Friction reducers and well treatment fluids

Abstract

The present invention relates to friction reducers and to well treatment fluids. In one embodiment there is provided a friction reducing composition comprising (a) a phosphonium compound and (b) a polymeric friction reducer. In a further embodiment there is provided a well treatment fluid comprising a phosphonium compound.

Claims

1. A well treatment fluid comprising: a phosphonium compound (a), wherein the phosphonium compound (a) comprises tri n-butyl n-tetradecyl phosphonium chloride (TTPC); a polymeric friction reducer (b), which comprises a copolymer of acrylamide and acrylic acid; and Poly [oxyethyl ene(dimethylimino)ethylene(dimethylimino)ethylene dichloride].

2. A well treatment fluid according to claim 1, wherein the well treatment fluid comprises TTPC in an amount of at least 5 ppm.

3. A well treatment fluid according to claim 1, wherein the fluid further comprises an amphoteric surfactant.

4. A well treatment fluid according to claim 1, wherein the polymeric friction reducer (b) comprises a high or very high molecular weight copolymer of acrylamide and acrylic acid and wherein the fluid optionally further comprises an alkyl iminodipropionate amphoteric surfactant.

5. A well treatment fluid according to claim 1, wherein the polymeric friction reducer (b) comprises a copolymer of acrylamide and acrylic acid having a number average molecular weight of from 12 million and wherein the well treatment fluid optionally further comprises an alkyl iminodipropionate amphoteric surfactant.

6. A well treatment fluid according to claim 1, wherein the well treatment fluid further comprises water and the phosphonium compound (a), the polymeric friction reducer (b), and the water are present in a combined amount of at least 90% by weight of the well treatment fluid.

7. A well treatment fluid according to claim 1, wherein the well treatment fluid further comprises water and the polymeric friction reducer (b) is present in an amount of at least 500 ppm.

8. A well treatment fluid according to claim 1, wherein the polymeric friction reducer (b) comprises a copolymer of acrylamide and acrylic acid having a number average molecular weight of from 12 million and being present in an amount of at least 10 ppm.

9. A well treatment fluid according to claim 1 further comprising an alkyl iminodipropionate amphoteric surfactant.

10. A well treatment fluid according to claim 1, wherein the well treatment fluid does not include an alkyl iminodipropionate amphoteric surfactant.

11. A method of modifying a well treatment fluid, wherein the method comprises adding a phosphonium compound (a) to a well treatment fluid, wherein the phosphonium compound (a) comprises tri n-butyl n-tetradecyl phosphonium chloride (TTPC), and wherein the well treatment fluid comprises a polymeric friction reducer (b), which comprises a copolymer of acrylamide and acrylic acid, and wherein the method further comprises adding Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] to the well treatment fluid.

12. A method according to claim 11, wherein the method comprises adding TTPC in an amount of at least 5 ppm.

13. A method of modifying a well treatment fluid according to claim 11, wherein the polymeric friction reducer (b) comprises a copolymer of acrylamide and acrylic acid having a number average molecular weight of from 12 million.

14. A method according to claim 11, wherein the method comprises providing a well treatment fluid which further comprises an amphoteric surfactant.

15. A method according to claim 11, wherein the polymeric friction reducer (b) comprises a high or very high molecular weight copolymer of acrylamide and acrylic acid and wherein the method optionally comprises providing a fluid which further comprises an alkyl iminodipropionate amphoteric surfactant.

16. A method according to claim 11, wherein the polymeric friction reducer (b) comprises a copolymer of acrylamide and acrylic acid having a number average molecular weight of from 12 million and wherein the method optionally further comprises adding an alkyl iminodipropionate amphoteric surfactant to the well treatment fluid.

17. A method according to claim 11, wherein the method comprises adding an aqueous composition comprising TTPC.

18. A method according to claim 11, wherein the well treatment fluid comprises a fluid prepared from brine.

19. A method according to claim 11, wherein the well treatment fluid does not include an alkyl iminodipropionate amphoteric surfactant.

20. A method of fracturing a geological formation and/or extracting oil and/or gas from a geological formation, wherein the method comprises providing a well treatment fluid comprising: a phosphonium compound (a), wherein the phosphonium compound (a) comprises tri n-butyl n-tetradecyl phosphonium chloride (TTPC); a polymeric friction reducer (b), which comprises a copolymer of acrylamide and acrylic acid; and Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride].

21. A method according to claim 20, wherein the well treatment fluid further comprises an amphoteric surfactant.

22. A method according to claim 20, wherein the polymeric friction reducer (b) comprises a high or very high molecular weight copolymer of acrylamide and acrylic acid and wherein the well treatment fluid optionally further comprises an alkyl iminodipropionate amphoteric surfactant.

23. A well treatment fluid comprising: a phosphonium compound (a), wherein the phosphonium compound (a) comprises tri n-butyl n-tetradecyl phosphonium chloride (TTPC), the TTPC being present in an amount of at least 5 ppm; a polymeric friction reducer (b), which comprises a copolymer of acrylamide and acrylic acid having a number average molecular weight of from 12 million, the polymeric friction reducer (b) being present in an amount of at least 500 ppm; Poly [oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride]; and optionally an alkyl iminodipropionate amphoteric surfactant.

24. A well treatment fluid according to claim 23, wherein the well treatment fluid does not include an alkyl iminodipropionate amphoteric surfactant.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The present invention will now be illustrated by way of example with reference to the accompanying drawings in which:

(2) FIG. 1 shows a graph illustrating friction reduction in an example well fluid.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(3) Well treatment fluids comprising a friction reducing composition were prepared and tested in an apparatus adapted to determine friction reduction.

(4) Test Apparatus

(5) The apparatus comprised a 20 gallon holding vessel and a test section comprising a loop of half inch pipe having a length of 5 feet. The apparatus comprised a 2 horse power centrifugal pump to circulate fluid via the test section. The apparatus comprised a transmitter to measure differential pressure across the test section. The apparatus further comprised a data logger to record flowrate, temperature and pressure drop across the test section.

(6) Well Treatment Fluid Preparation

(7) Well treatment fluids were prepared within the apparatus. The holding vessel was filled with fresh water or brine as detailed in the examples which follow.

(8) A phosphonium compound (a) was added to the water. In some examples a polymeric ammonium compound (c) or a polymeric ammonium compound (c) and an amphoteric surfactant (d) were also added together with the phosphonium compound (a).

(9) Following the addition of the phosphonium compound (a) the fluid was mixed by being passed through the test loop for 60 seconds.

(10) The friction test procedure was then commenced and a polymeric friction reducer (b) was added to the fluid to form the well treatment fluid during the test procedure.

(11) Friction Test Procedure

(12) 9 gallons of fluid was circulated at 21.1 GPM (gallons per minute) (Reynolds number=170,000) and a baseline was run for 2 minutes.

(13) After 2 minutes of circulation the polymeric friction reducer (b) was added to the fluid and the fluid was recirculated for a further 10 minutes.

(14) The data collected by the apparatus and the fluid physical properties were used to compile test results. The differential pressure (pressure drop) across the test section versus flow rate was measured. The friction reduction was calculated using the equation:
(Differential pressure/Flow corrected base differential pressure)×100=% Friction reduction.

(15) The % Friction reduction was calculated as a maximum value and also as a value after 5 minutes and 10 minutes of circulation.

EXAMPLES

Example 1

(16) Brine solution well treatment fluids were prepared and tested.

(17) Well treatment fluids were prepared by adding a phosphonium compound (a) and a polymeric friction reducer (b) to brine solution as detailed in Table 1.

(18) In each case 20 gallons of a brine solution comprising water and 3% potassium chloride plus 500 mg L.sup.−1 calcium chloride were prepared.

(19) The phosphonium compound (a) comprised TTPC. Bellacide 355, an aqueous composition comprising 5% TTPC available from BWA Water Additives was added to provide fluids comprising TTPC in the stated ppm.

(20) The polymeric friction reducer (b) comprised a high molecular weight anionic polyacrylamide friction reducer. KemFlow A-4251 available from Kemira was added to provide fluids comprising a friction reducer composition in the stated ppm calculated on a product (rather than active) basis.

(21) The fluids were tested according to the friction test method and the results are detailed in Table 1.

(22) TABLE-US-00001 TABLE 1 Concentration of polymeric friction TTPC reducer Percent Friction Concentration composition Reduction (ppm active) (ppm product) pH Max 5 min. 10 min. 0 (control) 500 7.51 57.01 40.90 35.30 20 500 7.53 56.82 41.54 36.04 30 500 7.50 56.94 42.76 36.66

(23) As can be seen, well treatment fluids comprising TTPC in an amount of 20 ppm active or greater maintained a higher percent friction reduction over time compared to the control.

(24) FIG. 1 illustrates the temperature (1), flow rate (2), % friction reduction (3) and differential pressure (4) relative to the elapsed time during the testing of the well treatment fluid of Example 1 comprising 20 ppm active TTPC.

Example 2

(25) Brine solution well treatment fluids were prepared and tested.

(26) Well treatment fluids were prepared by adding a phosphonium compound (a) and a polymeric friction reducer (b) to brine solution as detailed in Table 2.

(27) In each case 20 gallons of a brine solution comprising water and 3% potassium chloride plus 500 mg L.sup.−1 calcium chloride brine solution were prepared.

(28) The phosphonium compound (a) comprised TTPC. Bellacide 355, an aqueous composition comprising 5% TTPC available from BWA Water Additives was added to provide fluids comprising TTPC in the stated ppm.

(29) The polymeric friction reducer (b) comprised a very high molecular weight anionic polyacrylamide friction reducer. KemFlow A-4451 available from Kemira was added to provide fluids comprising a friction reducer composition in the stated ppm calculated on a product (rather than active) basis.

(30) The fluids were tested according to the friction test method and the results are detailed in Table 2.

(31) TABLE-US-00002 TABLE 2 Concentration of polymeric friction TTPC reducer Percent Friction Concentration composition Reduction (ppm active) (ppm product) pH Max 5 min. 10 min. 0 (control) 500 7.62 56.35 36.05 34.32 0 (control) 1000 7.55 56.74 45.86 40.64 10 500 7.52 56.15 39.43 36.35 20 500 7.56 57.31 45.53 38.20 30 500 7.50 56.59 46.58 40.39 10 1000 7.40 56.12 46.05 41.54 20 1000 7.38 56.24 47.80 43.32 30 1000 7.38 57.23 51.26 48.52

(32) As can be seen, well treatment fluids comprising TTPC in an amount of 10 ppm active or greater maintained a higher percent friction reduction over time compared to the control.

Example 3

(33) Fresh water well treatment fluids were prepared and tested.

(34) Well treatment fluids were prepared by adding a phosphonium compound (a), a polymeric ammonium compound (c) and a polymeric friction reducer (b) to fresh water as detailed in Table 3.

(35) The phosphonium compound (a) comprised TTPC and the polymeric ammonium compound (c) comprised Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] (also known as PQ). Bellacide 300, an aqueous composition comprising 2.8% TTPC and 2.2% Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] available from BWA Water Additives was added to provide fluids comprising TTPC and Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] in the stated combined ppm.

(36) The polymeric friction reducer (b) comprised a high molecular weight anionic polyacrylamide friction reducer. KemFlow A-4251 available from Kemira was added to provide fluids comprising a friction reducer composition in the stated ppm calculated on a product (rather than active) basis.

(37) The fluids were tested according to the friction test method and the results are detailed in Table 3.

(38) TABLE-US-00003 TABLE 3 Concentration of polymeric friction TTPC & PQ reducer Percent Friction Concentration composition Reduction (ppm active) (ppm product) pH Max 5 min. 10 min. 0 (control) 500 6.30 51.48 48.45 44.01 0 (control) 1000 6.34 55.42 54.06 52.12 10 500 6.15 52.34 48.54 44.52 20 500 6.10 53.97 49.05 45.65 30 500 6.05 54.04 49.06 45.60 10 1000 6.16 55.88 54.78 52.60 20 1000 6.21 56.39 54.58 53.25 30 1000 6.17 56.47 54.94 53.41

(39) As can be seen, well treatment fluids comprising TTPC and PQ in an amount of 10 ppm active or greater maintained a higher percent friction reduction over time compared to the control.

Example 4

(40) Fresh water well treatment fluids were prepared and tested.

(41) Well treatment fluids were prepared by adding a phosphonium compound (a), a polymeric ammonium compound (c) and a polymeric friction reducer (b) to fresh water as detailed in Table 4.

(42) The phosphonium compound (a) comprised TTPC and the polymeric ammonium compound (c) comprised Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] (also known as PQ). Bellacide 300, an aqueous composition comprising 2.8% TTPC and 2.2% Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] available from BWA Water Additives was added to provide fluids comprising TTPC and Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] in the stated combined ppm.

(43) The polymeric friction reducer (b) comprised a very high molecular weight anionic polyacrylamide friction reducer. KemFlow A-4451 available from Kemira was added to provide fluids comprising a friction reducer composition in the stated ppm calculated on a product (rather than active) basis.

(44) The fluids were tested according to the friction test method and the results are detailed in Table 4.

(45) TABLE-US-00004 TABLE 4 Concentration of polymeric friction TTPC & PQ reducer Percent Friction Concentration composition Reduction (ppm active) (ppm product) pH Max 5 min. 10 min. 0 (control) 1000 6.13 55.91 54.69 53.78 10 1000 6.37 57.41 57.11 55.73 20 1000 6.35 57.21 56.22 54.27 30 1000 6.33 57.99 56.85 54.60

(46) As can be seen, well treatment fluids comprising TTPC and PQ in an amount of 10 ppm active or greater maintained a higher percent friction reduction over time compared to the control.

Example 5

(47) Brine solution well treatment fluids were prepared and tested.

(48) Well treatment fluids were prepared by adding a phosphonium compound (a), a polymeric ammonium compound (c) and a polymeric friction reducer (b) to brine solution as detailed in Table 5.

(49) In each case 20 gallons of a brine solution comprising water and 3% potassium chloride plus 500 mg L.sup.−1 calcium chloride brine solution were prepared.

(50) The phosphonium compound (a) comprised TTPC and the polymeric ammonium compound (c) comprised Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] (also known as PQ). Bellacide 300, an aqueous composition comprising 2.8% TTPC and 2.2% Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] available from BWA Water Additives was added to provide fluids comprising TTPC and Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] in the stated combined ppm.

(51) The polymeric friction reducer (b) comprised a very high molecular weight anionic polyacrylamide friction reducer. KemFlow A-4451 available from Kemira was added to provide fluids comprising a friction reducer composition in the stated ppm calculated on a product (rather than active) basis.

(52) The fluids were tested according to the friction test method and the results are detailed in Table 5.

(53) TABLE-US-00005 TABLE 5 Concentration of polymeric friction TTPC & PQ reducer Percent Friction Concentration composition Reduction (ppm active) (ppm product) pH Max 5 min. 10 min. 0 (control) 1000 7.62 56.74 45.86 40.64 10 1000 7.54 57.02 47.05 42.35 30 1000 7.52 57.62 46.69 42.35

(54) As can be seen, well treatment fluids comprising TTPC and PQ maintained a higher percentage friction reduction over time compared to the control.

Example 6

(55) Fresh water well treatment fluids were prepared and tested.

(56) Well treatment fluids were prepared by adding a phosphonium compound (a), a polymeric ammonium compound (c), an amphoteric surfactant (d) and a polymeric friction reducer (b) to fresh water as detailed in Table 6.

(57) The phosphonium compound (a) comprised TTPC, the polymeric ammonium compound (c) comprised Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] (also known as PQ) and the amphoteric surfactant (d) comprised an alkyl iminodipropionate amphoteric surfactant.

(58) Bellacide 303, an aqueous composition comprising 15% TTPC and 12% Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] and 9.8% alkyl iminodipropionate amphoteric surfactant available from BWA Water Additives was added to provide fluids comprising TTPC and Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] and amphoteric surfactant in the stated combined ppm.

(59) The polymeric friction reducer (b) comprised a high molecular weight anionic polyacrylamide friction reducer. KemFlow A-4251 available from Kemira was added to provide fluids comprising a friction reducer composition in the stated ppm calculated on a product (rather than active) basis.

(60) The fluids were tested according to the friction test method and the results are detailed in Table 6.

(61) TABLE-US-00006 TABLE 6 Concentration of TTPC & PQ & polymeric friction Amphoteric reducer Percent Friction Concentration composition Reduction (ppm active) (ppm product) pH Max 5 min. 10 min. 0 1000 6.34 55.42 54.06 52.12 13.6 1000 6.20 55.78 54.67 52.94 27.2 1000 6.09 55.68 54.41 53.58 40.8 1000 6.04 56.75 55.21 53.52

(62) As can be seen, well treatment fluids comprising TTPC and PQ and amphoteric surfactant maintained a higher percent friction reduction over time compared to the control.

Example 7

(63) Brine solution well treatment fluids were prepared and tested.

(64) Well treatment fluids were prepared by adding a phosphonium compound (a), a polymeric ammonium compound (c), an amphoteric surfactant (d) and a polymeric friction reducer (b) to brine solution as detailed in Table 7.

(65) In each case 20 gallons of a brine solution comprising water and 3% potassium chloride plus 500 mg L.sup.−1 calcium chloride brine solution were prepared.

(66) The phosphonium compound (a) comprised TTPC, the polymeric ammonium compound (c) comprised Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] (also known as PQ) and the amphoteric surfactant (d) comprised an alkyl iminodipropionate amphoteric surfactant.

(67) Bellacide 303, an aqueous composition comprising 15% TTPC and 12% Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] and 9.8% alkyl iminodipropionate amphoteric surfactant available from BWA Water Additives was added to provide fluids comprising TTPC and Poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] and amphoteric surfactant in the stated combined ppm.

(68) The polymeric friction reducer (b) comprised a very high molecular weight anionic polyacrylamide friction reducer. KemFlow A-4451 available from Kemira was added to provide fluids comprising a friction reducer composition in the stated ppm calculated on a product (rather than active) basis.

(69) The fluids were tested according to the friction test method and the results are detailed in Table 7.

(70) TABLE-US-00007 TABLE 7 Concentration of TTPC & PQ & polymeric friction Amphoteric reducer Percent Friction Concentration composition Reduction (ppm active) (ppm product) pH Max 5 min. 10 min. 0 500 7.62 56.35 36.05 34.32 0 1000 7.55 56.74 45.86 40.64 40.8 500 7.51 56.09 43.56 37.22 13.6 1000 7.50 57.42 45.21 42.92 27.2 1000 7.50 57.68 49.26 41.94 40.8 1000 7.51 57.99 46.07 43.03

(71) As can be seen, well treatment fluids comprising TTPC and PQ and amphoteric surfactant maintained a higher percentage friction reduction over time compared to the control.

(72) It will be appreciated that well treatment fluids according to the present invention may have desirable friction properties.

(73) Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

(74) All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

(75) Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

(76) The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.