Enhanced cement slurry for well cementing and its use

Abstract

The application relates to the technical field of cement slurry preparation in well drilling, and discloses a reinforced cementing slurry and application thereof, the cement slurry comprising: 100 parts by weight of cement, 4-10 parts by weight of a fluid loss reducer, 0.1-0.5 parts by weight of a defoaming agent, 5-8 parts by weight of a nano filler, 1-5 parts by weight of a polyaniline / graphene intercalation compound, 35-110 parts by weight of water, 0-30 parts by weight of a high-temperature stabilizer, 0-200 parts by weight of a density regulator, 0-2 parts by weight of a dispersing agent and 0-1.5 parts by weight of a retarder. The reinforced cementing slurry provided by the application can effectively improve the overall mechanical strength of the cementing cement by adding the polyaniline / graphene intercalation compound, and can be applied to API oil well cements of all levels.

Description

Technical Field

[0001] This invention relates to the field of cement slurry preparation technology in drilling, specifically to an enhanced cement slurry and its application. Background Technology

[0002] Cement slurry is the working fluid used in well cementing, and its function is to cement the well. The cementing operation involves injecting cement slurry into the annulus between the wellbore and the casing through the casing, allowing it to rise to a certain height. The cement slurry then turns into cement stone, solidifying the wellbore and the casing to form a sealing cement annulus.

[0003] Conventional cement slurry typically consists of water, cement, admixtures (fluid loss reducers, retarders, dispersants, etc.), and additives (fibers, silica fume, etc.). The cement stone formed by conventional cement slurry is a brittle material. During later stages of oil well production or operations, the cement sheath is prone to cracks or micro-annular gaps, leading to damage to the cement sheath's integrity, seal failure, and jeopardizing the safe production of oil and gas wells, posing a potential safety hazard.

[0004] Therefore, there is an urgent need to provide an enhanced cement slurry that can improve the hardness and brittleness of cement stone and enhance its mechanical properties. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem of poor mechanical properties of cement stone in the prior art and to provide an enhanced cement slurry. The overall mechanical properties (such as compressive strength and impact strength) of the cement stone formed after the cement slurry is cured are significantly improved compared with conventional cement stone. Under high temperature and high pressure, it can improve the hard and brittle characteristics of cement stone, reduce the permeability of cement stone, ensure subsequent mining, and extend the production life of oil and gas wells.

[0006] To achieve the above objectives, a first aspect of the present invention provides an enhanced cement slurry, wherein the cement slurry comprises: 100 parts by weight of cement, 4-10 parts by weight of filtration reducer, 0.1-0.5 parts by weight of defoamer, 5-8 parts by weight of nanofiller, 1-5 parts by weight of polyaniline / graphene intercalation composite, 35-110 parts by weight of water, 0-30 parts by weight of high-temperature stabilizer, 0-200 parts by weight of density modifier, 0-2 parts by weight of dispersant, and 0-1.5 parts by weight of retarder.

[0007] The second aspect of the present invention provides the application of the enhanced cementing slurry described in the first aspect of the present invention in oil well cementing.

[0008] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0009] 1) The enhanced cement slurry provided by this invention has a good enhancement effect by adding a polyaniline / graphene intercalation composite with good hydrophilicity. It can effectively improve the overall mechanical strength of cement, especially the compressive strength and impact strength, meet the requirements of high temperature cementing construction, and is applicable to API oil well cement of all grades.

[0010] 2) The enhanced cement slurry provided by this invention has good compatibility among its components, is easy to mix, has stable performance, and is simple to prepare, making it suitable for industrial promotion. Detailed Implementation

[0011] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0012] A first aspect of the present invention provides an enhanced cement slurry, wherein the cement slurry comprises: 100 parts by weight of cement, 4-10 parts by weight of filtration loss reducer, 0.1-0.5 parts by weight of defoamer, 5-8 parts by weight of nanofiller, 1-5 parts by weight of polyaniline / graphene intercalation composite, 35-110 parts by weight of water, 0-30 parts by weight of high temperature stabilizer, 0-200 parts by weight of density modifier, 0-2 parts by weight of dispersant, and 0-1.5 parts by weight of retarder.

[0013] The enhanced cement slurry provided in this invention has components that interact with each other, which can improve the overall mechanical strength of the cement sheath formed after the cement slurry solidifies. This solves the problem of oil and gas reservoir channeling caused by the damage to the integrity of the cement sheath due to the impact load generated during perforation development and fracturing operations, ensuring the safety of subsequent production and extending the production life of oil and gas wells.

[0014] In one embodiment of the present invention, the amount of the above-mentioned components can be any value within the defined range. For example, the weight parts of the filtration loss reducer can be any value between 4 and 10, such as 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, and 10, and any value within the range consisting of any two of the above values. The weight parts of the defoamer can be any value between 0.1 and 0.5, such as 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, and 0.5, and any value within the range consisting of any two of the above values. The weight parts of the nanofiller can be any value between 5 and 8, such as 5, 5.5, 6, 6.5, 7, 7.5, and 8, and any value within the range consisting of any two of the above values. The polyaniline / graphene intercalation composite can be any value between 1 and 5 by weight, for example, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5, or any value within any range of any two of the above values. The water can be any value between 35 and 110 by weight, for example, 35, 40, 50, 60, 70, 80, 90, 100, and 110, or any value within any range of any two of the above values.

[0015] In one embodiment of the present invention, the filtration loss reducing agent is one or more of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) polymer, ketaldehyde condensate, and polyvinyl alcohol (PVA) system.

[0016] In one embodiment of the present invention, the defoamer is selected from polyether defoamers.

[0017] In one embodiment of the present invention, the nanofiller is selected from one or more of liquid nano silica, nano titanium dioxide, calcium carbonate, carbon black, and precipitated silica.

[0018] In one embodiment of the present invention, the preparation method of the polyaniline / graphene intercalation composite includes the following steps:

[0019] 1) Under ice bath conditions, expanded graphite is first dispersed in an aniline-hydrochloric acid mixture, and then an initiator is added to react and a reaction solution containing precipitate is obtained.

[0020] 2) After adding ammonia water to the reaction solution containing the precipitate, solid-liquid separation was performed to obtain the polyaniline / graphene intercalation composite.

[0021] In step 1):

[0022] In one embodiment of the present invention, the expanded graphite is worm-shaped expanded graphite. The method for preparing the worm-shaped expanded graphite includes calcining graphite raw material at 800-1000℃ for 30-60 seconds to obtain worm-shaped expanded graphite. The present invention does not impose any special limitations on the graphite raw material used to prepare the worm-shaped expanded graphite; the graphite raw material can be a conventional commercially available product, such as flake graphite.

[0023] In one embodiment of the present invention, the graphite raw material has an expansion coefficient of 15-30 mL / g and a particle size of 80-1200 mesh.

[0024] In step 2):

[0025] In one embodiment of the present invention, the present invention does not impose a special limitation on the temperature of the ice bath, and the temperature of the ice bath can be 0-10℃, preferably 0-5℃.

[0026] In one embodiment of the present invention, the preparation method of the aniline-hydrochloric acid mixture includes: adding aniline to a hydrochloric acid solution under ice bath conditions, and stirring at a stirring rate of 300-600 rpm for 10-40 min to obtain the aniline-hydrochloric acid mixture.

[0027] In one embodiment of the present invention, the volume ratio of aniline to hydrochloric acid solution is 1:50-100, and the concentration of hydrochloric acid solution is 0.5-2.5 mol / L.

[0028] In one embodiment of the present invention, the dispersion process includes: adding expanded graphite to an aniline-hydrochloric acid mixture under ice bath conditions, ultrasonically pulverizing it for 30-90 minutes at an ultrasonic power of 100-500W, and then stirring it at a stirring rate of 300-600rpm for 2-6 hours to obtain a dispersion; wherein the ratio of expanded graphite to aniline is 5-15mg:1mL.

[0029] In one embodiment of the present invention, the initiator is selected from azo initiators and / or persulfate initiators; wherein the azo initiator is selected from one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, and azobisisobutyram hydrochloride; and the persulfate initiator is selected from potassium persulfate, sodium persulfate, and ammonium persulfate. In a further preferred embodiment, the initiator is ammonium persulfate.

[0030] In one embodiment of the present invention, the mass ratio of the initiator to the expanded graphite is 1-5g:10mg.

[0031] In one embodiment of the present invention, the initiator is added dropwise to the dispersion in the form of an initiator aqueous solution, more preferably in the form of an initiator-hydrochloric acid solution; wherein, in the initiator-hydrochloric acid solution, the ratio of initiator to hydrochloric acid is 2-8g:100mL, and the concentration of hydrochloric acid is 0.5-2.5mol / L.

[0032] In one embodiment of the present invention, the dispersion is stirred at a stirring rate of 300-600 rpm during the dropwise addition process.

[0033] In one embodiment of the present invention, after the reaction is completed (i.e. after the dropwise addition is completed), the mixture is left to stand at room temperature for 12-20 hours to obtain a reaction solution containing a precipitate.

[0034] In step 3):

[0035] In one embodiment of the present invention, the concentration of the ammonia water is 1-3 mol / L, and the volume ratio of the ammonia water to the reaction solution containing the precipitate is 1:10-50.

[0036] In one embodiment of the present invention, the present invention does not impose any special limitation on the separation, the separation is preferably centrifugal separation; wherein, the centrifugation rate is 8000-15000 rpm and the centrifugation time is 5-10 min.

[0037] The inventors of this invention discovered through research that adding 1-5 parts by weight of polyaniline / graphene intercalation composite to cement slurry can significantly improve the overall mechanical properties of cement stone, such as compressive strength and flexural strength, making the cement stone exhibit a stronger ability to resist external load impact, reducing permeability, and improving the sealing and safety of oil and gas wells.

[0038] In one embodiment of the present invention, the purity of the water is ≥99.5%. Preferably, the salt content in the water is ≤0.5 g / L.

[0039] In one embodiment of the present invention, the high-temperature stabilizer is selected from microsilica powder or amorphous silica with a purity of ≥95%.

[0040] In one embodiment of the present invention, the density regulator is a weighting agent or a weight-reducing agent.

[0041] In one embodiment of the present invention, the weighting agent is barite and / or iron ore powder, and the weighting agent is 0-200 parts by weight, preferably 0-50 parts.

[0042] In one embodiment of the present invention, the weight-reducing agent is fly ash and / or cenospheres; the weight of the weight-reducing agent is 0-100 parts, preferably 0-35 parts.

[0043] In one embodiment of the present invention, the dispersant is selected from one or more of aldehyde-ketone condensates, naphthalene-based dispersants, and polycarboxylic acid dispersants.

[0044] In one embodiment of the present invention, the retarder is an AMPS polymer.

[0045] In this invention, the filtration loss reducer, defoamer, dispersant, and retarder are all conventional additives in the art. The filtration loss reducer and retarder can be selected individually from AMPS polymers, and preferably, the filtration loss reducer and retarder are different AMPS polymers.

[0046] In one embodiment of the present invention, the method for preparing cement slurry includes mixing the aforementioned cement, filtration loss reducer, defoamer, nanofiller, polyaniline / graphene intercalation composite, water, optional high-temperature stabilizer, optional density modifier, optional dispersant and optional retarder to obtain the cement slurry.

[0047] A second aspect of the present invention provides an application of the enhanced cementing slurry described in the first aspect of the present invention in oil well cementing.

[0048] The enhanced cement slurry provided by this invention can effectively improve the overall mechanical strength of cement by adding polyaniline / graphene intercalation composite, and is applicable to API oil well cement of all grades.

[0049] The present invention will be described in detail below through embodiments.

[0050] The cement used in the examples and comparative examples was Jiahua G-grade oil well cement, purchased from Sichuan Jiahua Cement Plant. The filtration loss reducer was model DZJ-Y, the defoamer was DZX-1, the dispersant was SCD-150L, ​​the retarder was DZH-2, and the nanofiller was nano-silica liquid, model SCLS, all sourced from Dezhou Continental Shelf Petroleum Engineering Technology Co., Ltd. The high-temperature stabilizer was 80-mesh microsilica powder, sourced from Fengyang Guangming Industrial Materials Co., Ltd. The graphite raw material was purchased from Qingdao Yanhai Carbon Materials Co., Ltd., with an expansion coefficient of 20 mL / g and a particle size of 80-1200 mesh.

[0051] Preparation Example 1 (Polyaniline / graphene intercalation composite)

[0052] 1) Under ice bath conditions of 0-5℃, add 2 mL of aniline to 200 mL of hydrochloric acid solution (1 mol / L) and stir at a stirring rate of 300 rpm for 30 min to obtain aniline-hydrochloric acid mixture.

[0053] The graphite raw material was placed in a muffle furnace and calcined at 900℃ for 30s to obtain worm-like expanded graphite; under ice bath conditions of 0-5℃, 20mg of worm-like expanded graphite was added to the above aniline-hydrochloric acid mixture, and ultrasonically pulverized at 300W ultrasonic power for 60min, and then stirred at 300rpm for 4h to obtain a dispersion.

[0054] Under ice bath conditions of 0-5℃, 100 mL of hydrochloric acid solution of ammonium persulfate (4.56 g of ammonium persulfate) was added dropwise to the above dispersion. The stirring rate during the dropwise addition was 300 rpm. After the dropwise addition was completed, the mixture was allowed to stand at room temperature for 16 h to obtain a reaction solution containing a dark green precipitate.

[0055] 2) Add 10 mL of 2 mol / L concentrated ammonia solution to the above reaction solution, and then centrifuge (10000 rpm, 5 min) to obtain polyaniline / graphene intercalation composite A.

[0056] Preparation Example 2

[0057] Similar to Preparation Example 1, except that the amount of aniline was changed. In step (1), 4 mL of aniline was added to 200 mL of hydrochloric acid solution (1 mol / L) to obtain polyaniline / graphene intercalation composite B.

[0058] Example 1

[0059] Mix 100g cement, 5g filtration loss reducer, 0.2g defoamer, 5g nano filler, 2g polyaniline / graphene intercalation composite A, 52g water, 30g high temperature stabilizer, 1.2g dispersant, and 0.5g retarder evenly to obtain reinforced cement slurry.

[0060] Example 2

[0061] Mix 100g cement, 5g filtration loss reducer, 0.2g defoamer, 5g nanofiller, 3g polyaniline / graphene intercalation composite A, 80g water, 30g high temperature stabilizer, 70g weighting agent (hematite powder, 250 mesh), 1.2g dispersant, and 0.5g retarder evenly to obtain reinforced cement slurry.

[0062] Example 3

[0063] Mix 100g cement, 5g filtration loss reducer, 0.2g defoamer, 5g nano filler, 2g polyaniline / graphene intercalation composite B, 52g water, 30g high temperature stabilizer, 1.2g dispersant, and 0.5g retarder evenly to obtain reinforced cement slurry.

[0064] Comparative Example 1

[0065] Similar to Example 1, except that no polyaniline / graphene intercalation composite was added to obtain the cementing slurry.

[0066] Comparative Example 2

[0067] Similar to Example 2, except that no polyaniline / graphene intercalation composite was added to obtain the cementing slurry.

[0068] The composition and content of cement slurry in the examples and comparative examples are shown in Table 1:

[0069] Table 1

[0070]

[0071]

[0072] Test Example 1

[0073] The performance of the cement slurry obtained in the examples and comparative examples was tested, and the results are shown in Table 2:

[0074] The density was tested according to GB / T50080. The cement slurry obtained in the examples and comparative examples was cured at 80℃ and 20MPa for 72h, and then the compressive strength and tensile strength were tested. The compressive strength was tested according to GB / T50081, and the tensile strength was tested according to GB / T50081.

[0075] Table 2

[0076] <![CDATA[Density / g / cm 3 > Compressive strength / MPa Tensile strength / MPa Example 1 1.90 39.7 4.2 Example 2 2.25 29.7 3.4 Example 3 1.90 41.1 4.3 Comparative Example 1 1.90 27.1 2.9 Comparative Example 2 2.25 20.5 2.2

[0077] As can be seen from Table 2, the enhanced cement slurry provided by the present invention can effectively improve the overall mechanical strength of cement by adding polyaniline / graphene intercalation composite, and can be applied to API oil well cement of all grades.

[0078] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A reinforced cementing slurry, characterized in that, The cement slurry comprises: 100 parts by weight of cement, 4-10 parts by weight of filtration loss reducer, 0.1-0.5 parts by weight of defoamer, 5-8 parts by weight of nano filler, 1-5 parts by weight of polyaniline / graphene intercalation composite, 35-110 parts by weight of water, 0-30 parts by weight of high temperature stabilizer, 0-200 parts by weight of density regulator, 0-2 parts by weight of dispersant, and 0-1.5 parts by weight of retarder; The filtration loss reducer is one or more of 2-acrylamido-2-methylpropanesulfonic acid polymer, ketone-aldehyde condensate, and polyvinyl alcohol systems; the defoamer is selected from polyether defoamers; and the nanofiller is one or more of liquid nano silica, nano titanium dioxide, calcium carbonate, carbon black, and precipitated silica. The preparation method of the polyaniline / graphene intercalation composite includes the following steps: 1) Under ice bath conditions, expanded graphite is first dispersed in an aniline-hydrochloric acid mixture, and then an initiator is added to react and obtain a reaction solution containing a precipitate. 2) After adding ammonia water to the reaction solution containing the precipitate, solid-liquid separation was performed to obtain the polyaniline / graphene intercalation composite.

2. The cement grout according to claim 1, wherein, The expanded graphite is worm-shaped expanded graphite.

3. The cement grout according to claim 2, wherein, The method for preparing the worm-like expanded graphite includes: calcining graphite raw material at 800-1000℃ for 30-60s to obtain worm-like expanded graphite.

4. The cement grout according to claim 3, wherein, The graphite raw material has an expansion coefficient of 15-30 mL / g and a particle size of 80-1200 mesh.

5. The cement grout according to claim 1, wherein, The preparation method of the aniline-hydrochloric acid mixture includes: adding aniline to a hydrochloric acid solution under ice bath conditions, and stirring at a stirring rate of 300-600 rpm for 10-40 min to obtain the aniline-hydrochloric acid mixture.

6. The cement grout according to claim 1, wherein, The volume ratio of aniline to hydrochloric acid solution is 1:50-100, and the concentration of hydrochloric acid solution is 0.5-2.5 mol / L.

7. The cement grout according to claim 1, wherein, The dispersion process includes: adding expanded graphite to an aniline-hydrochloric acid mixture under ice bath conditions, ultrasonically pulverizing it for 30-90 minutes at an ultrasonic power of 100-500W, and then stirring it at a stirring rate of 300-600rpm for 2-6 hours to obtain a dispersion; wherein the ratio of expanded graphite to aniline is 5-15mg:1mL.

8. The cement grout according to claim 1, wherein, The initiator is selected from azo initiators and / or persulfate initiators; wherein the azo initiator is selected from one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, and azobisisobutyram hydrochloride; and the persulfate initiator is selected from potassium persulfate, sodium persulfate, and ammonium persulfate.

9. The cement grout according to claim 1, wherein, The mass ratio of the initiator to the expanded graphite is 1-5g:10mg.

10. The cement grout according to claim 7, wherein, The initiator is added dropwise to the dispersion in the form of an aqueous initiator solution.

11. The cement grout according to claim 10, wherein, The initiator is added dropwise to the dispersion in the form of an initiator-hydrochloric acid solution; wherein, in the initiator-hydrochloric acid solution, the ratio of initiator to hydrochloric acid solution is 2-8g:100mL, and the concentration of hydrochloric acid solution is 0.5-2.5mol / L.

12. The cement grout according to claim 10 or 11, wherein, During the dropwise addition, the dispersion is stirred at a stirring rate of 300-600 rpm.

13. The cement grout according to claim 12, wherein, After the addition is complete, let it stand at room temperature for 12-20 hours to obtain a reaction solution containing a precipitate.

14. The cement grout according to claim 1, wherein, The concentration of the ammonia water is 1-3 mol / L, and the volume ratio of the ammonia water to the reaction solution containing the precipitate is 1:10-50.

15. The cement grout according to claim 1, wherein, The solid-liquid separation is centrifugal separation; wherein the centrifugation rate is 8000-15000 rpm and the centrifugation time is 5-10 min.

16. The cement grout according to claim 1, wherein, The high-temperature stabilizer is selected from microsilica powder or amorphous silica with a purity of ≥95%.

17. The cement grout according to claim 1, wherein, The density regulator is a weighting agent or a weight-reducing agent, wherein the weighting agent is selected from barite and / or iron ore powder, and the weight-reducing agent is selected from fly ash and / or cenospheres.

18. The cement grout according to claim 1, wherein, The dispersant is selected from one or more of aldehyde-ketone condensates, naphthalene-based dispersants, and polycarboxylic acid dispersants.

19. The cement grout according to claim 1, wherein, The retarder is an AMPS polymer.

20. The application of the enhanced cementing slurry according to any one of claims 1-19 in oil well cementing.

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