High-temperature-resistant cement and cement paste system for well cementation, and preparation method therefor

Abstract

A high-temperature-resistant cement and a cement paste system for well cementation, and a preparation method therefor. The high-temperature-resistant cement for well cementation comprises the following components in parts by weight: 40-55 parts of G-grade oil well cement, 40-55 parts of low-calcium silicate cement, 1-5 parts of gypsum, 1-10 parts of sulphoaluminate cement and 1-10 parts of a composite admixture. The applicable temperature of the cement and the cement paste system is in the range of 150-240ºC, and the compressive strength of cement stone, which has been maintained for 28 days, is larger than 40 MPa and does not reduce, thereby guaranteeing well cementation sealing effects of high-temperature and ultra-high-temperature deep wells and ultra-deep wells.

Description

A high temperature resistant cement and cement slurry system for cementing and preparation method thereof Technical Field

[0001] The invention relates to a high-temperature resistant cement and cement slurry system for well cementing and a preparation method thereof, and belongs to the field of oil and natural gas exploration and development. Background Art

[0002] With the deepening of exploration and development, high-temperature and ultra-high-temperature deep wells are increasing in number, drilling depths are gradually increasing towards 10,000 meters, and bottomhole circulating temperatures are gradually approaching ultra-high temperatures of 240°C. Under these high and ultra-high temperature conditions, the strength of Portland cement paste deteriorates significantly, posing a significant challenge to ensuring the integrity of the cement sheath seal. The current common practice is to blend appropriate siliceous admixtures such as quartz sand with Portland cement. However, sand-added cement undergoes changes in its hydration products at temperatures above 200°C, resulting in significant strength degradation and failure to meet the requirements of long-term production of high-temperature oil and gas wells. Therefore, it is necessary to develop a high-temperature-resistant cement slurry system to prevent the strength degradation of cement paste at high temperatures, thereby ensuring the safety and quality of cementing operations in high-temperature deep wells.

[0003] CN112094060A discloses a high-temperature well cement, its preparation method, and its application. This cement is composed of 69-72% cement raw material and 28-31% quartz sand. The raw materials are composed of G-grade oil well cement and nuclear power cement in a mass ratio of 4:6 to 5:5. However, this high-temperature well cement is primarily suitable for well cementing projects in Africa, and its strength decreases slightly at temperatures between 130°C and 200°C.

[0004] CN101906291A discloses a high-temperature, special oil well cement material and its preparation method. The oil well cement material comprises the following components by weight: 100 parts high-belite cement, 10-25 parts quartz sand powder, and 0.22-0.32 parts lignin sulfonate or modified lignin sulfonate, or 0.9-1.5 parts ethylenediaminetetramethylenephosphonate. This cement product has advantages such as high thermal stability and low pollution, but is primarily used in oil and gas well repair projects. Its application is limited, and it is only suitable for wells with a bottomhole circulation temperature of 60°C to 130°C.

[0005] CN113582605A discloses a high-temperature-resistant cement system and its preparation method. The cement system consists of 25-85 parts by weight of cement, 4-60 parts by weight of silica sand, and 4-60 parts by weight of fly ash, along with additives. This cement system can address the strength degradation of cement paste in ultra-high-temperature environments, while also addressing the land occupation and environmental pollution issues associated with fly ash. Its applicable temperature range is up to 200°C. However, after 30 days of curing, the compressive strength of the cement paste exhibits a decline compared to that of cement paste cured for only two days.

[0006] CN115304317A discloses a high-temperature strength-degradation-resistant oil well cement slurry system. This slurry system consists of 47.5-72.5 wt% of a cementitious material, 15-25 wt% of silica sand, 10-25 wt% of a high-temperature strength-degradation-resistant material, 2 wt% of a high-temperature stabilizer, and 0.5 wt% of a dispersant. This high-temperature strength-degradation-resistant oil well cement slurry system offers the advantages of high-temperature strength-degradation resistance and stable high-temperature performance, effectively alleviating the strength-degradation problem of cement paste under high-temperature conditions.

[0007] CN113683354A discloses an oil well cement slurry system with high-temperature strength-fading resistance. The oil well cement slurry system comprises the following components, calculated by weight: 100 parts oil well cement, 30.0-50.0 parts quartz sand, 10.0-20.0 parts high-temperature strength-fading inhibitor, 3.0-5.0 parts whisker material, 0.5-2.0 parts modified carbon nanotubes, 1.0-3.0 parts dispersant, 2-4 parts high-temperature stabilizer, 1.0-3.0 parts high-temperature fluid loss additive, 3.0-5.0 parts high-temperature retarder, and 65.0-75.0 parts water. The high-temperature strength-fading inhibitor comprises two or more of mica, kaolin, wollastonite, chlorite, and sepiolite. After curing for 90 days at 240°C, the compressive strength of the cement paste of this cement slurry system is greater than 48 MPa. However, high-temperature strength decay inhibitors and modified carbon nanotubes may shorten the thickening time of the cement slurry to varying degrees, resulting in abnormal setting properties of the cement slurry and affecting the safety of cementing construction.

[0008] Currently, the cements used to combat high-temperature decay are mostly aluminate cement, phosphate cement, or the addition of ultrafine silica to G-grade oilwell cement. While these methods mitigate strength decay at high temperatures, they do not fundamentally address the problem of cement paste strength decay. Conventional Portland cement paste experiences strength decay at curing temperatures around 110°C due to the transformation of its hydration products from amorphous CSH gel to crystalline dicalcium silicate hydrate, which exhibits inferior properties. When the bottomhole circulating temperature exceeds 110°C, the addition of silica dioxide can reduce the total calcium-silicon ratio of oilwell cement, converting the cement hydration products into the relatively high-performance tobermorite and xonotlite, thereby maintaining stable strength. For many years, the generally accepted optimal silica sand dosage was 30% to 40% of the cement mass. However, recent research has shown that at higher temperatures (>150°C), Portland cement systems containing silica sand still exhibit significant microstructural coarsening and strength decay. Increasing the silica sand dosage (50% to 65%) at temperatures above 200°C can mitigate the severe strength decay, but it still does not fundamentally resolve the problem. In recent years, the addition of high-temperature strength-degradation-resistant materials, such as metakaolin and sepiolite, to cement slurries has effectively prevented strength degradation at temperatures between 150°C and 200°C. However, in engineering applications, these materials can affect the thickening time of the cement slurry, making it difficult to ensure safe cementing operations. Therefore, ensuring the long-term strength stability of cement slurries at temperatures above 200°C remains a pressing issue in cementing projects.

[0009] Based on these problems, it is of great significance to develop a high-temperature resistant cement for cementing to prevent the strength decline of cement stone under high temperature conditions of 200°C and above.

[0010] Summary of the Invention

[0011] To solve the above technical problems, the present invention aims to provide a high-temperature resistant cement and cement slurry system for cementing and a preparation method thereof. The high-temperature resistant cement and cement slurry system provided by the present invention can prevent the strength decline of cement paste under high and ultra-high temperature conditions.

[0012] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a high-temperature resistant cement for cementing, which comprises the following components, in parts by weight: 40 to 55 parts of G-grade oil well cement, 40 to 55 parts of low-calcium silicate cement, 1 to 5 parts of gypsum, 1 to 10 parts of sulfoaluminate cement and 1 to 10 parts of composite admixture; wherein the composite admixture comprises a mixture of carbide slag, phosphorus slag, mussel shell powder and sugar filter mud in a weight ratio of 10 to 15:5 to 10:3 to 6:1 to 3.

[0013] In the above-mentioned high-temperature resistant cement for cementing, preferably, the weight ratio of G-grade oil well cement, low-calcium silicate cement, gypsum, sulphoaluminate cement and composite admixture is 40-50:40-50:1-3:5-10:3-6, more preferably 43:43:2:8:4.

[0014] In the above-mentioned high-temperature resistant cement for well cementing, preferably, the weight ratio of carbide slag, phosphorus slag, mussel shell powder and sugar filter mud is 10-13:5-8:3-5:1-3.

[0015] In the above-mentioned high-temperature resistant cement for well cementing, preferably, based on the total weight of the G-grade oil well cement being 100%, the G-grade oil well cement comprises the following components: 95% to 97% of Portland cement clinker and 3% to 5% of gypsum; wherein, based on the total weight of the Portland cement clinker being 100%, the Portland cement clinker comprises the following mineral composition: 40% to 65% of tricalcium silicate, 15% to 25% of dicalcium silicate, 10% to 30% of tricalcium aluminate and tetracalcium aluminoferrite, 1% to 5% of free calcium oxide and free magnesium oxide, and 0% to 0.6% of sodium oxide and potassium oxide.

[0016] In the above-mentioned high-temperature resistant cement for well cementing, preferably, based on the total weight of the low-calcium silicate cement being 100%, the low-calcium silicate cement comprises the following components: 94% to 99% of low-calcium silicate cement clinker and 1% to 6% of gypsum; wherein, based on the total weight of the low-calcium silicate cement clinker being 100%, the low-calcium silicate cement clinker comprises the following mineral composition: 45% to 70% of dicalcium silicate, 10% to 40% of tricalcium silicate, 10% to 30% of tricalcium aluminate and tetracalcium aluminoferrite, 1% to 5% of free calcium oxide and free magnesium oxide, and 0% to 0.6% of sodium oxide and potassium oxide.

[0017] In the above-mentioned high-temperature resistant cement for well cementing, preferably, based on the total weight of the sulfoaluminate cement being 100%, the sulfoaluminate cement comprises the following components: 92% to 95% of sulfoaluminate cement clinker and 5% to 8% of gypsum; wherein, based on the total weight of the sulfoaluminate cement clinker being 100%, the sulfoaluminate cement clinker comprises the following mineral composition: 55% to 75% of calcium sulfoaluminate, 8% to 37% of dicalcium silicate, 15% to 35% of tetracalcium aluminoferrite, 0% to 3% of calcium sulfate, 1% to 5% of free calcium oxide and free magnesium oxide, and 0% to 0.6% of sodium oxide and potassium oxide.

[0018] In the above-mentioned high-temperature resistant cement for well cementing, preferably, the gypsum includes one or more combinations of natural dihydrate gypsum, anhydrite (i.e., natural anhydrous gypsum) and mixed gypsum. Those skilled in the art should understand that mixed gypsum is a uniform gypsum powder with a gelling effect prepared by fully mixing, calcining, grinding and other processes of any two or more gypsum raw materials (such as natural dihydrate gypsum, anhydrite or various industrial by-product gypsum). The present invention does not limit the specific composition of the mixed gypsum, which can be obtained commercially. The gypsum refers to the gypsum in the components of high-temperature resistant cement for well cementing, the gypsum in the components of G-grade oil well cement, the gypsum in the components of low-calcium silicate cement, and the gypsum in the components of sulfoaluminate cement.

[0019] In the above-mentioned high-temperature resistant cement for well cementing, preferably, the mass content of Ca(OH)2 in the carbide slag is 70% to 80%.

[0020] In the above-mentioned high-temperature resistant cement for well cementing, preferably, the particle size of the carbide slag is 10 to 15 μm.

[0021] In the above-mentioned high-temperature resistant cement for cementing, preferably, the mass content of P2O5 in the phosphorus slag is 40% to 43%, the mass content of SiO2 is 47% to 52%, the mass content of Fe2O3 is 2% to 5%, the mass content of fluoride is 0.8% to 3%, and the mass content of Al2O3 is 0.8% to 2.5%.

[0022] In the above-mentioned high-temperature resistant cement for well cementing, preferably, the particle size of the phosphorus slag is 0.5 to 5 mm.

[0023] In the above-mentioned high-temperature resistant cement for well cementing, preferably, the CaCO3 content in the mussel shell powder is 90% to 96%.

[0024] In the above-mentioned high-temperature resistant cement for well cementing, preferably, the particle size of the mussel shell powder is 200 to 300 μm.

[0025] In the above-mentioned high-temperature resistant cement for well cementing, preferably, the mass content of CaCO3 in the sugar filter mud is 55% to 70%.

[0026] According to a specific embodiment of the present invention, the high-temperature resistant cement for cementing is prepared by the following steps: G-grade oil well cement, low-calcium silicate cement, gypsum, sulphoaluminate cement and composite admixtures are uniformly mixed according to the above-mentioned weight parts to obtain the high-temperature resistant cement for cementing.

[0027] A second aspect of the present invention provides a high-temperature resistant cement slurry system for cementing, which includes the following components, in parts by weight: 100 parts of the above-mentioned high-temperature resistant cement for cementing, 0 to 70 parts of quartz sand, 1 to 6 parts of a suspension stabilizer, 2 to 9 parts of a fluid loss additive, 0.5 to 1.5 parts of a dispersant, 1 to 9 parts of a retarder, 0.1 to 0.5 parts of a defoaming agent, and 40 to 100 parts of water.

[0028] In the above-mentioned high temperature resistant cement slurry system for cementing, preferably, the particle size of the quartz sand is 50 mesh to 5000 mesh. According to a specific embodiment of the present invention, the quartz sand includes ordinary quartz sand and / or acid washed quartz sand.

[0029] In the aforementioned high-temperature-resistant cement slurry system for well cementing, the suspension stabilizer can be a conventional suspension stabilizer for oil well cement, such as an acrylamide polymer suspension stabilizer. Preferably, the suspension stabilizer comprises a polymer suspension stabilizer prepared from monomers including 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, diallyldimethylammonium chloride, and N-vinylpyrrolidone. This polymer suspension stabilizer can be prepared according to the procedures disclosed in CN113736016A.

[0030] In the above-mentioned high-temperature resistant cement slurry system for cementing, the fluid loss reducer can be a conventional fluid loss reducer for oil well cement in the art, such as a 2-acrylamido-2-methylpropanesulfonic acid polymer fluid loss reducer. Preferably, the fluid loss reducer includes a polymer fluid loss reducer prepared from 2-acrylamido-2-methylpropanesulfonic acid, N,N-dimethylacrylamide and an unsaturated carboxylic acid as monomers. The unsaturated carboxylic acid can be acrylic acid or itaconic acid. The polymer fluid loss reducer can be prepared by referring to, but not limited to, the steps disclosed in the synthesis and performance evaluation of salt-resistant fluid loss reducer AMPS / DMAA / IA (Yu Wenjuan et al., Chemical Industry and Engineering, 2018, 35(1):6).

[0031] In the above-mentioned high-temperature resistant cement slurry system for well cementing, the dispersant can be a conventional oil well cement dispersant in the art. Preferably, the dispersant includes an aldehyde-ketone condensation polymer dispersant and / or a polycarboxylic acid dispersant.

[0032] In the above-mentioned high-temperature resistant cement slurry system for well cementing, the retarder can be a conventional oil well cement retarder in the art. Preferably, the retarder includes one or a combination of hydroxyethylene diphosphonic acid (HEDP), ethylenediamine tetramethylene phosphonic acid (EDTMPA), and ethylenediamine tetramethylene phosphonate.

[0033] In the above-mentioned high-temperature resistant cement slurry system for well cementing, the defoaming agent can be a conventional defoaming agent for oil well cement in the art. Preferably, the defoaming agent includes one or a combination of tributyl phosphate, polyoxypropylene glycerol ether, and polydimethylsiloxane.

[0034] According to a specific embodiment of the present invention, the above-mentioned high-temperature resistant cement slurry system for cementing is prepared by dry-mixing and wet-mixing the components according to the dry and wet states, and then mixing the dry mixture with the wet mixture. Preferably, the above-mentioned high-temperature resistant cement slurry system for cementing is prepared by the following steps: uniformly mixing high-temperature resistant cement for cementing, quartz sand, suspension stabilizer, and dispersant according to the above-mentioned weight parts to obtain a dry mixture; uniformly mixing a fluid loss reducer, a retarder, a defoaming agent, and water according to the above-mentioned weight parts to obtain a wet mixture; at a speed of 4000±200r / min, evenly pouring the dry mixture into the wet mixture, and after the dry mixture is completely added to the wet mixture, adjusting the speed to 12000±500r / min, and continuing stirring for 15 to 35s to obtain the above-mentioned high-temperature resistant cement slurry system for cementing.

[0035] A third aspect of the present invention provides a method for preparing the above-mentioned high-temperature resistant cement slurry system for cementing, which comprises the following steps:

[0036] The high-temperature resistant cement for cementing, quartz sand, a suspension stabilizer, and a dispersant are uniformly mixed according to parts by weight to obtain a dry mix; a fluid loss additive, a retarder, a defoamer, and water are uniformly mixed according to parts by weight to obtain a wet mix; the dry mix is ​​evenly poured into the wet mix at a rotation speed of 4000±200 r / min. After the dry mix is ​​completely added to the wet mix, the rotation speed is adjusted to 12000±500 r / min, and stirring is continued for 15 to 35 seconds to obtain the high-temperature resistant cement slurry system for cementing.

[0037] The technical solution of the present invention has at least the following beneficial effects:

[0038] (1) Under ultra-high temperature conditions of 240°C, as the high-temperature curing age of conventional sanded cement paste increases, the interlaced and overlapping network structure of needle-shaped xonotlite grains in the hydration product disappears, the tightness between the crystals decreases significantly, and the xonotlite grains coarsen, resulting in a serious reduction in the high-temperature mechanical properties of the sanded oil well cement paste. The present invention optimizes the calcium, silicon, and aluminum ratio of the cement by compounding G-grade oil well cement, low-calcium silicate cement, sulphoaluminate cement, gypsum, and composite admixtures, thereby optimizing the hydration product components and effectively improving the mechanical properties of the cement paste at high temperatures. The present invention uses a composite admixture, which is a mixture of carbide slag, phosphorus slag, mussel shell powder, and sugar filter mud in a weight ratio of 10-15:5-10:3-6:1-3. The composite admixture designed by the present invention can effectively improve the high-temperature strength decline resistance of the cement paste. The design of the cement formula of the present invention can prevent the grain coarsening of the hydration product and maintain a network structure of interlaced and overlapping grains. The dense structure formed by the main hydration product, xonotlite, plays a key role in improving the mechanical properties of high-temperature cement stone.

[0039] (2) Conventional G-grade oil well cement sand-adding systems must be supplemented with reinforcing materials and anti-strength decay materials to achieve the effect of preventing cement stone strength decay under high temperature conditions. However, there are many types of reinforcing materials and anti-strength decay materials and they are expensive. Special cements such as phosphates and aluminates require special admixtures. The research and development costs of these special admixtures are high and their economic efficiency is poor. The high-temperature resistant cement components for cementing of the present invention include G-grade oil well cement, low-calcium silicate cement, gypsum, sulfoaluminate cement and composite admixtures. The composite admixtures include a mixture of carbide slag, phosphorus slag, mussel shell powder and sugar filter mud in a weight ratio of 10-15:5-10:3-6:1-3. The raw materials used in the present invention are cement, gypsum and solid waste, which are low in price and effectively save engineering costs.

[0040] (3) The high-temperature resistant cement for well cementing provided by the present invention can be used in combination with only quartz sand and a basic admixture of silicate cement to form a high-temperature resistant cement slurry system for well cementing. The high-temperature resistant cement slurry system for well cementing provided by the present invention has an adjustable thickening time and does not require the addition of external reinforcing materials or anti-strength decay materials. This avoids the occurrence of problems such as excessive additions in the cement slurry system leading to unadjustable thickening time, slurry thickening, and thus affecting cementing construction safety.

[0041] In summary, the present invention provides a high-temperature resistant cement and cement slurry system for cementing and a preparation method thereof. The applicable bottom hole circulation temperature range of the cement and cement slurry system of the present invention is 150°C to 240°C. The compressive strength of the cement stone cured for 28 days in this temperature range is greater than 40MPa, and there is no decline in the compressive strength of the cement stone cured for 2 days, which solves the problem that the strength decline of cement stone above 200°C affects high-quality exploration and development. At the same time, the high-temperature resistant cement slurry system for cementing of the present invention has a suitable thickening time, and there is no problem of abnormal setting performance of the cement slurry due to too short thickening time. The high-temperature resistant cement and cement slurry system for cementing provided by the present invention ensures the cementing sealing effect and cementing construction safety under high-temperature, ultra-high-temperature deep well and ultra-deep well conditions, and improves the cementing quality. DETAILED DESCRIPTION

[0042] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0043] In the following examples and comparative examples, the raw materials used include G-grade oil well cement (high sulfate resistance), low-calcium Portland cement, anhydrite, natural dihydrate gypsum, sulfoaluminate cement, carbide slag, phosphorus slag, mussel shell powder, sugar filter mud, quartz sand, suspension stabilizer, retarder, fluid loss additive, dispersant, and defoamer, all of which are commercially available. Distilled water was used.

[0044] Among them, based on the total weight of G-grade oil well cement as 100%, its components are: 96% of Portland cement clinker and 4% of gypsum; based on the total weight of Portland cement clinker as 100%, its mineral composition is: 54% of tricalcium silicate, 23% of dicalcium silicate, 2% of tricalcium aluminate, 17% of tetracalcium aluminoferrite, 1.7% of free calcium oxide, 2% of free magnesium oxide, 0.1% of sodium oxide and 0.2% of potassium oxide.

[0045] Based on the total weight of low-calcium Portland cement being 100%, its components are: 97% of low-calcium Portland cement clinker and 3% of gypsum; based on the total weight of low-calcium Portland cement clinker being 100%, its mineral composition is: 49% of dicalcium silicate, 29% of tricalcium silicate, 2% of tricalcium aluminate, 16% of tetracalcium aluminoferrite, 2.1% of free calcium oxide, 1.6% of free magnesium oxide, 0.1% of sodium oxide and 0.2% of potassium oxide.

[0046] Based on the total weight of sulphoaluminate cement being 100%, its components are: 94% of sulphoaluminate cement clinker and 6% of gypsum; based on the total weight of sulphoaluminate cement clinker being 100%, its mineral composition is: 64% of calcium sulphoaluminate, 16% of dicalcium silicate, 15% of tetracalcium aluminoferrite, 2.1% of free calcium oxide, 2.7% of free magnesium oxide, 0.1% of sodium oxide and 0.1% of potassium oxide.

[0047] The gypsum in the components of G-grade oil well cement, the gypsum in the components of low-calcium silicate cement, and the gypsum in the components of sulphoaluminate cement are all mixtures of anhydrite and natural dihydrate gypsum in a mass ratio of 1:1.

[0048] The mass content of Ca(OH)2 in the carbide slag is 70% to 80%. The particle size of the carbide slag is 10 to 15 μm.

[0049] The mass content of P2O5 in the phosphorus slag is 40% to 43%, the mass content of SiO2 is 47% to 52%, the mass content of Fe2O3 is 2% to 5%, the mass content of fluoride is 0.8% to 3%, and the mass content of Al2O3 is 0.8% to 2.5%. The particle size of the phosphorus slag is 0.5 to 5 mm.

[0050] The content of CaCO3 in the mussel shell powder is 90% to 96%, and the particle size of the mussel shell powder is 200 to 300 μm.

[0051] The mass content of CaCO3 in sugar filter mud is 55% to 70%.

[0052] The suspension stabilizer is a product of China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd., model DRK-3S.

[0053] The retarder is a product of China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd., model DRH-3L.

[0054] The fluid loss additive is a product of China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd., model DRF-3L.

[0055] The dispersant is a product of China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd., model DRS-2S.

[0056] The defoaming agent is a product of China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd., model DRX-1L.

[0057] Example 1

[0058] This embodiment provides a high-temperature resistant cement for well cementing, comprising the following components, measured in parts by weight: 43 parts of G-grade oil well cement, 43 parts of low-calcium Portland cement, 2 parts of gypsum, 8 parts of sulfoaluminate cement, and 4 parts of a composite admixture; wherein the composite admixture is a mixture of carbide slag, phosphorus slag, mussel shell powder, and sugar filter mud in a weight ratio of 10:5:3:1. The gypsum is a mixture of anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0059] This embodiment also provides a high-temperature resistant cement slurry system for well cementing. The system comprises the following components, measured in parts by weight: 100 parts of the high-temperature resistant cement for well cementing, 30 parts of 200-mesh ordinary quartz sand, 20 parts of 1500-mesh ordinary quartz sand, 3 parts of a suspension stabilizer, 4 parts of a fluid loss additive, 1.2 parts of a dispersant, 3 parts of a retarder, 0.2 parts of a defoaming agent, and 51 parts of water. The density of the high-temperature resistant cement slurry system for well cementing is 1.90 g / cm³.

[0060] The high-temperature resistant cement slurry system for cementing in this embodiment is prepared by the following steps: mixing high-temperature resistant cement for cementing, quartz sand, a suspension stabilizer, and a dispersant in the above-mentioned weight portions to obtain a dry mix; mixing a fluid loss additive, a retarder, a defoamer, and water in the above-mentioned weight portions to obtain a wet mix; using a mixer, at a speed of 4000±200 r / min, evenly pouring the dry mix into the wet mix; after the dry mix is ​​completely added to the wet mix, covering the mixer with a lid, adjusting the speed to 12000±500 r / min, and continuing stirring for 35 seconds to obtain the high-temperature resistant cement slurry system for cementing.

[0061] Example 2

[0062] This example provides a high-temperature-resistant cement slurry system for well cementing. The system comprises the following components, measured in parts by weight: 100 parts of the high-temperature-resistant cement for well cementing provided in Example 1, 30 parts of 200-mesh ordinary quartz sand, 20 parts of 1500-mesh ordinary quartz sand, 4 parts of a suspension stabilizer, 5 parts of a fluid loss additive, 1.2 parts of a dispersant, 5 parts of a retarder, 0.2 parts of a defoamer, and 49 parts of water. The density of the high-temperature-resistant cement slurry system is 1.90 g / cm³. The preparation steps for the high-temperature-resistant cement slurry system are the same as those for Example 1.

[0063] Example 3

[0064] This example provides a high-temperature-resistant cement slurry system for well cementing. The system comprises the following components, measured in parts by weight: 100 parts of the high-temperature-resistant cement for well cementing provided in Example 1, 4 parts of a suspension stabilizer, 3 parts of a fluid loss additive, 1 part of a dispersant, 2 parts of a retarder, 0.2 parts of a defoamer, and 39 parts of water. The density of the high-temperature-resistant cement slurry system is 1.90 g / cm³. The preparation steps for the high-temperature-resistant cement slurry system are the same as those for Example 1.

[0065] Example 4

[0066] This embodiment provides a high-temperature resistant cement for well cementing, comprising the following components, measured in parts by weight: 55 parts of G-grade oil well cement, 40 parts of low-calcium Portland cement, 1 part of gypsum, 2 parts of sulfoaluminate cement, and 2 parts of a composite admixture; wherein the composite admixture is a mixture of carbide slag, phosphorus slag, mussel shell powder, and sugar filter mud in a weight ratio of 10:5:3:1. The gypsum is a mixture of anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0067] This embodiment also provides a high-temperature resistant cement slurry system for well cementing. The system comprises the following components, measured in parts by weight: 100 parts of the high-temperature resistant cement for well cementing, 30 parts of 200-mesh ordinary quartz sand, 20 parts of 1500-mesh ordinary quartz sand, 3 parts of a suspension stabilizer, 4 parts of a fluid loss additive, 1.2 parts of a dispersant, 3 parts of a retarder, 0.2 parts of a defoaming agent, and 51 parts of water. The density of the high-temperature resistant cement slurry system for well cementing is 1.90 g / cm³.

[0068] Example 5

[0069] This embodiment provides a high-temperature resistant cement for well cementing, comprising the following components, measured in parts by weight: 40 parts of G-grade oil well cement, 55 parts of low-calcium Portland cement, 1 part of gypsum, 2 parts of sulfoaluminate cement, and 2 parts of a composite admixture; wherein the composite admixture is a mixture of carbide slag, phosphorus slag, mussel shell powder, and sugar filter mud in a weight ratio of 10:5:3:1. The gypsum is a mixture of anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0070] This embodiment also provides a high-temperature resistant cement slurry system for well cementing. The system comprises the following components, measured in parts by weight: 100 parts of the high-temperature resistant cement for well cementing, 30 parts of 200-mesh ordinary quartz sand, 20 parts of 1500-mesh ordinary quartz sand, 3 parts of a suspension stabilizer, 4 parts of a fluid loss additive, 1.2 parts of a dispersant, 3 parts of a retarder, 0.2 parts of a defoaming agent, and 51 parts of water. The density of the high-temperature resistant cement slurry system for well cementing is 1.90 g / cm³.

[0071] Example 6

[0072] This embodiment provides a high-temperature resistant cement for well cementing, comprising the following components, measured in parts by weight: 40 parts of G-grade oil well cement, 40 parts of low-calcium Portland cement, 5 parts of gypsum, 5 parts of sulfoaluminate cement, and 10 parts of a composite admixture; wherein the composite admixture is a mixture of carbide slag, phosphorus slag, mussel shell powder, and sugar filter mud in a weight ratio of 10:5:3:1. The gypsum is a mixture of anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0073] This embodiment also provides a high-temperature resistant cement slurry system for well cementing. The system comprises the following components, measured in parts by weight: 100 parts of the high-temperature resistant cement for well cementing, 30 parts of 200-mesh ordinary quartz sand, 20 parts of 1500-mesh ordinary quartz sand, 3 parts of a suspension stabilizer, 4 parts of a fluid loss additive, 1.2 parts of a dispersant, 3 parts of a retarder, 0.2 parts of a defoaming agent, and 51 parts of water. The density of the high-temperature resistant cement slurry system for well cementing is 1.90 g / cm³.

[0074] Example 7

[0075] This embodiment provides a high-temperature resistant cement for well cementing, comprising the following components, measured in parts by weight: 40 parts of G-grade oil well cement, 40 parts of low-calcium Portland cement, 5 parts of gypsum, 5 parts of sulfoaluminate cement, and 10 parts of a composite admixture; wherein the composite admixture is a mixture of carbide slag, phosphorus slag, mussel shell powder, and sugar filter mud in a weight ratio of 15:10:6:3. The gypsum is a mixture of anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0076] This embodiment also provides a high-temperature resistant cement slurry system for well cementing. The system comprises the following components, measured in parts by weight: 100 parts of the high-temperature resistant cement for well cementing, 30 parts of 200-mesh ordinary quartz sand, 20 parts of 1500-mesh ordinary quartz sand, 3 parts of a suspension stabilizer, 4 parts of a fluid loss additive, 1.2 parts of a dispersant, 3 parts of a retarder, 0.2 parts of a defoaming agent, and 51 parts of water. The density of the high-temperature resistant cement slurry system for well cementing is 1.90 g / cm³.

[0077] Comparative Example 1

[0078] This comparative example provides a cementing slurry system for well cementing. The system comprises the following components, measured in parts by weight: 100 parts of Grade G oil well cement, 30 parts of 200-mesh ordinary quartz sand, 20 parts of 1500-mesh ordinary quartz sand, 3 parts of a suspension stabilizer, 4 parts of a fluid loss additive, 1.2 parts of a dispersant, 3 parts of a retarder, 0.2 parts of a defoamer, and 51 parts of water. The density of the cementing slurry system is 1.90 g / cm³. The preparation steps for the cementing slurry system are the same as those in Example 1.

[0079] Comparative Example 2

[0080] This comparative example provides a cementing slurry system for well cementing. The system comprises the following components, measured in parts by weight: 100 parts of Grade G oil well cement, 30 parts of 200-mesh ordinary quartz sand, 20 parts of 1500-mesh ordinary quartz sand, 4 parts of a suspension stabilizer, 5 parts of a fluid loss additive, 1.2 parts of a dispersant, 5 parts of a retarder, 0.2 parts of a defoamer, and 49 parts of water. The density of the cementing slurry system is 1.90 g / cm³. The preparation steps for the cementing slurry system are the same as those in Example 1.

[0081] Comparative Example 3

[0082] This comparative example provides a cement for well cementing, comprising the following components, measured in parts by weight: 34 parts of G-grade oil well cement, 52 parts of low-calcium Portland cement, 4 parts of gypsum, 6 parts of sulfoaluminate cement, and 4 parts of a composite admixture; wherein the composite admixture is a mixture of carbide slag, phosphorus slag, mussel shell powder, and sugar filter mud in a weight ratio of 10:5:3:1. The gypsum is a mixture of anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0083] This comparative example also provides a cementing slurry system, comprising the following components, in parts by weight: 100 parts of the cementing cement of this comparative example, 30 parts of 200-mesh ordinary quartz sand, 20 parts of 1500-mesh ordinary quartz sand, 4 parts of a suspension stabilizer, 5 parts of a fluid loss additive, 1.2 parts of a dispersant, 5 parts of a retarder, 0.2 parts of a defoamer, and 49 parts of water. The density of this cementing slurry system is 1.90 g / cm³. The preparation steps for this cementing slurry system are the same as those in Example 1.

[0084] Comparative Example 4

[0085] This comparative example provides a cement for well cementing, comprising the following components, measured in parts by weight: 52 parts of G-grade oil well cement, 34 parts of low-calcium Portland cement, 5 parts of gypsum, 5 parts of sulfoaluminate cement, and 4 parts of a composite admixture; wherein the composite admixture is a mixture of carbide slag, phosphorus slag, mussel shell powder, and sugar filter mud in a weight ratio of 10:5:3:1. The gypsum is a mixture of anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0086] This comparative example also provides a cementing slurry system, comprising the following components, in parts by weight: 100 parts of the cementing cement of this comparative example, 30 parts of 200-mesh ordinary quartz sand, 20 parts of 1500-mesh ordinary quartz sand, 4 parts of a suspension stabilizer, 5 parts of a fluid loss additive, 1.2 parts of a dispersant, 5 parts of a retarder, 0.2 parts of a defoamer, and 49 parts of water. The density of this cementing slurry system is 1.90 g / cm³. The preparation steps for this cementing slurry system are the same as those in Example 1.

[0087] Comparative Example 5

[0088] This comparative example provides a cement for well cementing, comprising the following components, measured in parts by weight: 43 parts of Grade G oil well cement, 43 parts of low-calcium Portland cement, 2 parts of gypsum, 8 parts of sulfoaluminate cement, and 4 parts of a composite admixture; the composite admixture is a mixture of carbide slag, phosphorus slag, and mussel shell powder in a weight ratio of 20:4:2. The gypsum is a mixture of anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0089] This comparative example also provides a cementing slurry system, comprising the following components, in parts by weight: 100 parts of the cementing cement of this comparative example, 30 parts of 200-mesh ordinary quartz sand, 20 parts of 1500-mesh ordinary quartz sand, 3 parts of a suspension stabilizer, 4 parts of a fluid loss additive, 1.2 parts of a dispersant, 3 parts of a retarder, 0.2 parts of a defoamer, and 51 parts of water. The density of this cementing slurry system is 1.90 g / cm³. The preparation steps for this cementing slurry system are the same as those in Example 1.

[0090] Comparative Example 6

[0091] This comparative example provides a cement for well cementing, comprising the following components, measured in parts by weight: 45 parts of Grade G oil well cement, 45 parts of low-calcium Portland cement, 2 parts of gypsum, and 8 parts of sulfoaluminate cement. The gypsum is a mixture of anhydrite and natural dihydrate gypsum in a mass ratio of 1:1.

[0092] This comparative example also provides a cementing slurry system, comprising the following components, in parts by weight: 100 parts of the cementing cement of this comparative example, 30 parts of 200-mesh ordinary quartz sand, 20 parts of 1500-mesh ordinary quartz sand, 3 parts of a suspension stabilizer, 4 parts of a fluid loss additive, 1.2 parts of a dispersant, 3 parts of a retarder, 0.2 parts of a defoamer, and 51 parts of water. The density of this cementing slurry system is 1.90 g / cm³. The preparation steps for this cementing slurry system are the same as those in Example 1.

[0093] Comparative Example 7

[0094] This comparative example provides a cement slurry system for well cementing, comprising the following components, in parts by weight: 100 parts of the cement provided in Comparative Example 6, 30 parts of 200-mesh ordinary quartz sand, 20 parts of 1500-mesh ordinary quartz sand, 4 parts of a suspension stabilizer, 5 parts of a fluid loss additive, 1.2 parts of a dispersant, 5 parts of a retarder, 0.2 parts of a defoamer, and 49 parts of water. The density of this cement slurry system is 1.90 g / cm³. The preparation steps for this cement slurry system are the same as those in Example 1.

[0095] Test Case

[0096] The thickening time and compressive strength of the cement pastes provided in Examples 1-7 and Comparative Examples 1-7 were tested according to the standard GB / T 19139-2012, "Test Methods for Oil Well Cement." The primary experimental instruments used during the tests included a 30-60 ribbed agitator (Chadler, USA), an 8240 high-temperature and high-pressure thickener (Chadler, USA), and an ultra-high-temperature curing kettle (Shenyang Tiger Petroleum Instruments and Equipment Manufacturing Co., Ltd.). The test results are shown in Table 1.

[0097] Table 1

[0098] As shown in Table 1, at 200°C, the compressive strength of the cement paste of the conventional G-grade oil well cement and sand-added slurry system provided in Comparative Example 1, cured for 28 days, significantly degrades compared to the compressive strength of the cement paste cured for 2 days. A comparison of Example 1 and Comparative Example 1 reveals that, given a similar difference in thickening time, the high-temperature-resistant cement slurry system for well cementing in Example 1 exhibits a strength of 45.8 MPa after 2 days of curing and 53.8 MPa after 28 days of curing. This demonstrates that the cement slurry system in Example 1 exhibits no strength degradation at 200°C, and the compressive strength of the cement paste is higher at both 2 and 28 days than the G-grade oil well cement and sand-added slurry system in Comparative Example 1. Furthermore, the cement slurry system in Example 1 exhibits an adjustable thickening time and a normal thickening curve, meeting engineering performance requirements.

[0099] At 240°C, the compressive strength of the cement paste of the conventional G-grade oil well cement and sand-added slurry system provided in Comparative Example 2 significantly declined after 28 days of curing compared to the compressive strength of the cement paste cured for 2 days. A comparison of Example 2 and Comparative Example 2 shows that, given a similar difference in thickening time, the cement paste strength of the high-temperature-resistant cement slurry system for well cementing in Example 2 reached 48.4 MPa after 2 days of curing, and 56.1 MPa after 28 days of curing. This demonstrates that the cement slurry system in Example 2 exhibits no strength decline under ultra-high temperature conditions of 240°C, and that the compressive strength of the cement paste at both 2 and 28 days is higher than that of the G-grade oil well cement and sand-added slurry system provided in Comparative Example 2.

[0100] Under the condition of 150°C, the compressive strength of the cement paste cured for 28 days by the high-temperature resistant cement slurry system for cementing without adding sand provided in Example 3 is still greater than 40 MPa, and there is no decline in the compressive strength of the cement paste cured for 2 days.

[0101] The weight ratios of G-grade oil well cement, low-calcium Portland cement, gypsum, sulfoaluminate cement, and composite admixtures in the cementing cements of Example 2, Comparative Example 3, and Comparative Example 4 were 43:43:2:8:4, 34:52:4:6:4, and 52:34:5:5:4, respectively. At 240°C, the cement paste prepared in Example 2, which employed a weight ratio of 43:43:2:8:4 for G-grade oil well cement, low-calcium Portland cement, gypsum, sulfoaluminate cement, and composite admixtures, had the highest compressive strength. However, the cement pastes of Comparative Examples 3 and 4, whose weight ratios of the components were outside the scope of the present invention, had low compressive strength. The 28-day compressive strength of the cement pastes of Example 2 and Comparative Examples 3 and 4 showed no decline in compressive strength compared to their 2-day compressive strength. This demonstrates that well cementing cement made from Grade G oil well cement, low-calcium Portland cement, gypsum, sulfoaluminate cement, and composite admixtures helps improve the mechanical properties of cement paste under high-temperature conditions and prevents high-temperature strength degradation. However, the optimal weight ratio of the components in the cement of the present invention is 43:43:2:8:4, which is the optimal weight ratio of the Grade G oil well cement, low-calcium Portland cement, gypsum, sulfoaluminate cement, and composite admixtures in the high-temperature-resistant cement of the present invention.

[0102] The composite admixture in the high-temperature resistant cement for well cementing of Example 1 is a mixture of carbide slag, phosphorus slag, mussel shell powder, and sugar filter mud in a weight ratio of 10:5:3:1. The composite admixture in the cement for well cementing of Comparative Example 5 is a mixture of carbide slag, phosphorus slag, and mussel shell powder in a weight ratio of 20:4:2. The cement for well cementing of Comparative Example 6 does not use composite admixtures. Under the condition of 200°C, the compressive strength of the cement paste of Example 1 is the highest, while the compressive strength of the cement paste of Comparative Example 6 is the lowest; and the 28-day compressive strength of the cement pastes of Example 1 and Comparative Examples 5 and 6 does not decline compared to the 2-day compressive strength. The high-temperature resistant cement slurry systems for well cementing of Examples 4 to 7 do not decline in strength under high temperature conditions of 200°C; and the 28-day compressive strength of the cement pastes of Examples 4 to 7 is higher than that of Comparative Examples 5 and 6.

[0103] The composite admixture in the high-temperature-resistant cement for well cementing in Example 2 is a mixture of carbide slag, phosphorus slag, mussel shell powder, and sugar filter mud in a weight ratio of 10:5:3:1. The cement for well cementing in Comparative Example 7 does not use any composite admixture. At 240°C, the compressive strength of the cement paste in Example 2 is significantly higher than that in Comparative Example 7.

[0104] This indicates that the weight ratio of G-grade oil well cement, low-calcium Portland cement, gypsum, and sulphoaluminate cement, as described in the present invention, can achieve a certain degree of effectiveness in preventing the high-temperature strength degradation of cement paste. Furthermore, the composite admixture designed in the present invention has a significant effect on improving the mechanical properties of cement paste.

[0105] In summary, the high-temperature resistant cement and cement slurry system for cementing provided by the present invention is applicable to a bottom hole circulation temperature range of 150°C to 240°C. The compressive strength of the cement stone cured for 28 days in this temperature range is greater than 40MPa (the compressive strength of the cement stone cured for 28 days by the sand-added cement slurry system is greater than 50MPa), and there is no decline in the compressive strength of the cement stone cured for 2 days, which solves the problem that the strength decline of cement stone above 200°C affects high-quality exploration and development. At the same time, the high-temperature resistant cement slurry system for cementing provided by the present invention has a suitable thickening time, and the thickening time is adjustable. There is no problem of abnormal setting performance of the cement slurry due to too short thickening time. The high-temperature resistant cement and cement slurry system for cementing provided by the present invention ensures the cementing sealing effect and cementing construction safety under high-temperature, ultra-high-temperature deep well and ultra-deep well conditions, and improves the cementing quality.

[0106] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A high temperature resistant cement for cementing, comprising the following components, in parts by weight: 40-55 parts of G-grade oil well cement, 40-55 parts of low calcium silicate cement, 1-5 parts of gypsum, 1-10 parts of sulphoaluminate cement and 1-10 parts of composite admixture; wherein: The composite admixture comprises a mixture of carbide slag, phosphorus slag, mussel shell powder and sugar filter mud in a weight ratio of 10-15:5-10:3-6:1-3.

2. The high temperature resistant cement for cementing according to claim 1, wherein: Taking the total weight of the G-grade oil well cement as 100%, the G-grade oil well cement includes the following components: 95% to 97% of silicate cement clinker and 3% to 5% of gypsum; wherein, taking the total weight of the silicate cement clinker as 100%, the silicate cement clinker includes the following mineral composition: 40% to 65% of tricalcium silicate, 15% to 25% of dicalcium silicate, 10% to 30% of tricalcium aluminate and tetracalcium aluminoferrite, 1% to 5% of free calcium oxide and free magnesium oxide, and 0% to 0.6% of sodium oxide and potassium oxide.

3. The high temperature resistant cement for cementing according to claim 1, wherein: Taking the total weight of the low-calcium silicate cement as 100%, the low-calcium silicate cement includes the following components: 94% to 99% of low-calcium silicate cement clinker and 1% to 6% of gypsum; wherein, taking the total weight of the low-calcium silicate cement clinker as 100%, the low-calcium silicate cement clinker includes the following mineral composition: 45% to 70% of dicalcium silicate, 10% to 40% of tricalcium silicate, 10% to 30% of tricalcium aluminate and tetracalcium aluminoferrite, 1% to 5% of free calcium oxide and free magnesium oxide, and 0% to 0.6% of sodium oxide and potassium oxide.

4. The high temperature resistant cement for cementing according to claim 1, wherein: Taking the total weight of the sulphoaluminate cement as 100%, the sulphoaluminate cement includes the following components: 92% to 95% of sulphoaluminate cement clinker and 5% to 8% of gypsum; wherein, taking the total weight of the sulphoaluminate cement clinker as 100%, the sulphoaluminate cement clinker includes the following mineral composition: 55% to 75% of calcium sulphoaluminate, 8% to 37% of dicalcium silicate, 15% to 35% of tetracalcium aluminoferrate, 0% to 3% of calcium sulfate, 1% to 5% of free calcium oxide and free magnesium oxide, and 0% to 0.6% of sodium oxide and potassium oxide.

5. The high temperature resistant cement for cementing according to claim 1, wherein: The gypsum includes one or a combination of natural dihydrate gypsum, anhydrite and mixed gypsum.

6. The high temperature resistant cement for cementing according to claim 1, wherein: The mass content of Ca(OH)2 in the carbide slag is 70% to 80%; the particle size of the carbide slag is 10 to 15 μm.

7. The high temperature resistant cement for cementing according to claim 1, wherein: The mass content of P2O5 in the phosphorus slag is 40% to 43%, the mass content of SiO2 is 47% to 52%, the mass content of Fe2O3 is 2% to 5%, the mass content of fluoride is 0.8% to 3%, and the mass content of Al2O3 is 0.8% to 2.5%; the particle size of the phosphorus slag is 0.5 to 5 mm.

8. The high temperature resistant cement for cementing according to claim 1, wherein: The content of CaCO3 in the mussel shell powder is 90% to 96%; the particle size of the mussel shell powder is 200 to 300 μm.

9. The high temperature resistant cement for cementing according to claim 1, wherein: The mass content of CaCO3 in the sugar filter mud is 55% to 70%.

10. A high temperature resistant cement slurry system for cementing, which, in parts by weight, Includes the following components: 100 parts of the high temperature resistant cement for cementing as claimed in claim 1, 0 to 70 parts of quartz sand, 1 to 6 parts of a suspension stabilizer, 2 to 9 parts of a fluid loss reducer, 0.5 to 1.5 parts of a dispersant, 1 to 9 parts of a retarder, 0.1 to 0.5 parts of a defoaming agent and 40 to 100 parts of water.

11. The high temperature resistant cement slurry system for cementing according to claim 10, wherein: The particle size of the quartz sand is 50-5000 mesh, and the quartz sand includes ordinary quartz sand and / or acid-washed quartz sand.

12. The high temperature resistant cement slurry system for cementing according to claim 10, wherein: The suspension stabilizer includes an acrylamide polymer suspension stabilizer.

13. The high temperature resistant cement slurry system for cementing according to claim 12, wherein: The suspension stabilizer comprises a polymer suspension stabilizer prepared from 2-acrylamide-2-methylpropane sulfonic acid, acrylamide, diallyldimethylammonium chloride and N-vinyl pyrrolidone as monomers.

14. The high temperature resistant cement slurry system for cementing according to claim 10, wherein: The fluid loss reducer includes a 2-acrylamide-2-methylpropanesulfonic acid polymer type fluid loss reducer.

15. The high temperature resistant cement slurry system for cementing according to claim 14, wherein: The fluid loss reducer comprises a polymer fluid loss reducer prepared from 2-acrylamide-2-methylpropanesulfonic acid, N,N-dimethylacrylamide and unsaturated carboxylic acid as monomers.

16. The high temperature resistant cement slurry system for cementing according to claim 10, wherein: The dispersant includes an aldehyde-ketone polycondensate dispersant and / or a polycarboxylic acid dispersant.

17. The high temperature resistant cement slurry system for cementing according to claim 10, wherein: The retarder comprises one or a combination of hydroxy ethylene diphosphonic acid, ethylenediamine tetramethylene phosphonic acid and ethylenediamine tetramethylene phosphonate.

18. The high temperature resistant cement slurry system for cementing according to claim 10, wherein: The defoaming agent comprises one or a combination of tributyl phosphate, polyoxypropylene glycerol ether and polydimethylsiloxane.

19. A method for preparing the high temperature resistant cement slurry system for cementing according to claim 10, comprising the following steps: The high temperature resistant cement for cementing, quartz sand, suspension stabilizer and dispersant are mixed uniformly according to weight parts to obtain a dry mix; the fluid loss reducer, retarder, defoamer and water are mixed uniformly according to weight parts to obtain a wet mix; at a rotation speed of 4000±200r / min, the dry mix is ​​evenly poured into the wet mix, and after the dry mix is ​​completely added to the wet mix, the rotation speed is adjusted to 12000±500r / min, and stirring is continued for 15-35s to obtain the high temperature resistant cement slurry system for cementing.

Images