A cement slurry system for ultra-high temperature cementing, its preparation method and application

Abstract

This invention provides a cement slurry system for ultra-high temperature cementing, its preparation method, and its application. The cement slurry system comprises cement, an ultra-high temperature strength stabilizer, an ultra-high temperature reinforcing material, a density regulator, an ultra-high temperature suspension stabilizer, a dispersant, a fluid loss reducing agent, a retarder, an defoamer, and water. The ultra-high temperature suspension stabilizer consists of 1-3 parts by weight of ether starch, 1-3 parts by weight of aluminosilicate, and 1-2 parts by weight of polyol polymer. The preparation method of the cement slurry system involves dry-mixing and wet-mixing each raw material separately until uniform, then mixing the dry and wet mixtures uniformly to obtain the cement slurry system. This invention also provides the application of this cement slurry system in cementing in high-temperature, ultra-high-temperature, and ultra-deep wells. The ultra-high temperature cement slurry system provided by this invention has strong temperature resistance, a wide range of applications, excellent settling stability, and can prevent the high-temperature strength degradation of cement stone, ensuring the cementing sealing effect and improving cementing quality.

Description

Technical Field

[0001] This invention relates to a cement slurry system for cementing under ultra-high temperature conditions, its preparation method and application, and belongs to the field of drilling technology in the oil extraction industry. Background Technology

[0002] In recent years, with the deepening of oil and gas reservoir exploration and development, the depth of deep and ultra-deep wells has been increasing. The high temperature and pressure of deep wells can cause a series of problems, such as abrupt changes in cement slurry thickening time, poor cement slurry settling stability, excessive water loss of cement slurry, and decline in cement stone strength. Therefore, it is necessary to develop new high-temperature resistant cement slurry systems to improve the high-temperature resistance and stability of cement slurry systems, and reduce their temperature sensitivity, so as to ensure the safety of cementing operations in high-temperature deep wells and improve cementing quality.

[0003] To address the aforementioned issues, research institutions have conducted relevant research and development. CN111807748A discloses a high-temperature stabilizer for high-density cement slurry and its preparation method. This high-temperature stabilizer is composed of 76-84 parts by weight of bentonite, 10-14 parts by weight of modified sizing agent, and 6-10 parts by weight of crosslinked copolymer. However, this stabilizer is only suitable for high-density systems, and the density difference between the upper and lower layers exceeds 0.03 g / cm³. 3 .

[0004] CN107162512A discloses a high-temperature resistant cement slurry system for ultra-deep wells, comprising the following components by weight: 100 parts cement, 6-18 parts high-temperature water loss reducing agent, 25-40 parts silica sand, 6-15 parts high-temperature retarder, 3-5 parts high-temperature stabilizer, and 0.4-2 parts dispersant. This cement slurry system improves the water loss performance of the cement slurry by developing a high-temperature resistant water loss reducing agent and a retarder, ensuring adjustable thickening time of the cement slurry at 200℃. However, it does not solve the problems of poor sedimentation stability and cement stone strength degradation under high-temperature conditions.

[0005] Currently, existing suspension stabilizers can ensure the settling stability of cement slurry below 200℃, but some problems still exist: (1) The thickening effect at room temperature is obvious, which easily affects the cement slurry settling time, and the initial consistency of the cement slurry is generally too high, increasing the difficulty of on-site construction operations; (2) Under high temperature conditions, the cement slurry will experience a "core-encasing" phenomenon, resulting in a decrease in the suspension stability of the cement slurry; (3) The high-temperature thickening polymer powder material in the suspending agent is currently mainly imported, and the price remains high, resulting in a high market price for cement slurry suspension stabilizers; (4) When the temperature exceeds 200℃, the settling stability of the cement slurry system has not been well resolved, and the density difference between the upper and lower parts of the cement slurry system exceeds 0.03 g / cm³. 3 .

[0006] Currently, there is limited research on the instability mechanism of cement slurry under ultra-high temperature conditions. The main approach is to improve the stability of the cement slurry system through engineering methods to meet application requirements, such as reducing the liquid-to-solid ratio, incorporating ultrafine active materials, and compact packing. However, the problem of settlement instability of cement slurry system under 220℃ conditions has not yet been effectively solved.

[0007] Currently, aluminate and phosphate cements are used in the field of high-temperature fading resistance, or ultrafine silica materials are added to G-grade cement. These methods reduce the strength fading phenomenon at high temperatures, but do not fundamentally solve the problem of cement stone strength fading.

[0008] Therefore, based on the above situation, the development of a cement slurry system for cementing with resistance to ultra-high temperature has become one of the urgent problems to be solved in this field. This system aims to improve the settling stability of cement slurry and prevent the degradation of cement stone strength, making it suitable for deep and ultra-deep well operations with ultra-high temperatures of 200°C or even 220°C or higher. Summary of the Invention

[0009] To address the aforementioned technical problems, the present invention aims to provide a cement slurry system for ultra-high temperature cementing, its preparation method, and its application. The ultra-high temperature cement slurry system provided by this invention exhibits strong temperature resistance, wide applicability, and excellent settling stability. Simultaneously, it prevents the degradation of cement stone strength at high temperatures, ensuring effective cementing sealing under high and ultra-high temperature conditions and improving cementing quality.

[0010] To achieve the above objectives, the present invention first provides a cement slurry system for cementing under ultra-high temperature conditions. By weight, its raw material composition includes: 100 parts cement, 15-50 parts ultra-high temperature strength stabilizer, 15-50 parts ultra-high temperature reinforcing material, 0-140 parts density regulator, 1-6 parts ultra-high temperature suspension stabilizer, 0-2 parts dispersant, 2-9 parts fluid loss reducer, 0.1-9 parts retarder, 0.1-0.5 parts defoamer, and 40-120 parts water. The ultra-high temperature suspension stabilizer, by weight, comprises: 1-3 parts ether starch, 1-3 parts aluminosilicate, and 1-2 parts polyol polymer.

[0011] According to a specific embodiment of the present invention, preferably, the raw material composition of the cement slurry system for cementing under ultra-high temperature conditions, by weight, includes: 100 parts cement, 20-50 parts ultra-high temperature strength stabilizer, 15-30 parts ultra-high temperature reinforcing material, 0-140 parts density regulator, 3-6 parts ultra-high temperature suspension stabilizer, 0.5-2 parts dispersant, 2-7 parts fluid loss reducer, 1-6 parts retarder, 0.1-0.5 parts defoamer, and 40-120 parts water.

[0012] In the above-mentioned cement slurry system for cementing under ultra-high temperature conditions, preferably, the ether starch includes one or a combination of several of carboxymethyl starch, carboxyethyl starch, carboxypropyl starch, carboxyhexyl starch, sulfoethyl starch, and sulfo-2-hydroxypropyl starch.

[0013] In the aforementioned cement slurry system for ultra-high temperature cementing, preferably, the aluminosilicate is a nano-sized aluminosilicate with a particle size ranging from 1 to 100 nm in diameter and 0.5 to 30 μm in length. More preferably, the nano-sized aluminosilicate includes one or a combination of several of nano-sized orthoclase, nano-sized zeolite, nano-sized anorthite, and nano-sized halloysite.

[0014] In the aforementioned cement slurry system for ultra-high temperature cementing, preferably, the polyol polymer includes one or a combination of several of polyvinyl alcohol, polyethylene glycol, and polyethylene oxide. Specifically, the molecular weight of polyethylene glycol is 200–20,000, and the molecular weight of polyethylene oxide is 20,000 or higher.

[0015] In the above-mentioned cement slurry system for cementing under ultra-high temperature conditions, preferably, the ultra-high temperature suspension stabilizer is prepared by the following steps: by weight, 1-3 parts of the ether starch, 1-3 parts of the aluminosilicate and 1-2 parts of the polyol polymer are mixed evenly to obtain the ultra-high temperature suspension stabilizer.

[0016] In the above-mentioned cement slurry system for ultra-high temperature cementing, preferably, the ultra-high temperature reinforcing material includes one or a combination of halloysite, mullite, and tricalcium phosphate. More preferably, the ultra-high temperature reinforcing material includes a mixture of halloysite, mullite, and tricalcium phosphate in a mass ratio of (1-2):(1-2):(1-2).

[0017] In the aforementioned cement slurry system for ultra-high temperature cementing, preferably, the ultra-high temperature strength stabilizer includes quartz sand, etc. More preferably, the ultra-high temperature strength stabilizer includes: high-purity 100-1500 mesh acid-washed quartz sand and / or high-purity 100-1500 mesh quartz sand; particularly preferably, the ultra-high temperature strength stabilizer includes: high-purity 600 mesh acid-washed quartz sand and / or high-purity 1500 mesh quartz sand. Wherein, the purity of both the high-purity acid-washed quartz sand and the high-purity quartz sand is 97% or higher.

[0018] In the aforementioned cement slurry system for ultra-high temperature cementing, preferably, the density regulator includes fine iron ore powder and / or glass microspheres, etc. More preferably, the density of the fine iron ore powder is 5.05-7.20 g / cm³. 3 The density of the glass microspheres is 0.44-0.65 g / cm³. 3 (Especially preferred is 0.6g / cm) 3 ).

[0019] In the aforementioned cement slurry system for ultra-high temperature cementing, preferably, the dispersant includes aldehyde-ketone condensate dispersants and / or polystyrene sulfonate dispersants. Both aldehyde-ketone condensate dispersants and polystyrene sulfonate dispersants can be dispersants conventionally used in cement slurry systems in the art. For example, aldehyde-ketone condensate dispersants may include one or a combination of several of dispersants such as DRS-1S, SAF, SXY, USZ, and SDJZ-1. Polystyrene sulfonate dispersants may include sodium polystyrene sulfonate. More preferably, the dispersant is DRS-1S.

[0020] In the aforementioned cement slurry system for ultra-high temperature cementing, preferably, the fluid loss reducing agent includes acrylamide polymer-based fluid loss reducing agents, etc. The fluid loss reducing agent can be a fluid loss reducing agent conventionally used in cement slurry systems in the art. More preferably, the fluid loss reducing agent includes one or a combination of several of the following: DRF-2L, PC-G83L, PC-G80L, and LX-1. Even more preferably, the fluid loss reducing agent is DRF-2L.

[0021] In the aforementioned cement slurry system for ultra-high temperature cementing, preferably, the retarder includes acrylamide polymer retarder and / or 2-acrylamide-2-methylpropanesulfonic acid polymer retarder, etc. The retarder can be a retarder conventionally used in cement slurry systems in the art. More preferably, the retarder includes one or a combination of several of retarder DRH-2L, retarder JXH-2L, and retarder HX-36L. More preferably, the retarder is retarder DRH-2L.

[0022] In the aforementioned cement slurry system for ultra-high temperature cementing, preferably, the defoamer includes one or a combination of several of organic esters, polyoxypropylene glycerol ethers, and polydimethylsiloxane; more preferably, the organic esters include tributyl phosphate. The defoamer can be a defoamer commonly used in cement slurry systems in the art. Particularly preferably, the defoamer is the organic ester defoamer DRX-1L.

[0023] In the aforementioned cement slurry system for ultra-high temperature cementing, preferably, the cement includes Grade G oil well cement. For example, one or a combination of several of the following: Jiahua Grade G, Huayou Grade G, Shengwei Grade G, and Mengcheng Grade G.

[0024] According to a specific embodiment of the present invention, preferably, the density of the ultra-high temperature resistant cement slurry system for cementing is 1.35-2.35 g / cm³. 3 The applicable temperature range is 30℃-240℃, and the density difference within the upper and lower limits of the applicable temperature range is no higher than 0.03g / cm³.3 More preferably, the applicable temperature range of the ultra-high temperature cement slurry system for cementing is 200℃-240℃, and within this applicable temperature range (i.e., under the condition of 200℃-240℃), the density difference between the upper and lower limits is not higher than 0.03g / cm³. 3 Particularly preferably, the applicable temperature range of the ultra-high temperature cement slurry system for cementing is 220℃-240℃, and within this applicable temperature range (i.e., under the condition of 220℃-240℃), the density difference between the upper and lower limits is not higher than 0.03g / cm³. 3 .

[0025] The ultra-high temperature suspension stabilizer used in the cement slurry system for cementing of the present invention is a composition of ether starch, aluminosilicate, and polyol polymer in a weight ratio of (1-3):(1-3):(1-2). This ultra-high temperature suspension stabilizer is formulated by compounding ether starch, aluminosilicate, and polyol polymer in the aforementioned specific ratio. Through the introduction of temperature-resistant and salt-resistant groups from the polyol polymer, and the introduction of inorganic mineral materials (i.e., aluminosilicate) and organic small-molecule thickening substances (i.e., ether starch), the synergistic effect of the specific ratio of these three components is achieved, resulting in excellent ultra-high temperature suspension stability in the cement slurry system, enabling the cement slurry system to maintain excellent settling stability even at a high temperature of 240℃.

[0026] The cement slurry system of this invention also contains other components such as ultra-high temperature reinforcing materials and ultra-high temperature strength stabilizers. These components work synergistically with the ultra-high temperature suspension stabilizer of this invention, making the applicable temperature range of the cement slurry system 30℃-240℃. The cement slurry system exhibits excellent settling stability at high temperatures, resulting in a density of 1.35-2.35 g / cm³. 3 The density difference between the upper and lower parts of the product during operation within the applicable temperature range shall not exceed 0.03 g / cm³. 3 Especially when operating at 220℃-240℃, the density difference between the upper and lower parts should not exceed 0.03g / cm³. 3 It has an adjustable density and a normal thickening curve, meeting the density requirements of cement slurry systems under different working conditions; at the same time, it can effectively prevent the high-temperature strength decay of cement stone, and the compressive strength of cement stone is as high as 35MPa; it can ensure the cementing sealing effect under high temperature, ultra-high temperature, and ultra-deep well conditions, and improve the cementing quality.

[0027] On the other hand, the present invention also provides a method for preparing the above-mentioned cement slurry system for cementing under ultra-high temperature conditions, which includes the following steps: (1) dispersing 100 parts of cement, 15-50 parts (preferably 20-50 parts) of ultra-high temperature strength stabilizer, 15-50 parts (preferably 15-30 parts) of ultra-high temperature reinforcing material, 0-140 parts of density regulator, 1-6 parts (preferably 3-6 parts) of ultra-high temperature suspension stabilizer, and 0-2 parts (preferably 0.5-2 parts) of [unspecified substance] by weight. (1) Mix the agents evenly to obtain a dry mixture; (2) Mix 2-9 parts (preferably 2-7 parts) of water loss reducer, 0.1-9 parts (preferably 1-6 parts) of retarder, 0.1-0.5 parts of defoamer and 40-120 parts of water evenly to obtain a wet mixture; (3) Under stirring conditions, add the dry mixture obtained in step (1) evenly to the wet mixture obtained in step (2), and continue stirring for a period of time to obtain the cement slurry system for cementing with resistance to ultra-high temperature.

[0028] In the above preparation method, preferably, in step (3), the dry mixture obtained in step (1) is uniformly added to the wet mixture obtained in step (2) at a rotation speed of 4000±200r / min, and then stirred for 35-50s at a rotation speed of 12000±500r / min to obtain the cement slurry system for cementing with resistance to ultra-high temperature.

[0029] In addition, the present invention also provides an application of the above-mentioned cement slurry system for cementing in high temperature and / or ultra-high temperature, deep wells and / or ultra-deep wells and / or extra-ultra-deep wells.

[0030] In the application of the above-mentioned cement slurry system for cementing under ultra-high temperature conditions in high-temperature and / or ultra-high temperature, deep wells and / or ultra-deep wells, preferably, the high-temperature and / or ultra-high temperature is 200℃-240℃, more preferably 220℃-240℃, the depth of the deep well is 4500-6000m, the depth of the ultra-deep well is 6000-9000m, and the depth of the extra-ultra-deep well is above 9000m.

[0031] In summary, the ultra-high temperature cement slurry system for cementing provided by this invention exhibits strong temperature resistance, a wide range of applications (30℃-240℃), and excellent settling stability. The density of this cement slurry system is 1.35-2.35 g / cm³. 3 When operating within the applicable temperature range (especially within the 220℃-240℃ temperature range), the density difference between the upper and lower parts should not exceed 0.03 g / cm³. 3The density is adjustable, meeting the density requirements of the cement slurry system under different working conditions. Furthermore, the thickening time of this cement slurry system is adjustable within the applicable temperature range, with low initial consistency and short slurry loading time (within 50 seconds). It also exhibits excellent rheological properties and low thixotropy, avoiding problems such as "bulging" or "stepping" in the thickening curve, resulting in a normal thickening curve. Simultaneously, the cement slurry system of this invention can prevent the high-temperature strength degradation of the cement stone, with a 28-day compressive strength greater than 35 MPa. Therefore, the ultra-high temperature cement slurry system of this invention can ensure cementing sealing performance under high-temperature, ultra-high-temperature, deep-well, ultra-deep-well, and extra-ultra-deep-well conditions, improving cementing quality. Detailed Implementation

[0032] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail with reference to the following specific embodiments, but this should not be construed as limiting the scope of implementation of the present invention.

[0033] Experiments were conducted according to GB / T 19139-2012 "Test Methods for Oil Well Cement" to evaluate the thickening properties, fluidity, API water loss, free water content, settling stability, and compressive strength of the cement slurry systems prepared in the following examples and comparative examples. The main experimental instruments included: a 30-60 type corrugated stirrer, an 8240 type high-temperature and high-pressure thickener (CHANDLER products); and an HH-420 type constant temperature digital display water tank (Changzhou Yineng Experimental Instrument Factory).

[0034] The oil well cement used in the following experiments was high sulfate-resistant (HSR) grade G oil well cement, manufactured by Jiahua Special Cement Co., Ltd. Distilled water was used in the experiments. The biopolymer suspension stabilizer DRK-3S, sulfonated aldehyde-ketone condensate dispersant DRS-1S, acrylamide polymer retarder DRH-2L, acrylamide polymer fluid loss reducer DRF-2L, and organic ester defoamer DRX-1L in the cement slurry formulation were all products manufactured by CNPC Engineering Technology Research Institute Co., Ltd.

[0035] Example 1

[0036] This embodiment provides a cement slurry system for ultra-high temperature cementing. By weight, its raw material composition includes: 100 parts of Jiahua G-grade oil well cement, 50 parts of ultra-high temperature strength stabilizer (which is acid-washed quartz sand with a purity of 97% or higher at 600 mesh), 20 parts of ultra-high temperature reinforcing material (which is a mixture of halloysite, mullite, and tricalcium phosphate in a mass ratio of 1:1:1), 3 parts of ultra-high temperature suspension stabilizer (which is a mixture of sodium carboxymethyl starch, nano-sized halloysite powder, and polyethylene glycol in a mass ratio of 1:2:1, wherein the size of the nano-sized halloysite powder is 30-100 nm in diameter and 0.5-1 μm in length), 1.2 parts of dispersant DRS-1S, 4 parts of fluid loss reducing agent DRF-2L, 3 parts of retarder DRH-2L, 0.2 parts of defoamer DRX-1L, and 58 parts of water.

[0037] The cement slurry system for cementing under ultra-high temperature conditions in this embodiment is prepared by the following method: (1) G-grade oil well cement, ultra-high temperature strength stabilizer, ultra-high temperature reinforcing material, ultra-high temperature suspension stabilizer and dispersant are mixed evenly according to the above proportion to obtain a dry mixture; (2) a water loss reducer, retarder, defoamer and water are mixed evenly according to the above proportion to obtain a wet mixture; (3) the dry mixture obtained in step (1) is evenly added to the wet mixture obtained in step (2) at a rotation speed of 4000±200r / min. After the dry mixture is completely added to the wet mixture, the stirring cup is covered, the stirring speed is adjusted to 12000±500r / min, and stirring is continued for 35s to obtain the cement slurry system for cementing under ultra-high temperature conditions.

[0038] The density of the ultra-high temperature cement slurry system for cementing in this embodiment is 1.90 g / cm³. 3 The results of the experiments are shown in Table 1.

[0039] Example 2

[0040] This embodiment provides a cement slurry system for cementing under ultra-high temperature conditions. By weight, its raw material composition includes: 100 parts Jiahua G-grade oil well cement, 30 parts ultra-high temperature strength stabilizer (which is acid-washed quartz sand with a purity of 97% or higher at 600 mesh), 20 parts ultra-high temperature reinforcing material (which is a mixture of halloysite, mullite, and tricalcium phosphate in a mass ratio of 1:1:1), and 35 parts density modifier (which is hollow glass microspheres with a density of 0.60 g / cm³). 3 ), 4.5 parts of ultra-high temperature suspension stabilizer (which is a mixture of sodium carboxymethyl starch, nano-sized halloysite powder and polyethylene glycol in a mass ratio of 1:2:1, wherein the size of the nano-sized halloysite powder is 30-100 nm in diameter and 0.5-1 μm in length), 1 part of dispersant DRS-1S, 6 parts of water loss reducing agent DRF-2L, 4 parts of retarder DRH-2L, 0.2 parts of defoamer DRX-1L and 115 parts of water.

[0041] The cement slurry system for cementing under ultra-high temperature conditions in this embodiment is prepared by the following method: (1) G-grade oil well cement, ultra-high temperature strength stabilizer, ultra-high temperature reinforcing material, density regulator, ultra-high temperature suspension stabilizer and dispersant are mixed evenly according to the above proportion to obtain a dry mixture; (2) a fluid loss reducer, retarder, defoamer and water are mixed evenly according to the above proportion to obtain a wet mixture; (3) the dry mixture obtained in step (1) is evenly added to the wet mixture obtained in step (2) at a rotation speed of 4000±200r / min. After the dry mixture is completely added to the wet mixture, the cup lid is covered, the speed of the stirrer is adjusted to 12000±500r / min, and stirring is continued for 35s to obtain the cement slurry system for cementing under ultra-high temperature conditions.

[0042] The density of the ultra-high temperature cement slurry system for cementing in this embodiment is 1.35 g / cm³. 3 The results of the experiments are shown in Table 1.

[0043] Example 3

[0044] This embodiment provides a cement slurry system for ultra-high temperature cementing. By weight, its raw material composition includes: 100 parts of Jiahua G-grade oil well cement, 50 parts of ultra-high temperature strength stabilizer (which is acid-washed quartz sand with a purity of 97% or higher at 600 mesh), 20 parts of ultra-high temperature reinforcing material (which is a mixture of halloysite, mullite, and tricalcium phosphate in a mass ratio of 1:1:1), 4 parts of ultra-high temperature suspension stabilizer (which is a mixture of sodium carboxymethyl starch, nano-sized halloysite powder, and polyethylene glycol in a mass ratio of 1:2:1, wherein the size of the nano-sized halloysite powder is 30-100 nm in diameter and 0.5-1 μm in length), 1.2 parts of dispersant DRS-1S, 3.2 parts of fluid loss reducing agent DRF-2L, 3.2 parts of retarder DRH-2L, 0.2 parts of defoamer DRX-1L, and 58 parts of water.

[0045] The preparation method of the cement slurry system for ultra-high temperature cementing in this embodiment is the same as that in Example 1.

[0046] The density of the ultra-high temperature cement slurry system for cementing in this embodiment is 1.90 g / cm³. 3 The results of the experiments are shown in Table 1.

[0047] Example 4

[0048] This embodiment provides a cement slurry system for ultra-high temperature cementing. By weight, its raw material composition includes: 100 parts Jiahua G-grade oil well cement, 50 parts ultra-high temperature strength stabilizer (which is acid-washed quartz sand with a purity of 97% or higher at 600 mesh), 20 parts ultra-high temperature reinforcing material (which is a mixture of halloysite, mullite, and tricalcium phosphate in a mass ratio of 1:1:1), and 140 parts density modifier (which is iron ore powder with a density of 7.20 g / cm³). 3 ), 5.5 parts ultra-high temperature suspension stabilizer (which is a mixture of sodium carboxymethyl starch, nano-sized halloysite powder and polyethylene glycol in a mass ratio of 1:2:1, wherein the size of the nano-sized halloysite powder is 30-100 nm in diameter and 0.5-1 μm in length), 1.5 parts dispersant DRS-1S, 4.5 parts water loss reducing agent DRF-2L, 3.5 parts retarder DRH-2L, 0.2 parts defoamer DRX-1L and 96 parts water.

[0049] The preparation method of the cement slurry system for ultra-high temperature cementing in this embodiment is the same as that in Example 2.

[0050] The density of the ultra-high temperature cement slurry system for cementing in this embodiment is 2.35 g / cm³. 3 The results of the experiments are shown in Table 1.

[0051] Example 5

[0052] This embodiment provides a cement slurry system for ultra-high temperature cementing. By weight, its raw material composition includes: 100 parts of Jiahua G-grade oil well cement, 50 parts of ultra-high temperature strength stabilizer (which is acid-washed quartz sand with a purity of 97% or higher at 600 mesh), 20 parts of ultra-high temperature reinforcing material (which is a mixture of halloysite, mullite and tricalcium phosphate in a mass ratio of 1:1:1), 4.5 parts of ultra-high temperature suspension stabilizer (which is a mixture of sodium carboxymethyl starch, nano-sized halloysite powder and polyethylene glycol in a mass ratio of 1:2:1, wherein the size of the nano-sized halloysite powder is 30-100 nm in diameter and 0.5-1 μm in length), 1.2 parts of dispersant DRS-1S, 5.5 parts of fluid loss reducing agent DRF-2L, 5 parts of retarder DRH-2L, 0.2 parts of defoamer DRX-1L, and 58 parts of water.

[0053] The preparation method of the cement slurry system for ultra-high temperature cementing in this embodiment is the same as that in Example 1.

[0054] The density of the ultra-high temperature cement slurry system for cementing in this embodiment is 1.90 g / cm³. 3 The results of the experiments are shown in Table 1.

[0055] Example 6

[0056] This embodiment provides a cement slurry composition for ultra-high temperature cementing, which, by weight, comprises: 100 parts of Jiahua G-grade oil well cement, 50 parts of ultra-high temperature strength stabilizer (which is acid-washed quartz sand with a purity of 97% or higher at 600 mesh), 20 parts of ultra-high temperature reinforcing material (which is a mixture of halloysite, mullite, and tricalcium phosphate in a mass ratio of 1:1:1), 4 parts of ultra-high temperature suspension stabilizer (which is a mixture of sodium carboxymethyl starch, nano-sized halloysite powder, and polyethylene glycol in a mass ratio of 1:1:1, wherein the nano-sized halloysite powder has a diameter of 30-100 nm and a length of 0.5-1 μm), 1.2 parts of dispersant DRS-1S, 3.2 parts of fluid loss reducing agent DRF-2L, 3.2 parts of retarder DRH-2L, 0.2 parts of defoamer DRX-1L, and 58 parts of water.

[0057] The preparation method of the cement slurry composition for ultra-high temperature cementing in this embodiment is the same as that in Example 1.

[0058] The density of the cement slurry composition for ultra-high temperature cementing in this embodiment is 1.90 g / cm³. 3 The results of the various experiments are shown in Table 2.

[0059] Example 7

[0060] This embodiment provides a cement slurry composition for ultra-high temperature cementing, which, by weight, comprises: 100 parts of Jiahua G-grade oil well cement, 50 parts of ultra-high temperature strength stabilizer (which is acid-washed quartz sand with a purity of 97% or higher at 600 mesh), 20 parts of ultra-high temperature reinforcing material (which is a mixture of halloysite, mullite, and tricalcium phosphate in a mass ratio of 2:2:1), 4 parts of ultra-high temperature suspension stabilizer (which is a mixture of sodium carboxymethyl starch, nano-sized halloysite powder, and polyethylene glycol in a mass ratio of 1:2:1, wherein the nano-sized halloysite powder has a diameter of 30-100 nm and a length of 0.5-1 μm), 1.2 parts of dispersant DRS-1S, 3.2 parts of fluid loss reducing agent DRF-2L, 3.2 parts of retarder DRH-2L, 0.2 parts of defoamer DRX-1L, and 58 parts of water.

[0061] The preparation method of the cement slurry composition for ultra-high temperature cementing in this embodiment is the same as that in Example 1.

[0062] The density of the cement slurry composition for ultra-high temperature cementing in this embodiment is 1.90 g / cm³. 3 The results of the various experiments are shown in Table 2.

[0063] Example 8

[0064] This embodiment provides a cement slurry composition for ultra-high temperature cementing, which, by weight, comprises: 100 parts of Jiahua G-grade oil well cement, 50 parts of ultra-high temperature strength stabilizer (which is acid-washed quartz sand with a purity of 97% or higher at 600 mesh), 20 parts of ultra-high temperature reinforcing material (which is a mixture of halloysite, mullite, and tricalcium phosphate in a mass ratio of 1:1:1), 4 parts of ultra-high temperature suspension stabilizer (which is a mixture of sodium carboxymethyl starch, nano-sized halloysite powder, and polyethylene oxide in a mass ratio of 1:2:1, wherein the nano-sized halloysite powder has a diameter of 30-100 nm and a length of 0.5-1 μm), 1.2 parts of dispersant DRS-1S, 3.2 parts of fluid loss reducing agent DRF-2L, 3.2 parts of retarder DRH-2L, 0.2 parts of defoamer DRX-1L, and 58 parts of water.

[0065] The preparation method of the cement slurry composition for ultra-high temperature cementing in this embodiment is the same as that in Example 1.

[0066] The density of the cement slurry composition for ultra-high temperature cementing in this embodiment is 1.90 g / cm³. 3 The results of the various experiments are shown in Table 2.

[0067] Comparative Example 1

[0068] This comparative example provides a cement slurry system, which, by weight, comprises: 100 parts of Jiahua G-grade oil well cement, 50 parts of ultra-high temperature strength stabilizer (which is acid-washed quartz sand with a purity of 97% or higher at 600 mesh), 2.5 parts of biopolymer suspension stabilizer DRK-3S, 1.2 parts of dispersant DRS-1S, 4 parts of water loss reducer DRF-2L, 3 parts of retarder DRH-2L, 0.2 parts of defoamer DRX-1L, and 51 parts of water.

[0069] The cement slurry system of this comparative example was prepared by the following method: (1) G-grade oil well cement, ultra-high temperature strength stabilizer, suspension stabilizer and dispersant were mixed evenly according to the above proportion to obtain a dry mixture; (2) water loss reducer, retarder, defoamer and water were mixed evenly according to the above proportion to obtain a wet mixture; (3) the dry mixture obtained in step (1) was evenly added to the wet mixture obtained in step (2) at a speed of 4000±200r / min. After the dry mixture was completely added to the wet mixture, the cup lid was covered, the speed of the stirrer was adjusted to 12000±500r / min, and stirring was continued for 35s to obtain the cement slurry system.

[0070] The density of the cement paste system in this comparative example is 1.90 g / cm³. 3 The results of the various experiments are shown in Table 3.

[0071] Comparative Example 2

[0072] This comparative example provides a cement slurry system, which, by weight, comprises: 100 parts of Jiahua G-grade oil well cement, 50 parts of ultra-high temperature strength stabilizer (which is acid-washed quartz sand with a purity of 97% or higher at 600 mesh), 3 parts of biopolymer suspension stabilizer DRK-3S, 1.2 parts of dispersant DRS-1S, 4.5 parts of water loss reducer DRF-2L, 4 parts of retarder DRH-2L, 0.2 parts of defoamer DRX-1L, and 51 parts of water.

[0073] The preparation method of the cement slurry system in this comparative example is the same as that in Comparative Example 1.

[0074] The density of the cement paste system in this comparative example is 1.90 g / cm³. 3 The results of the various experiments are shown in Table 3.

[0075] Comparative Example 3

[0076] This comparative example provides a cement slurry system, which, by weight, comprises: 100 parts of Jiahua G-grade oil well cement, 50 parts of ultra-high temperature strength stabilizer (which is acid-washed quartz sand with a purity of 97% or higher at 600 mesh), 3.5 parts of biopolymer suspension stabilizer DRK-3S, 1.2 parts of dispersant DRS-1S, 5.5 parts of water loss reducer DRF-2L, 5 parts of retarder DRH-2L, 0.2 parts of defoamer DRX-1L, and 51 parts of water.

[0077] The preparation method of the cement slurry system in this comparative example is the same as that in Comparative Example 1.

[0078] The density of the cement paste system in this comparative example is 1.90 g / cm³. 3 The results of the various experiments are shown in Table 3.

[0079] Comparative Example 4

[0080] This comparative example provides a cement slurry system, which, by weight, comprises: 100 parts of Jiahua G-grade oil well cement, 50 parts of ultra-high temperature strength stabilizer (which is acid-washed quartz sand with a purity of 97% or higher at 600 mesh), 20 parts of ultra-high temperature reinforcing material (which is a mixture of halloysite, mullite, and tricalcium phosphate in a mass ratio of 1:1:1), 4 parts of high temperature suspension stabilizer (which is a mixture of sodium carboxymethyl starch, aluminum sulfate, and polyethylene glycol in a mass ratio of 1:2:1), 1.2 parts of dispersant DRS-1S, 5.5 parts of water loss reducing agent DRF-2L, 5.5 parts of retarder DRH-2L, 0.2 parts of defoamer DRX-1L, and 58 parts of water.

[0081] The preparation method of the cement slurry system in this comparative example is the same as that in Comparative Example 1.

[0082] The density of the cement paste system in this comparative example is 1.90 g / cm³.3 The results of the various experiments are shown in Table 3.

[0083] Comparative Example 5

[0084] This comparative example provides a cement slurry system, which, by weight, comprises: 100 parts of Jiahua G-grade oil well cement, 50 parts of ultra-high temperature strength stabilizer (which is acid-washed quartz sand with a purity of 97% or higher at 600 mesh), 20 parts of ultra-high temperature reinforcing material (which is a mixture of halloysite, mullite, and tricalcium phosphate in a mass ratio of 1:1:1), 4.5 parts of high temperature suspension stabilizer (which is a mixture of sodium carboxymethyl starch and nano-sized halloysite powder in a mass ratio of 1:2, wherein the nano-sized halloysite powder has a diameter of 30-100 nm and a length of 0.5-1 μm), 1.2 parts of dispersant DRS-1S, 5.5 parts of water loss reducing agent DRF-2L, 5 parts of retarder DRH-2L, 0.2 parts of defoamer DRX-1L, and 58 parts of water.

[0085] The preparation method of the cement slurry system in this comparative example is the same as that in Comparative Example 1.

[0086] The density of the cement paste system in this comparative example is 1.90 g / cm³. 3 The results of the various experiments are shown in Table 3.

[0087] Comparative Example 6

[0088] This comparative example provides a cement slurry system, which, by weight, comprises: 100 parts of Jiahua G-grade oil well cement, 50 parts of ultra-high temperature strength stabilizer (which is 600-mesh acid-washed quartz sand with a purity of 97% or higher), 20 parts of high temperature reinforcing material (which is 300-mesh metakaolin), 4.5 parts of ultra-high temperature suspension stabilizer (which is a mixture of sodium carboxymethyl starch, nano-sized halloysite powder, and polyethylene glycol in a mass ratio of 1:2:1, wherein the nano-sized halloysite powder has a diameter of 30-100 nm and a length of 0.5-1 μm), 1.2 parts of dispersant DRS-1S, 5.5 parts of water loss reducing agent DRF-2L, 5 parts of retarder DRH-2L, 0.2 parts of defoamer DRX-1L, and 58 parts of water.

[0089] The preparation method of the cement slurry system in this comparative example is the same as that in Comparative Example 1.

[0090] The density of the cement paste system in this comparative example is 1.90 g / cm³. 3 The results of the various experiments are shown in Table 3.

[0091] Table 1

[0092]

[0093] Table 2

[0094]

[0095] Table 3

[0096]

[0097] As shown in Tables 1 and 2, the density of the ultra-high temperature cement slurry system for cementing according to the present invention is adjustable. The fluidity of the ultra-high temperature cement slurry system in all embodiments is greater than 22 cm, the API water loss is less than 50 mL, and the free water content is 0, meeting the requirements for cementing construction. Thickening performance tests show that the thickening time of the ultra-high temperature cement slurry system in all embodiments of the present invention is adjustable, and the thickening curve is normal, without any abnormal phenomena such as "bulging". Cement stone compressive strength tests show that the cement stone cured by the ultra-high temperature cement slurry system in all embodiments of the present invention has a 7-day compressive strength greater than 40 MPa for both the conventional density system and the high density system, and a 7-day compressive strength greater than 35 MPa for the low density system.

[0098] The main difference between the cement slurry systems of Example 1 and Comparative Example 1 is that in Example 1, 2.5 parts of suspension stabilizer were replaced with 3 parts of ultra-high temperature suspension stabilizer, and 20 parts of ultra-high temperature reinforcing material were added. A comparison of the data in Tables 1 and 3 shows that, under the same experimental conditions, the flowability of the cement slurry system in Comparative Example 1 was 21 cm, while that in Example 1 was 24 cm, indicating that the ultra-high temperature suspension stabilizer of the present invention improved the flowability of the cement slurry system. The 7-day compressive strength of the cement stone cured with the cement slurry system of Comparative Example 1 was 35 MPa, while that of the cement stone cured with the cement slurry system of Example 1 was 42.5 MPa, representing an increase of 21.4%. This demonstrates that the ultra-high temperature reinforcing material of the present invention effectively improved the mechanical properties of the cement stone at high temperatures.

[0099] The main difference between the cement slurry system of Example 3 and Comparative Example 2 is that in Example 3, the 3 parts of suspension stabilizer in Comparative Example 2 were replaced with 4 parts of ultra-high temperature suspension stabilizer, and 20 parts of ultra-high temperature reinforcing material were added. Under the same experimental conditions, the thickening curve of the cement slurry system of Comparative Example 2 showed a "bulge," with a density difference of 0.34 g / cm³. 3 The free water content was 0.01%; the thickening curve of the cement slurry system in Example 3 was normal, with a density difference of 0.02 g / cm³. 3The free water content is 0. The ultra-high temperature suspension stabilizer of this invention effectively solves the problems of abnormal thickening curves, cement slurry core formation, and sedimentation, thus improving the stability of the cement slurry. The 7-day compressive strength of the cement stone cured from the cement slurry system of Comparative Example 2 is 30 MPa, while the 7-day compressive strength of the cement stone cured from the cement slurry system of Example 3 is 40.8 MPa, representing a 36% increase in 7-day compressive strength. This demonstrates that the ultra-high temperature reinforcing material of this invention effectively improves the mechanical properties of cement stone under ultra-high temperatures.

[0100] Examples 2, 3, and 4 have a density of 1.35 g / cm³. 3 1.90g / cm 3 2.35g / cm 3 The cement slurry system. In Example 2, the 7-day compressive strength of the cement stone was 36.4 MPa, and the density difference between the upper and lower layers of the cement slurry was 0.02 g / cm³. 3 The API water loss was 46 ml. The 7-day compressive strength of the cement stone in Example 3 was 40.8 MPa, and the density difference between the upper and lower layers was 0.02 g / cm³. 3 The API water loss was 37 ml. The 7-day compressive strength of the cement stone in Example 4 was 43.6 MPa, and the density difference between the upper and lower layers was 0.03 g / cm³. 3 The API water loss was 42 ml. Under the same experimental conditions, the compressive strength of the cement stone was effectively improved compared to Comparative Example 2, and the density difference between the upper and lower parts was less than or equal to 0.03 g / cm³. 3 Its density is adjustable, and all other properties meet the requirements for ultra-high temperature cementing construction.

[0101] The main difference between the cement slurry system of Example 5 and Comparative Example 3 is that in Example 5, the 3.5 parts of suspension stabilizer in Comparative Example 3 were replaced with 4.5 parts of ultra-high temperature suspension stabilizer, and 20 parts of ultra-high temperature reinforcing material were added. Under the same experimental conditions, the thickening curve of the cement slurry system of Comparative Example 3 showed a "stepped" shape, the fluidity of the cement slurry system was 20 cm, and the density difference between the upper and lower sections was 0.40 g / cm³. 3 The free water content was 0.02%; the thickening curve of the cement slurry system in Example 5 was normal, the fluidity of the cement slurry system was 23 cm, and the density difference between the upper and lower parts was 0.03 g / cm³. 3 The free water content is 0, indicating that the ultra-high temperature suspension stabilizer of the present invention effectively solves the problem of poor fluidity and stability of cement slurry system at 240℃.

[0102] The main difference between the cement slurry systems of Example 5 and Comparative Examples 4 and 5 is that Example 5 adjusted the specific formulation of the high-temperature suspension stabilizer in Comparative Examples 4 and 5. Under the same experimental conditions, the density difference between the upper and lower layers of the cement slurry system in Comparative Example 4 was 0.19 g / cm³. 3The free water content was 0.01%; the density difference between the upper and lower layers of the cement paste system in Comparative Example 5 was 0.17 g / cm³. 3 The free water content was 0.01%; the density difference between the upper and lower layers of the cement slurry system in Example 5 was 0.03 g / cm³. 3 The free water content is 0, indicating that only the specific composition of the ultra-high temperature suspension stabilizer provided by this invention can effectively solve the problem of poor stability of the cement slurry system at 240℃. The main difference between the cement slurry system of Example 5 and Comparative Example 6 is that in Example 5, the high-temperature reinforcing material metakaolin in Comparative Example 6 is replaced with an ultra-high temperature reinforcing material. Under the same experimental conditions, the cement slurry system of Comparative Example 6 thickens significantly, and the thickening time is shortened considerably. This is mainly because although metakaolin has a high-temperature anti-fading effect, its compatibility with the system is poor. In contrast, the ultra-high temperature reinforcing material of this invention has good compatibility with the system, effectively improving the mechanical properties of cement paste at high temperatures.

[0103] Therefore, the ultra-high temperature cement slurry system for cementing provided by this invention has strong temperature resistance, a wide range of applications (30℃-240℃), and excellent settling stability. The density of this cement slurry system is 1.35-2.35 g / cm³. 3 The density difference between the upper and lower parts of the product during operation within the applicable temperature range shall not exceed 0.03 g / cm³. 3 Especially under conditions of 220℃-240℃, the density difference between the upper and lower parts is no higher than 0.03g / cm³. 3 The density is adjustable, meeting the density requirements of cement slurry systems under different working conditions. Furthermore, the cement slurry system of this invention exhibits excellent rheological properties at high temperatures, low thixotropy, adjustable thickening time within the applicable temperature range, low initial consistency, and short cementing time (within 50 seconds), avoiding problems such as "bulging" and "stepping" in the thickening curve. The thickening curve is normal, solving the problems of poor stability and strength degradation of cement slurry systems under 220℃-240℃ conditions. Moreover, the linear relationship between thickening time and temperature and density is good. Simultaneously, the cement slurry system of this invention can prevent high-temperature strength degradation of cement stone, with a 28-day compressive strength greater than 35MPa. The ultra-high temperature resistant cement slurry system of this invention can ensure the safety of cementing construction in high-temperature, ultra-high temperature, deep, ultra-deep, and extra-ultra-deep wells, guaranteeing cementing sealing effects and improving cementing quality.

Claims

1. A cement slurry system for well cementing, comprising, by weight, the following raw materials: 100 parts cement, 15-50 parts ultra-high temperature strength stabilizer, 15-50 parts ultra-high temperature reinforcing material, 0-140 parts density regulator, 1-6 parts ultra-high temperature suspension stabilizer, 0-2 parts dispersant, 2-9 parts water loss reducer, 0.1-9 parts retarder, 0.1-0.5 parts defoamer, and 40-120 parts water; The ultra-high temperature suspension stabilizer comprises, by weight, 1-3 parts of ether starch, 1-3 parts of aluminosilicate, and 1-2 parts of polyol polymer; wherein the aluminosilicate is a nano-sized aluminosilicate. The ultra-high temperature reinforced material comprises a mixture of halloysite, mullite, and tricalcium phosphate in a mass ratio of (1-2):(1-2):(1-2); The ultra-high temperature strength stabilizer includes quartz sand.

2. The cement slurry system for cementing according to claim 1, wherein, The ether starches include one or a combination of several of carboxymethyl starch, carboxyethyl starch, carboxypropyl starch, carboxyhexyl starch, sulfoethyl starch, and sulfo-2-hydroxypropyl starch.

3. The cement slurry system for cementing according to claim 1, wherein, The nanoscale aluminosilicates include one or a combination of several of nanoscale orthoclase, nanoscale zeolite, nanoscale anorthite, and nanoscale halloysite.

4. The cement slurry system for cementing according to claim 1, wherein, The polyol polymers include one or more of polyvinyl alcohol, polyethylene glycol, and polyethylene oxide.

5. The cement slurry system for cementing according to claim 1, wherein, The density regulator includes refined iron ore powder and / or glass microspheres; The dispersant includes aldehyde-ketone condensate dispersants and / or polystyrene sulfonate dispersants; The water loss reducing agent includes acrylamide polymer-based water loss reducing agents; The retarder includes acrylamide polymer retarder and / or 2-acrylamide-2-methylpropanesulfonic acid polymer retarder; The defoamer includes one or a combination of several of organic esters, polyoxypropylene glycerol ethers, and polydimethylsiloxane.

6. The cement slurry system for cementing according to claim 1, wherein, The ultra-high temperature strength stabilizer includes: high-purity 100-1500 mesh acid-washed quartz sand and / or high-purity 100-1500 mesh quartz sand.

7. The cement slurry system for cementing according to claim 5, wherein, The density of the refined iron ore powder is 5.05-7.20 g / cm³. 3 The density of the glass microspheres is 0.44-0.65 g / cm³. 3 ; The organic esters include tributyl phosphate.

8. The cement slurry system for cementing according to claim 1, wherein, The cement includes Grade G oil well cement.

9. The cement slurry system for cementing according to any one of claims 1-8, wherein the density is 1.35-2.35 g / cm³, the applicable temperature is 30℃-240℃, and the density difference within the applicable temperature range is not higher than 0.03 g / cm³. 3 .

10. The cement slurry system for cementing according to claim 9, wherein the applicable temperature is 200℃-240℃, and the density difference within the applicable temperature range is not higher than 0.03 g / cm³. 3 .

11. The cement slurry system for cementing according to claim 10, wherein the applicable temperature is 220℃-240℃, and the density difference within the applicable temperature range is not higher than 0.03 g / cm³. 3 .

12. A method for preparing a cement slurry system for cementing according to any one of claims 1-11, comprising the following steps: (1) By weight, 100 parts of cement, 15-50 parts of ultra-high temperature strength stabilizer, 15-50 parts of ultra-high temperature reinforcing material, 0-140 parts of density regulator, 1-6 parts of ultra-high temperature suspension stabilizer, and 0-2 parts of dispersant are mixed evenly to obtain a dry mixture; (2) By weight, 2-9 parts of water loss reducer, 0.1-9 parts of retarder, 0.1-0.5 parts of defoamer, and 40-120 parts of water are mixed evenly to obtain a wet mixture; (3) Under stirring conditions, the dry mixture obtained in step (1) is evenly added to the wet mixture obtained in step (2), and after stirring for a period of time, the cement slurry system for well cementing is obtained.

13. The method for preparing the cement slurry system for cementing according to claim 12, wherein, In step (3), the dry mixture obtained in step (1) is uniformly added to the wet mixture obtained in step (2) at a rotation speed of 4000±200r / min, and then stirred for 35-50s at a rotation speed of 12000±500r / min to obtain the cement slurry system for cementing.

14. The application of a cement slurry system for cementing according to any one of claims 1-11 in cementing at high and / or ultra-high temperatures, in deep and / or ultra-deep and / or extra-ultra-deep wells.

15. The application of the cement slurry system for cementing according to claim 14 in cementing at high and / or ultra-high temperatures, in deep and / or ultra-deep and / or extra-ultra-deep wells, wherein, The high temperature and / or ultra-high temperature is 200℃-240℃; the depth of the deep well is 4500-6000m, the depth of the ultra-deep well is 6000-9000m, and the depth of the extra-ultra-deep well is above 9000m.

16. The application of the cement slurry system for cementing according to claim 15 in cementing at high and / or ultra-high temperatures, in deep and / or ultra-deep and / or extra-ultra-deep wells, wherein, The high temperature and / or ultra-high temperature is 220℃-240℃.

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