COMPOSITIONS AND METHODS FOR WELL COMPLETIONS

Abstract

Well-cementing compositions for use in high-pressure, high-temperature (HPHT) wells usually contain a complex array of cement additives, including retarders, dispersants and fluid-loss additives. Under these extreme conditions additive degradation, reactions between additives, reactions between additives and the cement, or combinations thereof may occurcausing slurry gelation, premature setting or both. Incorporation of organoamine compounds in the cement compositions may help prevent or reduce the severity of slurry gelation, setting-time reduction or both.

Claims

1. A well-cementing composition, comprising: water; Portland cement; one or more organoamine compounds; one or more retarders; one or more borate compounds; and at least one fluid-loss additive, wherein the one or more organoamine compounds is present at a concentration between 0.2 L/tonne and 5.0 L/tonne of cement slurry, and wherein the organoamine compounds are one or more members selected from the group consisting of monoethanolamine, diethanolamine, monoisopropanolamine, diisopropanolamine, monoethylenediamine, diethylenetriamine, triethylenetetramine, pentaethylenehexamine, and tetraethylenepentamine.

2. The composition of claim 1, wherein the organoamine compounds are chosen from the list comprising: monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, monoethylenediamine, diethylenetriamine, triethylenetetramine, pentaethylenehexamine, and tetraethylenepentamine, or mixtures thereof.

3. The composition of claim 1, wherein the retarder comprises a copolymer of styrene sulfonate and maleic acid, one or more organophosphonate compounds, or both; wherein the organophosphonate compounds are chosen from the list comprising: amino trimethylene phosphonic acid; 1-hydroxyethylidene-1,1,-disphosphonic acid; ethylene diamine tetramethylene phosphonic acid, hexamethylenediamine methylene phosphonic acid, diethylene triamine pentamethylene phosphonic acid; polyamino phosphonic acid, 2-phosphono-butane-tricarboxylic acid-1,2,4; bis(hexamethylene triamine pentamethylene phosphonic acid) and salts thereof.

4. The composition of claim 1, wherein the fluid-loss additive comprises a copolymer of AMPS and acrylamide, a copolymer of AMPS and acrylic acid, or both.

5. The composition of claim 1, wherein the borate compounds comprise boric acid, sodium metaborate, potassium metaborate, sodium diborate, potassium diborate, sodium triborate, potassium triborate, sodium tetraborate, potassium tetraborate, sodium pentaborate, and potassium pentaborate, or mixtures thereof.

6. The composition of claim 1, wherein the organoamine-compound concentration is between about 0.2 L/tonne and about 5.0 L/tonne of blend.

7. The composition of claim 1, wherein the borate-compound concentration is between about 0.5% and about 2.5% by weight of blend.

8. The composition of claim 1, wherein the retarder concentration is between about 0.1% and about 1.5% by weight of blend.

9. The composition of claim 1, wherein the fluid-loss-additive concentration is between about 0.2% and about 1.0% by weight of blend.

10. A method for controlling the rheological properties, the setting time, or both of a cement slurry, comprising: (i) providing a cement slurry comprising water and Portland cement; and (ii) incorporating one or more organoamine compounds, one or more organophosphonate compound and one or more borate compounds in the slurry.

11. The method of claim 10, wherein the organoamine compounds are chosen from the list comprising: monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, monoethylenediamine, diethylenetriamine, triethylenetetramine, pentaethylenehexamine, and tetraethylenepentamine, or mixtures thereof.

12. The method of claim 10, wherein the retarder comprises a copolymer of styrene sulfonate and maleic acid, one or more organophosphonate compounds, or both; wherein the organophosphonate compounds are chosen from the list comprising: amino trimethylene phosphonic acid; 1-hydroxyethylidene-1,1,-disphosphonic acid; ethylene diamine tetramethylene phosphonic acid, hexamethylenediamine methylene phosphonic acid, diethylene triamine pentamethylene phosphonic acid; polyamino phosphonic acid, 2-phosphono-butane-tricarboxylic acid-1,2,4; bis(hexamethylene triamine pentamethylene phosphonic acid) and salts thereof.

13. The method of claim 10, wherein the fluid-loss additive comprises a copolymer of AMPS and acrylamide, a copolymer of AMPS and acrylic acid, or both.

14. The method of claim 10, wherein the borate compounds comprise boric acid, sodium metaborate, potassium metaborate, sodium diborate, potassium diborate, sodium triborate, potassium triborate, sodium tetraborate, potassium tetraborate, sodium pentaborate, and potassium pentaborate, or mixtures thereof.

15. A method for cementing a subterranean well, comprising: (i) providing a cement slurry comprising water and Portland cement; (ii) incorporating one or more organoamine compounds, one or more organophosphonate compounds and one or more borate compounds in the slurry; and (iii) placing the slurry in the well.

16. The method of claim 15, wherein the organoamine compounds are chosen from the list comprising: monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, monoethylenediamine, diethylenetriamine, triethylenetetramine, pentaethylenehexamine, and tetraethylenepentamine, or mixtures thereof.

17. The method of claim 15, wherein the retarder comprises a copolymer of styrene sulfonate and maleic acid, one or more organophosphonate compounds, or both; wherein the organophosphonate compounds are chosen from the list comprising: amino trimethylene phosphonic acid; 1-hydroxyethylidene-1,1,-disphosphonic acid; ethylene diamine tetramethylene phosphonic acid, hexamethylenediamine methylene phosphonic acid, diethylene triamine pentamethylene phosphonic acid; polyamino phosphonic acid, 2-phosphono-butane-tricarboxylic acid-1,2,4; bis(hexamethylene triamine pentamethylene phosphonic acid) and salts thereof.

18. The method of claim 15, wherein the fluid-loss additive comprises a copolymer of AMPS and acrylamide, a copolymer of AMPS and acrylic acid, or both.

19. The method of claim 15, wherein the borate compounds comprise boric acid, sodium metaborate, potassium metaborate, sodium diborate, potassium diborate, sodium triborate, potassium triborate, sodium tetraborate, potassium tetraborate, sodium pentaborate, and potassium pentaborate, or mixtures thereof.

20. The method of claim 15, wherein the organoamine-compound concentration is between about 0.2 L/tonne and about 5.0 L/tonne of blend.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 shows two thickening-time traces that illustrate the effect of TEPA on cement-slurry behavior at 260 C. and 140 MPa pressure.

[0015] FIG. 2 shows two thickening-time traces that illustrate the effect of TEPA on the cement-slurry behavior at 260 C. and 203 MPa pressure.

DETAILED DESCRIPTION

[0016] At the outset, it should be noted that in the development of any such actual embodiment, numerous implementationspecific decisions must be made to achieve the developer's specific goals, such as compliance with system related and business related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. In addition, the composition used/disclosed herein can also comprise some components other than those cited. In the summary of the invention and this detailed description, each numerical value should be read once as modified by the term about (unless already expressly so modified), and then read again as not so modified unless otherwise indicated in context. Also, in the summary of the invention and this detailed description, it should be understood that a concentration range listed or described as being useful, suitable, or the like, is intended that any and every concentration within the range, including the end points, is to be considered as having been stated. For example, a range of from 1 to 10 is to be read as indicating each and every possible number along the continuum between about 1 and about 10. Thus, even if specific data points within the range, or even no data points within the range, are explicitly identified or refer to only a few specific, it is to be understood that inventors appreciate and understand that any and all data points within the range are to be considered to have been specified, and that inventors possessed knowledge of the entire range and all points within the range. All ratios or percentages described here after are by weight unless otherwise stated.

[0017] As stated earlier, there is a need for means by which cement-slurry gelation, premature setting, or both, may be prevented when cementing HPHT wells. The inventors have surprisingly discovered that organoamine compounds are useful for stabilizing the rheological properties of Portland-cement slurries, preventing premature setting, or both. Furthermore, adequate fluid-loss control is preserved.

[0018] In an aspect, embodiments relate to well-cementing compositions that comprise water, Portland cement, one or more organoamine compounds, one or more retarder compounds, one or more borate compounds and at least one fluid-loss additive. The composition may also be pumpable. Those skilled in the art will recognize that a pumpable cement slurry usually has a viscosity lower than 1000 mPa-s at a shear rate of 100 s.sup.1.

[0019] In a further aspect, embodiments relate to methods for controlling the rheological properties, setting time or both of a cement slurry. A cement slurry is provided that comprises water and Portland cement. Incorporated into the slurry are one or more organoamine compounds, one or more retarder compounds, one or more borate compounds and at least one fluid-loss additive.

[0020] In yet a further aspect, embodiments relate to methods for cementing subterranean wells. A cement slurry is provided that comprises water and Portland cement. Incorporated into the slurry are one or more organoamine compounds, one or more retarder compounds, one or more borate compounds and at least one fluid-loss additive. The slurry comprising the organoamine, retarder and borate compounds, and at least one fluid-loss additive, is placed in the well. Those skilled in the art will recognize that the methods may pertain to both primary and remedial cementing operations.

[0021] For all embodiments, the organoamine compounds may be chosen from the list comprising: monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, monoethylenediamine, diethylenetriamine, triethylenetetramine, pentaethylenehexamine and tetraethylenepentamine, or mixtures thereof. Of these, the ethyleneamine compounds are preferred. Tetraethylenepentamine (TEPA) is most preferred. The organoamine-compound concentration is preferably between about 0.2 L/tonne of cement slurry and about 5.0 L/tonne of cement slurry. A more preferred concentration range lies between about 0.5 L/tonne of cement slurry and about 4.0 L/tonne of cement slurry.

[0022] For all embodiments, the retarder compounds may comprise a copolymer of styrene sulfonate and maleic acid, one or more organophosphonate compounds, or a combination thereof. The organophosphonate compounds may be chosen from the list comprising amino trimethylene phosphonic acid; 1-hydroxyethylidene-1,1,-disphosphonic acid; ethylene diamine tetramethylene phosphonic acid, hexamethylenediamine methylene phosphonic acid, diethylene triamine pentamethylene phosphonic acid; polyamino phosphonic acid, 2-phosphono-butane-tricarboxylic acid-1,2,4; bis(hexamethylene triamine pentamethylene phosphonic acid) and salts thereof, or mixtures thereof. Of these, the pentasodium salt of ethylene diamine tetramethylene phosphonic acid (EDTMP) is preferred. The retarder concentration is preferably between about 0.1% and about 1.5% by weight of solids in the slurry. This concentration scheme is commonly called by weight of blend, and will hereinafter appear as the abbreviation BWOB. The organophosphonate concentration in the slurry is preferably between about 0.02% and 0.4% BWOB. The concentration of the copolymer of styrene sulfonate and maleic acid is preferably between about 0.5% and about 1.5% BWOB.

[0023] For all embodiments, the borate compounds may comprise boric acid, sodium metaborate, potassium metaborate, sodium diborate, potassium diborate, sodium triborate, potassium triborate, sodium tetraborate, potassium tetraborate, sodium pentaborate, and potassium pentaborate, or mixtures thereof. These compounds may be anhydrous or contain waters of hydration. Of these, sodium tetraborate, potassium tetraborate, sodium pentaborate and potassium pentaborate are preferred. Sodium pentaborate is most preferred. The concentration of the borate compound is preferably between about 0.5% and 2.5% BWOB.

[0024] For all embodiments, the fluid-loss additive preferably comprises a copolymer of 2-Acrylamido-2-methylpropane sulfonic acid (AMPS) and acrylamide, a copolymer of AMPS and acrylic acid, or both. The concentration of the fluid-loss additive is preferably between about 0.2% and about 1.0% BWOB or, if in liquid form, between about 16.7 L/tonne and about 83.5 L/tonne of cement slurry. A suitable fluid-loss additive is the copolymer as disclosed in U.S. Pat. No. 6,277,900.

[0025] For all embodiments, the cement compositions may further comprise more additives such as (but not limited to) extenders, lost-circulation additives, additives for improving set-cement flexibility, chemical-expansion agents, self-healing additives, antifoam agents, gas generating additives and anti-settling agents.

EXAMPLES

[0026] The following examples serve to further illustrate some embodiments.

[0027] For all examples, cement-slurry preparation, thickening-time measurements and fluid-loss measurements were performed according to procedures published in ISO Publication 10426-2. Fluid-loss measurements were performed with a stirred fluid-loss cell.

[0028] Cement slurries were prepared with a blend that contained 33% by volume of blend (BVOB) Portland cement (Dyckerhoff Black Label Class G or Texas Lehigh Class H cement), 10% BVOB fine silica (CEMPLUS GEO Microfine Silica, available from Imextco, Singapore), 7% BVOB medium-size hematite (PMR300, available from Plomp Mineral Services, The Netherlands), 9% BVOB manganese tetraoxide (Micromax FF, available from Elkem Chemicals, Inc.), and 41% BVOB coarse silica (LG50, available from Plomp Mineral Services).

[0029] Compared to the other materials in the blend, the cement has a medium particle size. Therefore, the blend contained approximately 41% BVOB coarse particles, 40% BVOB medium-size particles and 19% BVOB fine particles.

[0030] To minimize foaming during cement-slurry mixing, 4.2 L/tonne of silicone antifoam agent were added to all slurries. In some cases, bentonite was added to help prevent solids sedimentation or the development of free fluid in the slurries when exposed to high temperatures.

[0031] A fluid-loss-control additive was incorporated into all slurriesa high-molecular-weight copolymer of AMPS and acrylamide (UNIFLAC Liquid, available from Schlumberger). The retarder formulation contained two materials: (1) an aqueous solution containing sodium pentaborate and pentasodium EDTMP (weight ratio: 6.7); (2) a copolymer of styrene sulfonate and maleic acid (molar ratio=1) (Narlex D-72, available from ALCO Chemical).

[0032] The cement slurries were prepared at a solid-volume-fraction of 0.59 to 0.61, depending upon the additive concentrations. The slurry densities varied slightly, but were always close to 2277 kg/m.sup.3 (19 lbm/gal). Liquid additives were added to the mix fluid (tap water), and solid additives were dry blended with the cement.

[0033] Thickening times were measured with a pressurized consistometer rotating at 150 RPM. The initial hydrostatic pressure in the consistometer was 13.8 MPa (2000 psi), and the final hydrostatic pressures varied between 140 MPa (20,300 psi) and 203 MPa (29,500 psi). Experiments were conducted at three final temperatures: 260 C. (500 F.), 274 C. (525 F.) and 302 C. (575 F.), and the heat-up times to reach the final temperatures were 90 min, 105 min and 130 min, respectively. The thickening time corresponds to the time necessary to reach 100 Bearden units (Bc).

Example 1

[0034] Nine cement slurries were prepared, the compositions of which are presented in Table 1. The slurries were designed with two different batches of Class H (Designs 1-6) cement and one batch of Class G cement (Designs 7-9).

[0035] Thickening times were measured at 260 F. (500 F.). Designs that contained TEPA had significantly longer thickening times.

TABLE-US-00001 TABLE 1 Effect of TEPA on Cement-Slurry Thickening Times Design # 1 2 3 4 5 6 7 8 9 Cement Class H Class H Batch 1 Batch 2 Class G Bentonite (% BWOB) 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Retarder (L/tonne) 49.2 49.2 49.2 49.2 49.2 49.2 49.2 49.2 49.2 Dispersant (% BWOB) 0.5 0.5 1 1 1 1 1 1 1 Fluid-Loss Add. (L/tonne) 33.4 33.4 33.4 33.4 25.1 25.1 25.1 25.1 25.1 TEPA Additive* (L/tonne) 3.3 3.3 3.3 0.8 1.65 Thickening time (hr:min) 9:17 10:12 10:37 22:45 13:03 26:32 9:53 14:46 20:58 Pressure, MPa (psi) 140 (20,300) 203 (29,500) *95 wt % TEPA, 6 wt % pentaethylenehexamine, 2 wt % triethylenetetramine

Example2

[0036] The following series of experiments involved 11 slurry designs. Thickening-time tests were performed at 260 C., 274 C. and 302 C. All tests were performed at 203 MPa pressure. The results show that adding TEPA to the cement formulations may prevent the occurrence of gelation, known as a quaternary gel. Such gels may adversely affect the operator's ability to achieve proper cement placement.

[0037] The quaternary gels were detected during the thickening-time tests, and appeared as peaks on the thickening-time curve. Therefore, the magnitude of the gels is expressed in Bearden units (Bc). At the three temperatures, addition of TEPA prevented the occurrence of quaternary gels. Thickening-time curves for Designs 11 and 12 are shown in FIG. 1. Thickening-time curves for Designs 13 and 14 are shown in FIG. 2.

TABLE-US-00002 TABLE 2 Effect of TEPA on Cement-Slurry Thickening Times and the Formation of Quaternary Gels. Design # 10 11 12 13 14 15 16 Temperature, C. 260 Bentonite (% bwob) 1.0 1.0 1.0 0.8 0.8 Retarder (L/tonne) 49.2 49.2 49.2 49.2 49.2 49.2 49.2 Dispersant (% bwob) 1.0 1.0 1.0 0.5 0.5 1 1 Fluid-Loss Add. (L/tonne) 33.4 33.4 33.4 33.4 33.4 33.4 TEPA Additive (L/tonne) 2.5 3.3 3.3 Thickening time (hr:min) 28:03 17:28 26:30 14:14 17:02 10:37 22:45 Quaternary gel (Bc) None 53 None 44 None 36 None Cement Class G Class H, batch 1 Class H, batch 2 Design # 17 18 19 20 Temperature, C. 274 302 Bentonite (% bwob) 0.8 0.8 1.0 1.0 Retarder (L/tonne) 49.2 49.2 125 125 Dispersant (% bwob) 0.5 0.5 0.75 0.75 Fluid-Loss Add. (L/tonne) 33.4 33.4 33.4 33.4 TEPA Additive (L/tonne) 3.3 3.3 Thickening time (hr:min) 10:00 10:30 1:32 4:46 Quaternary gel (Bc) 44 None 100 None Cement Class H, batch 1

Example3

[0038] The fluid-loss behavior of seven slurry designs was tested. The results, shown in Table 3, show that adding TEPA did not have a detrimental effect on fluid-loss control.

TABLE-US-00003 TABLE 3 Effect of TEPA on Cement-Slurry Fluid-Loss Control. Design # 21 22 23 24 25 26 27 Test temperature ( C.) 260 274 302 Bentonite (% bwob) 0.8 0.8 0.8 0.8 0.8 Retarder (L/tonne) 49.2 49.2 49.2 49.2 49.2 49.2 49.2 Dispersant (% bwob) 0.5 0.5 1 1 1 1 1 Fluid-Loss Add. (L/tonne) 33.4 33.4 25.1 25.1 33.4 33.4 25.1 TEPA Additive (L/tonne) 3.3 3.3 3.3 2.1 2.1 API Fluid Loss (mL/30 min) 74 68 35 26 11 20 27 Cement Class H, batch 1 Class G Class H, batch 1