Corrosion-resistant material for cement slurry, carbon dioxide corrosion resistant cement slurry, preparation method, and use

Abstract

A corrosion-resistant material for a cement slurry, a carbon dioxide corrosion resistant cement slurry, a preparation method, and a use. The corrosion-resistant material comprises a mixture A and a mixture B, wherein the mixture A comprises activated carbon, nanosilicon dioxide, and nano-alumina; the mixture B comprises a component C and a component D; the component C is selected from diatomite and / or fly ash; and the component D is selected from one or more of metakaolin, pumice, and coal gangue. The carbon dioxide corrosion resistant cement slurry made of the corrosion-resistant material has good corrosion resistance in a CO2 corrosion environment; the cement stone before corrosion has a high compressive strength and a compact structure; and the cement stone after corrosion has good comprehensive properties, for example, has no obvious decrease in compressive strength, small permeability, good mechanical properties, good settling stability, and good rheology, such that the cementing quality of a CCUS well is guaranteed, and efficient storage of CO2 is achieved.

Description

Anti-corrosion material for cement slurry, carbon dioxide corrosion-resistant cement slurry, and preparation method and application thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application No. 202310740303.6 filed on June 21, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of cement slurry for oil and gas well cementing, and in particular to an anti-corrosion material for cement slurry, carbon dioxide corrosion-resistant cement slurry, and a preparation method and application thereof. Background Art

[0004] Carbon capture, utilization, and storage (CCUS) is currently the only viable technology capable of significantly reducing CO2 emissions. The integrity of the cement sheath is crucial for the successful implementation and ultimate long-term storage of CO2 geological storage projects. As is well known, CO2 exists in a supercritical CO2 state underground, characterized by low viscosity and high permeability. Furthermore, Portland cement systems are highly alkaline, while CO2 is an acidic gas. Under long-term CO2 erosion, the cement sheath is susceptible to excessive carbonation and decalcification, resulting in compositional changes, strength degradation, increased porosity and permeability, and ultimately, structural damage to the cement sheath, compromising the long-term effectiveness of the wellbore seal.

[0005] At present, to address the corrosion problem of acidic gases such as CO2 on cement sheaths, corrosion-resistant cement slurry systems are widely used both domestically and internationally. Oil well cement CO2 corrosion-resistant materials mainly use ultrafine inert materials and active siliceous materials. For example, the Sinopec Dezhou Research Institute has added inert ultrafine barite and other materials, and Li Guanying and others from National Cheng Kung University in Taiwan have improved the CO2 corrosion resistance of cement paste by adding active materials such as fly ash and silica fume. This reduces the permeability of cement paste through a physical close-packing effect and reacts with cement minerals to reduce the alkalinity of cement paste, thereby improving the cement paste's CO2 corrosion resistance. This method only weakens the exchange source of dissolved ions and minimizes the penetration rate of CO2 corrosive media. Once the corrosive media enters the cement paste, it will continue to damage the gel structure of the cement paste, and its anti-corrosion function will no longer be able to be exerted. Therefore, the anti-corrosion effect is not very ideal.

[0006] CN114133172A discloses a CO2 corrosion-resistant cement slurry for well cementing and a preparation method thereof. The CO2 corrosion-resistant cement slurry is obtained by using silicate cement, nano-silica, UF cellulose fiber, a fluid loss additive, and a dispersant. The nano-silica fills and plugs the micropores within the cement stone, participates in the hydration reaction, increases the Si / Ca ratio of the hydration product, and improves the corrosion resistance of the hydration product. The UF cellulose improves the mechanical properties of the cement stone. However, the applicable temperature range is not given. In the embodiment, the temperature is 60°C, which is a small applicable temperature range and the system adaptability is insufficient.

[0007] Therefore, it is urgent to develop a cement slurry with good corrosion resistance in a CO2 corrosive environment to ensure the cementing quality of CCUS wells and achieve efficient CO2 storage.

[0008] Summary of the Invention

[0009] The present invention aims to overcome the existing problem of cement stone being unable to sustain corrosion protection after being invaded by the corrosive medium of CO2, and to provide an anti-corrosion material for cement slurry, a CO2-resistant cement slurry, and its preparation method and application. The CO2-resistant cement slurry produced using the anti-corrosion material of the present invention exhibits high compressive strength, low permeability, good sedimentation stability, excellent rheological properties, and a wide applicable temperature range after corrosion under the corrosive conditions of CO2 geological storage wells, thereby ensuring long-term effective sealing of the CO2 geological storage wells.

[0010] In order to achieve the above-mentioned objectives, the first aspect of the present invention provides an anti-corrosion material for cement slurry, wherein the anti-corrosion material comprises a mixture A and a mixture B; wherein the mixture A comprises activated carbon, nano-silica and nano-alumina; the mixture B comprises a component C and a component D; the component C is selected from diatomaceous earth and / or fly ash; and the component D is selected from one or more of metakaolin, pumice and coal gangue.

[0011] Preferably, in the mixture A, the mass ratio of activated carbon, nano-silicon dioxide and nano-alumina is 1:0.05-0.1:0.05-0.1.

[0012] Preferably, the mass ratio of component C to component D is 1-2:1.

[0013] Preferably, the mass ratio of the mixture A to the mixture B is 1:2-4.

[0014] Preferably, the average particle size of the activated carbon is 40-60 μm.

[0015] Preferably, the SiO2 content of the nano-silicon dioxide is greater than 99%, and the average particle size is 30-40 nm.

[0016] Preferably, the Al2O3 content of the nano-alumina is greater than 99%, and the average particle size is 10-30 nm.

[0017] Preferably, the average particle size of component C is 10-20 μm.

[0018] Preferably, the average particle size of component D is 20-40 μm.

[0019] A second aspect of the present invention provides a method for preparing an anti-corrosion material for cement slurry, the preparation method comprising:

[0020] Mixing activated carbon, nano-silicon dioxide and nano-alumina to obtain mixture A;

[0021] Mixing component C and component D to obtain a mixture B; wherein the component C is selected from diatomaceous earth and / or fly ash; and the component D is selected from one or more of metakaolin, pumice and coal gangue;

[0022] The mixture A and the mixture B are mixed under a low stirring rate condition, and then stirred at a high speed to obtain the anti-corrosion material.

[0023] Preferably, the low stirring rate is 3800-4200 r / min, and the high-speed stirring rate is 11500-12500 r / min.

[0024] The third aspect of the present invention provides the use of the anti-corrosion material described in the first aspect or the anti-corrosion material prepared by the preparation method described in the second aspect in cement slurry, preferably in cement slurry resistant to carbon dioxide corrosion.

[0025] The fourth aspect of the present invention provides a carbon dioxide corrosion-resistant cement slurry, which is made of the following raw materials in parts by weight: 100 parts of G-grade oil well cement, 2-6 parts of anti-corrosion material, 2-5 parts of microsilica, 3-6 parts of reinforcing material, 3-5 parts of expansion toughening material, 1-3 parts of latex powder, 0-2 parts of stabilizer, 0.3-2 parts of dispersant, 2-5 parts of fluid loss additive, 0.1-2 parts of retarder, 0.2-0.5 parts of defoaming agent and 48-56 parts of water, wherein the anti-corrosion material is the anti-corrosion material described in the first aspect or the anti-corrosion material prepared by the preparation method described in the second aspect.

[0026] A fifth aspect of the present invention provides a method for preparing carbon dioxide corrosion-resistant cement slurry, the preparation method comprising:

[0027] Mixing G-grade oil well cement with anti-corrosion material, micro-silicon, reinforcing material, expansion toughening material, latex powder, stabilizer and dispersant to obtain a dry mix;

[0028] mixing a fluid loss additive with a retarder, a defoamer and water to obtain a wet mix;

[0029] The dry mix and the wet mix are mixed to obtain carbon dioxide corrosion resistant cement slurry.

[0030] The sixth aspect of the present invention provides the use of the carbon dioxide corrosion resistant cement slurry described in the fourth aspect or the carbon dioxide corrosion resistant cement slurry prepared by the preparation method described in the fifth aspect in oil and gas well cementing operations.

[0031] Preferably, the operating temperature of the carbon dioxide corrosion resistant cement slurry is 30-150°C.

[0032] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0033] (1) The applicable temperature range of the cement slurry prepared by using the anti-corrosion material for cement slurry provided by the present invention is 30-150°C. The compressive strength of the cement stone after corrosion is greater than 20 MPa, and the permeability is less than 0.1 mD, or even less than 0.05 mD, which significantly improves the CO2 corrosion resistance of the cement stone. At the same time, it has no adverse effect on other engineering properties of the cement slurry, and can ensure long-term effective sealing of the cement ring under CCUS corrosion conditions.

[0034] (2) The carbon dioxide corrosion resistant cement slurry of the present invention has good corrosion resistance in a CO2 corrosion environment. Before corrosion, the cement stone has high compressive strength and dense structure. After corrosion, the cement stone has no obvious decline in compressive strength, low permeability, good mechanical properties, good sedimentation stability, good rheological properties and other comprehensive properties. It is suitable for CO2 corrosion resistant cement slurry systems with temperatures of 30-150°C and below, ensuring the cementing quality of CCUS wells and ensuring the long-term effective sealing performance of the cement ring under CCUS corrosion conditions, thereby achieving efficient CO2 storage. DETAILED DESCRIPTION

[0035] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0036] A first aspect of the present invention provides an anti-corrosion material for cement slurry, the anti-corrosion material comprising a mixture A and a mixture B; wherein the mixture A comprises activated carbon, nano-silica and nano-alumina; the mixture B comprises a component C and a component D; the component C is selected from diatomaceous earth and / or fly ash; and the component D is selected from one or more of metakaolin, pumice and coal gangue.

[0037] In the present invention, mixture A includes activated carbon, nano-silicon dioxide and nano-alumina. Nano-silicon dioxide and nano-alumina are adsorbed in the pores of the activated carbon and can be slowly released, lasting and repairing. Mixture A mainly works in the later stage.

[0038] In the present invention, after the cement stone comes into contact with carbon dioxide, mixture B has a strong volcanic ash activity and takes the lead in the volcanic ash reaction, consuming the Ca (OH) 2 in the cement stone, generating dense substances such as hydrated calcium silicate and hydrated calcium aluminate, which adhere to the outside of the cement stone to play a protective role and prevent CO 2 from continuing to penetrate the cement stone. That is, a protective film is initially formed on the outside of the cement stone. As the hydration reaction continues, the hydration products such as hydrated calcium silicate and hydrated calcium aluminate are continuously consumed, and the protective film is destroyed, causing the cement stone microstructure to show signs of damage again. Mixture A slowly releases the nano-silica and nano-alumina therein, which play a filling and plugging role, forming a dense protective film on the outside of the cement stone. At the same time, the nano-silica continues to react with the Ca (OH) 2 in the cement stone, preventing acidic gases from continuing to enter the cement stone. That is, mixture A can play a role in reinforcing and encrypting the outer protective film of the cement stone, thereby achieving long-term and effective corrosion protection of the cement stone. The present invention achieves long-term corrosion protection by optimizing the formula of the anti-corrosion material, and the long-term anti-corrosion effect is good.

[0039] The present invention mixes mixture A and mixture B, so the operation is simple and convenient and the feasibility is strong.

[0040] In some embodiments of the present invention, in the mixture A, the mass ratio of activated carbon, nano-silicon dioxide and nano-alumina is 1:0.05-0.1:0.05-0.1.

[0041] In some embodiments of the present invention, the mass ratio of component C to component D is 1-2:1.

[0042] In some embodiments of the present invention, the mass ratio of mixture A to mixture B is 1:2-4.

[0043] The carbon dioxide corrosion-resistant cement slurry made from the above raw materials has good corrosion resistance in a CO2 corrosion environment. Before corrosion, the cement stone has high compressive strength and dense structure. After corrosion, the compressive strength of the cement stone has no obvious decline (the strength decline rate is less than 20%), and the permeability is less than 0.1mD, or even less than 0.05mD.

[0044] The cement slurry containing the above anti-corrosion materials has an applicable temperature range of 30-150℃, which can significantly improve the anti-CO2 corrosion ability of cement stone. After corrosion, the compressive strength of cement stone is greater than 20MPa and the permeability is small. At the same time, it has no adverse effect on other properties of cement stone, and can ensure the long-term effective sealing performance of cement ring under CCUS corrosion conditions.

[0045] In some embodiments of the present invention, the average particle size of the activated carbon is 40-60 μm.

[0046] In some embodiments of the present invention, the SiO2 content of the nano-silicon dioxide is greater than 99%, and the average particle size is 30-40 nm.

[0047] In some embodiments of the present invention, the Al2O3 content of the nano-alumina is greater than 99%, and the average particle size is 10-30 nm.

[0048] In some embodiments of the present invention, the average particle size of component C is 10-20 μm.

[0049] In some embodiments of the present invention, the average particle size of component D is 20-40 μm.

[0050] A second aspect of the present invention provides a method for preparing an anti-corrosion material for cement slurry, the preparation method comprising:

[0051] Mixing activated carbon, nano-silicon dioxide and nano-alumina to obtain mixture A;

[0052] Mixing component C and component D to obtain a mixture B; wherein the component C is selected from diatomaceous earth and / or fly ash; and the component D is selected from one or more of metakaolin, pumice and coal gangue;

[0053] The mixture A and the mixture B are mixed under a low stirring rate condition, and then stirred at a high speed to obtain the anti-corrosion material.

[0054] In some embodiments of the present invention, the low stirring rate is 3800-4200 r / min, and the high-speed stirring rate is 11500-12500 r / min.

[0055] In some embodiments of the present invention, in the mixture A, the mass ratio of activated carbon, nano-silicon dioxide and nano-alumina is 1:0.05-0.1:0.05-0.1.

[0056] In some embodiments of the present invention, the mass ratio of component C to component D is 1-2:1.

[0057] In some embodiments of the present invention, the mass ratio of mixture A to mixture B is 1:2-4.

[0058] In some embodiments of the present invention, the activated carbon has a particle size of 40-60 μm.

[0059] In some embodiments of the present invention, the SiO2 content of the nano-silicon dioxide is greater than 99%, and the average particle size is 30-40 nm.

[0060] In some embodiments of the present invention, the Al2O3 content of the nano-alumina is greater than 99%, and the average particle size is 10-30 nm.

[0061] In some embodiments of the present invention, the average particle size of component C is 10-20 μm.

[0062] In some embodiments of the present invention, the average particle size of component D is 20-40 μm.

[0063] The third aspect of the present invention provides the use of the anti-corrosion material described in the first aspect or the anti-corrosion material prepared by the preparation method described in the second aspect in cement slurry, preferably in cement slurry resistant to carbon dioxide corrosion.

[0064] The anti-corrosion material of the present invention is used to prepare carbon dioxide corrosion-resistant cement slurry, which can be implemented simply and conveniently. After the cement stone contacts carbon dioxide, mixture B undergoes a pozzolanic reaction, consuming Ca(OH)2 in the cement stone to produce substances such as hydrated calcium silicate and hydrated calcium aluminate, thereby protecting the cement stone from carbon dioxide corrosion and initially forming a protective film. As the hydration reaction continues, the hydration products are continuously consumed, causing signs of damage to the cement stone microstructure. At this time, mixture A slowly releases nano-silicon dioxide and nano-alumina therein, which play a filling and blocking role, forming a dense protective film on the outside of the cement stone. At the same time, the nano-silicon dioxide continues to react with the Ca(OH)2 in the cement stone to prevent acidic gases from continuing to enter the cement stone. Therefore, the prepared cement slurry can play a role in lasting carbon dioxide corrosion resistance.

[0065] The fourth aspect of the present invention provides a carbon dioxide corrosion-resistant cement slurry, which is made of the following raw materials in parts by weight: 100 parts of G-grade oil well cement, 2-6 parts of anti-corrosion material, 2-5 parts of microsilica, 3-6 parts of reinforcing material, 3-5 parts of expansion toughening material, 1-3 parts of latex powder, 0-2 parts of stabilizer, 0.3-2 parts of dispersant, 2-5 parts of fluid loss additive, 0.1-2 parts of retarder, 0.2-0.5 parts of defoaming agent and 48-56 parts of water, wherein the anti-corrosion material is the anti-corrosion material described in the first aspect or the anti-corrosion material prepared by the preparation method described in the second aspect.

[0066] In the present invention, the carbon dioxide corrosion-resistant cement slurry prepared by the above raw materials has good corrosion resistance in a CO2 corrosion environment. The cement stone has high compressive strength and dense structure before corrosion. After corrosion, the compressive strength of the cement stone does not decline significantly, the permeability is small, and the mechanical properties are good. At the same time, the comprehensive properties such as sedimentation stability and rheological properties are good. It can be used in a CO2 corrosion-resistant cement slurry system with a temperature of 30-150°C and below, ensuring the cementing quality of CCUS wells and realizing efficient CO2 storage.

[0067] In some embodiments of the present invention, the SiO2 content of the micro-silicon is not less than 90%, the average particle size is 5-10 μm, and the 45 μm sieve residue is ≤5%.

[0068] In the present invention, the reinforcing material is selected from reinforcing materials for cementing oil wells.

[0069] In some embodiments of the present invention, the reinforcing material is selected from inorganic mineral powder materials, preferably mineral powder DRB-1S produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0070] In the present invention, the expansion toughening material is selected from the expansion toughening material for cementing oil well cement.

[0071] In some embodiments of the present invention, the expansion toughening material is selected from rubber materials, preferably rubber DRE-3S.

[0072] In the present invention, the latex powder is selected from latex powder for cementing oil well cement.

[0073] In some embodiments of the present invention, the latex powder is selected from polymers, preferably polymer DRT-1S.

[0074] In the present invention, the stabilizer is selected from stabilizers for cementing oil wells.

[0075] In some embodiments of the present invention, the stabilizer is selected from attapulgite materials, preferably ore powder DRK-2S.

[0076] In some embodiments of the present invention, the dispersant is selected from polystyrene sulfonate compounds and / or condensation products of formaldehyde and acetone.

[0077] In some embodiments of the present invention, the fluid loss additive is selected from polyacrylamide compounds.

[0078] In some embodiments of the present invention, the retarder is selected from acrylamide compounds.

[0079] In some embodiments of the present invention, the defoaming agent is selected from one or more of tributyl phosphate, polyoxypropylene glycerol and polydimethylsiloxane.

[0080] A fifth aspect of the present invention provides a method for preparing carbon dioxide corrosion-resistant cement slurry, the preparation method comprising:

[0081] Mixing G-grade oil well cement with anti-corrosion material, micro-silicon, reinforcing material, expansion toughening material, latex powder, stabilizer and dispersant to obtain a dry mix;

[0082] mixing a fluid loss additive with a retarder, a defoamer and water to obtain a wet mix;

[0083] The dry mix and the wet mix are mixed to obtain carbon dioxide corrosion resistant cement slurry.

[0084] The above-mentioned G-grade oil well cement, anti-corrosion material, microsilica, reinforcing material, expansion toughening material, latex powder, stabilizer, dispersant, fluid loss additive, retarder and defoaming agent are the same as those in the fourth aspect. Please refer to the previous description for details and will not be repeated here.

[0085] The sixth aspect of the present invention provides the use of the carbon dioxide corrosion resistant cement slurry described in the fourth aspect or the carbon dioxide corrosion resistant cement slurry prepared by the preparation method described in the fifth aspect in oil and gas well cementing operations.

[0086] In some embodiments of the present invention, the operating temperature of the carbon dioxide corrosion resistant cement slurry is 30-150°C.

[0087] According to a particularly preferred embodiment of the present invention, the method for preparing carbon dioxide corrosion resistant cement slurry specifically comprises the following steps:

[0088] (1) Preparation of an anti-corrosion material: Activated carbon, nano-silicon dioxide, and nano-alumina are mixed uniformly in a mass ratio of 1:0.05-0.1:0.05-0.1 to obtain a mixture A; at least one of diatomaceous earth and fly ash is mixed uniformly with at least one of metakaolin, pumice, and coal gangue in a mass ratio of 1-2:1 to obtain a mixture B; the mixture A and the mixture B are mixed uniformly in a mass ratio of 1:2-4 to obtain an anti-corrosion material;

[0089] (2) Weighing oil well cement, anti-corrosion material, microsilicon, reinforcing material, expansion toughening material, latex powder, stabilizer and dispersant according to the formula amount, and evenly mixing to obtain a dry mix; weighing fluid loss reducer, retarder and defoamer according to the formula amount, and stirring evenly to obtain a wet mix; pouring the dry mix evenly into the wet mix at a speed of 4000±200r / min, after the dry mix is ​​completely added to the wet mix, cover the mixing cup, adjust the stirrer speed to 12000±500r / min, and continue stirring for 30-40s, preferably 35s, to obtain a carbon dioxide corrosion resistant cement slurry.

[0090] The present invention will be described in detail below through examples.

[0091] In the following examples and comparative examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents and instruments used, if no manufacturer is specified, are commercially available conventional products.

[0092] G-grade oil well cement is high sulfate resistance (HSR) G-grade oil well cement, produced by Dalian Cement Group Co., Ltd.

[0093] Microsilicon: Its SiO2 content is 95%, the average particle size is 8μm, and the 45μm sieve residue is 4.2%.

[0094] The reinforcing material is DRB-1S, a reinforcing material for oil well cementing, produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0095] The expansion toughening material is rubber DRE-3S, a toughening material for oil well cementing, produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0096] The latex powder is latex powder polymer DRT-1S for cementing oil well cement, produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0097] The stabilizer is DRK-2S, a high-temperature stabilizer ore powder for oil well cementing, produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0098] The dispersant is DRS-1S, an aldehyde-ketone polycondensate dispersant for oil well cementing, produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0099] The fluid loss reducer is acrylamide-based fluid loss reducer DRF-1S for oil well cementing, produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0100] The retarder is an organic acid retarder DRH-1L for oil well cementing, produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0101] The defoaming agent is organic ester DRX-1L for oil well cementing, produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0102] Experiments were conducted in accordance with the national standard GB / T 19139-2012, "Test Methods for Oil Well Cement," to evaluate the conventional engineering properties of the cement slurry system (density, fluidity, API water loss), as well as the compressive strength and permeability before and after corrosion. Key experimental instruments included: a 30-60 tile-edge agitator; a TG7370D pressurized curing kettle, manufactured by Shenyang Tiger Petroleum Instruments and Equipment Manufacturing Co., Ltd.; an HH-420 constant temperature digital display water tank, manufactured by Changzhou Yineng Experimental Instrument Factory; a YAW-300B hydraulic pressure testing machine, manufactured by Jinan Xinshijin Testing Machine Co., Ltd.; and a CO2 corrosion environment simulation system, manufactured by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0103] Fluidity: Tested in accordance with the national standard GB / T 19139-2012 "Test methods for oil well cement".

[0104] API water loss: Tested in accordance with the national standard GB / T 19139-2012 "Test methods for oil well cement".

[0105] Cement stone corrosion is cured by using the "CO2 corrosion environment simulation system" invented by China National Petroleum Corporation Engineering Technology Co., Ltd. or a device capable of pressurized curing in a CO2 gas / liquid environment.

[0106] Compressive strength before and after corrosion: tested in accordance with the national standard GB / T 19139-2012 "Test methods for oil well cement".

[0107] Strength loss rate: Strength loss rate = (T2-T1) / T1, where T1 is the compressive strength of cement paste before corrosion and T2 is the compressive strength of cement paste after corrosion.

[0108] Permeability: Tested in accordance with the national standard GB / T 19139-2012 "Test Methods for Oil Well Cement".

[0109] Preparation Example 1

[0110] A method for preparing an anti-corrosion material comprises the following steps:

[0111] (1) Activated carbon, nano-silicon dioxide, and nano-alumina were thoroughly mixed in a mass ratio of 1:0.05:0.05. The activated carbon was commercially available, 325 mesh; the nano-silicon dioxide was commercially available, with a SiO2 content of 99.5% and an average particle size of 30 nm; and the nano-alumina was commercially available, with an average particle size of 30 nm and an Al2O3 content of 99.3%. The three substances were uniformly mixed to obtain a mixture A.

[0112] (2) mixing diatomaceous earth and metakaolin in a mass ratio of 1:1 to obtain a mixture B;

[0113] (3) The mixture A and the mixture B are uniformly mixed in a mass ratio of 1:2 to obtain an anti-corrosion material.

[0114] Preparation Example 2

[0115] A method for preparing an anti-corrosion material comprises the following steps:

[0116] (1) Activated carbon, nano-silicon dioxide, and nano-alumina were thoroughly mixed in a mass ratio of 1:0.1:0.1. The nano-silicon dioxide was commercially available, had a SiO2 content of 99.9%, and an average particle size of 40 nm. The nano-alumina was commercially available, had an average particle size of 20 nm, and had an Al2O3 content of 99.9%. The three substances were uniformly mixed to obtain a mixture A.

[0117] (2) mixing fly ash and coal gangue evenly in a mass ratio of 2:1 to obtain mixture B;

[0118] (3) The mixture A and the mixture B are uniformly mixed in a mass ratio of 1:3 to obtain an anti-corrosion material.

[0119] Preparation Example 3

[0120] A method for preparing an anti-corrosion material comprises the following steps:

[0121] (1) Activated carbon, nano-silicon dioxide, and nano-alumina were thoroughly mixed in a mass ratio of 1:0.2:0.1. The activated carbon was commercially available, 325 mesh; the nano-silicon dioxide was commercially available, with a SiO2 content of 99.8% and an average particle size of 30 nm; and the nano-alumina was commercially available, with an average particle size of 30 nm and an Al2O3 content of 99.5%. The three substances were uniformly mixed to obtain a mixture A.

[0122] (2) fly ash and pumice were mixed uniformly in a mass ratio of 3:1 to obtain mixture B;

[0123] (3) The mixture A and the mixture B are uniformly mixed in a mass ratio of 1:5 to obtain an anti-corrosion material.

[0124] Preparation Comparative Example 1

[0125] The diatomaceous earth and coal gangue are mixed and stirred evenly in a mass ratio of 2:1 to obtain an anti-corrosion material.

[0126] Preparation Comparative Example 2

[0127] (1) Nano-silicon dioxide and nano-alumina were thoroughly mixed in a mass ratio of 1:1. The nano-silicon dioxide was commercially available and had a SiO2 content of 99.5% and an average particle size of 30 nm. The nano-alumina was commercially available and had an average particle size of 30 nm and an Al2O3 content of 99.3%. The two substances were uniformly mixed to obtain a mixture A.

[0128] (2) mixing diatomaceous earth and metakaolin in a mass ratio of 1:1 to obtain a mixture B;

[0129] (3) The mixture A and the mixture B are uniformly mixed in a mass ratio of 1:3 to obtain an anti-corrosion material.

[0130] Example 1

[0131] The cement slurry formula is as follows by weight percentage: 100 parts of G-grade oil well cement, 3 parts of the anti-corrosion material obtained in Preparation Example 1, 3 parts of microsilica, 5 parts of reinforcing material, 4 parts of expansion toughening material, 2 parts of latex powder, 1 part of stabilizer, 1 part of dispersant, 3 parts of fluid loss additive, 0.5 parts of retarder, 0.2 parts of defoamer, and 53 parts of water. The cement slurry density is 1.88 g / cm 3 , the experimental results are shown in Table 1.

[0132] Example 2

[0133] The cement slurry formula is as follows by weight percentage: 100 parts of G-grade oil well cement, 3 parts of the anti-corrosion material obtained in Preparation Example 2, 3 parts of microsilica, 5 parts of reinforcing material, 4 parts of expansion toughening material, 2 parts of latex powder, 1 part of stabilizer, 1 part of dispersant, 3 parts of fluid loss additive, 0.5 parts of retarder, 0.2 parts of defoamer, and 53 parts of water. The cement slurry density is 1.88 g / cm 3 , the experimental results are shown in Table 1.

[0134] Example 3

[0135] Compared with Example 2, different amounts of anti-corrosion materials were added. The cement slurry formulation, by weight percentage, was as follows: 100 parts of G-grade oil well cement, 5 parts of the anti-corrosion material obtained in Preparation Example 2, 3 parts of microsilica, 5 parts of reinforcing material, 4 parts of expansive toughening material, 2 parts of latex powder, 1 part of stabilizer, 1 part of dispersant, 3 parts of fluid loss additive, 0.5 parts of retarder, 0.2 parts of defoamer, and 53 parts of water. The cement slurry density was 1.88 g / cm 3 , the experimental results are shown in Table 1.

[0136] Example 4

[0137] The cement slurry formula is as follows by weight: 100 parts of G-grade oil well cement, 6 parts of the anti-corrosion material obtained in Preparation Example 2, 2 parts of microsilica, 6 parts of reinforcing material, 3 parts of expansion toughening material, 1 part of latex powder, 2 parts of stabilizer, 2 parts of dispersant, 2 parts of fluid loss additive, 2 parts of retarder, 0.2 parts of defoamer, and 56 parts of water. The cement slurry density is 1.88 g / cm 3 , the experimental results are shown in Table 1.

[0138] Example 5

[0139] The cement slurry formula is as follows by weight: 100 parts of G-grade oil well cement, 2 parts of the anti-corrosion material obtained in Preparation Example 2, 5 parts of microsilica, 3 parts of reinforcing material, 6 parts of expansion toughening material, 3 parts of latex powder, 0.4 parts of stabilizer, 1 part of dispersant, 5 parts of fluid loss additive, 0.1 parts of retarder, 0.2 parts of defoamer, and 48 parts of water. The cement slurry density is 1.88 g / cm 3 , the experimental results are shown in Table 1.

[0140] Example 6

[0141] Compared with Example 2, different anti-corrosion materials were added. The cement slurry formula was as follows by weight: 100 parts G-grade oil well cement, 3 parts anti-corrosion material obtained in Preparation 3, 3 parts microsilica, 5 parts reinforcing material, 4 parts expansion toughening material, 2 parts latex powder, 1 part stabilizer, 1 part dispersant, 3 parts fluid loss additive, 0.5 part retarder, 0.2 part defoamer, and 53 parts water. The cement slurry density was 1.88 g / cm 3 , the experimental results are shown in Table 1.

[0142] Comparative Example 1

[0143] Compared with Example 2, different anti-corrosion materials were added. The cement slurry formula was as follows by weight percentage: 100 parts of G-grade oil well cement, 3 parts of the anti-corrosion material obtained in Comparative Example 1, 3 parts of microsilica, 5 parts of reinforcing material, 4 parts of expansion toughening material, 2 parts of latex powder, 1 part of stabilizer, 1 part of dispersant, 3 parts of fluid loss additive, 0.5 parts of retarder, 0.2 parts of defoamer, and 53 parts of water. The cement slurry density was 1.88 g / cm 3 , the experimental results are shown in Table 1.

[0144] Comparative Example 2

[0145] Compared with Example 2, different anti-corrosion materials were added. The cement slurry formula was as follows by weight percentage: 100 parts of G-grade oil well cement, 3 parts of the anti-corrosion material obtained in Comparative Example 2, 3 parts of microsilica, 5 parts of reinforcing material, 4 parts of expansion toughening material, 2 parts of latex powder, 1 part of stabilizer, 1 part of dispersant, 3 parts of fluid loss additive, 0.5 parts of retarder, 0.2 parts of defoamer, and 53 parts of water. The cement slurry density was 1.88 g / cm 3 , the experimental results are shown in Table 1.

[0146] Comparative Example 3

[0147] Compared with Example 2, no anti-corrosion material was added. The cement slurry formula was as follows by weight: 100 parts of G-grade oil well cement, 3 parts of microsilica, 5 parts of reinforcing material, 4 parts of expansive toughening material, 2 parts of latex powder, 1 part of stabilizer, 1 part of dispersant, 3 parts of fluid loss additive, 0.5 parts of retarder, 0.2 parts of defoamer, and 53 parts of water. The cement slurry density was 1.88 g / cm 3 , the experimental results are shown in Table 1.

[0148] Table 1 Experimental results of examples and comparative examples

[0149] Table 1 Experimental results of examples and comparative examples (continued)

[0150] As shown in Table 1, all examples exhibited fluidity greater than 20 cm and API water loss less than 50 mL, meeting cementing construction requirements. All examples also exhibited post-corrosion compressive strength greater than 20 MPa, with strength loss rates less than 20%, and permeability less than 0.1 mD, demonstrating excellent performance and meeting cementing sealing requirements.

[0151] The experimental data from Examples 1-3 show that, using the cement slurry of Example 1, the compressive strength declined from 32.6 MPa to 27.9 MPa after 60 days of corrosion. After corrosion, the compressive strength was greater than 20 MPa, and the permeability was less than 0.05 mD. The mechanical properties of the corroded cement paste were excellent, meeting the sealing requirements. Within the scope defined by the present invention, adjusting the ratio of the components in the anti-corrosion material and the amount of anti-corrosion material added had no adverse effects on the density, fluidity, API water loss, and other characteristics of the cement slurry system. Furthermore, after corrosion, the compressive strength of the cement paste was greater than 20 MPa, and the permeability was less than 0.05 mD, indicating excellent anti-corrosion performance.

[0152] It can be seen from the experimental data of Example 2 and Examples 4 and 5 that after the temperature changes, the amount of different admixtures is adjusted as needed, and the resulting cement slurry system has good engineering performance. At the same time, after curing under corrosive conditions, the compressive strength is greater than 20 MPa, the permeability is less than 0.05 mD, and the corrosion resistance is good. That is, within the range of the amount of each material added, adjustments can be made according to different temperatures to meet the use requirements at different temperatures.

[0153] From the data of Example 2 and Comparative Examples 1-2, it can be seen that after corrosion, the compressive strength of Comparative Examples 1-2 decreased significantly, both less than 20 MPa, and the permeability also increased significantly, even greater than 0.1 mD, and the fluidity of Comparative Example 2 was 17 cm, and the fluidity deteriorated.

[0154] From the data of Comparative Example 4, it can be seen that when no anti-corrosion material is added to the cement slurry, the strength of the cement stone before corrosion is 31.5 MPa, but after 60 days of corrosion, the compressive strength declines to 15.6 MPa, a decline of 50.48%, and the permeability increases from 0.049 mD to 0.203 mD. The strength declines significantly and the permeability increases significantly.

[0155] In summary, the cement slurry of the present invention has an applicable temperature range of 30-150°C. The compressive strength of the cement stone after corrosion is greater than 20 MPa, and the permeability is less than 0.05 mD. This significantly improves the cement stone's ability to resist CO2 corrosion. At the same time, it has no adverse effects on other engineering properties of the cement slurry, and can ensure long-term effective sealing of the cement ring under CCUS corrosion conditions.

[0156] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. An anti-corrosion material for cement slurry, characterized in that: The anti-corrosion material includes mixture A and mixture B; wherein mixture A includes activated carbon, nano-silicon dioxide and nano-alumina; mixture B includes component C and component D; component C is selected from diatomaceous earth and / or fly ash; and component D is selected from one or more of kaolin, pumice and coal gangue.

2. The anti-corrosion material according to claim 1, wherein: In the mixture A, the mass ratio of activated carbon, nano silicon dioxide and nano aluminum oxide is 1:0.05-0.1:0.05-0.1; And / or, the mass ratio of component C to component D is 1-2:1; And / or, the mass ratio of the mixture A to the mixture B is 1:2-4.

3. The anticorrosion material according to claim 1 or 2, wherein: The average particle size of the activated carbon is 40-60 μm; And / or, the SiO2 content of the nano-silicon dioxide is greater than 99% and the average particle size is 30-40nm; And / or, the Al2O3 content of the nano-alumina is greater than 99%, and the average particle size is 10-30nm; And / or, the average particle size of component C is 10-20 μm; And / or, the average particle size of component D is 20-40 μm.

4. A method for preparing an anti-corrosion material for cement slurry, characterized in that: The preparation method comprises: Mixing activated carbon, nano silicon dioxide and nano aluminum oxide to obtain a mixture A; Mixing component C and component D to obtain a mixture B; wherein the component C is selected from diatomaceous earth and / or fly ash; and the component D is selected from one or more of metakaolin, pumice and coal gangue; Under low stirring speed conditions, the mixture A and the mixture B are mixed, and then stirred at high Stirring at a high speed to obtain the anti-corrosion material; Preferably, the low stirring rate is 3800-4200 r / min, and the high-speed stirring rate is 11500-12500 r / min.

5. The preparation method according to claim 6, wherein In the mixture A, the mass ratio of activated carbon, nano silicon dioxide and nano aluminum oxide is 1:0.05-0.1:0.05-0.1; And / or, the mass ratio of component C to component D is 1-2:1; And / or, the mass ratio of the mixture A to the mixture B is 1:2-4.

6. The preparation method according to claim 4 or 5, wherein: The average particle size of the activated carbon is 40-60 μm; And / or, the SiO2 content of the nano-silicon dioxide is greater than 99% and the average particle size is 30-40nm; And / or, the Al2O3 content of the nano-alumina is greater than 99%, and the average particle size is 10-30nm; And / or, the average particle size of component C is 10-20 μm; And / or, the average particle size of component D is 20-40 μm.

7. Use of the anti-corrosion material described in any one of claims 1 to 3 or the anti-corrosion material prepared by the preparation method described in any one of claims 4 to 6 in cement slurry, preferably in cement slurry resistant to carbon dioxide corrosion.

8. A cement slurry for resisting carbon dioxide corrosion, characterized in that: The cement slurry is made of the following raw materials in parts by weight: 100 parts of G-grade oil well cement, 2-6 parts of anti-corrosion material, 2-5 parts of microsilicon, 3-6 parts of reinforcing material, 3-5 parts of expansion toughening material, 1-3 parts of latex powder, 0-2 parts of stabilizer, 0.3-2 parts of dispersant, 2-5 parts of fluid loss reducer, 0.1-2 parts of retarder, 0.2-0.5 parts of defoaming agent and 48-56 parts of water; wherein the anti-corrosion material is the anti-corrosion material described in any one of claims 1 to 3 or the anti-corrosion material prepared by the preparation method described in any one of claims 4 to 6.

9. The cement slurry according to claim 8, wherein: The SiO2 content of the micro-silicon is not less than 90%, the average particle size is 5-10 μm, and the 45 μm sieve residue is ≤5%.

10. The cement slurry according to claim 8 or 9, wherein: The reinforcing material is selected from inorganic ore powder materials, preferably ore powder DRB-1S; And / or, the expansion toughening material is selected from rubber materials, preferably rubber DRE-3S; And / or, the latex powder is selected from polymers, preferably polymer DRT-1S; And / or, the stabilizer is selected from attapulgite materials, preferably ore powder DRK-2S.

11. The cement slurry according to any one of claims 8 to 10, wherein: The dispersant is selected from polystyrene sulfonate compounds and / or condensation products of formaldehyde and acetone; And / or, the fluid loss reducer is selected from polyacrylamide compounds; And / or, the retarder is selected from acrylamide compounds; And / or, the defoaming agent is selected from one or more of tributyl phosphate, polyoxypropylene glycerol and polydimethylsiloxane.

12. A method for preparing carbon dioxide corrosion resistant cement slurry, characterized in that: The preparation method comprises: Mixing G-grade oil well cement with anti-corrosion material, micro-silicon, reinforcing material, expansion toughening material, latex powder, stabilizer and dispersant to obtain a dry mix; wherein the anti-corrosion material is the anti-corrosion material according to any one of claims 1 to 3 or the anti-corrosion material obtained by the preparation method according to any one of claims 4 to 6; mixing the fluid loss reducer with a retarder, a defoamer and water to obtain a wet mix; The dry mix and the wet mix are mixed to obtain carbon dioxide corrosion resistant cement slurry.

13. Use of the carbon dioxide corrosion resistant cement slurry according to any one of claims 8 to 11 or the carbon dioxide corrosion resistant cement slurry prepared by the preparation method according to claim 12 in cementing operations of oil and gas wells.

14. The use according to claim 13, wherein: The use temperature of the carbon dioxide corrosion resistant cement slurry is 30-150°C.

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