NO165672B - PROCEDURE FOR RETARDING THE STRENGTH OF AN Aqueous Cement Suspension by the Addition of Methylene Phosphonic Acid Preparations Prepared from Amino Hydrocarbyl Piperazine Urea Substances. - Google Patents

Description

The present invention relates to a method for retarding an aqueous cement slurry which comprises the addition of an organic phosphonate retarder to the slurry.

The use of methylenephosphonic acid substituted alkylene polyamines

for metal ion control in less than stoichiometric amounts was proposed in US patent 2,609,390. Later, it was stated that a water-dispersible polymeric amine-elating agent comprising alkylene phosphonate derivatives had "threshold" effects when used to prevent galling (US patent 3,331,773), this term being used to describe the use of the agent in less than stoichiometric amounts. The diamine and polyamine methylene phosphonate derivatives are taught and claimed respectively in US Patents 3,336,221

and 3,434,969. Some of the products described in these two patents are available commercially and are recommended as stone inhibitors when used in threshold amounts.

Some other patents that describe heterocyclic nitrogen-containing compounds that are useful as gelling agents and that can be used in threshold amounts are US Patents 3,674,804, 3,720,498, 3,743,603, 3,859,211 and 3,954,761. Some of the compounds described therein are heterocyclic compounds of the formulas: where R is hydrogen or alkyl and M is hydrogen, alkali metal, ammonium or a di- or triethanolamine radical,

Methylene phosphonates of polyalkylene polyamines, described in US patent 4,051,110, are prepared by reacting di- or polyamines with a chain-extending agent such as e.g. a dihalide or an epoxy halide, e.g. ethylene dichloride or epichlorohydrin and then with phosphoric acid and formaldehyde. Thus, for example, triethylenetetramine is reacted with epichlorohydrin in a ratio of approx. one to one, after which the product is reacted with phosphoric acid and formaldehyde in the presence of hydrochloric acid. The resulting methylenephosphonate polyamine is usable in small quantities as a scale inhibitor, being used in concentrations of 20-50 ppm.

Certain phosphonic acid derivatives of the aliphatic acids can be prepared by reacting phosphoric acid with acid anhydrides or acid chlorides, e.g. the anhydrides or chlorides of acetic, propionic, and valeric acids. The compounds produced have the formula

where R is a lower alkyl radical of 1 to 5 carbon atoms. The procedure for the manufacture and use of these products is described in US patent 3.214.4 54. It describes and requires the use of threshold amounts to prevent calcium precipitation in aqueous solutions.

Hydrophobically substituted phosphonic or phosphinic acids and their alkali metal salts have been used in cements, primarily in soil/cement blends, to improve freeze-thaw properties and salt resistance. Alkylphosphonic acids having six to eighteen carbon atoms or their alkali metal salts are thus described in US Patent 3,794,506. A sealing compound for high temperature oil and gas wells comprises Portland cement and 1-hydroxy-ethylidene-phosphonic acid trisodium or tripotassium salts as curing time extenders, herein described in Derwent abstract 7i37GB/39 (1979) of the USSR patent 640,019. The use of these phosphonate salts at temperatures of 75° to 150°C in amounts of

i - 0.3% by weight is described in the abstract.

Other organic phosphoric acid derivatives are described as useful additives in cement mixtures such as turbulence-inducing and flow-property-improving additives (respectively US Patent 3,964,921 and 4,040,854). Another turbulence inducing agent is a pyrolysis product of urea and a bis(alkylene pyrophosphate) (US Patent 3,409,080).

Alkylene diphosphonic acid and their water-soluble salts are described as curing time extenders and water reducing agents for gypsum mortars (US Patent 4,225,361). Lignins which are phosphono-alkylated via an ether bond or corresponding sulphonates, sulphides, hydroxyls or amine derivatives are described to be useful primarily as dispersants or surfactants (US patent 3,865,803) and are also described to

be applicable as "cement additives" without specifying specific applications.

Ultra-rapid setting Portland cement mixtures have been described containing various acid salt additives (US Patent 4,066,469). It is stated there that the use of acid phosphates as acid site additives is excluded since the phosphates have a characteristic strong retarding property which is special to them.

Most of the cement used in oil wells is called Portland cement. Portland cement is produced by calcining raw materials consisting of limestone, clay, shale and slag together at 1400 to 1550°C in a rotary kiln.

The resulting material is cooled and ground together with small amounts of gypsum to form Portland cement. In addition to the raw materials mentioned above, other components such as e.g. sand, bauxite, iron oxide, etc. are added to adjust the chemical composition depending on the type of portland cement desired.

The main ingredients in the finished Portland cement are lime, silicon oxide, aluminum oxide and iron. These constituents form the following complex compounds: Tricalcium aluminate, ( 3CaO-A^O^) » tetracalcium aluminum ferrite (4CaO-A^O^ • Fe203), tricalcium silicate, (3CaO-3102), and dicalcium silicate, (2CaO-SiO2).

When water is added to cement, solidification and hardening reactions begin immediately. The chemical compounds in 'j::xT.ue;\ undo ..hydratif.ering and recrystallization •■!.-.;<./3Scr, which results in a hardened product. The maximum amount of water that can be used in an oil well cement is the amount that can be added before separation of the solids occurs. The minimum amount of water is the amount required to render the slurry pumpable. The normal water ratio is therefore determined by the maximum and minimum limits for a particular class of cement.

Thickening time is the time when the cement remains pumpable in the well. This is the most critical property of an oil-burning cement. The thickening time must be long enough for the cement .-: 'ir. pumped into place and short enough to allow the operations . -jrtselcer quickly.. In general, three hours gives the necessary pla-ser inqstiucn plus a safety factor.

Other factors such as liquid loss, viscosity and density must be taken into account, and additives are known to those skilled in the art which affect each of these factors as well as the solidification or thickening time as mentioned above. Another parameter that has an effect on the solidification time is the temperature. Cement hardens more quickly when the temperature rises. This must be taken into account, especially when cement is to be pumped into deeper wells, since the temperature increases as the depth of the well increases. The temperature also affects the strength of the cement, as the strength decreases as the temperature increases.

Because of this temperature effect, it is important to delay the solidification of the cement used in deeper wells.

It has now been found that certain methylenephosphonic acid derivatives of aminohydrocarbylpiperazineurea adducts are good cement retarders.

According to the invention, a compound with the formula is used as organic phosphonate

where A is X is or H;'R is H, ammonium, an alkali or alkaline earth metal;'m is 0.-2-; n is 2 or 3; and where at least one X is

Ammopiperazine itself.: does not have particularly good cement retardation activity.

The compounds from which the methylene phosphonates are obtained (the "starting materials") have the formula

where A is

is hydrogen, and where m is 0-2 and n is 2 or 3. These compounds are prepared by reacting urea with an amino-hydrocarbypiperazine.

The starting materials in which A is according to formula (II) are easily prepared as follows:

Suitable aminoalkylpiperazines which may be used include those represented by the general formula

where R is a divalent hydrocarbyl group with Era approx. 2 to approx.

10, preferably from approx. 2 to approx. 4, and most preferably from approx. 2 to approx. 3 carbon atoms. The hydrocarbon group may be c/-disk, acyclic, aromatic or non-aromatic. Particularly suitable aminohydrocarbyl-piperazines include e.g. aminoethyl-1-piperazine, aminopropyl-piperazine, aminobutyl-piperazine, aminopentyl-piperazine, aminohexyl-piperazine, aminohepty1-piperazine, aminoocty1-piperazine, aminononyl-piperazine, aminodecyl-piperazine, mixtures thereof and the like.

Suitable catalysts that can be used include such basic catalysts as e.g. basic ion exchange resins, quaternary ammonium compounds, phosphonium compounds, imidazos, mixtures thereof and the like.

Suitable basic ion exchange resins include, for example, m0CW£a"m:-:A-1 (chloride or hydroxide form), "D0WEX"1, "D0WEX"2, "DOV/EX" 11, "D0WEX" 2iK, mixtures thereof and the like The ion exchange resin can be used either in the wet or dry form.

Suitable quaternary ammonium catalysts include e.g. benzyltrimethylammonium chloride, benzyltrimethylammonium bromide, benzyl trimethylammonium hydroxide, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium hydroxide, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium hydroxide, mixtures thereof and the like.

Suitable phosphonium catalysts include, for example, tetra-(hydroxymethyl)phosphonium chloride, tetrahydroxymethylphosphonium bromide, ethyltriphenylphosphonium iodide, butyltriphenylphosphonium halides, methyltriphenylphosphonium halides, tetrabutylphosphonium halides, methyltributylphosphonium halides, ethyltriphenylphosphonium uniacetate.acetic acid complex, tetrabutylphosphonium acetate.acetic acid complex, mixtures thereof and such.

Suitable imidazole catalysts that can be used here include e.g. 2-methyl-imidazole, mixtures thereof and the like.

Suitable molar ratios between aminohydrocarby1-piperazine and urea are from approx. 1.8:1 to approx. 6:1, preferably from approx. 1.6:1 to approx. 4:1, most preferred from approx. 1.8:1 to about 2.2:1.

The reaction may be carried out at any suitable temperature which may vary depending on the specific reactants and catalysts used. In general, however, .nvencos temperatures of from approx. 60 to approx. 185°C, preferably from approx. 80 tii approx. 160°C and most preferably from approx. 90 to approx. 13 5°C.

The particular reaction time depends on the particulars

the reactants, the catalyst, the reaction temperature and the pressure and when it is significantly short it can result in low conversion. Longer reaction times tend to form products with higher amine hydrogen equivalent weights as determined by titration with HCl and using bromothymol blue as an indicator, ride:; or usually from approx. 16 to approx. 200 hours (57,600-720,000 s), preferably from 18 to approx. 67 hours (64,800-241,200 s), and most preferred from approx. 18 to approx. 24 hours (64,800-86,400 s) .

If it is not necessary and will result in an egg removal or separation step, the method for producing the starting materials can be carried out in the presence of an inert organic reaction medium such as e.g. water, methanol,

ethane, propane, butane, mixtures thereof and the like.

The following are examples of the preparation of starting materials in which A is according to formula (II).

Example S-l

Aminoethylpiperazine (516.84g, 4 mol) was added to a 1 liter reaction vessel equipped with a stirrer, reflux condenser, temperature control and indicating devices. After raising the temperature to approximately 120°C, 0.32g (0.0039 mol) of 2-methylimidazole catalyst was added, immediately followed by the addition of 20g (0.3mol) of urea. After reaction for 2 hours at 120°C with stirring, a further 0.32g (0.0039 mol) of 2-methylimidazole catalyst was added, followed by the addition of 40g (0.7 mol) of urea. The progress of the reaction was periodically checked by titration with 1 N HCl using bromothymol blue as an indicator. The titration results after 54.3 hours were the same as those after 17.4 hours at 120°C. Excess aminoethylpiperazine was removed using a rotary evaporator at a temperature of 120°C and a pressure of 0.120 mm HgA (16.0 Pa, absolute). The product yield was >99% based on the urea conversion and 93.3% based on net product weight. The amino hydrogen equivalent weight was determined to be 195.3. The product was a very viscous, straw-coloured mass.

Examples S- 2 tii S- 20

All of the examples in Table I used either 500 ml, 1 liter, 5 liter 3-neck flask or 4 liter resin kettles.

These reaction vessels were stirred at 250 to 500 rpm. minute using a laboratory stirring motor with an attached stirring bar and stirrers. Attached to each of the reaction vessels was a water-cooled condenser, thermometer, a temperature control device manufactured by I<2>R Thermowatch Instruments, Cheltenham, Pa., and a heat lamp, except for the experiments: ~ed 4 a .i r or where used co heat lamps. The heating lamps bj.e reguiort using I "R "thermowatch" and the lamps bee placed in such a way that they prevented local heating' on the sides of the tub.

The liquid aminoethylpiperazine (AEP) was added to the vessel at ambient temperature. The stirrer and I<2>R "thermowatch" b-Le attached and the AEP were heated to the reaction temperature as indicated in Table I. The solid urea pellets were then added in small amounts of from 3 to 1 7 additions with approximately equal time- intervals between each addition. For most of the experiments shown in table 1, roughly equal amounts were added.

The reaction conditions for each example are listed in Table I. The molar ratio of AEP to urea varied from 1.9/J. tii 6.0/1. The reaction temperature varied from 118°C to 150°C, while the total time required to add urea-fat in small amounts to AEP varied from 1 hour to 3.1 hours. 1 each, for example, the urea added manually to the stirred AEP at or near the reaction temperature. Each addition took less than 1 minute (60 s) and the reaction vessel was quickly closed after the addition, which prevented ammonia from disappearing in any other way than through the water-cooled condenser. The rower prevented large amounts of AEP from being lost by being dragged along when the ammonia came out. The liberated ammonia was easily detected by holding a cork moistened with HC1 over the boiler, which caused white fumes over the cooler. It usually took from 2 to 5 minutes (120 to 300 s) after the first addition of ir.stof before any detection of liberated ammonia was possible. Then ammonia was continuously de-•.•lf. under heating the remaining additions and until reactions were finished by turning off the heat source and in the product;

Ln is.doter.T: of usually approx. 2°C to 3°C was always detected with each addition. Each urea addition was followed by a considerable foaming of the stirred reactants, caused by the avuoer.de ammonia.

When adding urine?: tor fet i sr ri/i amount)/, j;ie. "vor-foaming" of f iything product prevented ' islésiZtcrvri 1 lone moll «.m the additions were adjusted to allow the temperature to go back to the desired value.

Samples were withdrawn periodically and titrated with 1N" HCl to a green end point using bromothymol blue as indicator. The amine equivalent weight was then determined using the formula

In this method, no distinction was made between a primary and a secondary amine. E.g. two moles of HCl were required to titrate one mole of aminoethyl-piperazine.

Initially, the aminoethyl-piperazine before reaction with the urea had an amine equivalent weight very close to its molecular weight divided by 2 or 129.21 divided by 2 = 64.61. For all these examples, the reaction temperature was maintained and stirring continued until the amine equivalent weights indicated in Table II were obtained. The amine equivalent weights for these examples ranged from 123 to 207.

In general, the remaining AEP was from approx. 3 to approx. 10% for AEP/urea adducts prepared from AEP/urea molar ratios of 1.9/1 to 2.1/1. Residual AEP reduced the viscosity of the curing agent and facilitated mixing for curing epoxy resins.

In experiments where a significantly higher AEP/urea-morphol ratio was used, the unreacted aminoethyl-piperazine was removed by placing the product solution in a rotator flask. The flask was then connected to a rotary evaporator using a heat lamp and "variac" to regulate the evaporation temperature and a vacuum pump was used to reduce the pressure. Evaporation temperatures, evaporation times and pressures used are listed in Table I.

To a 4-liter resin kettle equipped with a water-cooled condenser, mechanical stirrer, thermometer, temperature controller, and heat lamps was added 2480.83 grams (19.2 moles) of aminoethylpiperazine (AEP). After heating to 120°C and stirring, 3.55 grams (0.0432 mol) of 2-methyl-imidazole were added. When the temperature again reached 120°C, 127 grams (2.11 moles) of urea was added over a 1 minute (60 s) period. During this time the temperature was cooled to 112°C. After 10 minutes (600 seconds), 353.48 grams (5.89 moles) of urea was added over a 4 minute (240 seconds) period. The flask temperature was 122°C and during the addition the flask was cooled to 112°C

due to liberated ammonia.

The reaction temperature rose to 120°C within 53 minutes (3180 s) after the last urea addition and this reaction temperature was maintained for a further 71 hours (255,600 s). Then a reaction temperature of 123 to 125°C was maintained for 23.72 hours (85,392 s). The reaction mixture was then cooled. A mass balance for this reaction gave 2695.3 grams. The ammonia weight loss was 269.56 grams (15.86 moles). The expected ammonia weight loss for 100% conversion to pure bis-aminoethylpiperazine/urea adduct with n=0 was 272 grams (16 moles), which corresponds to a loss of 2 moles of NH 2 for every 1 mole of urea. This gives a yield of 99.10%. A sample was titrated with IN HCl using bromothymol blue as an indicator and found to have an amine equivalent weight equal to 111.33. The product was a red-brown liquid which had a significantly lower viscosity due to the use of an excess of more than 2 mol AEP per moles of urea. Originally, in this experiment, 19.2 mol of AEP was used to 8 mol of urea, which is equal to a molar ratio of 2.4/1. This product was analyzed by liquid chromatography, which confirmed the presence of residual AEP and also confirmed that essentially all urea had been converted since only trace amounts were detectable. This was also confirmed by infrared and gel permeation chromatography. Analysis of this liquid product by NMR (nuclear magnetic resonance) analysis supports the presence of mostly disubstituted urea and some disubstituted urea compounds.

Exenpex s-22

A net weight of 339.3 grams of product from the above example would be placed in a 1-litre single-necked container. The flask was then connected to a rotary evaporator and residual amino-ethyl-piperazine was removed at 65 to 105°C, using a vacuum pump to reduce the pressure to about 3.5 mm Hg (460 Pa)" absolute pressure at the start of evaporation to about 0.05 mm Hg (6.7 Pa) at the end of evaporation. The total evaporation time was 95 minutes (5700 s). A net weight of 266.9 grams of a medium red viscous liquid (at ambient temperature) was obtained. Analyzes using nuclear magnetic resonance and infrared chromatography strongly supported that the reaction product was a bis AEP/urea adduct with n=0 and n=1. The sample was titrated with IN HCl using bromothymol blue as indicator and found to have an amine equivalent weight of 133.07.

The preparation of starting materials in which A is hydrogen is carried out in a similar manner.

The following example is representative of a preparation which gives a crystalline product with essentially a 1/1 molar ratio of AEP/urea.

Example S- 23

Into a 1 liter reaction flask equipped with a mechanical stirrer, thermometer, IR temperature control device and water-cooled condenser was added 4.86 moles (4.86 equivalents of primary amine) or 628 grams of N-(2-aminoethyl)piperazine (AEP) .

Then 0.93 grams (0.12% by weight of the total) of 2-methylimidazole was added as a catalyst. The reaction solution was heated to 20°C with good stirring and regulated to this temperature.

Then add 2.5 moles (5 equivalents) of urea added manually

4 small portions in 2.13 hours (7668 s). The reaction was allowed to proceed at 120°C for a further 3.5 hours (12,600 s).

Two small samples were taken during this time and titrated with

iN HC1 using bromothymol blue as indicator to determine % conversion. The heat and stirrer were turned off and the reaction solution was allowed to cool to ambient temperature

(-25°). About 80% by volume of the reaction flask crystallized.

A sample of this crude product (crystals and liquid) was found

to contain 4 8 moi% i-(2-piperazinoethyl)urea, 33 mol%

unreacted aminoethylpiperazine and approx. 19 mol% unknown contaminants

Die:; r-2 .vryntailinike the product (7 22 ora~; i: le pl.asserr

in a large vessel containing 1444 grams of acetone and stirred mechanically for 15 minutes (900 s). The crystalline product was then separated from the liquid phase by filtration through a medium sintered gas funnel using a vacuum flask. A second extraction was performed using fresh acetone and filtered as before. The remainder of the acetone was removed using a rotary evaporator at 30 to 40°C and less than 1 mm Hg absolute pressure. A white crystalline solid with a melting point of

147 to 152°C. The amine nitrogen equivalent weight calculated by titration with IN HCl was 168.14 compared to 172.27 (theory). This product was more than 90% pure as confirmed by liquid chromatography. Analysis by NMR and infrared was used to identify the product as 1-(2-piperazinoethyl)urea which can be represented by the following general formula

The products of the above reactions are then phosphonomethylated to give the desired products. The manufacturing process is shown in example 1 below. The preferred adduct is one that is fully phosphonomethylated. The most preferred is the completely phosphonomethylated adduct in which m is 0. As previously mentioned, the products have the formula where n is 2 or 3 and A is. where X is or H and where R is H', ammonium, an alkali or alkaline earth metal and m is 0-2, and where at least one X is

The following examples show representations, of these for-l.-.dei sen and their ^vondal;.: as "erskelr;idle-.

Oak simple i

150 g (0.53 noi) of an aminoethylpiperazine/urea (2/1 molar ratio) reaction product and 90 g of deionized water were added to a 500 mL round bottom flask equipped with a water-cooled reflux condenser, mechanical stirrer, thermometer with a temperature controller, and an addition funnel. About 200 g of concentrated hydrochloric acid and 92 g (1.1 mol) of phosphoric acid were added with stirring and the mixture heated to reflux and held there for one hour. Paraformaldehyde (37 g, 91%, 1.1 mol) was added over a one-hour period. The reaction mixture was heated under reflux for an additional two hours and then cooled. The product was assessed as a cement retarder.

Example 2

The aminoethylpiperazine/urea product used

in example i was phosphonomethylated with approximately 4 mol equivalents of formaldehyde and phosphoric acid according to the general procedure in example 1. The product was evaluated as a cement retarder.

Example 3

An aminoethylpiperazine/urea reaction product (1/1 moi ratio) was phosphonomethylated using the general procedure of Example 1. The reaction product was evaluated as a cement retarder.

The results of the cement retardation tests are shown in Table II.

pc. 4

The product, from Example 2 above, was tested as a cement retarder according to Section 8, API (American Petroleum Institute) Specification 10, using a base slurry, a Class H oilfield cement, 50% by weight water, 35% by weight silica flour, based on the applied weight of cement. The test was carried out at 204.4°C to determine the thickening time. Thickness of 70 Bc (Bearden consistency unit) was determined against time. Different amounts of retarder (based on the weight of the cement) were used. With 0.2, 0.5 and 0.7% of the retarder, the thickening time was 60, 180 and 300 minutes respectively.

Claims (1)

i. Method for retarding the solidification of an aqueous cement slurry comprising adding an organic phosphonate retarder to the slurry, characterized in that the organic phosphonate is a compound with the formula where A is or X; X is or H; R is H, ammonium, an alkali or alkaline earth metal; m is 0-2; n is 2 or 3; and where at least one X is 2. Method according to claim 1, characterized in that A is and each X is 3. Method according to claim 1, characterized in that A is X. 4. Method according to claim 1, characterized in that R is hydrogen. 5. Method according to claim 2 or 3, characterized in that R is an alkaline earth metal. 6. Method according to claim 2 or 3, characterized in that R is an alkali metal or ammonium. 7. Method according to claim 5, characterized in that the alkaline earth metal is magnesium or calcium. 8. Method according to one of the above claims, characterized in that n is 2.