A high-temperature resistant, high-strength, low-elastic-modulus, high-density cementing agent

Abstract

This invention discloses a high-temperature resistant, high-strength, low-elasticity, high-density cementing material, relating to the field of cementing materials technology in oil and gas development. It comprises the following components by weight: 100 parts oil well cement; 35-40 parts strength stabilizing material; 50-300 parts density regulator; 0.3-0.5 parts high-strength toughening material; 0.8-1.5 parts flexible sealant; 0.2-0.4 parts suspension stabilizer; 0.5-0.8 parts dispersant; 2-3 parts fluid loss reducing agent; and 0.8-2.0 parts retarder. The oil well cement is of grade G and grade D. The mixed oil well cement has a cement mass ratio of 8:2. The high-strength toughening material is a mixture of modified carbon fiber, modified polyether ether ketone fiber, modified polyether sulfone fiber, β-type silicon carbide whiskers and potassium hexatitanate whiskers in a mass ratio of 40-60:15-25:15-25:5-8:2-4. The flexible sealant is a mixture of high-temperature resistant modified polycarbonate and sulfonated asphalt in a mass ratio of 8:2. This mixture can achieve self-toughening of the cement stone, so that the prepared cement slurry not only has good construction performance, but also has the characteristics of high strength and low elastic modulus under high temperature conditions.

Description

Technical Field

[0001] This invention relates to the field of cementing materials technology in oil and gas development, specifically to a high-temperature resistant, high-strength, low-elastic-modulus, high-density cementing material. Background Technology

[0002] With the continuous deepening of oil and gas exploration and development, deep and ultra-deep wells have become important battlegrounds for increasing oil and gas production, and the number of cementing operations is also increasing. Consequently, the problems encountered during cementing are also growing. One of the primary challenges is dealing with high-pressure formation fluids (including oil, gas, and water). To balance formation pressure and ensure operational safety, high-density and ultra-high-density cement slurries are required. However, current high-density cement slurries cannot fully meet the high-quality cementing requirements for drilling into complex formations with high temperature and pressure, especially in small-bore, narrow-interval cementing and long horizontal well cementing operations. Ensuring both good workability and the hydraulic sealing performance of the cement slurry presents several challenges:

[0003] (1) The addition of high-density cement slurry weighting material results in a high solid content in the cement slurry and a poor flowability of the cement slurry, which has an adverse effect on the construction operation.

[0004] (2) Excessive addition of heavy materials can easily cause cement slurry to separate into layers. If the cement slurry has poor suspension performance, it will cause the light materials to float and the heavy materials to sink. This problem should be avoided, especially when cementing long horizontal wells.

[0005] (3) As an inert material, the weighting material will have a negative impact on the mechanical properties of the cement slurry after being added to it.

[0006] (4) High-density cement stone generally has poor toughness. After being subjected to external impacts during later construction operations, it is easy to cause cracks in the cement ring, which affects the hydraulic sealing integrity of the cement ring.

[0007] To address the aforementioned issues and improve the rheological properties of cement slurry and the mechanical properties of cement paste, methods such as altering the particle size distribution and incorporating appropriate toughening materials can be employed. Existing technologies include patent application CN113800832A, entitled "A Low-Friction High-Density Cement Slurry and Its Preparation Method," which processes the weighting material to obtain a cement slurry with good rheological properties; another example is patent application CN108439872A, entitled "A High-Temperature Resistant, High-Strength, Low-Modulus High-Density Cement Slurry," which uses a close-packed design of dry powder particle size distribution and the use of nano-reinforcing toughening agents to give the cement paste high strength and low elastic modulus mechanical properties; yet another example is patent application CN112390572A, entitled "Cement Slurry and Its Preparation Method," which improves the rheological properties of salt-containing high-density cement slurry by adding chain monomers, lubricants, and surfactants.

[0008] It is evident that existing technologies generally treat high-density cement slurry by improving the particle size distribution of the slurry or by using reinforcing and toughening materials, which can improve the cementing problem of high-density cement slurry to a certain extent, but some of the aforementioned defects still exist. Summary of the Invention

[0009] The purpose of this invention is to provide a high-temperature resistant, high-strength, low-elastic modulus, high-density cementing cement. By using high-strength, tough materials and flexible sealants, the settling stability and mechanical properties of the cement stone are significantly improved, especially the strength, toughness, and sealing integrity of the cement stone. This achieves self-toughening of the cement stone, so that the prepared cement slurry not only has good workability, but also has the characteristics of high strength and low elastic modulus under high temperature conditions.

[0010] This invention is achieved through the following technical solution:

[0011] This invention proposes a high-temperature resistant, high-strength, low-elasticity, high-density cementing material, relating to the field of cementing materials technology in oil and gas development. It comprises the following components by weight: 100 parts oil well cement; 35-40 parts strength stabilizing material; 50-300 parts density regulator; 0.3-0.5 parts high-strength toughening material; 0.8-1.5 parts flexible sealant; 0.2-0.4 parts suspension stabilizer; 0.5-0.8 parts dispersant; 2-3 parts fluid loss reducing agent; and 0.8-2.0 parts retarder. The high-strength toughening material is a mixture of modified carbon fiber, modified polyetheretherketone fiber, modified polyethersulfone fiber, β-type silicon carbide whiskers, and potassium hexatitanate whiskers in a weight ratio of 40-60:15-25:15-25:5-8:2-4. The flexible sealant is a mixture of high-temperature resistant modified polycarbonate and sulfonated asphalt in a weight ratio of 8:2.

[0012] In this invention, the oil well cement is a mixture of Grade G oil well cement and Grade D oil well cement in a mass ratio of 8:2; furthermore, the two types of oil well cement are high sulfate-resistant oil well cement (HSR).

[0013] In this invention, the strength-stabilizing material is a mixture of silica sand and nano-silica in a mass ratio of 9:1; wherein the particle size of the silica sand is in the range of 100-300 mesh, and the particle size of the nano-silica is in the range of 1-100 nm.

[0014] In this invention, the density regulator is either micro-manganese ore powder or iron powder; wherein the density of the micro-manganese ore powder is 4.8 g / cm³. 3 The density of the iron powder is 7.0 g / cm³. 3 .

[0015] In this invention, considering the harsh conditions of high-temperature formation environment encountered in cementing engineering, in order to ensure good engineering performance and cementing quality at high temperatures, the high-strength toughening material is made by high-speed mixing of high-temperature resistant and high-strength composite fibers and whiskers; specifically, the high-strength toughening material is made by high-speed airflow mixing of modified carbon fiber, modified polyetheretherketone fiber, modified polyethersulfone fiber, β-type silicon carbide whiskers and potassium hexatitanate whiskers in a mass ratio of 40-60:15-25:15-25:5-8:2-4.

[0016] More specifically, the preparation method of the high-strength toughening material in this invention is as follows: modified carbon fiber, modified polyether ether ketone fiber, modified polyether sulfone fiber, β-type silicon carbide whiskers and potassium hexatitanate whiskers are weighed according to the above mass ratio, and all of them are mixed uniformly by high-speed airflow at room temperature; wherein, the high-speed airflow mixing process can further increase the surface roughness of the material and improve the surface free energy, thereby increasing the contact area with the cement substrate.

[0017] To further stabilize the product performance in this scheme, the modified carbon fiber used in this scheme is prepared by mixing molten petroleum asphalt with styrene-butadiene-styrene block copolymer, nano-silicon carbide, graphite powder, and nano-zirconium carbide to obtain modified asphalt. The modified asphalt is then used to modify the carbon fiber bundles, followed by plasma treatment and sulfonation to obtain the modified carbon fiber.

[0018] The modified polyetheretherketone fiber is produced by mixing molten polyetheretherketone with nano-silicon carbide and nano-zirconium carbide, spinning the modified polyetheretherketone fiber, and then subjecting it to sulfonation treatment.

[0019] The modified polyethersulfone fiber is obtained by melt blending polyethersulfone, polytetrafluoroethylene, nano-silicon carbide, and nano-zirconium carbide to obtain modified polyethersulfone, then spinning the modified polyethersulfone into modified polyethersulfone fiber, and finally obtaining modified polyethersulfone fiber after sulfonation treatment.

[0020] Specifically, to improve the durability and long-term stability of carbon fibers at high temperatures, this invention provides a preferred method for preparing the modified carbon fibers. The method includes the following steps:

[0021] a1. First, heat 100 parts of petroleum asphalt to a molten state, then add 3 parts of styrene-butadiene-styrene block copolymer (SBS), 2 parts of nano-silicon carbide (nano-SiC), 2 parts of graphite oxide powder and 1 part of nano-zirconium carbide (nano-ZrC), and stir evenly for 180 minutes to obtain modified asphalt.

[0022] b1. Then, the carbon fiber bundles are immersed in molten modified bitumen, and the carbon fiber bundles are pulled out from the modified bitumen at a roller speed of 5 m / min. After cooling and drying, the surface of the bundles is uniformly covered with a modified bitumen layer. Then, the bundles are cut to a length of 3 mm to obtain preliminary modified carbon fibers.

[0023] c1. Then, the modified carbon fiber is subjected to low-temperature plasma treatment with O2 gas to introduce chemical bonds such as C=O and CO, which enhances its surface activity and hydrophilicity, while improving its surface roughness, thus obtaining secondary modified carbon fiber.

[0024] d1. Finally, it is placed in SO3 gas for sulfonation treatment to introduce sulfonic acid groups, which further enhances its surface activity and hydrophilicity, resulting in the final modified carbon fiber.

[0025] This invention also provides a method for preparing modified polyetheretherketone (PEEK) fibers, enabling the obtained modified PEEK fiber product to maintain good durability and long-term stability at high temperatures. Specifically, it includes the following steps:

[0026] a2. Heat 100 parts of polyether ether ketone to a molten state, then add 5 parts of nano-silicon carbide (nano-SiC) and 1 part of nano-zirconium carbide (nano-ZrC), stir evenly for 120 min to obtain modified polyether ether ketone;

[0027] b2. Modified polyetheretherketone (PEEK) fibers are then produced by melt spinning and cut into 1 mm lengths to obtain modified PEEK fibers.

[0028] c2. Then, place it in SO3 gas for sulfonation treatment to introduce sulfonic acid groups, resulting in multi-modified polyether ether ketone fibers. The surface of the sulfonated polyether ether ketone fibers can exhibit a three-dimensional porous network structure, and the surface roughness and hydrophilicity of the fibers are significantly improved.

[0029] This invention also provides a method for preparing modified polyethersulfone fibers, enabling the obtained modified polyethersulfone fiber product to maintain long-term stability and durability under high-temperature conditions at the bottom of the well. Specifically, it includes the following steps:

[0030] a3. After uniformly mixing 100 parts of polyethersulfone, 5 parts of polytetrafluoroethylene, 3 parts of nano-silicon carbide (nano-SiC) and 1 part of nano-zirconium carbide (nano-ZrC), modified polyethersulfone is obtained by melt blending.

[0031] b3. Modified polyethersulfone fibers are then produced by melt spinning and cut into 1mm lengths to obtain modified polyethersulfone fibers;

[0032] c3. Then place it in SO3 gas to sulfonate it, introduce sulfonic acid bonds to enhance its hydrophilicity and surface roughness, and obtain the final modified polyethersulfone fiber.

[0033] In this invention, the length of the β-type silicon carbide whisker ranges from 50 to 100 μm, and the diameter ranges from 5 to 10 μm.

[0034] In this invention, the potassium hexatite whiskers have a length range of 10-200 μm and a diameter range of 1-30 μm.

[0035] The main mechanism of action of the high-strength toughening material in this invention is as follows: there is a certain linear relationship between the mechanical properties of the cement stone itself, such as its strength and elastic modulus, and the material and dosage of the toughening agent added therein. When the toughening material incorporated therein possesses high strength and high modulus physical properties, the strength of the cement stone generally shows a linear growth trend. Secondly, through physical incorporation, the unmodified toughening material basically does not participate in the cement hydration process, but after surface modification, its surface activity is improved, which can improve the strength of the bonding surface between the toughening material and the cement stone to a certain extent. After the cement stone hardens and is formed, the toughening material incorporated therein further improves the mechanical properties of the cement stone through fiber pull-out, crack deflection, cross-sectional bridging, peeling, and pull-out energy dissipation, thereby achieving the purpose of enhancing the toughness of the cement stone. Modifying carbon fibers not only preserves their original properties but also increases their hydrophilicity and roughness through coating and subsequent modification. This enhances the bonding strength between the fiber and cement paste, thus positively impacting the mechanical properties of the cement paste. Similarly, modifying polyetheretherketone (PEEK) and polyethersulfone (PES) fibers also increases their hydrophilicity and roughness, further improving the mechanical properties of the cement paste. Using different ratios of modified fibers and whiskers can create multi-scale toughening materials. By controlling the dimensions, a relatively stable three-dimensional spatial structure can be formed in the slurry, significantly improving the macroscopic mechanical properties of the cement paste.

[0036] To enable the polycarbonate in the above-mentioned flexible sealant to have higher heat distortion temperature, thermal stability and corrosion resistance, this invention also provides a high-temperature modified polycarbonate prepared from polycarbonate, styrene-maleic anhydride copolymer, polyetherimide, polychlorotrifluoroethylene, nano-silicon nitride and carbon nanotubes, to meet the raw material requirements for preparing the target product.

[0037] Furthermore, a preferred preparation method for this high-temperature resistant modified polycarbonate is proposed, enabling it to maintain stable performance even in high-temperature environments at the bottom of wells. Specifically, the method includes the following steps:

[0038] a4. By mass, 100 parts of polycarbonate and 5 parts of styrene-maleic anhydride copolymer dry powder are mixed and heated to 250°C under argon as a protective gas, and melt-blended for 60 min to obtain preliminarily modified polycarbonate.

[0039] b4. Then, the preliminarily modified polycarbonate in step a4 is cooled to 200°C, and 5 parts by mass of polyetherimide, 5 parts by mass of polyvinyl chloride trifluoroethylene, 3 parts by mass of nano-silicon nitride and 2 parts by mass of carbon nanotubes are incorporated into it, and argon is used as a protective gas for melt blending for 90 min.

[0040] c4. Finally, cool it and grind it to a finer mesh than 500 to obtain high-temperature resistant modified polycarbonate.

[0041] Meanwhile, in order to ensure that the sealing flexibility agent can be uniformly dispersed and suspended in the cementing slurry, the sulfonated asphalt used in this invention has a particle size of 500 mesh or higher.

[0042] In this invention, to ensure good dispersibility and suspension properties of the suspension stabilizer, the suspension stabilizer is sodium bentonite, and the particle size is preferably 200 mesh or larger.

[0043] In this invention, to ensure good fluidity of the slurry at high temperatures, the dispersant is preferably one of carboxylates or polystyrene sulfonates.

[0044] In this invention, to ensure low water loss of the slurry at high temperatures, the water loss reducing agent is preferably an AMPS polymer-based water loss reducing agent.

[0045] In this invention, to ensure sufficient thickening time for the slurry at high temperatures and to meet construction requirements, the retarder is preferably an AMPS polymer retarder.

[0046] The cement prepared using the above-described method, when mixed with water at a liquid-to-solid ratio of 0.29-0.38, yields a high-temperature resistant, high-strength, low-elastic-modulus, high-density cement slurry. The density of the cement slurry ranges from 2.00 to 2.60 g / cm³. 3Its applicable temperature can reach 230℃. At high temperatures, the slurry has stable properties with no free liquid and no stratification. After curing for 72 hours, the compressive strength is greater than 28MPa, the flexural strength is greater than 8MPa, and the elastic modulus is less than 4.70GPa. It has the mechanical properties of high compressive strength and low elastic modulus.

[0047] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0048] 1. In this invention, the stability and suspension properties of the cement slurry system are improved by incorporating toughening materials, suspension stabilizers and flexible sealants. In particular, the toughening materials form a three-dimensional network structure in the slurry, and the suspension stabilizers and flexible sealants work together to ensure that the weighting materials in the slurry can be stably suspended, avoiding problems such as slurry instability and uneven performance caused by the sinking of the weighting materials.

[0049] 2. In this invention, the high-temperature resistant, high-strength, low-elasticity, high-density cement slurry is prepared by adding strength-stabilizing materials, high-strength and toughness materials, and flexible sealants, achieving stable slurry properties, good rheological properties, no free fluid, and no stratification; the density range of this cement slurry is 2.00-2.60 g / cm³. 3 Its applicable temperature can reach 230℃. After curing for 72 hours, the compressive strength is greater than 28MPa, the flexural strength is greater than 8MPa, and the elastic modulus is less than 4.70GPa.

[0050] 3. In this invention, modified composite fibers and whiskers are mixed as toughening agents, both of which are high-temperature resistant materials. This basically meets the harsh conditions of high-temperature formation environments faced in existing cementing projects, while maintaining good engineering performance at high temperatures, thus ensuring cementing quality. At the same time, modified polycarbonate and sulfonated asphalt are mixed as flexible sealants, which can significantly reduce the permeability of cement stone, improve its mechanical properties and toughness. When microcracks or other problems occur under ultra-high temperature conditions, the thermoplastic material can also seal and repair them accordingly, further ensuring the sealing integrity of the cement stone.

[0051] 4. In this invention, when the slurry is prepared by combining oil well cement, strength stabilizing materials, density regulators, toughening materials, flexible sealants and other materials, these materials have a certain particle size distribution effect, which not only improves the density of cement stone and reduces the permeability of cement stone, but also improves the rheological stability of the slurry. Attached Figure Description

[0052] Figure 1 This is a microstructure diagram of the cement stone in Example 1.

[0053] Figure 2 This is a microstructure diagram of cement stone in Example 3.

[0054] Figure 3 This is a microstructure diagram of the cement stone in Example 5.

[0055] Figure 4 This is a microstructure diagram of the cement stone in Example 7. Detailed Implementation

[0056] The technical solution of the present invention will be further described in detail below with reference to the embodiments. It should be noted that the embodiments described below are merely preferred embodiments of the present invention and not all embodiments. Therefore, these embodiments are only described to help understand the present invention and do not constitute a limitation of the present invention.

[0057] The materials (reagents) used in the following embodiments include:

[0058] Both Grade G and Grade D well cements are high sulfate-resistant (HSR) type.

[0059] The average particle size of silica sand is 200 mesh; the particle size range of nano silica is 1-100 nm, and Dv(50) is 38 nm.

[0060] The density of the micro-manganese ore powder is 4.8 g / cm³. 3 The density of the iron powder is 7.0 g / cm³. 3 .

[0061] The length of β-type silicon carbide whiskers ranges from 50 to 100 μm, and the diameter ranges from 5 to 10 μm, with 80% of them having a length of no more than 85 μm.

[0062] Potassium hexatitanate whiskers range in length from 10 to 200 μm and in diameter from 1 to 30 μm, with those no longer than 150 μm accounting for 85% of the total.

[0063] The modified carbon fiber material used was obtained by the following preparation method, including the following steps:

[0064] a1. Heat 100 parts of petroleum asphalt to a molten state, then add 3 parts of styrene-butadiene-styrene block copolymer (SBS), 2 parts of nano-silicon carbide (nano-SiC), 2 parts of graphite oxide powder and 1 part of nano-zirconium carbide (nano-ZrC), and stir evenly for 180 min to obtain modified asphalt.

[0065] b1. Then, the carbon fiber bundles are immersed in molten modified bitumen, and the carbon fiber bundles are pulled out from the modified bitumen at a roller speed of 5 m / min. After cooling and drying, the surface of the bundles is uniformly covered with a modified bitumen layer. Then, the bundles are cut to a length of 3 mm to obtain preliminary modified carbon fibers.

[0066] c1. Then, the modified carbon fiber is subjected to low-temperature plasma treatment with O2 gas to introduce chemical bonds such as C=O and CO, which enhances its surface activity and hydrophilicity, while improving its surface roughness, thus obtaining secondary modified carbon fiber.

[0067] d1. Finally, it is placed in SO3 gas for sulfonation treatment to introduce sulfonic acid groups, which further enhances its surface activity and hydrophilicity, resulting in the final modified carbon fiber.

[0068] The modified polyetheretherketone fiber material used was obtained by the following preparation method, including the following steps:

[0069] a2. Heat 100 parts of polyether ether ketone to a molten state, then add 5 parts of nano-silicon carbide (nano-SiC) and 1 part of nano-zirconium carbide (nano-ZrC), stir evenly for 120 min to obtain modified polyether ether ketone;

[0070] b2. Modified polyetheretherketone (PEEK) fibers are then produced by melt spinning and cut into 1 mm lengths to obtain modified PEEK fibers.

[0071] c2. Then, place it in SO3 gas for sulfonation treatment to introduce sulfonic acid groups, resulting in multi-modified polyether ether ketone fibers. The surface of the sulfonated polyether ether ketone fibers can exhibit a three-dimensional porous network structure, and the surface roughness and hydrophilicity of the fibers are significantly improved.

[0072] The modified polyethersulfone fiber material used was obtained by the following preparation method, including the following steps:

[0073] a3. After uniformly mixing 100 parts of polyethersulfone, 5 parts of polytetrafluoroethylene, 3 parts of nano-silicon carbide (nano-SiC) and 1 part of nano-zirconium carbide (nano-ZrC), modified polyethersulfone is obtained by melt blending.

[0074] b3. Modified polyethersulfone fibers are then produced by melt spinning and cut into 1mm lengths to obtain modified polyethersulfone fibers;

[0075] c3. Then place it in SO3 gas to sulfonate it, introduce sulfonic acid bonds to enhance its hydrophilicity and surface roughness, and obtain the final modified polyethersulfone fiber.

[0076] The length of β-type silicon carbide whiskers ranges from 50 to 100 μm, and the diameter ranges from 5 to 10 μm.

[0077] Potassium hexatitanate whiskers have a length of 10-200 μm and a diameter of 1-30 μm.

[0078] The modified polycarbonate material used was obtained by the following preparation method, with the specific steps as follows:

[0079] a4. By mass, 100 parts of polycarbonate and 5 parts of styrene-maleic anhydride copolymer dry powder are mixed and heated to 250°C under argon as a protective gas, and melt-blended for 60 min to obtain preliminarily modified polycarbonate.

[0080] b4. Then cool it down to 200℃, and add 5 parts polyetherimide, 5 parts polyvinyl chloride trifluoroethylene, 3 parts nano silicon nitride and 2 parts carbon nanotubes by mass, and melt-blend it again for 90 minutes with argon as a protective gas.

[0081] c4. Finally, cool it and grind it to a finer mesh than 500 to obtain high-temperature resistant modified polycarbonate.

[0082] The particle size of sulfonated asphalt is 500 mesh.

[0083] The suspension stabilizer is sodium bentonite with a particle size of 200 mesh.

[0084] The dispersant is a carboxylate or polystyrene sulfonate.

[0085] The water loss reducing agent is an AMPS polymer-based water loss reducing agent.

[0086] The retarder is an AMPS polymer retarder.

[0087] Example 1

[0088] As a preferred embodiment of the present invention, this embodiment discloses a high-temperature resistant, high-strength, low-elasticity, high-density cementing material, comprising the following components in the following mass ratios: 100 parts oil well cement, 35 parts strength stabilizing material, 50 parts density regulator, 0.5 parts high-strength toughening material, 1.5 parts flexible sealant, 0.2 parts suspension stabilizer, 0.5 parts dispersant, 3 parts fluid loss reducing agent, and 1 part retarder.

[0089] In this example, the oil well cement is a mixture of Grade G oil well cement and Grade D oil well cement in a mass ratio of 8:2.

[0090] In this example, the strength stabilizing material is a mixed strength stabilizing material of silica sand and nano-silica (nano-SiO2) in a mass ratio of 9:1.

[0091] In this example, the density regulator is micro-manganese mineral powder.

[0092] In this example, the high-strength and toughened material is prepared by high-speed airflow mixing of modified carbon fiber, modified polyetheretherketone fiber, modified polyethersulfone fiber, β-type silicon carbide whiskers, and potassium hexatitanate whiskers in a mass ratio of 40:25:25:7:3. The modified carbon fiber, modified polyetheretherketone fiber, and modified polyethersulfone fiber are prepared according to the aforementioned method. The calcium carbonate whiskers have a length of 50-100 μm; the potassium titanate whiskers have a length of 10-200 μm.

[0093] In this embodiment, the flexible sealant is a dry powder material made of high-temperature modified polycarbonate and sulfonated asphalt in a mass ratio of 8:2; wherein the high-temperature modified polycarbonate is prepared by the aforementioned method; and the sulfonated asphalt has a particle size of 500 mesh.

[0094] In this example, the suspension stabilizer is sodium bentonite powder with a particle size of 200 mesh.

[0095] In this example, the dispersant is a carboxylate dispersant.

[0096] In this example, the water loss reducing agent is an AMPS polymer-based water loss reducing agent.

[0097] In this example, the retarder is an AMPS polymer retarder.

[0098] In this embodiment, the prepared cementing cement is mixed with water at a liquid-to-solid ratio of 0.38 to prepare cementing slurry, and the density of the prepared cementing slurry is 2.00 g / cm³. 3 The microstructure diagram of the cement stone obtained in this embodiment is shown below. Figure 1 ...

[0099] Example 2

[0100] As another preferred embodiment of the present invention, this embodiment discloses a high-temperature resistant, high-strength, low-elastic modulus, high-density cementing material, comprising the following components in the following mass ratios: 100 parts oil well cement, 36 parts strength stabilizing material, 100 parts density regulator, 0.5 parts high-strength toughening material, 1.2 parts flexible sealant, 0.3 parts suspension stabilizer, 0.6 parts dispersant, 2.5 parts fluid loss reducing agent, and 1.5 parts retarder.

[0101] In this example, the oil well cement is a mixture of Grade G oil well cement and Grade D oil well cement in a mass ratio of 8:2.

[0102] In this embodiment, the strength stabilizing material is a mixed strength stabilizing material of silica sand and nano-silica (nano-SiO2) in a mass ratio of 9:1.

[0103] In this embodiment, the density regulator is micro manganese mineral powder.

[0104] In this embodiment, the high-strength and toughening material is prepared by high-speed airflow mixing of modified carbon fiber, modified polyetheretherketone fiber, modified polyethersulfone fiber, β-type silicon carbide whiskers, and potassium hexatitanate whiskers in a mass ratio of 48:22:18:8:4. The modified carbon fiber, modified polyetheretherketone fiber, and modified polyethersulfone fiber are prepared according to the aforementioned method. The calcium carbonate whiskers have a length of 50-100 μm; the potassium titanate whiskers have a length of 10-200 μm.

[0105] In this embodiment, the flexible sealant is a dry powder material made of high-temperature modified polycarbonate and sulfonated asphalt in a mass ratio of 8:2; wherein the high-temperature modified polycarbonate is prepared by the aforementioned method; and the sulfonated asphalt has a particle size of 500 mesh.

[0106] In this example, the suspension stabilizer is sodium bentonite powder with a particle size of 200 mesh.

[0107] In this example, the dispersant is a polystyrene sulfonate dispersant.

[0108] In this example, the water loss reducing agent is an AMPS polymer-based water loss reducing agent.

[0109] In this example, the retarder is an AMPS polymer retarder.

[0110] In this example, the prepared cementing cement was mixed with water at a liquid-to-solid ratio of 0.35 to prepare cementing slurry, and the density of the prepared cementing slurry was 2.10 g / cm³. 3 .

[0111] Example 3

[0112] As another preferred embodiment of the present invention, this embodiment discloses a high-temperature resistant, high-strength, low-elasticity, high-density cementing material, comprising the following components in the following mass ratios: 100 parts oil well cement, 37 parts strength stabilizing material, 150 parts density regulator, 0.4 parts high-strength toughening material, 1.0 part flexible sealant, 0.3 parts suspension stabilizer, 0.7 parts dispersant, 2.5 parts fluid loss reducing agent, and 2.0 parts retarder.

[0113] In this example, the oil well cement is a mixture of Grade G oil well cement and Grade D oil well cement in a mass ratio of 8:2.

[0114] In this embodiment, the strength stabilizing material is a mixed strength stabilizing material of silica sand and nano-silica (nano-SiO2) in a mass ratio of 9:1.

[0115] In this embodiment, the density regulator is micro manganese mineral powder.

[0116] In this embodiment, the high-strength and toughening material is prepared by high-speed airflow mixing of modified carbon fiber, modified polyetheretherketone fiber, modified polyethersulfone fiber, β-type silicon carbide whiskers, and potassium hexatitanate whiskers in a mass ratio of 52:20:20:5:3. The modified carbon fiber, modified polyetheretherketone fiber, and modified polyethersulfone fiber are prepared according to the aforementioned method. The calcium carbonate whiskers have a length of 50-100 μm; the potassium titanate whiskers have a length of 10-200 μm.

[0117] In this embodiment, the flexible sealant is a dry powder material made of high-temperature modified polycarbonate and sulfonated asphalt in a mass ratio of 8:2; wherein the high-temperature modified polycarbonate is prepared by the aforementioned method; and the sulfonated asphalt has a particle size of 500 mesh.

[0118] In this example, the suspension stabilizer is sodium bentonite powder with a particle size of 200 mesh.

[0119] In this example, the dispersant is a polystyrene sulfonate dispersant.

[0120] In this example, the water loss reducing agent is an AMPS polymer-based water loss reducing agent.

[0121] In this example, the retarder is an AMPS polymer retarder.

[0122] In this example, the prepared cementing cement was mixed with water at a liquid-to-solid ratio of 0.32 to prepare cementing slurry, and the density of the prepared cementing slurry was 2.20 g / cm³. 3 The microstructure diagram of the cement stone obtained in this embodiment is shown below. Figure 2 .

[0123] Example 4

[0124] As another preferred embodiment of the present invention, this embodiment discloses a high-temperature resistant, high-strength, low-elasticity, high-density cementing material, comprising the following components in the following mass ratios: 100 parts oil well cement, 40 parts strength stabilizing material, 200 parts density regulator, 0.4 parts high-strength toughening material, 0.8 parts flexible sealant, 0.4 parts suspension stabilizer, 0.8 parts dispersant, 2.2 parts fluid loss reducing agent, and 0.8 parts retarder.

[0125] In this example, the oil well cement is a mixture of Grade G oil well cement and Grade D oil well cement in a mass ratio of 8:2.

[0126] In this embodiment, the strength stabilizing material is a mixed strength stabilizing material of silica sand and nano-silica (nano-SiO2) in a mass ratio of 9:1.

[0127] In this embodiment, the density regulator is micro manganese mineral powder.

[0128] In this embodiment, the high-strength and toughening material is prepared by high-speed airflow mixing of modified carbon fiber, modified polyetheretherketone fiber, modified polyethersulfone fiber, β-type silicon carbide whiskers, and potassium hexatitanate whiskers in a mass ratio of 56:18:18:6:2. The modified carbon fiber, modified polyetheretherketone fiber, and modified polyethersulfone fiber are prepared according to the aforementioned method. The calcium carbonate whiskers have a length of 50-100 μm; the potassium titanate whiskers have a length of 10-200 μm.

[0129] In this embodiment, the flexible sealant is a dry powder material made of high-temperature modified polycarbonate and sulfonated asphalt in a mass ratio of 8:2; wherein the high-temperature modified polycarbonate is prepared by the aforementioned method; and the sulfonated asphalt has a particle size of 500 mesh.

[0130] In this example, the suspension stabilizer is sodium bentonite powder with a particle size of 200 mesh.

[0131] In this example, the dispersant is a polycarboxylate dispersant.

[0132] In this example, the water loss reducing agent is an AMPS polymer-based water loss reducing agent.

[0133] In this example, the retarder is an AMPS polymer retarder.

[0134] In this example, the prepared cementing cement was mixed with water at a liquid-to-solid ratio of 0.30 to prepare cementing slurry, and the density of the prepared cementing slurry was 2.30 g / cm³. 3 .

[0135] Example 5

[0136] As another preferred embodiment of the present invention, this embodiment discloses a high-temperature resistant, high-strength, low-elastic modulus, high-density cement slurry system, comprising the following components in the following mass ratios: 100 parts oil well cement, 38 parts strength stabilizing material, 250 parts density regulator, 0.4 parts high-strength toughening material, 1.2 parts flexible sealant, 0.3 parts suspension stabilizer, 0.7 parts dispersant, 2.2 parts fluid loss reducing agent, and 1.2 parts retarder.

[0137] In this example, the oil well cement is a mixture of Grade G oil well cement and Grade D oil well cement in a mass ratio of 8:2.

[0138] In this embodiment, the strength stabilizing material is a mixed strength stabilizing material of silica sand and nano-silica (nano-SiO2) in a mass ratio of 9:1.

[0139] In this embodiment, the density regulator is iron powder.

[0140] In this embodiment, the high-strength and toughening material is prepared by high-speed airflow mixing of modified carbon fiber, modified polyetheretherketone fiber, modified polyethersulfone fiber, β-type silicon carbide whiskers, and potassium hexatitanate whiskers in a mass ratio of 60:15:15:8:2. The modified carbon fiber, modified polyetheretherketone fiber, and modified polyethersulfone fiber are prepared according to the aforementioned method. The calcium carbonate whiskers have a length of 50-100 μm; the potassium titanate whiskers have a length of 10-200 μm.

[0141] In this embodiment, the flexible sealant is a dry powder material made of high-temperature modified polycarbonate and sulfonated asphalt in a mass ratio of 8:2; wherein the high-temperature modified polycarbonate is prepared by the aforementioned method; and the sulfonated asphalt has a particle size of 500 mesh.

[0142] In this example, the suspension stabilizer is sodium bentonite powder with a particle size of 200 mesh.

[0143] In this example, the dispersant is a polycarboxylate dispersant.

[0144] In this example, the water loss reducing agent is an AMPS polymer-based water loss reducing agent.

[0145] In this example, the retarder is an AMPS polymer retarder.

[0146] In this example, the prepared cementing cement was mixed with water at a liquid-to-solid ratio of 0.30 to prepare cementing slurry, and the density of the prepared cementing slurry was 2.40 g / cm³. 3 The microstructure diagram of the cement stone obtained in this embodiment is shown below. Figure 3 .

[0147] Example 6

[0148] As another preferred embodiment of the present invention, this embodiment discloses a high-temperature resistant, high-strength, low-elastic modulus, high-density cement slurry system, comprising the following components by mass percentage: 100 parts oil well cement, 39 parts strength stabilizing material, 280 parts density regulator, 0.3 parts high-strength toughening material, 1.0 part flexible sealant, 0.3 parts suspension stabilizer, 0.7 parts dispersant, 2.2 parts fluid loss reducing agent, and 1.7 parts retarder.

[0149] In this example, the oil well cement is a mixture of Grade G oil well cement and Grade D oil well cement in a mass ratio of 8:2.

[0150] In this embodiment, the strength stabilizing material is a mixed strength stabilizing material of silica sand and nano-silica (nano-SiO2) in a mass ratio of 9:1.

[0151] In this embodiment, the density regulator is iron powder.

[0152] In this embodiment, the high-strength and toughening material is prepared by high-speed airflow mixing of modified carbon fiber, modified polyetheretherketone fiber, modified polyethersulfone fiber, β-type silicon carbide whiskers, and potassium hexatitanate whiskers in a mass ratio of 55:20:15:6:4. The modified carbon fiber, modified polyetheretherketone fiber, and modified polyethersulfone fiber are prepared according to the aforementioned method. The calcium carbonate whiskers have a length of 50-100 μm; the potassium titanate whiskers have a length of 10-200 μm.

[0153] In this embodiment, the flexible sealant is a dry powder material made of high-temperature modified polycarbonate and sulfonated asphalt in a mass ratio of 8:2; wherein the high-temperature modified polycarbonate is prepared by the aforementioned method; and the sulfonated asphalt has a particle size of 500 mesh.

[0154] In this example, the suspension stabilizer is sodium bentonite powder with a particle size of 200 mesh.

[0155] In this example, the dispersant is a polystyrene sulfonate dispersant.

[0156] In this example, the water loss reducing agent is an AMPS polymer-based water loss reducing agent.

[0157] In this example, the retarder is an AMPS polymer retarder.

[0158] In this example, the prepared cementing cement was mixed with water at a liquid-to-solid ratio of 0.31 to prepare cementing slurry, and the density of the prepared cementing slurry was 2.50 g / cm³. 3 .

[0159] Example 7

[0160] As another preferred embodiment of the present invention, this embodiment discloses a high-temperature resistant, high-strength, low-elastic modulus, high-density cement slurry system, comprising the following components by mass percentage: 100 parts oil well cement, 37 parts strength stabilizing material, 300 parts density regulator, 0.3 parts high-strength toughening material, 0.8 parts flexible sealant, 0.4 parts suspension stabilizer, 0.8 parts dispersant, 2 parts fluid loss reducing agent, and 1.5 parts retarder.

[0161] In this example, the oil well cement is a mixture of Grade G oil well cement and Grade D oil well cement in a mass ratio of 8:2.

[0162] In this embodiment, the strength stabilizing material is a mixed strength stabilizing material of silica sand and nano-silica (nano-SiO2) in a mass ratio of 9:1.

[0163] In this embodiment, the density regulator is iron powder.

[0164] In this embodiment, the high-strength and toughening material is prepared by high-speed airflow mixing of modified carbon fiber, modified polyetheretherketone fiber, modified polyethersulfone fiber, β-type silicon carbide whiskers, and potassium hexatitanate whiskers in a mass ratio of 50:22:18:7:3. The modified carbon fiber, modified polyetheretherketone fiber, and modified polyethersulfone fiber are prepared according to the aforementioned method. The calcium carbonate whiskers have a length of 50-100 μm; the potassium titanate whiskers have a length of 10-200 μm.

[0165] In this embodiment, the flexible sealant is a dry powder material made of high-temperature modified polycarbonate and sulfonated asphalt in a mass ratio of 8:2; wherein the high-temperature modified polycarbonate is prepared by the aforementioned method; and the sulfonated asphalt has a particle size of 500 mesh.

[0166] In this example, the suspension stabilizer is sodium bentonite powder with a particle size of 200 mesh.

[0167] In this example, the dispersant is a polystyrene sulfonate dispersant.

[0168] In this example, the water loss reducing agent is an AMPS polymer-based water loss reducing agent.

[0169] In this example, the retarder is an AMPS polymer retarder.

[0170] In this example, the prepared cementing cement was mixed with water at a liquid-to-solid ratio of 0.29 to prepare cementing slurry, and the density of the prepared cementing slurry was 2.60 g / cm³. 3 The microstructure diagram of the cement stone obtained in this embodiment is shown below. Figure 2 .

[0171] Comparative Example 1

[0172] The high-density cement slurry prepared in this comparative example is the same as that in Example 1, except that the oil well cement is Grade G high sulfate-resistant cement, and all other materials are the same.

[0173] Comparative Example 2

[0174] The high-density cement slurry prepared in this comparative example is the same as that in Example 3, except that the high-temperature toughening material is carbon fiber, while all other materials are the same.

[0175] Comparative Example 3

[0176] The high-density cement slurry prepared in this comparative example is the same as that in Example 5, except that the flexible sealing material is sulfonated asphalt, and all other materials are the same.

[0177] Comparative Example 4

[0178] The high-density cement slurry prepared in this comparative example is the same as that in Example 7, except that it does not contain high-strength toughening materials and flexible sealing materials; all other materials are the same.

[0179] test

[0180] The composition (by weight) of the high-temperature resistant, high-strength, low-elastic modulus, high-density cement slurry system in Examples 1-7 and the composition of the cement slurry system in Comparative Examples 1-4 are shown in Table 1 below.

[0181] Table 1

[0182]

[0183] The high-temperature resistant, high-strength, low-elastic modulus, and high-density cement slurry systems of the present invention obtained in Examples 1-7 and Comparative Examples 1-4 were subjected to performance tests in accordance with GB / T 19139 "Test Methods for Cement in Oil Wells" and GB / T 50266 "Standard for Test Methods for Engineering Rock Mass". The experimental results are shown in Table 2 below.

[0184] Table 2

[0185]

[0186] Note: The thickening temperature in the above experiment was 170℃; the curing temperature was 220℃.

[0187] From Table 2, Figure 1-4 It is known that the cement prepared using this method, when water is added at a slurry liquid-to-solid ratio of 0.29-0.38, yields a high-temperature resistant, high-strength, low-elastic-modulus cement slurry with a density of 2.00-2.60 g / cm³. 3 Adjustments were made within a certain range, and the cement slurry exhibited good stability, with a maximum density difference of only 0.02 g / cm³. 3Furthermore, the cement stone is relatively dense with low porosity and low slurry water loss, and the thickening time can be adjusted as needed. After 72 hours of curing, the compressive strength is greater than 28 MPa, the flexural strength is greater than 8 MPa, and the elastic modulus is less than 4.70 GPa. The cement stone exhibits high strength and low elastic modulus mechanical properties, which has a significant impact on later-stage oil and gas extraction operations, especially in operations such as perforation and formation fracturing, which can greatly reduce the probability of cement stone cracking or other adverse conditions. In comparison, the mechanical properties of cement stone in Comparative Example 1 are relatively similar, but its gas channeling pressure is correspondingly reduced, and the elastic modulus of cement stone increases. In Comparative Example 2, the flow properties, gas channeling pressure, and elastic modulus parameters of cement slurry show significant differences and exhibit a deteriorating trend. In Comparative Example 3, the cement slurry thickening time increases, the strength decreases, the gas channeling pressure decreases, and the elastic modulus increases. In Comparative Example 4, the slurry suspension performance is poor, the density difference between the upper and lower parts of the slurry is large, the slurry thickening time is shortened, and the mechanical properties of cement stone deteriorate.

[0188] It is evident that the high-density cement used in this solution exhibits superior engineering performance compared to other technical solutions, and can better meet the requirements of on-site construction.

[0189] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A high temperature resistant, high strength, low modulus of elasticity, high density well cement, characterized in that, By mass fraction, the following components are included: 100 parts of oil well cement; 35-40 parts of strength stabilizing material; 50-300 parts of density adjusting agent; 0.3-0.5 parts of high-strength toughening material; 0.8-1.5 parts of flexible sealant; 0.2-0.4 parts of suspension stabilizer; 0.5-0.8 parts of dispersing agent; 2-3 parts of fluid loss additive; 0.8-2.0 parts of retarder; The oil well cement is a mixture of G-grade oil well cement and D-grade oil well cement in a mass ratio of 8:2; The high-strength toughening material is a mixture of modified carbon fiber, modified polyether ether ketone fiber, modified polyether sulfone fiber, beta-type silicon carbide whisker and potassium hexatitanate whisker in a mass ratio of 40-60:15-25:15-25:5-8:2-4; The flexible sealant is a mixture of high-temperature resistant modified polycarbonate and sulfonated asphalt in a mass ratio of 8:2; The modified carbon fiber is obtained by mixing molten petroleum asphalt with styrene-butadiene-styrene block copolymer, nano silicon carbide, graphite oxide powder and nano zirconium carbide, obtaining modified asphalt, then modifying carbon fiber bundle with the modified asphalt, and then obtaining modified carbon fiber by plasma treatment and sulfonation; The modified polyether ether ketone fiber is obtained by mixing molten polyether ether ketone with nano silicon carbide and nano zirconium carbide, then spinning the preliminary modified polyether ether ketone fiber, and then obtaining the modified polyether ether ketone fiber by sulfonation treatment; The modified polyether sulfone fiber is obtained by mixing polyether sulfone, polytetrafluoroethylene, nano silicon carbide and nano zirconium carbide, obtaining modified polyether sulfone, then spinning the preliminary modified polyether sulfone fiber, and then obtaining the modified polyether sulfone fiber by sulfonation treatment.

2. A high temperature resistant, high strength, low elastic modulus, high density well cementing cement according to claim 1, characterized in that: The strength stabilizing material is a mixture of silica sand and nano silicon dioxide in a mass ratio of 9:

1.

3. A high temperature resistant, high strength, low elastic modulus, high density well cementing cement according to claim 2, characterized in that: The particle size of the silica sand ranges from 100 to 300 mesh, and the particle size of the nano silicon dioxide ranges from 1 to 100 nm.

4. The high temperature resistant, high strength, low modulus of elasticity, high density well cementation cement of claim 1, wherein: The density adjusting agent is one of micro-manganese ore powder or iron powder.

5. A high temperature resistant, high strength, low elastic modulus, high density well cementing cement according to claim 4, characterized in that: The density of the micro-manganese ore powder is 4.8 g / cm 3 The density of the iron powder is 7.0 g / cm 3 .

6. The high temperature resistant, high strength, low elastic modulus, high density well cement of claim 1, wherein, The preparation method of the modified carbon fiber is as follows: a1. 100 parts of petroleum asphalt are heated to a molten state, and then 3 parts of styrene-butadiene-styrene block copolymer, 2 parts of nano silicon carbide, 2 parts of graphite oxide powder and 1 part of nano zirconium carbide are added, stirred for 180 min to obtain modified asphalt; b1. The carbon fiber bundle is immersed in the modified asphalt of step a1, and the carbon fiber bundle is pulled out of the modified asphalt at a roller speed of 5 m / min, and then cooled, dried and cut to 3 mm in length to obtain preliminary modified carbon fiber; c1. The carbon fiber is then treated by low-temperature plasma with O2 as the modified gas to obtain secondary modified carbon fiber; d1. Finally, the secondary modified carbon fiber is sulfonated to obtain the final modified carbon fiber.

7. The high temperature resistant, high strength, low elastic modulus, high density well cement of claim 1, wherein, The preparation method of the modified polyether ether ketone fiber is as follows: a2. 100 parts of polyether ether ketone are heated to a molten state, and then 5 parts of nano silicon carbide and 1 part of nano zirconium carbide are added, stirred for 120 min to obtain modified polyether ether ketone; b2. The modified polyether ether ketone fiber is then spun by a melting method, and the length is cut to 1 mm to obtain preliminary modified polyether ether ketone fiber; c2. Finally, the preliminary modified polyether ether ketone fiber in step b2 is subjected to sulfonation treatment to obtain the final modified polyether ether ketone fiber.

8. The high temperature resistant, high strength, low elastic modulus, high density well cement of claim 1, wherein, The preparation method of the modified polyether sulfone fiber is as follows: a3. 100 parts of polyether sulfone, 5 parts of polytetrafluoroethylene, 3 parts of nano silicon carbide and 1 part of nano zirconium carbide are uniformly mixed, and then a modified polyether sulfone is obtained by melt blending; b3. The modified polyether sulfone is then spun into a modified polyether sulfone fiber by a melt method, with a shear length of 1 mm, to obtain a preliminary modified polyether sulfone fiber; c3. Finally, the preliminary modified polyether sulfone fiber in step b3 is subjected to sulfonation treatment to obtain the final modified polyether sulfone fiber.

9. The high temperature resistant, high strength, low elastic modulus, high density well cement slurry of claim 1, wherein: The beta-type silicon carbide whisker has a length ranging from 50 to 100 μm and a diameter ranging from 5 to 10 μm; and the potassium hexatitanate whisker has a length ranging from 10 to 200 μm and a diameter ranging from 1 to 30 μm.

10. The high temperature resistant, high strength, low elastic modulus, high density well cement of claim 1, wherein, The high-temperature-resistant modified polycarbonate is prepared from polycarbonate, styrene-maleic anhydride copolymer, polyetherimide, polychlorotrifluoroethylene, nano silicon nitride and carbon nanotube.

11. A high temperature resistant, high strength, low elastic modulus, high density well cementing cement according to claim 10, characterized in that, The high-temperature-resistant modified polycarbonate is obtained by the following method, comprising the steps of: a4. 100 parts of polycarbonate and 5 parts of styrene-maleic anhydride copolymer dry powder are mixed according to the mass fraction; b4. The mixture in step a4 is heated to 250℃ to be in a molten state, argon gas is used as a protective gas, and melt blending is performed for 60 min to obtain a preliminary modified polycarbonate; c4. After cooling to 200℃, 5 parts of polyetherimide, 5 parts of polychlorotrifluoroethylene, 3 parts of nano silicon nitride and 2 parts of carbon nanotube are added thereto, argon gas is used as a protective gas, and melt blending is performed for 90 min, and then the high-temperature-resistant modified polycarbonate is obtained by cooling, grinding to more than 500 mesh.

12. The high temperature resistant, high strength, low elastic modulus, high density well cement slurry of claim 1, wherein: The particle size of the sulfonated asphalt is more than 500 mesh.

13. The high temperature resistant, high strength, low elastic modulus, high density well cement slurry of claim 1, wherein: The suspension stabilizer is nano-based bentonite with a particle size of more than 200 mesh; the dispersant is one of carboxylate and polystyrene sulfonate; the fluid loss additive is an AMPS polymer fluid loss additive; and the retarder is an AMPS polymer retarder.

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