High-thermal-conductivity solid-waste-applied well cementing slurry system, preparation method and application thereof

Abstract

The application discloses a high-thermal-conductivity cementing slurry system using solid waste, a preparation method and application thereof, and belongs to the technical field of geothermal resource development.The cementing slurry system comprises the following components: cement 40-60 parts, high-thermal-conductivity material 5-25 parts, high-temperature strength stabilizing material 30-45 parts, retarder 1-5 parts, fluid loss additive 1-5 parts, dispersant 0.4-2 parts, suspension stabilizer 3-4 parts and defoaming agent 0.05-0.2 parts.The high-thermal-conductivity material is formed by mixing wollastonite fibers and waste side blocks and cathode carbon blocks in treated electrolytic aluminum overhaul slag.The application uses electrolytic aluminum solid waste as the thermal-conductivity material, provides a harmless treatment method for the electrolytic aluminum solid waste, is green and environment-friendly, significantly reduces the use cost of silicon carbide and silicon nitride in the cementing slurry system, enhances the thermal-conductivity of the water cementing slurry, improves the high-temperature stability of the cement stone, reduces the corrosion of CO2 and inhibits the high-temperature strength decline of the cement stone.

Description

Technical Field

[0001] This invention belongs to the field of geothermal resource development technology, specifically relating to a high thermal conductivity cement slurry system for cementing wells using solid waste, its preparation method, and its application. Background Technology

[0002] Against the backdrop of accelerated global energy structure transformation, geothermal energy, as a stable and reliable renewable energy source, is receiving widespread attention. While geothermal resources possess significant advantages such as wide distribution and energy conversion efficiency unaffected by climate conditions, the commercial development of medium- and high-temperature geothermal resources still faces multiple technological bottlenecks. Among these, cementing engineering, as a core component ensuring the safe operation of geothermal wells throughout their entire lifecycle, has seen breakthroughs in the performance of its material systems become a key constraint on the industry's development.

[0003] Cementing is a crucial process for maintaining the safe and efficient production of geothermal wells, and the quality of the cement sheath directly impacts the operational effectiveness of these wells. Current cement sheath technology faces a dual technical challenge: firstly, cement sheaths are typical multiphase heterogeneous brittle materials with low thermal conductivity, which is detrimental to the efficient heat exchange of the heat transfer medium in water / gas injection wells; secondly, high temperatures also lead to performance degradation of the cement sheath, making it unable to effectively seal the formation. In particular, when CO2 is used as the heat exchange medium, the corrosive effect of CO2 on the cement stone further reduces its compressive strength. Based on these issues, developing a novel cementing system that combines high thermal conductivity, high-temperature stability, and resistance to CO2 corrosion is of paramount importance. Summary of the Invention

[0004] One aspect of this invention is to provide a high thermal conductivity cement slurry system for cementing wells using solid waste, which has excellent high-temperature strength stability, high thermal conductivity, and corrosion resistance.

[0005] The second objective of this invention is to provide a method for preparing the cement slurry system.

[0006] A third objective of this invention is to provide the application of this cement slurry system.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention discloses a high thermal conductivity cement slurry system for cementing wells using solid waste, comprising the following raw materials in parts by weight: 40-60 parts cement; 5-25 parts high thermal conductivity material; 30-45 parts high temperature strength stabilizing material; 1-5 parts retarder; 1-5 parts water loss reducing agent; 0.4-2 parts dispersant; 3-4 parts suspension stabilizer; and 0.05-0.2 parts defoamer.

[0009] In some embodiments of the present invention, the cement slurry system comprises the following raw materials in parts by weight: 47-60 parts cement; 5-23 parts high thermal conductivity material; 30-40 parts high temperature strength stabilizing material; 3-4 parts retarder; 1-3 parts water loss reducing agent; 0.4-1 part dispersant; 3-4 parts suspension stabilizer; and 0.05-0.2 parts defoamer.

[0010] In some embodiments of the present invention, the cement is selected from G-grade high sulfate-resistant cement; more preferably, it is G-grade high sulfate-resistant cement produced by Jiahua Special Cement Co., Ltd.

[0011] In some embodiments of the present invention, the high thermal conductivity material is composed of wollastonite fiber mixed with waste side blocks and cathode carbon blocks from the treated electrolytic aluminum overhaul slag;

[0012] Preferably, the mass ratio of the treated waste side block, the treated cathode carbon, and the wollastonite fiber is (5-8):(1-3):(0.5-3);

[0013] The waste side block in this invention contains 65-75 wt% silicon carbide and 15-25% silicon nitride.

[0014] The cathode carbon block in this invention is mainly composed of graphite, accounting for 65-70 wt%, with the remainder being 20-30 wt% fluoride and aluminum-containing compounds.

[0015] In some embodiments of the present invention, the method for preparing the high thermal conductivity material includes the following steps:

[0016] S1: Treatment of waste side block: The waste side block is mixed and ground with quicklime to obtain the treated waste side block powder; preferably, the mass ratio of waste side block to quicklime is 280-320:1; preferably, it is ground to a particle size of 150-200 mesh, more preferably 180 mesh;

[0017] S2: Treatment of cathode carbon blocks: The cathode carbon blocks are first soaked in hydrogen peroxide solution, then slaked lime is added and soaked for a longer time. After filtration and drying, the slaked lime is added and the blocks are ground to obtain the treated cathode carbon block powder.

[0018] Preferably, the concentration of the hydrogen peroxide solution is 1.0–2.0 wt%; the amount used is sufficient to completely submerge the cathode carbon block; and the soaking time with the hydrogen peroxide solution is 1–5 hours.

[0019] Preferably, the mass ratio of cathode carbon block to quicklime for soaking is 80-120:1; after adding quicklime, soaking continues for 1-5 hours;

[0020] Preferably, the mass ratio of the cathode carbon block to the quicklime added after filtration and drying is 250-350:1;

[0021] Preferably, the particles in S2 are ground to a particle size of 200-250 mesh, more preferably 230 mesh;

[0022] S3: Mixing: Mix the powder obtained by grinding S1 and S2 with wollastonite fibers evenly to obtain a high thermal conductivity material.

[0023] In some embodiments of the present invention, the high-temperature strength-stabilizing material is a mixture of waste aluminosilicate glass powder and industrial quartz sand; wherein the aluminosilicate glass powder accounts for 10-40 wt%, preferably 25-40 wt%, and the particle size is 150-200 mesh, preferably 170 mesh; the industrial quartz sand accounts for 60-90 wt%, preferably 60-75%; the industrial quartz sand particle size is divided into two gradations: 300-350 mesh and 700-900 mesh, preferably 325 mesh and 800 mesh; and the mass ratio is 40-62:5-25.

[0024] In some embodiments of the present invention, the retarder is at least one of gluconate and sulfonate;

[0025] Preferably, the water loss reducing agent is an AMPS-amide-carboxylic acid polymer;

[0026] Preferably, the dispersant is a formaldehyde-acetone condensate;

[0027] Preferably, the suspension stabilizer is at least one of AM-AMPS-NVP polymers and microsilica;

[0028] Preferably, the defoamer is tributyl phosphate.

[0029] Secondly, the present invention discloses a method for preparing the above-mentioned cement slurry system, wherein the cement slurry system is prepared in accordance with GB / T 19139-2012 Oil Well Cement Test Method.

[0030] Preferably, the water-cement ratio is 0.44.

[0031] Thirdly, the present invention discloses the application of the above-mentioned cement slurry system as a cementing slurry; preferably, as a cementing slurry for geothermal wells.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] This invention is scientifically designed and ingeniously conceived. It creatively uses electrolytic aluminum solid waste as a thermally conductive material, providing a harmless method for treating electrolytic aluminum solid waste. It is green and environmentally friendly, and significantly reduces the cost of using silicon carbide and silicon nitride in well cementing systems, while enhancing the thermal conductivity of water-cemented mudstone.

[0034] The electrolytic aluminum solid waste used in this invention contains residual cryolite (Na4AlF6) and fluorides. Among them, Al... 3+ It can increase the stability of calcium silicate (a high-temperature hydration product of oil well cement and siliceous materials), inhibit the transformation to hard calcium silicate, and improve the high-temperature stability of cement stone; while F - It can react with hydration products to form insoluble calcium fluoride, which coats the hydration products and fills the pores of cement stone. This reduces CO2 corrosion and decreases the Ca / Si ratio of the cement, inhibiting the high-temperature strength degradation of the cement stone. Experimental results show that the cementing slurry system of this invention has better corrosion resistance and thermal conductivity than ordinary cementing slurries. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is further described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0036] The cement described in this embodiment of the invention is Grade G high sulfate-resistant cement produced by Jiahua Special Cement Co., Ltd.

[0037] Example 1

[0038] As a preferred embodiment of the present invention, this embodiment provides a high-temperature corrosion-resistant and high thermal conductivity cementing slurry system, comprising the following components by mass parts, as detailed below:

[0039] Table 1

[0040] Components Number of parts by weight / part cement 52 High thermal conductivity materials 16 Strength stabilizer 32 Retarder 3 Water loss reducer 3 dispersant 0.8 suspension stabilizer 3 Defoamer 0.06 Mixing water 44

[0041] The preparation method of the high thermal conductivity material in this embodiment is as follows:

[0042] S1: Treatment of waste side block: Mix waste side block with quicklime at a mass ratio of 300:1 and grind until the particle size is 180 mesh to obtain treated waste side block powder;

[0043] S2: Treatment of cathode carbon blocks: The cathode carbon blocks are first soaked in a 1.5wt% hydrogen peroxide solution for 3 hours, then soaked in quicklime for another 3 hours, filtered, dried, and ground with quicklime until the particle size is 230 mesh to obtain the treated cathode carbon block powder; wherein the mass ratio of cathode carbon blocks to quicklime used for soaking is 100:1, and the mass ratio of cathode carbon blocks to quicklime added after filtration and drying is 300:1;

[0044] S3: Mixing: The powder obtained from grinding S1 and S2 is mixed evenly with wollastonite fiber to obtain a high thermal conductivity material. The mass ratio of the treated waste side block powder, the treated cathode carbon block powder and the wollastonite fiber is 7:2:1.

[0045] In this embodiment, the strength stabilizer is a mixture of aluminosilicate glass powder and industrial quartz sand, with a mass ratio of aluminosilicate glass powder: 325 mesh industrial quartz sand: 800 mesh industrial quartz sand = 3:4.5:2.5.

[0046] In this embodiment, the suspension stabilizer is an AM-AMPS-NVP polymer, the retarder is gluconate, the water loss reducing agent is an AMPS-amide-carboxylic acid polymer, the dispersant is a formaldehyde-acetone condensate, and the foaming agent is tributyl phosphate.

[0047] Example 2

[0048] As a preferred embodiment of the present invention, this embodiment provides a high-temperature corrosion-resistant and high thermal conductivity cementing slurry system, comprising the following components by mass parts, as detailed below:

[0049] Table 2

[0050] Components Number of parts by weight / part cement 47 High thermal conductivity materials 10 Strength stabilizer 43 Retarder 3 Water loss reducer 3 dispersant 0.4 suspension stabilizer 3 Defoamer 0.06 Mixing water 44

[0051] The preparation method of the high thermal conductivity material in this embodiment is the same as that in Example 1. The mass ratio of the treated waste side block powder, the treated cathode carbon block powder and the wollastonite fiber is 7:2.5:0.5, and all other conditions are the same.

[0052] In this embodiment, the strength stabilizer is a mixture of aluminosilicate glass powder and industrial quartz sand, with a mass ratio of aluminosilicate glass powder: 325 mesh industrial quartz sand: 800 mesh industrial quartz sand = 3:5.5:1.5.

[0053] In this embodiment, the suspension stabilizer is an AM-AMPS-NVP polymer, the retarder is gluconate, the water loss reducing agent is an AMPS-amide-carboxylic acid polymer, the dispersant is a formaldehyde-acetone condensate, and the foaming agent is tributyl phosphate.

[0054] Example 3

[0055] As a preferred embodiment of the present invention, this embodiment provides a high-temperature corrosion-resistant and high thermal conductivity cementing slurry system, comprising the following components by mass parts, as detailed below:

[0056] Table 3

[0057]

[0058]

[0059] The preparation method of the high thermal conductivity material in this embodiment is the same as that in Example 1. The mass ratio of the treated waste side block powder, the treated cathode carbon block powder and wollastonite fiber is 6:2:2, and all other conditions are the same.

[0060] In this embodiment, the strength stabilizer is a mixture of aluminosilicate glass powder and industrial quartz sand, with a mass ratio of aluminosilicate glass powder: 325 mesh industrial quartz sand: 800 mesh industrial quartz sand = 2.5: 6.2: 1.3.

[0061] In this embodiment, the suspension stabilizer is an AM-AMPS-NVP polymer, the retarder is gluconate, the water loss reducing agent is an AMPS-amide-carboxylic acid polymer, the dispersant is a formaldehyde-acetone condensate, and the foaming agent is tributyl phosphate.

[0062] Example 4

[0063] As a preferred embodiment of the present invention, this embodiment provides a high-temperature corrosion-resistant and high thermal conductivity cementing slurry system, comprising the following components by mass parts, as detailed below:

[0064] Table 4

[0065] Components Number of parts by weight / part cement 60 High thermal conductivity materials 8 Strength stabilizer 32 Retarder 4 Water loss reducer 3 dispersant 1 suspension stabilizer 4 Defoamer 0.06 Mixing water 44

[0066] The preparation method of the high thermal conductivity material in this embodiment is the same as that in Example 1. The mass ratio of the treated waste side block powder, the treated cathode carbon block powder and the wollastonite fiber is 5.5:2:2.5, and all other conditions are the same.

[0067] In this embodiment, the strength stabilizer is a mixture of aluminosilicate glass powder and industrial quartz sand, with a mass ratio of aluminosilicate glass powder: 325 mesh industrial quartz sand: 800 mesh industrial quartz sand 4:5.5:0.5.

[0068] In this embodiment, the suspension stabilizer is an AM-AMPS-NVP polymer, the retarder is gluconate, the water loss reducing agent is an AMPS-amide-carboxylic acid polymer, the dispersant is a formaldehyde-acetone condensate, and the foaming agent is tributyl phosphate.

[0069] Example 5

[0070] As a preferred embodiment of the present invention, this embodiment provides a high-temperature corrosion-resistant and high thermal conductivity cementing slurry system, comprising the following components by mass parts, as detailed below:

[0071] Table 5

[0072] Components Number of parts by weight / part cement 55 High thermal conductivity materials 5 Strength stabilizer 40 Retarder 3.5 Water loss reducer 3 dispersant 0.8 suspension stabilizer 3.5 Defoamer 0.06 Mixing water 44

[0073] The preparation method of the high thermal conductivity material in this embodiment is the same as that in Example 1. The mass ratio of the treated waste side block powder, the treated cathode carbon block powder and the wollastonite fiber is 8:1.5:0.5, and all other conditions are the same.

[0074] In this embodiment, the strength stabilizer is a mixture of aluminosilicate glass powder and industrial quartz sand, with a mass ratio of aluminosilicate glass powder: 325 mesh industrial quartz sand: 800 mesh industrial quartz sand 4:4:2.

[0075] In this embodiment, the suspension stabilizer is an AM-AMPS-NVP polymer, the retarder is gluconate, the water loss reducing agent is an AMPS-amide-carboxylic acid polymer, the dispersant is a formaldehyde-acetone condensate, and the foaming agent is tributyl phosphate.

[0076] Comparative Example 1

[0077] Prepare cement slurry according to the following mass percentages:

[0078] The cement slurry was prepared according to GB / T 19139 Oil Well Cement Test Method, with a water-cement ratio of 0.44. It contains 65% Grade G cement, 35% siliceous materials, 4% water loss reducing agent, 3% retarder, 2.5% suspension stabilizer, and 0.06% defoamer.

[0079] In this comparative example, the G-grade cement is G-grade high sulfate-resistant cement produced by Jiahua Special Cement Co., Ltd.; the siliceous material is 325 mesh industrial quartz sand; the water loss reducing agent is AMPS-amide-carboxylic acid polymer; the retarder is gluconate; and the foaming agent is tributyl phosphate.

[0080] Experimental Example 1

[0081] According to GB / T 19139 Test Methods for Cement in Oil Wells, the engineering performance of the cement slurry systems of Examples 1-5 and Comparative Example 1 was tested, and the experimental results are shown in Table 6.

[0082] Table 6. Test Results of Engineering Performance of Cement Slurry System

[0083]

[0084] As shown in Table 6, the water loss of the cement slurry prepared in Examples 1-5 is less than 50 ml / 30 min, the fluidity is in the range of 22-24 cm, which meets the technical requirements of cementing construction. The density difference between the upper and lower parts is small, the slurry has good stability, and the thickening time is controllable.

[0085] The test results of the cement paste are shown in Table 7. The cement paste was first cured in a high-temperature and high-pressure curing autoclave for 3 days to form a solid mass, and then transferred to a high-temperature and high-pressure corrosion reactor for further curing. The curing conditions in the high-temperature and high-pressure curing autoclave were 180℃ / 20.7MPa, and the curing conditions in the high-temperature and high-pressure corrosion reactor were 180℃, CO2 pressure 5MPa, and N2 partial pressure 5MPa.

[0086] Table 7 Cement stone test results

[0087]

[0088]

[0089] As shown in Table 7, the early compressive strength development of both the examples and the comparative examples was relatively rapid. Only the 3-day compressive strength of Examples 1 and 3 was slightly lower than that of Comparative Example 1. After being placed in a high-temperature and high-pressure corrosion autoclave for corrosion curing, the compressive strength of both examples and the comparative examples developed normally within a short period of time. However, when the corrosion age was extended to 28 days, the strength of Comparative Example 1 had already begun to decline, while the compressive strength of the examples maintained a slight increase, indicating that the corrosion resistance of the examples was better than that of the comparative example. From the results of the elastic modulus, due to the addition of wollastonite fibers, the elastic modulus of the examples was significantly reduced compared to the comparative example. The thermal conductivity of the examples was significantly increased compared to Comparative Example 1, indicating that the high thermal conductivity material described in this invention can effectively improve the thermal conductivity of cement paste.

[0090] The above description is merely a preferred embodiment of the invention and does not constitute any limitation on the invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments based on the technical essence of the invention and within the spirit and principles of the invention shall still fall within the protection scope of the invention's technical solution.

Claims

1. A high thermal conductivity cement slurry system for cementing wells using solid waste, characterized in that, The ingredients include the following parts by weight: 40-60 parts cement; 5-25 parts high thermal conductivity material; 30-45 parts high temperature strength stabilizing material; 1-5 parts retarder; 1-5 parts water loss reducer; 0.4-2 parts dispersant; 3-4 parts suspension stabilizer; 0.05-0.2 parts defoamer; The high thermal conductivity material is composed of wollastonite fiber mixed with waste side blocks and cathode carbon blocks from the treated electrolytic aluminum overhaul slag. The mass ratio of the treated waste side block, the treated cathode carbon, and the wollastonite fiber is (5~8):(1~3):(0.5~3).

2. The high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 1, characterized in that, 47-60 parts cement; 5-23 parts high thermal conductivity material; 30-40 parts high temperature strength stabilizing material; 3-4 parts retarder; 1-3 parts water loss reducer; 0.4-1 part dispersant; 3-4 parts suspension stabilizer; 0.05-0.2 parts defoamer.

3. A high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 1 or 2, characterized in that, The cement is selected from Grade G high sulfate-resistant cement.

4. The high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 1, characterized in that, The preparation method of the high thermal conductivity material includes the following steps: S1: Treatment of waste side block: Mix and grind the waste side block with quicklime to obtain treated waste side block powder; S2: Treatment of cathode carbon blocks: The cathode carbon blocks are first soaked in hydrogen peroxide solution, then slaked lime is added and soaked for a longer time. After filtration and drying, the slaked lime is added and the blocks are ground to obtain the treated cathode carbon block powder. S3: Mixing: Mix the powder obtained by grinding S1 and S2 with wollastonite fibers evenly to obtain a high thermal conductivity material.

5. A high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 4, characterized in that, In S1, the mass ratio of waste side block to quicklime is 280~320:

1.

6. The high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 4, characterized in that, In S1, the particles are ground to a size of 150-200 mesh.

7. A high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 6, characterized in that, In S1, the particles are ground to a size of 180 mesh.

8. A high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 4, characterized in that, In S2, the concentration of hydrogen peroxide solution is 1.0~2.0 wt%; the amount used should be sufficient to completely immerse the cathode carbon block; the soaking time of hydrogen peroxide solution is 1~5 hours.

9. A high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 4, characterized in that, In S2, the mass ratio of cathode carbon block to quicklime for soaking is 80~120:1; add quicklime and continue soaking for 1~5 hours.

10. A high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 4, characterized in that, In S2, the mass ratio of the cathode carbon block to the quicklime added after filtration and drying is 250~350:

1.

11. A high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 4, characterized in that, Grind in S2 to a particle size of 200-250 mesh.

12. A high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 11, characterized in that, Grind in S2 to a particle size of 230 mesh.

13. A high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 1 or 2, characterized in that, The high-temperature strength-stabilized material is a mixture of waste aluminosilicate glass powder and industrial quartz sand; The aluminosilicate glass powder accounts for 10~40wt% and has a particle size of 150~200 mesh; The industrial quartz sand accounts for 60~90wt%, and the particle size of the industrial quartz sand is divided into two gradations: 300~350 mesh and 700~900 mesh, with a mass ratio of 40~62:5~25.

14. A high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 13, characterized in that, The aluminosilicate glass powder accounts for 25~40wt%.

15. A high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 13, characterized in that, The aluminosilicate glass powder has a particle size of 170 mesh.

16. A high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 13, characterized in that, Industrial quartz sand accounts for 60-75%.

17. A high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 13, characterized in that, Industrial quartz sand is available in two particle sizes: 325 mesh and 800 mesh.

18. A high thermal conductivity cement slurry system for cementing wells using solid waste according to claim 1 or 2, characterized in that, The retarder is at least one of gluconate and sulfonate; The water loss reducing agent is an AMPS-amide-carboxylic acid polymer; The dispersant is a formaldehyde-acetone condensate; The suspension stabilizer is at least one of AM-AMPS-NVP polymers and microsilicon; The defoamer is tributyl phosphate.

19. A method for preparing a cement slurry system according to any one of claims 1-18, characterized in that, The cement slurry system was prepared according to GB / T 19139-2012 Oil Well Cement Test Method.

20. The method for preparing the cement slurry system according to claim 19, characterized in that, The water-cement ratio is 0.

44.

21. The application of the cement slurry system according to any one of claims 1-18, characterized in that, Applications as cementing slurry.

22. The application of the cement slurry system according to claim 21, characterized in that, Application as cement slurry for geothermal well cementing.

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