Setting retarder composition for use in cementation and recementation of cased oil wells

United States Patent

United States Patent	3,905,826
Ordonez , et al.	September 16, 1975

Abstract

A setting retarding composition for cement comprising a mixture of carboxymethyl cellulose, borax and dextrin in ranges producing a synergistic effect.

Inventors:	Ordonez; Raul Poblano (Xochimilco, MX); Rosado; Antonio Acuna (Tlalnepantla, MX); Petrirena; Francisco Garaicochea (Santa Maria la Rivera, MX); Rivera de Campos; Edith (Atzcapotzalco la Villa, MX)
Assignee:	Instituto Mexicano del Petroleo (Mexico, MX)
Appl. No.:	431806
Filed:	January 8, 1974

Foreign Application Priority Data


Jan 10, 1972 [MX]			133376

Current U.S. Class: 106/823 ; 106/803

Field of Search: 106/315,92,93

References Cited

U.S. Patent Documents


2374628	April 1945	Swayze
2673810	March 1954	Ludwig
3754953	August 1973	Martin

Primary Examiner: Poer; J.
Attorney, Agent or Firm: Ladas, Parry, Von Gehr, Goldsmith & Deschamps

Parent Case Text

This application is a continuation-in-part of our earlier filed application Ser. No. 292,588 filed Sept. 27, 1972 and now abandoned.

Claims

We claim:

1. A composition for retarding the setting of cement which comprises a mixture of at least one of the group consisting of carboxymethyl cellulose and alkali salts of carboxymethyl cellulose, borax and dextrin, in the porportions by weight of 35 to 40%, 30 to 35% and 25 to 30%, respectively.

2. A composition according to claim 1, which comprises 40% carboxymethyl cellulose alkali salt, 32.5% borax and 27.5% dextrin.

3. A composition according to claim 1 in which an inorganic salt selected from the group consisting of sodium sulphate and potassium sulphate is included.

Description

This invention relates to a composition for retarding the setting of cement. It particularly is useful in the cementation or recementation of oil well pipes and cased bore holes.

Cementation of cased bore holes has been a common practice in drill string, finishing and repairing operations for oil wells. The procedure comprises conveying a cement slurry to the bottom of a well through the pipe to be cemented and to force it into the annular space between the outside of the pipe and the wall of the well, where it sets and hardens.

Once cement has been mixed with water, the process of setting begins and becomes faster as the ambient temperature and atmospheric pressure rise. As the cement slurry proceeds to the bottom of the well, conditions tend to accelerate the rate of setting. However, for successful operation, it is necessary to keep the cement slurry in a fluid and workable condition so that it can be pumped.

Heretofore, various setting retarders have been incorporated in the cement slurry to counteract the setting acceleration. In particular carboxymethyl cellulose (CMC) and alkali salts thereof, borax (sodium tetraborate) and dextrin have been used individually. Each of these, under conditions of use have little effect on the setting rate and impart undesirable properties to the slurry.

It has now been unexpectedly found that the use of all three compounds simultaneously within certain specific ranges, produces a synergistic effect and optimum results.

In accordance with the invention a composition for retarding the setting of cement is provided which comprises a mixture of at least one of the group consisting of carboxymethyl cellulose and alkali salts of carboxymethyl cellulose, borax and dextrin, in the proportions by weight of 35 to 40%, 30 to 35% and 25 to 30%, respectively.

Inorganic alkali salts may if desired be included in the composition.

The compositions of the invention can be used with any conventional cement slurry.

In order that the invention may be fully understood, it will be described with reference to the accompanying Tables which set forth experimental results, various ingredients and concentrations using a cement slurry (Type G according to the cement classification of the American Petroleum Institute). The test results include thickening time, viscosity, yield point, compression resistance and water loss, of which the thickening time is the most important for satisfactory formulations of the composition.

Table I provides results for comparative purposes using no additives, and using NaCMC, borax and dextrin, individually.

Table II provides results using NaCMC, borax and dextrin in admixture in various formulations.

Table III provides results showing further improvements by including inorganic alkali salts in the formulations.

Upon analyzing the results of Table I, it is observed that CMC, borax and dextrin, if utilized separately for dosing slurries of Type "G" cement, at a temperature of 206.degree.F., have little effect as setting retarders; also, the slurries show the following undesirable properties:

a. The thickening time of slurries prepared with 0.3% by weight of CMC is only 1:12 hr./min. On the other hand, slurry properties with CMC at concentrations above 0.3% have the defect of being viscous and their yield points are extremely high, making it difficult and sometimes impossible to handle them with the equipment that is conventional in oil wells for carrying out cementations.

b. The slurries prepared with borax show adequate rheological properties and high resistance, but their thickening times are extremely low.

c. Dextrin destroys the consistency of the slurries making the solid cement particles segregate; also, the slurries containing Dextrin have the undesirable defect of regression in their thickening time.

Table II demonstrates by experimental results that by using the novel mixtures of CMC, borax and dextrin, according to the present invention, the undesirable effects caused by each one of these compounds are corrected and more than compensated, when said compounds are mixed in percentages ranging from 35-40, 30-35 and 25-30 of CMC, borax and dextrin, respectively. The viscosity effect and the high yield point of the slurries caused by CMC alone, is corrected when dextrin is used; reciprocally the defect due to dextrin, of destroying the consistency of the slurries, as well as the high water losses, are compensated by means of the CMC. Borax is utilized in order to increase the cement resistance; also, mixing it with CMC increases the thickening time. On the other hand, and according to the data of Table II, the adequate dosification of CMC, borax and dextrin eliminates the regression disadvantage of the thickening time due to dextrin.

It has been experimentally determined that the optimum formulation of CMC, borax and dextrin is achieved when said components participate in a percentage ratio of 40, 32.5 and 27.5, respectively.

The use of this formulation with alkali metal salts such as sodium and potassium salts also provides satisfactory results as it can be observed from the attached Table III.

All the test results in these tables were made following the laboratory procedures set forth by the American Petroleum Institute, noted in the API-RP-10B report "Recommended Practice for Testing Oil Well Cements and Cement Additives".

TABLE I __________________________________________________________________________ EXPERIMENTAL LABORATORY DATA AND RESULTS OF MIXTURES PREPARED WITH TYPE "G" CEMENT DIFFERENT CMC, BORAX AND DEXTRIN CONCENTRATIONS Yield Compression Water Loss Thickening Point Resistance % of active agent by weight of cement Time Viscosity Lb./100 at 8 hrs. cm.sup.3 /30 min. Hr./min. cp sq. ft. Kg./sq. cm. .DELTA.P = 1000 % of mixture 206.degree.F. 144.degree.F. 144.degree.F. 290.degree.F. psi. in cement Na CMC Borax Dextrin 206.degree.F. __________________________________________________________________________ 0.0 0.00 0.000 0.000 0:45 + 1000 0.3 0.30 -- -- 1:12 30 65 0.4 0.40 -- -- 1:25 30 * 0.5 0.50 -- -- 1:40* * * * LOW THICKENING TIMES AND YIELD POINTS EXTREMELY HIGH 0.4 -- 0.40 -- 0:55 22 48 280 + 1000 0.8 -- 0.80 -- 1:00* 20 45 305 + 1000 * LOW THICKENING TIMES 0.3 -- -- 0.3 2:50 23 0* + 1000 0.4 -- -- 0.4 4:32 22 0 + 1000 0.6 -- -- 0.6 2:29* 14 0 + 1000 1.0 -- -- 1.0 1:27 12 0 + 1000 __________________________________________________________________________ * UNDESIRABLE REGRESSION IN THICKENING TIME, SLURRY RHEOLOGICAL PROPERTIE ARE DESTROYED AND THERE IS HIGH WATER LOSS

TABLE II __________________________________________________________________________ Thickening Yield Compression Water Loss % of active agent by weight of cement Time Viscosity Point Resistance cm.sup.3 /30 min. Hr./min cp Lb./100 at 8 hrs. % of mix- sq. ft. Kg./sq. cm. .DELTA.P = 1000 ture in Na CMC Borax Dextrin 206.degree.F. 144.degree.F. 144.degree.F. 290.degree.F. psi. cement 206.degree.F. __________________________________________________________________________ % FORMULATION 5/85/10 __________________________________________________________________________ 0.4 0.020 0.3400 0.0400 1:05 20 50 245 + 1000 0.8 0.040 0.6800 0.0800 1:25 18 44 250 + 1000 1.0 0.050 0.8500 0.1000 1:30 -- -- -- - -- FORMULATION 10/30/60 __________________________________________________________________________ 0.4 0.040 0.1200 0.2400 2:30 30 12 0.8 0.080 0.2400 0.4800 4:00 26 8 1.0 0.100 0.3000 0.6000 2:20 16 0 FORMULATION 80/10/10 __________________________________________________________________________ 0.4 0.320 0.0400 0.0400 1:30 28 64 0.8 0.640 0.0800 0.0800 1:55 * * FORMULATION 60/20/20 __________________________________________________________________________ 0.4 0.240 0.0800 0.0800 1:50 25 60 0.8 0.480 0.1600 0.1600 2:10 54 100 FORMULATION 30/30/40 __________________________________________________________________________ 0.4 0.1200 0.1200 0.1600 2:30 0.8 0.2400 0.2400 0.3200 3:12 1.0 0.3000 0.3000 0.4000 3:25 1.5 0.4500 0.4500 0.6000 2:50 FORMULATION 35/35/30 __________________________________________________________________________ 0.4 0.1400 0.1400 0.1200 2:15 0.8 0.2800 0.2800 0.2400 3:20 1.0 0.3500 0.3500 0.3000 3:50 1.5 0.5250 0.5250 0.4500 4:15 % FORMULATION 40/30/30 __________________________________________________________________________ 0.4 0.1600 0.1200 0.1200 2:20 32 28 0.8 0.3200 0.2400 0.2400 3:35 30 24 1.0 0.4000 0.3000 0.3000 4:00 -- -- 1.5 0.6000 0.4500 0.4500 4:50 -- -- FORMULATION 40/32.5/27.5 __________________________________________________________________________ 0.3 0.1200 0.0975 0.0825 2:30 34 32 250 -- 0.4 0.1600 0.1300 0.1100 2:45 36 26 239 -- 0.6 0.2400 0.1950 0.1650 3:40 40 16 212 420 0.8 0.3200 0.2600 0.2200 4:15 43 8 190 412 1.0 0.4000 0.3250 0.2750 +5:00 43 6 160 340 1.2 0.4800 0.3900 0.3300 +6:00 45 4 -- 270 144.degree.F. 230.degree.F. 0.1 0.040 0.0325 0.0275 1:45 -- -- 245 -- 0.2 0.080 0.0650 0.0550 2:30 30 42 220 -- 172.degree.F. 260.degree.F. 0.2 0.080 0.0650 0.0550 2:10 30 42 250 -- 0.3 0.120 0.9750 0.0825 3:15 34 32 210 -- 213.degree.F. 290.degree.F. 0.8 0.3200 0.2600 0.2200 3:00 190 1.0 0.4000 0.3250 0.2750 3:45 43 6 160 340 1.2 0.4800 0.3900 0.3300 4:50 45 4 -- 270 230.degree.F. 290.degree.F. 1.0 0.4000 0.3250 0.2750 2:25 43 6 160 340 1.2 0.4800 0.3900 0.3300 3:15 45 4 -- 270 Thickening Yield Compression Water Loss % of active agent by weight of cement Time Viscosity Point Resistence cm.sup.3 /30 min. Hr/min. cp Lb/100 at 8 hrs. .DELTA.P = 1000 % of mix- sq. ft. Kg/sq. cm. psi ture in NH.sub.4 - Borax Dextrine cement CMC 206.degree.F. 144.degree.C 144.degree.F 290.degree.C 206.degree.C __________________________________________________________________________ % FORMULATION 40/32.5/27.5 __________________________________________________________________________ 0.4 0.160 0.130 0.1100 1:50 40 18 180 0.6 0.240 0.195 0.1650 3:16 45 12 160 213.degree.F 0.8 0.3200 0.2600 0.2200 2:04 50 4 1.0 0.4000 0.3250 0.2750 2:39 52 0 1.5 0.6000 0.4875 0.4125 5:08 -- -- 172.degree.C 0.2 0.080 0.0650 0.0550 1:39 35 35 0.3 0.120 0.0975 0.0825 2:20 40 25 0.4 0.160 0.1300

0.1100 3:35 40 18 0.5 0.200 0.1625 0.1375 4:53 42 15 144.degree.C 0.2 0.080 0.0650 0.0550 1:53 __________________________________________________________________________

TABLE III __________________________________________________________________________ LABORATORY DATA AND EXPERIMENTAL RESULTS UTILIZING SLURRIES PREPARED WITH TYPE G CEMENT, CMC, BORAX AND DEXTRINE AND SOME INORGANIC SALTS. Thickening time Viscosity Yield Point Compression % of active agent by weight Hr:min CP lb/100/sq.ft Resistance of cement. 206.degree.F 144.degree.F 144.degree.F at 8 hr. % NaCMC BORAX DEXTRINE Sodium kg/sq.cm Sulfate 290.degree.F __________________________________________________________________________ Formulation 40/32.5/27.5 __________________________________________________________________________ 0.4 0.1600 0.1300 0.1100 0.10 3:15 25 31 0.6 0.2400 0.1950 0.1650 0.20 3:25 25 30 0.8 0.3200 0.2600 0.2200 0.40 3:40 24 29 172.degree.F 0.3 0.1200 0.0975 0.0825 0.15 3:05 23 33 0.4 0.1600 0.1300 0.1100 0.30 3:20 25 31 0.4 0.1600 0.1300 0.1100 0.35 3:25 144.degree.F 0.2 0.0800 0.0650 0.0550 0.10 3:15 230.degree.F 1.2 0.4800 0.3900 0.3300 0.30 3:10 1.5 0.6000 0.4875 0.4125 0.40 3:25 Potassium Sulfate 144.degree.F 0.2 0.0800 0.0650 0.0550 0.10 3:00 186.degree.F 0.3 0.1200 0.0975 0.0825 0.30 3:10 0.4 0.1600 0.1300 0.1100 0.40 3:25 26 32 Thickening time Viscosity Yield Point Compression % of active agent by weight Hr:min CP lb/100/sq.ft Resistance of cement 144.degree.F 144.degree.F 144.degree.F at 8 hr. % NaCMC BORAX DEXTRINE Sodium kg/sq.cm. sulfate __________________________________________________________________________ FORMULATION 40/32.5/27.5 __________________________________________________________________________ 0.2 0.080 0.0650 0.0550 0.20 3:20 36 27 70 0.3 0.120 0.0975 0.0825 0.40 3:45 35 32 160 206.degree.F 290.degree.F 0.6 0.240 0.1950 0.1650 0.10 4:15 38 19 185 0.8 0.320 0.2600 0.2200 0.20 5:30 40 17 120 1.0 0.400 0.3250 0.2750 0.40 +6:00 44 6 40 __________________________________________________________________________

Previous Show 10 Next

For U.S. patent law, rules, and procedures see MPEP.

Disclaimer. Information presented on this page while believed to be reliable, is provided "as is" with no warranties of its accuracy or timeliness. For legal advice seek help of a licensed professional.