DE102006061327A1 - Grafting copolymer, useful e.g. as additives in construction chemical applications, water retention agents and fluid loss additives, comprises silica, which is reacted with an unsaturated silane and a polymer containing sulfonic acid - Google Patents

Abstract

Grafting copolymer comprises silica (A), which is reacted with an unsaturated silane and a polymer (B1>) containing sulfonic acid. An independent claim is included for the preparation of the grafting copolymer.

Description

object The present invention is a graft copolymer, a process for its production and its use.

copolymers, also in grafted form, are well known and are due their specific monomer composition in the most diverse Usage areas used.

in the In the field of chemical mixing, copolymers are also frequently used as water retention agents. which are also referred to as fluid loss additives used. One Special application is cementing in this context from boreholes in the development underground oil and natural gas deposits.

Under Fluid loss additives or water retention agents become compounds understood that reduce the release of water from a cement slurry. This is especially true in the field of oil and natural gas exploration of Meaning, since cement slurries, which consist essentially of cement and water during cementation the boreholes through the annulus between the so-called casing and the borehole wall be pumped. It can Amounts of water from the cement slurry be delivered to the underground formation. This is special then the case when the cement slurry in the well cementing on porous Rock strata flows past. That from the cement slurry originating, alkalized water can then be in the formations clays to swell and form carbon carbonate precipitates with carbon dioxide from the natural gas or petroleum. These effects reduce the permeability of the deposits and as a result, production rates are also adversely affected.

In addition, frozen the cement slurry by the water delivery to the porous underground formations not more homogeneous and is characterized for Gases as well as for liquid Hydrocarbons and water permeable. As a result, this leads to escape the fossil fuels through the filled with porous cement annulus.

you has therefore been longer Time continuously strives to such water losses of the cement slurry used to reduce a tolerable minimum.

Out EP 0 116 671 A1 For example, a cement slurry for deep wells is described above, which is intended to reduce the loss of water with their content of copolymers. An important component of the copolymers used are acrylamides and in particular acrylamido-methylpropanesulfonic acid (AMPS). According to this document, the cement slurries should contain between 0.1 and 3% by weight of the suitable copolymers.

With the well cementing and a suitable composition deals EP 1 375 818 A1 , Also for fluid loss control, a polymer additive is used, which in addition to AMPS additionally contains maleic acid, N-vinylcaprolactam and 4-hydroxybutyl vinyl ether.

Also based on AMPS or a hydrolyzed acrylamide is a copolymer corresponding US 4,015,991 , The copolymers described in this patent are also said to improve water retention in cementitious compositions. The primary field of application is the cementing of boreholes.

Compared to hydrolytic influences, stable polymers, which can also be used in well cementing, are described US 4,515,635 , In the respective cases of use, the loss of water should be reduced by the polymers described. The copolymers consist essentially of N, N-dimethylacrylamide and AMPS. Similar polymers are the U.S. Patent 4,555,269 refer to. The copolymers described herein have a specific ratio between the monomer components N, N-dimethylacrylamide and AMPS.

The following US patents also relate to compounds having water-retaining properties:
The water-soluble copolymers according to US 6,395,853 B1 contain, among other things, the building blocks acrylamide and AMPS. In the foreground of this patent is a process for reducing the loss of water in a slurry, which is used for the production of petroleum. Especially mentioned in this context are the well cementing and completion as well as the process steps preceding previous drilling mud.

At the heart of US 4,700,780 is a process for reducing water loss in cementitious compositions which also include defined salt concentrations. The water retention agent is again a polymer or polymer salt of AMPS, in which case the building blocks styrene and acrylic acid still have to be present.

Finally, that can US document 6,855,201 B2 a cement composition consisting of a hydraulic cement component, water and a polymeric fluid loss control additive. The copolymer is based on AMPS, the calcium salt of maleic acid, N-vinylcaprolactam and 4-hydroxybutyl vinyl ether. This polymer is added to the cement composition in amounts between 0.1 and 2% by weight.

These Have a variety of known co- or graft polymers, as already briefly addressed, depending from their monomer composition each have a different property profile with specific advantages and disadvantages. A general weakness that most of these polymers are theirs Fluid-Loss effect in the presence of divalent salts, as typically also in seawater, which is common for mixing the cement sludges at off-shore oil and gas wells are included, and / or at very high temperatures over 190 degrees Fahrenheit subsides whereby also a total loss of effect can occur.

As just exemplified, is for a long time trying intensively, new To provide polymers whose water retention capacity in particular in the field of oil and gas exploration is stable, so that assumed a favorable price / performance ratio can be.

There the salt resistance, but also the temperature tolerance still in specific applications of the Improvement needs, has become the present invention has the object, a new graft copolymer to provide that on the proven Monomer building blocks, but by variation of Pfropfungspartner leads to a property profile, which in particular in the presence of divalent salts and under very high temperatures shows significant improvements.

Was solved this object with a graft copolymer based on a component a) consisting of silica which has been reacted with an unsaturated silane is, and a sulfonic acid-containing Polymer component b).

It has now become surprising proved that this graft copolymer has a significantly improved effect as a water retention agent, with its advantages in particular in demanding conditions. Because of his Monomer building blocks, this graft copolymer can be very economical getting produced. Especially under saline conditions has become have shown that the fluid-loss effect of the graft copolymers according to the invention over the previously known copolymers has significant advantages.

With regard to the silica component in component a), it has proved to be advantageous in the context of the preliminary invention if this silica component is based on an aqueous colloidally disperse solution of amorphous silicon dioxide (SiO ₂ ). Particularly suitable for the subsequent reaction with an unsaturated silane, so-called nanosilica has been shown.

at Nanosilica is aqueous, colloidal solutions, the exclusively Containing silica. The mean particle size of this Silica ranges between 5 and 500 nm, with ranges between 15 and 100 nm, and especially between 30 and 70 nm are preferred.

The Silane compound obtained by reaction with said silica in the component a) is received, should according to the invention an ethylenically unsaturated Alkoxysilane be. Particularly suitable representatives are representatives the series 3-methacryloxypropyltrialkoxysilane, 3-methacryloxypropyldialkoxyalkylsilane, Methacryloxymethyltrialkoxysilane, (methacryloxymethyl) dialkoxyalkylsilane, Vinyldialkoxyalkylsilan or vinyltrialkoxysilane shown. Suitable are also silanes, which first have no double bond, but by implementation with a suitable ethylenically unsaturated Convert the compound into a double bond-containing silane. In question here, for example, the reaction product of aminopropyltrimethoxysilane and maleic anhydride. This can also be done gradually, d. H. you leave that at first Silica react with the aminosilane, then in the next step with maleic anhydride implemented and finally is polymerized at the double bond.

When suitable sulfonic acid-containing Polymer components b) have in particular copolymers of acrylamido-methyl-propane sulfonic acid (AMPS) with further ethylenically unsaturated Monomers shown. Selected Such monomers are preferably selected from the series of vinyl ethers, Acrylic acid, methacrylic acid, 2-ethylacrylic, 2-propylacrylic, Vinyl acetic acid, Crotonic and isocrotonic acid, maleic acid, fumaric acid, itaconic, citraconic as well as their amides. Also suitable are generally styrenes, vinylphosphonic acid or ethylenically unsaturated Silanes. Also several times ethylenically unsaturated compounds such as Ethylene glycol dimethacrylate, glycerol dimethacrylate or trimethylolpropane trimethacrylate can be used. Particularly preferred are acrylamide compounds and here in particular the N, N-dimethylacrylamide.

The variability with regard to the composition of the graft copolymer according to the invention is not only reflected in the choices that underlie him lying monomers, but also in the mass ratio of component a) and b) to each other. According to the present invention, this preferably 10 to 1: 1 to 10, and more preferably 5 to 1: to 1 to 5.

When Also particularly advantageous is a variant of the graft copolymer according to the invention in which this represents a nanocomposite. This should be the component b) covalently the silane to the surface be bound to the silica.

In addition to the polymer itself, the present invention also includes a process for its preparation, which presents itself overall as very simple:
In process step a), the respective silica is reacted with the unsaturated silane and then the monomers of the sulfonic acid-containing component b) are grafted in step b) the thus reacted silane. The molar ratio of silica and silane in process step a) should be 200: 1 to 20.

When Starter of the polymerization reaction in process stage b) has become Sodium peroxodisulfate especially proven. But also other common ones Initiators such as peroxides or diazo compounds are suitable.

The Process conditions are essentially uncritical. It has but as cheap when method steps a) and / or b) are independent of one another be carried out at temperatures between 30 and 100 ° C lie. For the process step a) temperatures between 60 and 75 ° are recommended being a temperature around 70 ° C is particularly suitable. For Process step b) should have a temperature range between 40 and 60 ° C chosen be, in which case temperatures around 50 ° C are particularly suitable.

As already mentioned, there is a special focus on the use of the graft copolymers of the invention in construction chemical applications. For this reason, the claimed present invention also the use of the graft copolymer as an additive in construction chemical applications and in particular in the development, Exploitation and completion of underground oil and gas deposits, where its use as a water retention agent is particularly advantageous is to be considered.

In summary can be stated that with the proposed graft copolymers Connections available are the use of sulfonic acid-containing additives in the construction chemical sector additionally improve further. Especially due to the salt tolerance and a significantly increased temperature stability in the area of ≥ 190 degrees Fahrenheit are the graft copolymers according to the present Invention excellent as a water retention agent or fluid loss additives suitable.

The The following examples illustrate these advantages.

Examples

1) Production Example:

131.6 g Levasil ^® 50/50% (silica sol of the Fa. HC Starck), 65.8 g of least. H ₂ O and 5.6 g of methacryloxypropyltrimethoxysilane (Dynasylan MEMO from Degussa AG) were stirred for 30 minutes. During this time, the mixture thickened noticeably and was therefore diluted with another 65.8 g of water. Subsequently, the mixture was heated with stirring at 70 ° C for 4 h. After cooling to room temperature, a solution of 30 g of AMPS, 20 g of DMA (N, N-dimethylacrylamide) and 5.76 g of Ca (OH) ₂ in 150 g of water was added. Subsequently, the reaction mixture was rinsed with N _{2 for} 1 h; then 2.28 g of Na ₂ S ₂ O ₈ were added as a starter and heated to 50 ° C. After a reaction time of 1.5 h, the mixture was allowed to cool to room temperature (about 22 ° C). A white gel having a solids content of 26.6% by weight was obtained.

2) Application examples

Application example 2.1

• 800 g Class G – Zement (Dyckerhoff Black Label)
• 352 g dest. H2O
• 1 ml Tributylphosphat

Fluid-Loss-Additiv mit Dosierung Fluid-Loss [ml] 1% bwoc Polymer gemäß Herstellungsbeispiel 1 (Erfindung) 64 0,4% bwoc (AMPS/DMA-Copolymer + 0,6% bwoc Levasil^® 50/50%)(Verleich) 82 The fluid loss was determined according to API standard 10 A at 125 ° F in the following sludge:

• 800 g Class G - Cement (Dyckerhoff Black Label)
• 352 g dist. H2O
• 1 ml of tributyl phosphate

Fluid loss additive with dosage Fluid loss [ml] 1% bwoc polymer according to Preparation Example 1 (invention) 64 0.4% bwoc (AMPS / DMA copolymer + 0.6% bwoc Levasil ^® 50/50%) (Verleich) 82

Of the Comparison of the nanocomposite according to the invention with a mixture of a standard AMPS / DMA copolymer and nanosilica, which the proportions of copolymer and silica in nanocomposite, shows that the fluid loss of the nanocomposite according to the invention at the relatively low measurement temperature only marginally better is the one of the comparison mixture.

Application example 2.2

• 800 g Class G – Zement (Dyckerhoff Black Label)
• 352 g dest. H2O
• 1 ml Tributylphosphat

Fluid-Loss-Additiv mit Dosierung Fluid-Loss [ml] 1% bwoc Polymer gemäß Herstellungsbeispiel 1 (Erfindung) 70 0,4% bwoc (AMPS/DMA-Copolymer + 0,6% bwoc Levasil^® 50/50%) (Vergleich) 180 The fluid loss was determined according to API standard 10 A at 190 ° F in the following sludge:

• 800 g Class G - Cement (Dyckerhoff Black Label)
• 352 g dist. H2O
• 1 ml of tributyl phosphate

Fluid loss additive with dosage Fluid loss [ml] 1% bwoc polymer according to Preparation Example 1 (invention) 70 0.4% bwoc (AMPS / DMA copolymer + 0.6% bwoc Levasil ^® 50/50%) (Comparative) 180

at the compared to the application 2.1 relatively high measurement temperature from 190 ° F are distinct differences between the nanocomposite according to the invention and the comparison mixture. During the fluid loss of the nanocomposite remains practically constant compared to the reading at 125 ° F, the fluid loss of the mixture deteriorates significantly. D. H. the fluid-loss behavior of the nanocomposite according to the invention is temperature independent.

Application Example 2.3:

• 800 g Class G – Zement (Dyckerhoff Black Label)
• 352 g dest. H2O
• 14,1 g Meersalz

Fluid-Loss-Additiv mit Dosierung Fluid-Loss [ml] 1% bwoc Polymer gemäß Herstellungsbeispiel 1 (Erfindung) 120 0,4% bwoc (AMPS/DMA-Copolymer + 0,6% bwoc Levasil^® 50/50%) (Vergleich) 218 The fluid loss was determined according to API standard 10 A at 125 ° F in the following sludge:

• 800 g Class G - Cement (Dyckerhoff Black Label)
• 352 g dist. H2O
• 14.1 g of sea salt

Fluid loss additive with dosage Fluid loss [ml] 1% bwoc polymer according to Preparation Example 1 (invention) 120 0.4% bwoc (AMPS / DMA copolymer + 0.6% bwoc Levasil ^® 50/50%) (Comparative) 218

Also Here are again significant differences between the nanocomposite according to the invention and the comparison mixture.

Though the fluid loss of the nanocomposite also increases with the addition of Sea salt significantly on; is the fluid loss of the comparison mixture but much higher.

Claims (11)

Graft copolymer based on a component a) consisting of silica which has been reacted with an unsaturated silane is, and a sulfonic acid-containing Polymer component b). Polymer according to claim 1, characterized in that the silica component in component a) is based on an aqueous colloidally disperse solution of amorphous silicon dioxide (SiO ₂ ) and preferably on a nanosilica. Polymer according to one of claims 1 or 2, characterized that the silane in component a) is an ethylenically unsaturated Alkoxysilane and in particular a member of the series 3-methacryloxypropyltrialkoxysilane, 3-Methacryloxypropyldialkoxyalkylsilan, Methacryloxymethyltrialkoxysilane, (methacryloxymethyl) dialkoxyalkylsilane, Vinyldialkoxyalkylsilan or vinyltrialkoxysilane is. Polymer according to one of Claims 1 to 3, characterized component b) is a copolymer of acrylamidomethylpropanesulfonic acid (AMPS) with further ethylenically unsaturated Monomers, wherein the monomers are preferably selected from the series vinyl ethers, acrylic acid, methacrylic acid, 2-ethylacrylic acid, 2-propylacrylic acid, vinylacetic acid, croton and isocrotonic acid, maleic acid, fumaric acid, itaconic, citraconic and their amides, styrenes, vinylphosphonic acid or ethylenically unsaturated silanes as well as polyunsaturated ethylenically Compounds such as ethylene glycol dimethacrylate, glycerol dimethacrylate or trimethylolpropane trimethacrylate. Polymer according to one of Claims 1 to 4, characterized that the component b) as comonomer an acrylamide compound and especially N, N-dimethylacrylamide. Polymer according to claim 4, characterized in that that it contains the components a) and b) in a mass ratio of 10 to 1: 1 to 10 and preferably in mass ratio 5 to 1: 1 to 5 contains. Polymer according to one of Claims 1 to 6, characterized it is a nanocomposite in which component b) covalently crosses the Silane to the surface the silica is bound. Process for the preparation of the polymer according to the claims 1 to 7, characterized in that a) the silica with the unsaturated Silane is reacted, and then b) the monomers of the sulfonic acid-containing Component b) are grafted to the silane. Method according to claim 8, characterized in that that in process step a) silica and silane in the molar ratio of 200: 1 to 20 are used. Method according to one of claims 8 to 9, characterized that the process steps a) and / or b) independently at temperatures from 30 to 100 ° C carried out be, wherein the process step a) preferably at temperatures between 60 and 75 ° C and in particular 70 ° C is carried out and the process step b) at temperatures between 40 and 60 ° C and in particular at 50 ° C. Use of the polymer according to one of claims 1 to 7 as an additive in building chemical applications and in exploitation, exploitation and completion of underground oil and gas deposits and especially as a water retention agent.