EP2285835A1

EP2285835A1 - Graft copolymer, method for the production thereof, and use thereof

Info

Publication number: EP2285835A1
Application number: EP08750360A
Authority: EP
Inventors: Roland Reichenbach-Klinke; Johann Plank; Peter Lange; Gregor Keilhofer
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2008-05-21
Filing date: 2008-05-21
Publication date: 2011-02-23
Also published as: MX2010012630A; CN102037023A; US20130203951A1; WO2009141007A1; BRPI0822660A2; US20110118382A1; CA2723941A1; RU2470041C2; RU2010152013A

Abstract

The invention relates to a graft copolymer on the basis of a component a), comprising silica, which has been converted using unsaturated silane, and a sulfonic acid-containing polymer component b). The silica used is preferably nanosilica, and the unsaturated silane is an ethylenically unsaturated alkoxy silane. Component b) is represented by a copolymer on the basis of AMPS and a further ethylenically unsaturated monomer. The polymer according to the invention, which generally constitutes a nanocomposite, is excellently suited as an additive in construction chemistry applications and for the development, extraction and completion of underground crude oil and natural gas deposits, wherein the effect thereof as a water retention agent is particularly advantageous for high salinity and elevated temperatures.

Description

Graft copolymer, process for its preparation and its use

description

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

Copolymers, even in grafted form, are well known and are used because of their specific monomer composition in a variety of applications.

In the construction chemical field, copolymers are also frequently used as water retention agents, which are also referred to as fluid loss additives. A special field of application in this context is the cementation of boreholes in the development of underground oil and gas deposits.

Fluid loss additives or water retention agents are compounds which reduce the release of water from a cement slurry. This is particularly important in the field of oil and natural gas exploration, as cement slurries, which essentially consist of cement and water, are pumped during the cementation of the boreholes through the annulus between the so-called casing and the borehole wall. In this case, quantities of water can be released from the cement slurry to the subsoil formation. This is particularly the case when the cement slurry flows past porous rock layers during well cementing. The alkalized water from the cement slurry can then swell clays in the formations and form calcium carbonate precipitates with carbon dioxide from the natural gas or petroleum. These effects reduce the permeability of the deposits and, as a consequence, the production rates are negatively affected.

In addition, the cement slurry does not solidify due to the release of water to the porous subsoil formations and thus becomes permeable to gases as well as to liquid hydrocarbons and water. As a result, this leads to the escape of fossil fuels through the filled with porous cement annulus. It is therefore for some time continuously striving to reduce such water loss of the cement slurry used to a tolerable minimum.

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

Borehole cementing and a composition suitable for this purpose is the subject of 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 according to 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.

US Pat. No. 4,515,635 describes polymers which are stable to hydrolytic influences and can also be used in well cementing. 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 can be found in US Pat. No. 4,555,269. 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 with water-retaining properties:

The water-soluble copolymers according to US Pat. No. 6,395,853 B1 also contain, among other things, the building blocks acrylamide and AMPS. At the forefront of this right is a process for reducing the loss of water in a slurry used to extract oil. Particularly noteworthy in this context are the drilling Lochzementierung and completion and the previous process steps preceding borehole sludge.

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

Finally, US Pat. No. 6,855,201 B2 discloses 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.

Copolymers with inorganic and / or organic silicon compounds are also known:

Patent EP043159 describes a carrier material for chromatography. This carrier material consists of inorganic, silanized particles to which a copolymer is covalently bonded. The inorganic particles are first reacted with a saturated alkoxysilane. Silanes which are mentioned are aminosilanes, mercaptosilanes, silanes containing ester groups and, preferably, glycidoxysilanes. Subsequently, in the sense of an addition polymerization, various acrylamides can be polymerized onto these silanized particles. As a suitable acrylamide is u. a. AMPS mentioned.

Patent EP0505230 describes silica particles in a polymer matrix having film-forming properties. Here, too, the silica particles are first functionalized with a silane, although these are double bond-containing silanes. Subsequently, various monomers are grafted onto these silanized silica particles. The monomers mentioned are alkyl (meth) acrylates, unsaturated monocarboxylic acids, aromatic vinyl compounds, dienes (butadiene, chloroprene), vinyl acetate, styrene. In addition, polybasic, unsaturated carboxylic acids or unsaturated sulfonic acids (eg AMPS) in proportions of up to 15% by weight. The use of these film-forming polymers is limited to the paint industry.

A coating consisting of a radical-curing monomer or oligomer and a surface-treated inorganic particle is known from WO

01/18082 known. The particle is coated with a fluorosilane and a crosslinkable silane, wherein as crosslinkable silanes and double bond-containing silanes are called. AMPS is mentioned as a suitable monomer.

Finally, DE102005000918 describes a process for the preparation of an aqueous multicomponent dispersion. This dispersion is prepared by radical polymerization of various monomers in the presence of inorganic particles and a dispersant. The monomer mixture contains at least one epoxide group-containing compound. As additional monomers also unsaturated silanes and sulfonic acids are mentioned.

This variety of known co- or graft polymers, as already briefly mentioned, depending on their monomer composition, each have a different property profile with specific advantages and disadvantages. A common weakness inherent in most of these polymers is that their fluid-leaching effect in the presence of divalent salts, as is typically the case in seawater, often contributes to the mixing of the cement slurries with respect to their use in the construction chemical field off-shore oil and gas wells are contained, and / or at high temperatures above 190 degrees Fahrenheit, whereby a total loss of efficiency may occur.

As just demonstrated by way of example, attempts have been made for a long time to provide new polymers whose water retention capacity is stable, in particular in the area of oil and gas exploration, so that an advantageous price / performance ratio can be assumed.

Since the salt resistance, but also the temperature tolerance still needs improvement in specific applications, the object of the present invention is to provide a novel graft copolymer which is based on the proven monomer building blocks, but by varying the grafting partners leads to a property profile which shows significant improvements especially in the presence of divalent salts and at very high temperatures.

This object has been achieved with a water-soluble graft copolymer based on a component a) consisting of silica, which has been reacted with an unsaturated silane, and a water-soluble sulfonic acid-containing polymer component b).

It has now surprisingly been found that this graft copolymer shows a significantly better performance as a water retention agent, with its advantages coming into play particularly under demanding conditions. Due to its monomer building this graft copolymer can be produced very economically. Especially under saline conditions it has been found that the fluid-loss effect of the graft copolymers of the invention over the hitherto known copolymers has significant advantages.

With regard to the silica constituent in component a), it has proved advantageous in the context of the provisional invention for this silica constituent to be 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 nano- and microsilica has been shown.

Nanosilica are aqueous, colloidal solutions containing only silica. The mean particle size of this silica ranges between 5 and 500 nm, with ranges between 15 and 100 nm, and in particular between 30 and 70 nm, being preferred.

Microsilica consists of particles with a size of 0.5 to about 100 microns. These include, for example, pyrogenic silicic acids, precipitated silicas, furnace dusts and fly ash.

The silane compound which is converted into component a) by reaction with said silica should, according to the invention, be an ethylenically unsaturated alkoxysilane. The number of carbon atoms in these alkoxysilanes should be between 5 and 15. Particularly suitable representatives are representatives of the series 3-

Methacryloxypropyltrialkoxysilane, 3-Methacryloxypropyldialkoxyalkylsilan, Methacrylo xymethyltrialkoxysilane, (methacryloxymethyl) dialkoxyalkylsilane, vinyldialkoxyalkylsilane or vinyltrialkoxysilane. Also suitable are silanes which initially have no double bond but can be converted into a double bond-containing silane by reaction with a suitable ethylenically unsaturated compound. In question here is, for example, the reaction product of aminopropyltrimethoxysilane and maleic anhydride. In this case, it is also possible to proceed stepwise, ie the silica is first allowed to react with the aminosilane, whereupon it is reacted with maleic anhydride in the next step and finally polymerized at the double bond.

Copolymers of acrylamido-methyl-propanesulfonic acid (AMPS) or vinylsulfonic acid with further ethylenically unsaturated monomers have in particular been shown to be suitable water-soluble sulfonic acid-containing polymer components b). Such monomers are preferably selected from the series of vinyl ethers, allyl ethers, acrylic acid, methacrylic acid, 2-ethylacrylic acid, 2-propylacrylic acid, vinylacetic acid, crotonic and isocrotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid and their amides. Also suitable in general are styrenes, vinylphosphonic acid or ethylenically unsaturated silanes. Also ethylenically unsaturated compounds such as ethylene glycol dimethacrylate, glycerol dimethacrylate or Trimethylolpropantrimethacrylat can be used. As particularly preferred unsaturated amide compounds, such as. As N-vinylformamide, N-vinylacetamide or acrylamide and derivatives thereof and in particular the N, N-dimethylacrylamide.

The variability in the composition of the grafting

Copolymers show not only in the choices of its underlying monomers, but also in the mass ratio of component a) and b) to each other. According to the present invention, this may preferably be 10 to 1: 1 to 10, and more preferably 5 to 1: to 1 to 5. It has also been found to be advantageous if the proportion of component a) in the graft copolymer of 10 bis 90 wt .-% and in particular from 40 to 70 wt .-% is. The proportion of component b) in the copolymer should be from 10 to 90% by weight and in particular from 30 to 60% by weight. Also particularly advantageous is a variant of the graft copolymer according to the invention, in which it represents a nanocomposite. Here, the component b) should be covalently bonded via the silane to the surface of the silica.

Finally, the claimed graft copolymer may be present as a solid, and in this case in particular as a powder, but also as a gel, colloid or suspension. Included is also a variant in which the copolymer has a water content of 50 to 70 wt .-%. Regardless of which of these forms or suitable mixtures thereof the copolymer is in, its average particle size should be between 5 and 2000 nm and in particular between 50 and 1000 nm.

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.

As the initiator of the polymerization reaction in process stage b), sodium peroxodisulfate has proven particularly suitable. But other common initiators such as peroxides, redox initiators or diazo compounds are suitable.

The process conditions are essentially uncritical. However, it has been found to be advantageous when the process steps a) and / or b) are performed independently of one another at temperatures between 30 and 100 ^0C. For process step a) temperatures between 60 and 75 ° are recommended, with a temperature around 70 ⁰ C is particularly suitable. For the process step b), a temperature range between 40 and 60 ⁰ C should be selected, in which case temperatures around 50 ⁰ C are particularly suitable.

As already mentioned, special attention is paid to the use of the graft copolymers according to the invention in the construction chemical applications. For this reason, the present invention also claims the use of the graft copolymer as an additive in building chemical applications, and in particular in the development, exploitation and completion of underground oil and gas deposits, its use as a water retention agent is considered to be particularly advantageous.

In summary, it can be stated that the proposed graft copolymers provide compounds which additionally further improve the use of sulfonic acid-containing additives in the construction chemical sector. In particular, due to the salt tolerance and a significantly increased temperature stability in the range of> 190 ° Fahrenheit, the graft copolymers according to the present invention are outstandingly suitable as water retention agents or fluid loss additives.

The following examples illustrate these advantages.

Examples

1) Production Example:

131, 6 g Levasil® 50/50% (silica sol from the company HC Starck), 65.8 g dist. 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. The mixture was then heated with stirring for ⁴ h at 70 ⁰ C. 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 Os were added as a starter and heated to 50 ⁰ 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

The fluid loss was determined according to API standard 10A at 125 ° F in the following sludge: 800 g Class G cement (Dyckerhoff Black Label) 352 g dist. H2O

1 ml of tributyl phosphate

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

Application example 2.2

The fluid loss was determined according to API standard 10A at 190 ⁰ F in the following sludge: 800 g Class G - Cement (Dyckerhoff Black Label)

352 g dist. H2O

1 ml of tributyl phosphate

In comparison to Application Example 2.1 significantly increased measurement temperature of 190 ⁰ F, significant differences between the nanocomposite according to the invention and the comparison mixture are identified. During the fluid loss of the nanocomposite relative to the measurement temperature of 125 ° F remains practically constant, the fluid loss of the mixture at 190 ⁰ F deteriorated significantly. That is, the fluid-loss behavior of the nanocomposite according to the invention is temperature independent.

Application Example 2.3:

The fluid loss was determined according to API standard 10A 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

Again, significant differences between the nanocomposite according to the invention and the comparison mixture are again noticeable. Although the fluid loss of the nanocomposite increases significantly by the addition of sea salt; but the fluid loss of the comparison mixture is about twice as high.

Claims

Graft copolymer, process for its preparation and its use Patent claims

1. graft copolymer based on a component a) consisting of silica, which has been reacted with an unsaturated silane, and a water-soluble sulfonic acid-containing polymer component b).

2. Polymer according to claim 1, characterized in that the silica constituent in component a) is based on an aqueous colloidally disperse solution of amorphous silicon dioxide (SiO 2) and preferably on a nanosilica.

3. Polymer according to one of claims 1 or 2, characterized in that it is the silane in component a) is an ethylenically unsaturated alkoxysilane having 5 to 15 carbon atoms and in particular a representative of

Series 3-methacryloxypropyltrialkoxysilane, 3

Methacryloxypropyldialkoxyalkylsilane, methacryloxymethyltrialkoxysilane, (methacryloxymethyl) dialkoxyalkylsilane, vinyldialkoxyalkylsilane or vinyltrialkoxysilane.

4. Polymer according to any one of claims 1 to 3, characterized in that it is the water-soluble component b) is a copolymer of acrylamidomethyl-propane sulfonic acid (AMPS) with other 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, crotonic and isocrotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid and their amides, styrenes, vinylphosphonic acid or ethylenically unsaturated silanes and polyethylenically unsaturated compounds such as ethylene glycol dimethacrylate, glycerol dimethacrylate or trimethylolpropane trimethacrylate.

5. Polymer according to any one of claims 1 to 4, characterized in that component b) contains as comonomer an acrylamide compound and in particular N, N-dimethylacrylamide.

6. Polymer according to one of claims 1 to 5, characterized in that it contains components a) and b) in a mass ratio of 10 to 1: 1 to 10 and preferably in a mass ratio of 5 to 1: 1 to 5.

7. Polymer according to any of Ansrpüche 1 to 6, characterized in that it contains component a) in proportions of 10 to 90 wt .-% and in particular from 40 to 70 wt .-%.

8. Polymer according to one of claims 1 to 7, characterized in that it contains the component b) in proportions of 10 to 90 wt .-% and in particular from 30 to 60 wt .-%.

9. Polymer according to one of claims 1 to 8, characterized in that it represents a nanocomposite, in which the component b) is covalently bonded via the silane to the surface of the silica.

10. Polymer according to one of claims 1 to 9, characterized in that it has an average particle size between 5 and 2000 nm and in particular between 50 and 1000 nm.

1 1. Polymer according to one of claims 1 to 10, characterized in that it is present as a solid and in particular as a powder, as a gel, colloid or suspension, and preferably with a water content of 50 to 70 wt .-%.

12. A process for preparing the polymer according to any one of claims 1 to 11, characterized in that a) the silica is reacted with the unsaturated silane, and then b) the monomers of the sulfonic acid-containing component b) are grafted to the silane.

13. The method according to claim 12, characterized in that in process step a) silica and silane in a molar ratio of 200: 1 to 20 are used.

14. The method according to any one of claims 12 to 13, characterized in that the process steps a) and / or b) are carried out independently at temperatures of 30 to 100 ⁰ C, wherein the process step a) preferably at temperatures between 60 and 75 ° C and in particular 70 ⁰ C is carried out and the process step b) at temperatures between 40 and 60 ⁰ C and in particular at 50 ° C.

15. Use of the polymer according to any one of claims 1 to 1 as an additive in building chemical applications and in the development, exploitation and completion of underground oil and gas deposits and in particular as a water retention agent.