone and/or it is returned to the surface. The gravel pack produced functions as a filter to separate formation solids from produced fluids while permitting the produced fluids to flow into and through the well bore.

[0006] After a subterranean producing zone has been gravel packed and produced, it is often necessary to isolate one or more portions of the producing zone to prevent the inflow of undesirable fluids such as salt water using a hardenable, low density sealing composition. While hardenable low density sealing compositions have been developed and used heretofore, there are continuing needs for improved hardenable, low density sealing compositions for sealing pipe or forming annular barriers in well bores. In addition, there are needs for such sealing compositions that can be placed into a gravel pack by directly injecting the hardenable, low density sealing compositions through gravel pack screens or expandable screens.

SUMMARY OF THE INVENTION

[0007] By the present invention improved methods and compositions for sealing pipe and forming barriers in well bores are provided which meet the needs described above and overcome the shortcomings of the prior art. The hardenable, low density sealing compositions of this invention are furan sealant compositions which are very resistant to chemicals and high temperature environments. The furan sealing compositions also provide greatly superior and longer lasting seals between well bores and strings of pipe as well as for forming barriers in well bores than the sealing compositions used heretofore.

[0008] The sealing compositions of this invention are basically comprised of a hardenable furan liquid resin mixture, an organosilane coupling agent, a cationic surfactant, and hollow microspheres. The sealing compositions can also optionally include a solvent or diluent, a dispersing agent, and a light weight filler.

[0009] The methods of this invention for sealing pipe or forming a barrier in a well bore are comprised of the following steps. A hardenable, low density sealing composition is prepared comprising a hardenable furan liquid resin mixture, an organosilane coupling agent, a cationic surfactant, and hollow microspheres. The sealing composition is placed in a well bore and then allowed to harden into an impermeable mass.

[0010] The objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of preferred embodiments which follows.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0011] The hardenable, low density sealing compositions of this invention basically comprise a hardenable furan liquid resin mixture, an organosilane coupling agent, a cationic surfactant, and hollow microspheres.

[0012] Furan resin can withstand high temperatures without deterioration, i.e., temperatures up to about 600° F., and are resistant to contact with harsh chemicals. Furan resin is self-catalyzed and cures at temperatures above about 275° F. At temperatures below about 275° F., a delayed or encapsulated catalyst is utilized to cause the furan resin to cure and harden.

[0013] The hardenable furan liquid resin mixture in the sealing composition of this invention comprises a 2-furanmethanol homopolymer present in the mixture in an amount in the range of from about 55% to about 60% by weight thereof and furfuryl alcohol present in the mixture in an amount in the range of from about 40% to about 45% by weight thereof. The furan liquid resin mixture is present in the sealing composition in an amount in the range of from about 10% to about 50% by weight thereof, preferably in an amount of about 35%.

[0014] Various solvents or diluents can optionally be used to thin down the resin mixture if necessary to obtain a desirable viscosity and especially when solid particulate fillers are blended in the resin mixture. Examples of solvents or diluents that can be used include, but are not limited to, 2-butoxy ethanol, butyl acetate, furfuryl acetate, or mixtures thereof. Of these, furfuryl acetate is preferred. When used, the solvent or diluent is included in the sealing composition in an amount in the range of from about 5% to about 60% by weight of the sealing composition.

[0015] Examples of organosilane coupling agents that can be utilized in the sealing compositions include, but are not limited to, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-gylcidoxypropyltrimethoxysilane and n-beta(aminoethyl)-gamma-aminopropyltrimethoxysilane. Of these, n-beta(aminoethyl)-gamma-aminopropyltrimethoxysilane is preferred. The organosilane coupling agent is included in the sealing composition in an amount in the range of from about 0.1% to about 3% by weight thereof, preferably in an amount of about 1%.

[0016] The cationic surfactant in the sealing composition functions to improve the contact of the furan sealing composition with surfaces of particulate fillers and strengthen the bond of the sealing composition to the surfaces it contacts. Examples of cationic surfactants that can be used include, but are not limited to, ethoxylated nonyl phenol phosphate ester, C12-C22 alkyl phosphonates, and mixtures of one or more cationic surfactants and one or more non-ionic surfactants. Of these, a C12-C22 alkyl phosphonate surfactant is preferred. The cationic surfactant is present in the sealing composition in an amount in the range of from about 0.1% to about 10% by weight thereof, preferably in an amount of about 5%.

[0017] Examples of dispersing agents that can optionally be utilized in the sealing compositions include, but are not limited to, naphthalene-sulfonate-formaldehyde condensates, acetone-formaldehyde-sulfite condensates and glucano-delta-lactone. Of these, naphthalene-sulfonate-formaldehyde condensates are preferred. When used, the dispersing agent which functions to disperse solids in the sealing composition is generally present in the sealing composition in an amount in the range of from about 0.1% to about 5% by weight thereof, preferably in an amount of about 1%.

[0018] A variety of light weight fillers can optionally be included in the sealing composition including, but not limited to, amorphous silica, fumed silica, diatomaceous earth and fly ash. Of these, amorphous silica is preferred. When used, the light weight filler is present in the sealing composition in an amount in the range of from about 5% to about 50% by weight thereof, preferably in an amount of about 30%.

[0019] The hollow microspheres are included in the sealing compositions of this invention to lower the density of the compositions. A variety of hollow microspheres can be utilized in accordance with this invention including, but not limited to, hollow mineral glass spheres that are commercially available under the trade name “SPHERELITES™” from Halliburton Energy Services of Duncan, Okla.; hollow cenospheres formed of silica and alumina filled with low pressure gases commercially available under the trade designation “CENOLIGHT®” from Microspheres, S.A.; hollow microspheres that are formed of glass and are commercially available under the trade designation “SCOTCHLIGHT™” from the 3-M Company of St. Paul, Minn.; and microspheres formed of ceramic material that are commercially available under the trade designation “Z-LIGHT SPHERES™” from the 3-M Company of St. Paul, Minn. Of these, mineral glass spheres are generally preferred. The hollow microspheres utilized are generally present in the sealing composition in an amount in the range of from about 5% to about 50% by weight thereof.

[0020] The sealing compositions of this invention can also optionally include sand as an additional filler. When used, the sand preferably has a mesh size in the range of from about 70 mesh to about 140 mesh and is present in the sealing composition in an amount in the range of from about 5% to about 30% by weight of the sealing composition.

[0021] As mentioned above, when the temperature to which a sealing composition of this invention is exposed is below about 275° F., the sealing composition includes a delayed catalyst for causing the sealing composition to harden. While a variety of catalysts can be utilized, presently preferred catalysts include, but are not limited to, encapsulated hydrochloric acid, encapsulated maleic acid, encapsulated salicylic acid, encapsulated sodium bisulfate, encapsulated phosphoric acid, and encapsulated sulfonic acid. Of these, encapsulated sulfonic acid is the most preferred. The encapsulated material on the catalysts slowly dissolves or otherwise releases the catalysts over time. When used, the catalyst is present in the sealing composition in an amount in the range of from about 0.1% to about 5% by weight of the composition.

[0022] The low density furan sealing compositions of this invention include solid materials of small diameters whereby the compositions can be injected through sand screens and the like to form annular barriers therein. Additionally, the low density furan sealing compositions can be utilized for sealing casing and liners in well bores, for sealing holes and cracks in casing and liners, for sealing voids in the annuluses behind sand control screens or expandable screens, and for plugging fractures and the like in well bores.

[0023] The methods of the present invention for sealing pipe or forming a barrier in a well bore basically comprise the following steps. A hardenable, low density sealing composition is prepared or provided comprising a hardenable furan liquid resin mixture, an organosilane coupling agent, a cationic surfactant, and hollow microspheres. The sealing composition is placed in the well bore and then allowed to harden into an impermeable mass therein.

[0024] A preferred hardenable, low density sealing composition of this invention comprises: a hardenable furan liquid resin mixture; an organosilane coupling agent; a cationic surfactant; and hollow microspheres.

[0025] A preferred method of sealing pipe or forming a barrier in a well bore comprises the steps of: (a) preparing or providing a hardenable, low density sealing composition comprising a hardenable furan liquid resin mixture, an organosilane coupling agent, a cationic surfactant, and hollow microspheres; (b) placing the sealing composition in the well bore; and (c) allowing the sealing composition to harden into an impermeable mass.

[0026] In order to further illustrate the methods and compositions of this invention, the following example is given.

EXAMPLE

[0027] A number of samples of the low density sealant compositions of the present invention were prepared containing furan liquid resin mixtures comprising 55% of 2-furanmethanol by weight and 45% furfuryl alcohol by weight purchased from Durez Corp. of New York. The furan liquid resin mixtures were mixed with butyl acetate diluent or furfuryl acetate diluent and the resulting mixtures were then blended with N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, sodium bisulfate acid catalyst, water for dissolving the acid catalyst, 70/170-mesh sand filler, and hollow microspheres. The samples were then cured at a temperature of 325° F. for various cure times. After curing, the compressive strengths of the samples were measured. The amounts of the components in each low density sealant composition sample, the curing times of the samples, and the compressive strengths of the samples are given in Table 1 below.

1TABLE 1CompositionSample 1Sample 2Sample 3Sample 4Furan System, mL20202020Butyl Acetate (BA) or5 (BA)5 (BA)5 (FA)5 (FA)Furfuryl Acetate (FA),mLSilane coupling agent,0.20.20.20.2mLSodium Bisulfate, grams1313Water, mL131370/170-mesh sand, grams1313Hollow Microspheres1313(Z-LIGHTSPHERES ™), gramsCure time @ 325° F.,96969696hoursCompressive Strength,3609350459156218psi

[0028] Thus, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned as well as those which are inherent therein. While numerous changes may be made by those skilled in the art, such changes are encompassed within the spirit of this invention as defined by the appended claims.

Claims

1. A method of sealing pipe or forming a barrier in a well bore comprising the steps of: (a) preparing or providing a hardenable, low density sealing composition comprising a hardenable furan liquid resin mixture, an organosilane coupling agent, a cationic surfactant, and hollow microspheres; (b) placing said sealing composition in said well bore; and (c) allowing said sealing composition to harden into an impermeable mass.
2. The method of claim 1 wherein said hardenable furan liquid resin mixture comprises a 2-furanmethanol homopolymer present in said mixture in an amount in the range of from about 55% to about 60% by weight thereof and furfuryl alcohol present in said mixture in an amount in the range of from about 40% to about 45% by weight thereof.
3. The method of claim 1 wherein said hardenable furan liquid resin mixture is present in said sealing composition in an amount in the range of from about 10% to about 50% by weight thereof.
4. The method of claim 1 wherein said organosilane coupling agent is selected from the group consisting of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-gylcidoxypropyltrimethoxysilane and n-beta(aminoethyl)-gamma-aminopropyltrimethoxysilane.
5. The method of claim 1 wherein said organosilane coupling agent is N-2-(aminoethyl)-3-aminopropyltrimethoxysilane.
6. The method of claim 1 wherein said organosilane coupling agent is present in said sealing composition in an amount in the range of from about 0.1% to about 3% by weight thereof.
7. The method of claim 1 wherein said cationic surfactant is selected from the group consisting of ethoxylated nonyl phenol phosphate ester, C12-C22 alkyl phosphonates and mixtures of one or more cationic surfactants and one or more non-ionic surfactants.
8. The method of claim 1 wherein said cationic surfactant is a C12-C22 alkyl phosphonate.
9. The method of claim 1 wherein said cationic surfactant is present in said sealing composition in an amount in the range of from about 0.1% to about 10% by weight thereof.
10. The method of claim 1 wherein said hollow microspheres are selected from the group consisting of hollow mineral glass spheres, hollow silica-alumina spheres, glass spheres and ceramic spheres.
11. The method of claim 1 wherein said hollow microspheres are mineral glass spheres.
12. The method of claim 1 wherein said hollow microspheres are present in said sealing composition in an amount in the range of from about 5% to about 50% by weight thereof.
13. The method of claim 1 wherein said sealing composition further comprises a solvent or diluent selected from the group consisting of 2-butoxy ethanol, butyl acetate, furfuryl acetate and mixtures thereof.
14. The method of claim 13 wherein said sealing composition is furfuryl acetate.
15. The method of claim 13 wherein said solvent or diluent is present in said sealing composition in an amount in the range of from about 5% to about 60% by weight thereof.
16. The method of claim 1 wherein said sealing composition further comprises a dispersing agent selected from the group consisting of naphthalene-sulfonate-formaldehyde condensate, acetone-formaldehyde-sulfite condensate and glucano-delta-lactone.
17. The method of claim 16 wherein said dispersing agent is naphthalene-sulfonate-formaldehyde condensate.
18. The method of claim 16 wherein said dispersing agent is present in said sealing composition in an amount in the range of from about 0.1% to about 10% by weight thereof.
19. The method of claim 1 wherein said sealing composition further comprises a lightweight, filler selected from the group consisting of amorphous silica, fumed silica, diatomaceous earth, and fly ash.
20. The method of claim 19 wherein said lightweight filler is amorphous silica.
21. The method of claim 19 wherein said lightweight filler is present in said sealing composition in an amount in the range of from about 5% to about 50% by weight thereof.
22. The method of claim 1 wherein said sealing composition further comprises sand.
23. The method of claim 22 wherein said sand has a mesh size in the range of from about 70 mesh to about 140 mesh.
24. The method of claim 22 wherein said sand is present in said sealing composition in an amount in the range of from about 5% to about 30% by weight thereof.
25. The method of claim 1 wherein said sealing composition further comprises a delayed catalyst for causing said sealing composition to harden selected from the group consisting of encapsulated hydrochloric acid, encapsulated maleic acid, encapsulated salicylic acid and encapsulated sodium bisulfate.
26. The method of claim 25 wherein said delayed catalyst is encapsulated sodium bisulfate.
27. The method of claim 25 wherein said delayed catalyst is present in said sealing composition in an amount in the range of from about 0.1% to about 5% by weight thereof.
28. A hardenable, low density sealing composition comprising: a hardenable furan liquid resin mixture; an organosilane coupling agent; a cationic surfactant; and hollow microspheres.
29. The sealing composition of claim 28 wherein said hardenable furan liquid resin mixture comprises a 2-furanmethanol homopolymer present in said mixture in an amount in the range of from about 55% to about 60% by weight thereof and furfuryl alcohol present in said mixture in an amount in the range of from about 40% to about 45% by weight thereof.
30. The sealing composition of claim 28 wherein said hardenable furan liquid resin mixture is present in an amount in the range of from about 10% to about 50% by weight thereof.
31. The sealing composition of claim 28 wherein said organosilane coupling agent is selected from the group consisting of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-gylcidoxypropyltrimethoxysilane and n-beta(aminoethyl)-gamma-aminopropyltrimethoxysilane.
32. The sealing composition of claim 28 wherein said organosilane coupling agent is N-2-(aminoethyl)-3-aminopropyltrimethoxysilane.
33. The sealing composition of claim 28 wherein said organosilane coupling agent is present in an amount in the range of from about 0.1% to about 3% by weight thereof.
34. The sealing composition of claim 28 wherein said cationic surfactant is selected from the group consisting of ethoxylated nonyl phenol phosphate ester, C12-C22 alkyl phosphonates and mixtures of one or more cationic surfactants and one or more non-ionic surfactants.
35. The sealing composition of claim 28 wherein said cationic surfactant is a C12-C22 alkyl phosphonate.
36. The sealing composition of claim 28 wherein said cationic surfactant is present in an amount in the range of from about 0.1% to about 10% by weight thereof.
37. The sealing composition of claim 28 wherein said hollow microspheres are selected from the group consisting of hollow mineral glass spheres, hollow silica-alumina spheres, glass spheres and ceramic spheres.
38. The sealing composition of claim 28 wherein said hollow microspheres are mineral glass spheres.
39. The sealing composition of claim 28 wherein said hollow microspheres are present in an amount in the range of from about 5% to about 50% by weight thereof.
40. The sealing composition of claim 28 which further comprises a solvent or diluent selected from the group consisting of 2-butoxy ethanol, butyl acetate, furfuryl acetate and miktures thereof.
41. The sealing composition of claim 40 wherein said solvent or diluent is furfuryl acetate.
42. The sealing composition of claim 40 wherein said solvent or diluent is present in an amount in the range of from about 5% to about 60% by weight thereof.
43. The sealing composition of claim 28 which further comprises a dispersing agent selected from the group consisting of naphthalene-sulfonate-formaldehyde condensate, acetone-formaldehyde-sulfite condensate and glucano-delta-lactone.
44. The sealing composition of claim 43 wherein said dispersing agent is naphthalene-sulfonate-formaldehyde condensate.
45. The sealing composition of claim 43 wherein said dispersing agent is present in an amount in the range of from about 0.1% to about 10% by weight thereof.
46. The sealing composition of claim 28 which further comprises a lightweight filler selected from the group consisting of amorphous silica, fumed silica, diatomaceous earth, and fly ash.
47. The sealing composition of claim 46 wherein said lightweight filler is amorphous silica.
48. The sealing composition of claim 46 wherein said lightweight filler is present in an amount in the range of from about 5% to about 50% by weight thereof.
49. The sealing composition of claim 28 which further comprises sand.
50. The sealing composition of claim 49 wherein said sand has a mesh size in the range of from about 70 mesh to about 140 mesh.
51. The sealing composition of claim 49 wherein said sand is present in an amount in the range of from about 5% to about 30% by weight thereof.
52. The sealing composition of claim 28 which further comprises a delayed catalyst for causing said sealing composition to harden selected from the group consisting of encapsulated hydrochloric acid, encapsulated maleic acid, encapsulated salicylic acid and encapsulated sodium bisulfate.
53. The sealing composition of claim 52 wherein said delayed catalyst is encapsulated sodium bisulfate.
54. The sealing composition of claim 52 wherein said delayed catalyst is present in an amount in the range of from about 0.1% to about 5% by weight thereof.

Methods and compositions for sealing pipe and forming barriers in well bores

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