High temperature resistant cement and cement paste system for well cementing and method for their production

Abstract

FIELD: cements.SUBSTANCE: invention relates to a high-temperature-resistant cement and a cement paste system for well cementing, as well as a method for producing them. High-temperature-resistant well-cementing cement contains 40-55 parts of G-class oil well cement by weight, 40-55 parts of low-calcium Portland cement, 1-5 parts of gypsum, 1-10 parts of sulfoaluminate cement, and 1-10 parts of composite additive. The application temperature of cement and cement paste system is in the range of 150-240 °C, and the compressive strength of cement stone, which is maintained for 28 days, is more than 40 MPa and does not decrease.EFFECT: guaranteeing the cementing sealing effects of high-temperature and ultra-high-temperature deep wells and ultra-deep wells.19 cl, 1 tbl, 13 ex

Description

[0001] FIELD OF TECHNOLOGY

[0002] The present invention relates to a high-temperature-resistant well cement and a cement slurry system, and a method for producing the same, which relate to the field of oil and gas exploration and development.

[0003] STATE OF THE ART

[0004] With the deepening of exploration and development, the number of deep wells with high and ultra-high temperatures is increasing, with drilling depths gradually increasing to 10,000 meters. The circulating temperature at the wellbore bottom is also gradually moving toward ultra-high temperatures of 240°C. Under high and ultra-high temperature conditions, the strength degradation of Portland cement is serious, posing a major challenge to ensuring the integrity of the cement sheath seal. Currently, the common measure is to select suitable siliceous additives, such as quartz sand, for mixing with Portland cement. However, sand cement undergoes hydration product changes under high temperatures of 200°C or more, resulting in significant strength degradation, making it unsuitable for the long-term operation 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 stone at high temperatures, so as to ensure the safety of cementing structures in high-temperature deep wells and improve the quality of well cementing.

[0005] CN112094060A discloses high-temperature well cement, its production method, and its application. The well cement consists of 69-72% cement raw materials and 28-31% quartz sand. The cement raw materials are composed of grade G oil well cement and nuclear power cement in a weight ratio of 4:6-5:5. However, this high-temperature well cement is mainly suitable for well cementing work in Africa, and its strength is slightly reduced under conditions of 130°C-200°C.

[0006] CN101906291A discloses a high-temperature special oil well cement material and a method for producing the same. The oil well cement material contains by weight: 100 parts of high-concrete cement, 10-25 parts of quartz sand powder, and 0.22-0.32 parts of lignosulfonate or modified lignosulfonate or 0.9-1.5 parts of ethylenediaminetetrakis(methylenephosphonate). The cement product has the advantages of high thermal stability and low pollution, but it is primarily used in oil and gas well workover operations. It has certain limitations in its application and is only suitable for wells with bottomhole circulation temperatures of 60°C to 130°C.

[0007] CN113582605A discloses a high-temperature-resistant cement for well cementing systems and a method for producing the same. The cement system consists of 25-85 parts by weight of cement, 4-60 parts by weight of quartz sand, and 4-60 parts by weight of fly ash and additives. This cement system can solve the problem of strength degradation of cement stone used in well cementing in ultra-high-temperature environments. It can also address land use and environmental pollution issues caused by fly ash, and its applicable temperature can reach up to 200°C. However, after 30 days of curing, the compressive strength showed a decrease in strength compared with that of cement stone cured for 2 days.

[0008] CN115304317A discloses a high-temperature strength degradation-resistant cement slurry system for oil wells. The cement slurry system consists of 47.5-72.5 wt% cement material, 15-25 wt% quartz sand, 10-25 wt% high-temperature strength degradation-resistant material, 2 wt% high-temperature stabilizer, and 0.5 wt% dispersant. The high-temperature strength degradation-resistant cement slurry system for oil wells has the advantages of high-temperature strength degradation resistance and stable high-temperature performance, and can effectively alleviate the problem of strength degradation of cement stone under high-temperature conditions.

[0009] CN113683354A discloses a high-temperature strength degradation-resistant and inhibitory cement slurry system for oil wells. The cement slurry system for oil wells contains by weight: 100.0 parts of oil well cement, 30.0-50.0 parts of quartz sand, 10.0-20.0 parts of a high-temperature strength degradation inhibitor, 3.0-5.0 parts of a filiform material, 0.5-2.0 parts of modified carbon nanotubes, 1.0-3.0 parts of a dispersant, 2-4 parts of a high-temperature stabilizer, 1.0-3 parts of a high-temperature fluid loss reducing agent, 3.0 parts of a high-temperature retarder, and 65.0-75.0 parts of water. The high temperature degradation resistant strength inhibitor comprises two or more of mica, kaolin, wollastonite, chlorite and sepiolite.The cement mortar system has a compressive strength of cement stone greater than 48 MPa after 90 days of curing at 240°C, but each of the high-temperature degradation-resistant strength inhibitor, modified carbon nanotubes and the like can shorten the thickening time of the cement mortar to different degrees, resulting in abnormal conditioning performance of the cement mortar, affecting the safety of the cementitious structure.

[0010] Currently, cement used for high-temperature degradation resistance is primarily aluminate cement, phosphate cement, or Class G oil well cement with the addition of ultrafine silica. Although this reduces the phenomenon of strength degradation at high temperatures, it does not fundamentally solve the problem of strength degradation of cement paste. Conventional Portland cement pastes experience strength degradation at a curing temperature of approximately 110°C due to the conversion of hydration products from amorphous C-S-H gel to crystalline dicalcium silicate hydrates with poor performance. When the downhole circulation temperature exceeds 110°C, reducing the total calcium-to-silica ratio in oil well cement by adding silica can convert the cement hydration products into relatively superior tobermorite and xonotlite, thereby maintaining strength stability.The optimal initial amount of silica sand, recognized for many years, is 30% to 40% of the cement mass. However, recent studies have shown that at higher temperatures (>150°C), adding quartz sand to a Portland cement system still leads to significant microstructural coarsening and strength degradation. At temperatures above 200°C, increasing the amount of quartz sand (50% to 65%) can reduce severe strength degradation, but the problem remains fundamentally unresolved. In recent years, the addition of materials resistant to high-temperature strength degradation, such as metakaolin and sepiolite, to the cement slurry can effectively prevent strength degradation of cement paste at 150-200°C.However, in technical applications, materials resistant to high-temperature strength degradation can affect the thickening time of cement slurry, making it difficult to guarantee the safety of cementing operations. Therefore, ensuring the long-term strength stability of cement paste at temperatures exceeding 200°C remains a critical issue in the field of cementation.

[0011] Considering these problems, it is of great importance to develop high temperature resistant cement for well cementing to prevent the degradation of cement stone strength under high temperature conditions of 200°C and above.

[0012] BRIEF DESCRIPTION OF THE INVENTION

[0013] To solve the above technical problems, the object of the present invention is to provide a high-temperature-resistant well cement and cement slurry system and a method for producing the same. The high-temperature-resistant well cement and cement slurry system proposed according to the present invention can prevent the degradation of cement stone under high-temperature and ultra-high-temperature conditions.

[0014] In order to achieve the above-mentioned object, the first aspect of the present invention provides a high-temperature-resistant cement for well cementing, which contains by weight: 40-55 parts of class G oil well cement, 40-55 parts of low-calcium Portland cement, 1-5 parts of gypsum, 1-10 parts of sulfoaluminate cement and 1-10 parts of a composite additive; wherein the composite additive contains a mixture of carbide slag, phosphorus slag, mussel shell powder and filter drilling mud in a weight ratio of 10-15:5-10:3-6:1-3.

[0015] In the above-mentioned high temperature resistant well cement, it is preferable that the weight ratio of class G oil well cement, low calcium Portland cement, gypsum, sulfoaluminate cement and composite additive is 40-50:40 -50:1-3:5-10:3-6, more preferably 43:43:2:8:4.

[0016] In the above-mentioned high temperature resistant well cement, the weight ratio of carbide slag, phosphorus slag, mussel shell powder and filter solution is preferably 10-13:5-8:3-5:1-3.

[0017] In the above-mentioned high temperature resistant cement for well cementing, preferably, based on 100% of the total weight of the class G oil well cement, the class G oil well cement contains 95% to 97% of Portland cement clinker and 3% to 5% of gypsum; wherein, based on 100% of the total weight of the Portland cement clinker, the Portland cement clinker contains 40% to 65% of tricalcium silicate, 15% to 25% of dicalcium silicate, 10% to 30% of tricalcium aluminate and tetracalcium ferroaluminate, 1% to 5% of free calcium oxide and free magnesium oxide, 0% to 0.6% of sodium oxide and potassium oxide.

[0018] In the above-mentioned high temperature-resistant well cement, preferably, based on 100% of the total weight of the low-calcium Portland cement, the low-calcium Portland cement contains 94% to 99% of the low-calcium Portland cement clinker and 1% to 6% of gypsum; wherein, based on 100% of the total weight of the low-calcium Portland cement clinker, the low-calcium Portland cement clinker contains 45% to 70% of dicalcium silicate, 10% to 40% of tricalcium silicate, 10% to 30% of tricalcium aluminate and tetracalcium ferroaluminate, 1% to 5% of free calcium oxide and free magnesium oxide, and 0% to 0.6% of sodium oxide and potassium oxide.

[0019] In the above-mentioned high temperature resistant cement for well cementing, preferably, based on 100% of the total weight of the sulfoaluminate cement, the sulfoaluminate cement contains 92% to 95% of the sulfoaluminate cement clinker and 5% to 8% of gypsum; wherein, based on 100% of the total weight of the sulfoaluminate cement clinker, the sulfoaluminate cement clinker contains 55% to 75% of calcium sulfoaluminate, 8% to 37% of dicalcium silicate, 15% to 35% of tetracalcium ferroaluminate, 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.

[0020] In the above-mentioned high-temperature-resistant cement for well cementing, the gypsum preferably contains one or more of the following: natural dihydrate gypsum, anhydrite (i.e., natural anhydrite gypsum), and mixed gypsum. Those skilled in the art should understand that the gypsum mixture is a uniform gypsum powder with cementing effects obtained by processing any two or more gypsum raw materials (for example, natural dihydrate gypsum, anhydrite, or various types of industrial by-product gypsum) by methods such as thorough mixing, calcination, and grinding. The specific composition of the mixed gypsum is not limited in the present invention and may be commercially available. Gypsum refers to components of high-temperature-resistant cement for well cementing, components of Class G oil well cement, components of low-calcium Portland cement, and components of sulfoaluminate cement.

[0021] In the above-mentioned high temperature resistant well cement, it is preferable that the mass content of Ca(OH)2 in the carbide slag is 70% to 80%.

[0022] In the above-mentioned high temperature resistant well cement, the carbide slag preferably has a particle size of 10-15μm.

[0023] In the above-mentioned high temperature resistant cement for well cementing, preferably the phosphorus slag contains P2O5 in a mass content of 40% to 43%, SiO2 in a mass content of 47% to 52%, Fe2O in a mass content of 2% to 5%, fluoride in a mass content of 0.8% to 3%, and Al2O3 in a mass content of 0.8% to 2.5%.

[0024] In the above-mentioned high temperature resistant well cement, the phosphorus slag preferably has a particle size of 0.5-5mm.

[0025] In the above-mentioned high temperature resistant well cement, the CaCO3 content of mussel shell powder is preferably 90%-96%.

[0026] In the above-mentioned high temperature resistant well cement, the mussel shell powder preferably has a particle size of 200-300μm.

[0027] In the above-mentioned high temperature resistant well cement, it is preferable that the mass content of CaCO3 in the filter drilling fluid is 55% to 70%.

[0028] According to a specific embodiment of the present invention, a high-temperature-resistant cement for well cementing is obtained by mixing grade G oil well cement, low-calcium Portland cement, gypsum, sulfoaluminate cement and a composite additive in parts by weight as described above to obtain a high-temperature-resistant cement for well cementing.

[0029] In a second aspect, the present invention provides a high-temperature-resistant cement slurry system for well cementing, which comprises by weight: 100 parts of the above-mentioned high-temperature-resistant cement for well cementing, 0-70 parts of quartz sand, 1-6 parts of a suspension stabilizer, 2-9 parts of a fluid loss reducing agent, 0.5-1.5 parts of a dispersant, 1-9 parts of a retarder, 0.1-0.5 parts of an antifoam agent, and 40-100 parts of water.

[0030] In the above-mentioned high-temperature-resistant cement slurry system for well cementing, the quartz sand preferably has a particle size of 50-5000 mesh. According to a specific embodiment of the present invention, the quartz sand comprises ordinary quartz sand and / or acid-washed quartz sand.

[0031] In the above-mentioned high-temperature-resistant cement slurry system for well cementing, a conventional suspension stabilizer for oil well cements in the art, such as an acrylamide polymer suspension stabilizer or the like, can be used as a suspension stabilizer. Preferably, the suspension stabilizer comprises a polymer suspension stabilizer obtained from 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, diallyldimethylammonium chloride, and N-vinylpyrrolidone as monomers. The polymer suspension stabilizer can be prepared in accordance with the steps described in CN113736016A.

[0032] In the above-mentioned high-temperature-resistant cement slurry system for well cementing, a conventional fluid loss reducing agent for oil well cement in the art can be used as a fluid loss reducing agent, such as a polymeric fluid loss reducing agent based on 2-acrylamido-2-methylpropanesulfonic acid or the like. Preferably, the fluid loss reducing agent comprises a polymeric fluid loss reducing agent derived from 2-acrylamido-2-methylpropanesulfonic acid, N,N-dimethylacrylamide, and an unsaturated carboxylic acid as monomers. Acrylic acid, itaconic acid, or the like can be used as the unsaturated carboxylic acid. The polymeric fluid loss reducing agent can be prepared according to the steps described in Synthesis and Performance Evaluation of Salt-Resistant Fluid Loss Additive AMPS / DMAA / IA (Wenjuan Yu et al., Chemical Industry and Engineering, 2018, 35(1):6).

[0033] In the above-mentioned high-temperature-resistant cement slurry system for well cementing, a conventional dispersant for oil well cement in the art can be used as a dispersant. Preferably, the dispersant comprises an aldehyde ketone condensate-based dispersant and / or a polycarboxylic acid-based dispersant, etc.

[0034] In the above-mentioned high-temperature-resistant cement slurry system for well cementing, a conventional retarder for oil well cement in the art can be used as a retarder. Preferably, the retarder contains one or more of the following: hydroxyethylidenediphosphonic acid (HEDP), ethylenediaminetetrakis(methylenephosphonic acid) (EDTMPA), ethylenediaminetetrakis(methylenephosphonate), and the like.

[0035] In the above-mentioned high-temperature-resistant cement slurry system for well cementing, a conventional defoamer for oil well cement in the art can be used as the defoamer. Preferably, the defoamer contains one or more of the following: tributyl phosphate, polyoxypropylene glycerol ether, polydimethylsiloxane, and the like.

[0036] According to a specific embodiment of the present invention, the above-mentioned high-temperature-resistant cement slurry system for well cementing is obtained by dry mixing and wet mixing each of the components according to the state of dry and wet, respectively, and then mixing the dry mixture with the wet mixture.Preferably, the above-mentioned high-temperature-resistant cement slurry system for well cementing is obtained by: mixing high-temperature-resistant cement for well cementing, quartz sand, a suspension stabilizer and a dispersant in parts by weight as described above to obtain a dry mixture; mixing a fluid loss reducing agent, a retarder, a defoamer and water in parts by weight as described above to obtain a wet mixture; uniformly pouring the dry mixture into the wet mixture at a rotation speed of 4000±200 rpm; after completely adding the dry mixture to the wet mixture, bringing the rotation speed to 12000±500 rpm and mixing for another 15-35 s, to obtain a high-temperature-resistant cement slurry system for well cementing.

[0037] In a third aspect of the present invention, there is provided a method for producing a high temperature resistant cement slurry system for well cementing as described above, which comprises the following steps:

[0038] Mixing high-temperature-resistant well cement, quartz sand, suspension stabilizer and dispersant in parts by weight to obtain a dry mixture; mixing fluid loss reducing agent, retarder, defoamer and water in parts by weight to obtain a wet mixture; uniformly pouring the dry mixture into the wet mixture at a rotating speed of 4000±200rpm; after completely adding the dry mixture into the wet mixture, adjust the rotating speed to 12000±500rpm and stir for another 15-35s to obtain a high-temperature-resistant well cement slurry system.

[0039] The technical solution according to the present invention has at least the following advantageous effects:

[0040] (1) Under the ultra-high temperature condition of 240°C, as the high-temperature curing period is prolonged, ordinary sandy cement stone suffers from the loss of the network structure in which the acicular xonotlite grains in the hydration product are interconnected, the degree of compactness between the crystals is significantly reduced, and the coarsening of the xonotlite grains leads to a serious deterioration in the high-temperature mechanical properties of sandy cement stone for oil wells. By compounding class G oil well cement, low-calcium Portland cement, sulfoaluminate cement, gypsum, and a composite additive, the present invention optimizes the ratio of calcium, silica, and aluminum in the cement, which in turn optimizes the components of the hydration product and effectively improves the high-temperature mechanical properties of the cement stone.The present invention utilizes a composite additive comprising a mixture of carbide slag, phosphorus slag, mussel shell powder, and filter drilling mud in a weight ratio of 10-15:5-10:3-6:1-3. The composite additive proposed in this invention can effectively improve the resistance to high-temperature strength degradation of cement stone. By developing a cement composition according to the present invention, grain coarsening in the hydration product is prevented, a network structure in which grains intersect is maintained, and xonotlite in the main hydration product forms a dense structure, which plays an important role in improving the mechanical properties of high-temperature cement stone.

[0041] (2) In order to achieve the effect that the strength of cement stone does not decrease under high temperature conditions, reinforcing materials and strength degradation-resistant materials must be added to the general G-class oil well sand cement system. The reinforcing materials and strength degradation-resistant materials have different types and high prices; phosphate, aluminate and other special cements must be supplemented with special additives, and the research and development of these special additives is expensive and uneconomical.At the same time, the components of the high-temperature-resistant cement for well cementing according to the present invention contain class G oil well cement, low-calcium Portland cement, gypsum, sulfoaluminate cement and a composite additive; the composite additive includes a mixture of carbide slag, phosphorus slag, mussel shell powder and filter drilling mud in a weight ratio of 10-15:5-10:3-6:1-3. The raw materials used in the present invention are cements, gypsum and solid waste, which are inexpensive and thus effectively reduce design costs.

[0042] (3) A high-temperature-resistant cement slurry system for well cementing can be formed only by using the high-temperature-resistant cement for well cementing proposed according to the present invention, together with quartz sand and basic additives supplemented with Portland cement. The high-temperature-resistant cement slurry system for well cementing according to the present invention has an adjustable thickening time without the need for additional reinforcing materials, materials resistant to strength degradation, and the like, which can avoid problems such as uncontrolled thickening time, increased thickening of the paste, and the subsequent impact on the safety of cementing the structure due to excessive impurities in the cement slurry system.

[0043] Thus, the present invention provides a high-temperature-resistant well cement and cement slurry system and a method for producing the same. The cement and cement slurry system according to the present invention are applicable to a downhole circulation temperature in the range of 150°C to 240°C. The compressive strength of the cement stone within this temperature range is greater than 40 MPa for 28 days, and there is no degradation of the compressive strength of the cement stone compared to the compressive strength of the cement stone within 2 days. This solves the problem that the degradation of the strength of the cement stone at 200°C or higher affects high-quality exploration and development.Meanwhile, the high-temperature-resistant cement slurry system for well cementing according to the present invention has a desirable thickening time, eliminating the problem of abnormal cement slurry conditioning performance due to excessively short thickening times. The high-temperature-resistant cement and cement slurry system proposed in accordance with the present invention ensure sealing efficiency and cementing structure safety in high-temperature and ultra-high-temperature conditions in deep wells and ultra-deep wells, thereby improving cementing quality.

[0044] DETAILED DESCRIPTION OF IMPLEMENTATION OPTIONS

[0045] In order to have a clearer understanding of the technical features, objective and advantageous effects of the present invention, the technical solutions of the present invention are described in detail below, but they should not be understood as limiting the implementable scope of the present invention.

[0046] In the following examples and comparative examples, the raw materials used include Class G oil well cement (high sulfate-resistant type), low-calcium Portland cement, anhydrite, natural dihydrate gypsum, sulfoaluminate cement, carbide slag, phosphorus slag, mussel shell powder, filter drilling mud, quartz sand, suspension stabilizer, retarder, fluid loss reducing agent, dispersant, and defoamer, all of which are commercially available. The water used is distilled water.

[0047] Based on 100% of the total weight of grade G oil well cement, the components are 96% Portland cement clinker and 4% gypsum. Based on 100% of the total weight of Portland cement clinker, the mineral composition is: 54% tricalcium silicate, 23% dicalcium silicate, 2% tricalcium aluminate, 17% tetracalcium ferroaluminate, 1.7% free calcium oxide, 2% free magnesium oxide, 0.1% sodium oxide, and 0.2% potassium oxide.

[0048] Based on 100% of the total mass of low-calcium Portland cement, the components are 97% low-calcium Portland cement clinker and 3% gypsum. Based on 100% of the total mass of low-calcium Portland cement, the mineral composition is: 49% dicalcium silicate, 29% tricalcium silicate, 2% tricalcium aluminate, 16% tetracalcium ferroaluminate, 2.1% free calcium oxide, 1.6% free magnesium oxide, 0.1% sodium oxide and 0.2% potassium oxide.

[0049] Based on 100% of the total mass of sulfoaluminate cement, the components are 94% sulfoaluminate cement clinker and 6% gypsum. Based on 100% of the total mass of sulfoaluminate cement, the mineral composition is: 64% calcium sulfoaluminate, 16% dicalcium silicate, 15% tetracalcium ferroaluminate, 2.1% free calcium oxide, 2.7% free magnesium oxide, 0.1% sodium oxide, and 0.1% potassium oxide.

[0050] Each of the gypsum in the components of grade G oil well cement, in the components of low calcium Portland cement and in the components of sulfoaluminate cement is a mixture obtained by mixing anhydrite with natural dihydrate gypsum in a weight ratio of 1:1.

[0051] The mass content of Ca(OH)2 in carbide slag is 70-80%. The particle size of carbide slag is 10-15 μm.

[0052] In phosphorus slag, the mass content of P2O5 is 40% - 43%, the mass content of SiO2 is 47% - 52%, the mass content of Fe2O3 is 2% - 5%, the mass content of fluoride is 0.8% - 3%, and the mass content of Al2O3 is 0.8% - 2.5%. The particle size of phosphorus slag is 0.5-5 mm.

[0053] The CaCO3 content of mussel shell powder is 90% - 96%. The particle size of mussel shell powder is 200-300 μm.

[0054] The mass content of CaCO3 in sugar filter drilling mud is 55% - 70%.

[0055] Slurry stabilizer is the product of CNPC Engineering Technology R&D Company Limited, Model DRK-3S.

[0056] The retarder is a product of CNPC Engineering Technology R&D Company Limited, Model DRH-3L.

[0057] The fluid loss reducing agent is the product of CNPC Engineering Technology R&D Company Limited, Model DRF-3L.

[0058] The disperser is a product of CNPC Engineering Technology R&D Company Limited, Model DRS-2S.

[0059] The defoamer is a product of CNPC Engineering Technology R&D Company Limited, Model DRX-1L.

[0060] Example 1

[0061] This example provides a high-temperature-resistant cement for well cementing, which contains 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 additive; wherein the composite additive is a mixture of carbide slag, phosphorus slag, mussel shell powder and filter drilling mud in a weight ratio of 10:5:3:1, and wherein the gypsum is a mixture obtained by mixing anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0062] This example also provides a high-temperature-resistant cement slurry system for well cementing, which contains by weight: 100 parts of the high-temperature-resistant cement for well cementing according to this example, 30 parts of ordinary 200-mesh quartz sand, 20 parts of ordinary 1500-mesh quartz sand, 3 parts of a suspension stabilizer, 4 parts of a fluid loss reducing agent, 1.2 parts of a dispersant, 3 parts of a retarder, 0.2 parts of an antifoam, and 51 parts of water. The density of the high-temperature-resistant cement slurry system for well cementing was 1.90 g / cm³.

[0063] The high temperature resistant well cement slurry system in this example was prepared by: mixing the high temperature resistant well cement, quartz sand, suspension stabilizer and dispersant in parts by weight as described above to obtain a dry mixture; mixing the fluid loss reducing agent, retarder, defoamer and water in parts by weight as described above to obtain a wet mixture; uniformly pouring the dry mixture into the wet mixture at a rotating speed of 4000±200 rpm using a mixer; after completely adding the dry mixture into the wet mixture, closing the mixer cover, adjusting the rotating speed to 12000±500 rpm and stirring for another 35 s to obtain the high temperature resistant well cement slurry system.

[0064] Example 2

[0065] This example provides a high-temperature-resistant well cement slurry system comprising by weight: 100 parts of the high-temperature-resistant well cement of 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 reducing agent, 1.2 parts of a dispersant, 5 parts of a retarder, 0.2 parts of an antifoam, and 49 parts of water. The density of the high-temperature-resistant well cement slurry system was 1.90 g / cm³. The steps for producing the well cement slurry system were the same as those in Example 1.

[0066] Example 3

[0067] This example provides a high-temperature-resistant well cement slurry system comprising by weight: 100 parts of the high-temperature-resistant well cement slurry given in Example 1, 4 parts of a suspension stabilizer, 3 parts of a fluid loss reducing agent, 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 well cement slurry system was 1.90 g / cm³. The steps for producing the well cement slurry system were the same as in Example 1.

[0068] Example 4

[0069] This example provides a high-temperature-resistant cement for well cementing, which contains by weight: 55 parts of class G 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 additive; wherein the composite additive is a mixture of carbide slag, phosphorus slag, mussel shell powder and filter drilling mud in a weight ratio of 10:5:3:1, and wherein the gypsum is a mixture obtained by mixing anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0070] This example also provides a high-temperature-resistant cement slurry system for well cementing, which contains by weight: 100 parts of the high-temperature-resistant cement for well cementing according to this 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 reducing agent, 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 high-temperature-resistant cement slurry system for well cementing was 1.90 g / cm 3 .

[0071] Example 5

[0072] This example provides a high-temperature-resistant cement for well cementing, which contains by weight: 40 parts of class G 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 additive; wherein the composite additive is a mixture of carbide slag, phosphorus slag, mussel shell powder and filter drilling mud in a weight ratio of 10:5:3:1, and wherein the gypsum is a mixture obtained by mixing anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0073] This example also provides a high-temperature-resistant cement slurry system for well cementing, which contains by weight: 100 parts of the high-temperature-resistant cement for well cementing according to this example, 30 parts of ordinary 200-mesh quartz sand, 20 parts of ordinary 1500-mesh quartz sand, 3 parts of a suspension stabilizer, 4 parts of a fluid loss reducing agent, 1.2 parts of a dispersant, 3 parts of a retarder, 0.2 parts of an antifoam, and 51 parts of water. The density of the high-temperature-resistant cement slurry system for well cementing was 1.90 g / cm³.

[0074] Example 6

[0075] This example provides a high-temperature-resistant cement for well cementing, which contains by weight: 40 parts of class G 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 additive; wherein the composite additive is a mixture of carbide slag, phosphorus slag, mussel shell powder and filter drilling mud in a weight ratio of 10:5:3:1, and wherein the gypsum is a mixture obtained by mixing anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0076] This example also provides a high-temperature-resistant cement slurry system for well cementing, which contains by weight: 100 parts of the high-temperature-resistant cement for well cementing according to this example, 30 parts of ordinary 200-mesh quartz sand, 20 parts of ordinary 1500-mesh quartz sand, 3 parts of a suspension stabilizer, 4 parts of a fluid loss reducing agent, 1.2 parts of a dispersant, 3 parts of a retarder, 0.2 parts of an antifoam, and 51 parts of water. The density of the high-temperature-resistant cement slurry system for well cementing was 1.90 g / cm³.

[0077] Example 7

[0078] This example provides a high-temperature-resistant cement for well cementing, which contains by weight: 40 parts of class G 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 additive; wherein the composite additive is a mixture of carbide slag, phosphorus slag, mussel shell powder and filter drilling mud in a weight ratio of 15:10:6:3, and wherein the gypsum is a mixture obtained by mixing anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0079] This example also provides a high-temperature-resistant cement slurry system for well cementing, which contains by weight: 100 parts of the high-temperature-resistant cement for well cementing according to this example, 30 parts of ordinary 200-mesh quartz sand, 20 parts of ordinary 1500-mesh quartz sand, 3 parts of a suspension stabilizer, 4 parts of a fluid loss reducing agent, 1.2 parts of a dispersant, 3 parts of a retarder, 0.2 parts of an antifoam, and 51 parts of water. The density of the high-temperature-resistant cement slurry system for well cementing was 1.90 g / cm³.

[0080] Comparative Example 1

[0081] This comparative example proposes a well cementing slurry system containing by weight: 100 parts of Class G oil well cement, 30 parts of 200 mesh ordinary quartz sand, 20 parts of 1500 mesh ordinary quartz sand, 3 parts of suspension stabilizer, 4 parts of fluid loss reducing agent, 1.2 parts of dispersant, 3 parts of retarder, 0.2 parts of defoamer, and 51 parts of water. The density of the well cementing slurry system was 1.90 g / cm³. The steps for producing the well cementing slurry system were the same as those in Example 1.

[0082] Comparative Example 2

[0083] This comparative example proposes a well cementing slurry system containing by weight: 100 parts of Class G oil well cement, 30 parts of 200 mesh ordinary quartz sand, 20 parts of 1500 mesh ordinary quartz sand, 4 parts of suspension stabilizer, 5 parts of fluid loss reducing agent, 1.2 parts of dispersant, 5 parts of retarder, 0.2 parts of defoamer, and 49 parts of water. The density of the well cementing slurry system was 1.90 g / cm³. The steps for producing the well cementing slurry system were the same as those in Example 1.

[0084] Comparative Example 3

[0085] This comparative example provides a well cementing cement that contains by weight: 34 parts of class G 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 additive; wherein the composite additive is a mixture of carbide slag, phosphorus slag, mussel shell powder, and filter drilling mud at a weight ratio of 10:5:3:1, and wherein the gypsum is a mixture obtained by mixing anhydrite and natural dihydrate gypsum at a weight ratio of 1:1.

[0086] This comparative example also provides a well cementing slurry system that contains by weight: 100 parts of the well cementing cement according to the said 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 reducing agent, 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 well cementing slurry system was 1.90 g / cm³. The steps for producing the well cementing slurry system were the same as those in Example 1.

[0087] Comparative Example 4

[0088] This comparative example provides a well cementing cement that contains by weight: 52 parts of class G 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 additive; wherein the composite additive is a mixture of carbide slag, phosphorus slag, mussel shell powder, and filter drilling mud in a weight ratio of 10:5:3:1, and wherein the gypsum is a mixture obtained by mixing anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0089] This comparative example also provides a well cementing slurry system that contains by weight: 100 parts of the well cementing cement according to the said 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 reducing agent, 1.2 parts of a dispersant, 5 parts of a retarder, 0.2 parts of an antifoam agent, and 49 parts of water. The density of the well cementing slurry system was 1.90 g / cm³. The steps for producing the well cementing slurry system were the same as those in Example 1.

[0090] Comparative Example 5

[0091] This comparative example provides a well cementing cement that contains by weight: 43 parts of class 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 additive; wherein the composite additive is a mixture of carbide slag, phosphorus slag, and mussel shell powder in a weight ratio of 20:4:2, and wherein the gypsum is a mixture obtained by mixing anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0092] This comparative example also provides a well cementing slurry system that contains, by weight, 100 parts of the well cementing cement according to the said 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 reducing agent, 1.2 parts of a dispersant, 3 parts of a retarder, 0.2 parts of an antifoam agent, and 51 parts of water. The density of the well cementing slurry system was 1.90 g / cm³. The steps for producing the well cementing slurry system were the same as those in Example 1.

[0093] Comparative Example 6

[0094] This comparative example provides a well cementing cement that contains by weight: 45 parts of Class G oil well cement, 45 parts of low calcium Portland cement, 2 parts of gypsum, and 8 parts of sulfoaluminate cement, and wherein the gypsum is a mixture obtained by mixing anhydrite and natural dihydrate gypsum in a weight ratio of 1:1.

[0095] This comparative example also provides a well cementing slurry system that contains by weight: 100 parts of the well cementing cement according to the said 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 reducing agent, 1.2 parts of a dispersant, 3 parts of a retarder, 0.2 parts of an antifoam agent, and 51 parts of water. The density of the well cementing slurry system was 1.90 g / cm³. The steps for producing the well cementing slurry system were the same as those in Example 1.

[0096] Comparative Example 7

[0097] This comparative example provides a well cementing slurry system comprising by weight: 100 parts of the well cementing cement given 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 reducing agent, 1.2 parts of a dispersant, 5 parts of a retarder, 0.2 parts of an antifoam agent, and 49 parts of water. The density of the well cementing slurry system was 1.90 g / cm³. The steps for producing the well cementing slurry system were the same as those in Example 1.

[0098] Test example

[0099] The thickening time and compressive strength of the cement stone for the cement slurry systems shown in Examples 1–7 and Comparative Examples 1–7 were tested according to GB / T 19139-2012 “Test Method for Oil Well Cement.” The experimental equipment used during the test mainly included a Model 30-60 corrugated mixer (CHANDLER Company, USA), a Model 8240 high-temperature and high-pressure thickener (CHANDLER Company, USA), and an ultra-high-temperature curing autoclave (Shenyang Taige Oil Equipment Co., Ltd.). The test results are shown in Table 1.

[0100] Table 1

[0101] Experimental temperature (°C) Quantity of quartz sand used (parts by weight) Density (g / cm³) Thickening time (min) Compressive strength of cement stone (MPa) 2 days 28 days Example 1 200 30 parts 200 mesh + 20 parts 1500 mesh 1,9 309 45,8 53,8 Example 2 240 30 parts 200 mesh + 20 parts 1500 mesh 1,9 298 48,4 56,1 Example 3 150 0 1,9 313 33 41,6 Example 4 200 30 parts 200 mesh + 20 parts 1500 mesh 1,9 319 41,2 50,2 Example 5 200 30 parts 200 mesh + 20 parts 1500 mesh 1,9 307 42,1 50,9 Example 6 200 30 parts 200 mesh + 20 parts 1500 mesh 1,9 295 43,5 51,5 Example 7 200 30 parts 200 mesh + 20 parts 1500 mesh 1,9 290 42,3 51,1 Comparative example 1 200 30 parts 200 mesh + 20 parts 1500 mesh 1,9 315 37,5 31,7 Comparative example 2 240 30 parts 200 mesh + 20 parts 1500 mesh 1,9 330 40,7 33,1 Comparative example 3 240 30 parts 200 mesh + 20 parts 1500 mesh 1,9 321 41,8 43,3 Comparative example 4 240 30 parts 200 mesh + 20 parts 1500 mesh 1,9 305 35,4 40,6 Comparative example 5 200 30 parts 200 mesh + 20 parts 1500 mesh 1,9 290 40,1 45,5 Comparative example 6 200 30 parts 200 mesh + 20 parts 1500 mesh 1,9 318 38,9 41,1 Comparative example 7 240 30 parts 200 mesh + 20 parts 1500 mesh 1,9 309 40,5 42,9

[0102] As can be seen from Table 1, for the conventional cement slurry system of Class G oil well cement with sand shown in Comparative Example 1, under the condition of 200°C, the compressive strength of the cement stone after 28 days was seriously reduced compared with that of the cement stone after 2 days. Comparing Example 1 and Comparative Example 1, it can be seen that in the case where the difference in thickening time was small, the cement stone strength of the high-temperature-resistant well cement slurry system of Example 1 was 45.8 MPa after curing for 2 days, and the cement stone strength was 53.8 MPa after curing for 28 days, demonstrating that there was no degradation of the strength of the cement slurry system of Example 1 under the high temperature condition of 200°C.In addition, both the 2-day compressive strength and the 28-day compressive strength of the cement stone were higher than those of the cement slurry system of class G oil well cement with sand in Comparative Example 1. In addition, the cement slurry system of Example 1 had an adjustable thickening time and a normal thickening curve, and thus the technical performance requirements could be met.

[0103] For the general cement slurry system of grade G oil well cement with sand shown in Comparative Example 2, under the condition of 240°C, the compressive strength of the cement paste cured for 28 days was greatly reduced compared with that of the cement paste cured for 2 days. Comparing Example 2 and Comparative Example 2, it can be seen that, in the case where the difference in thickening time was small, the strength of the cement paste of the high-temperature-resistant well cement slurry system of Example 2 was 48.4 MPa after curing for 2 days, and the strength of the cement paste was 56.1 MPa after curing for 28 days, which demonstrates that the strength of the cement slurry system of Example 2 did not deteriorate at an ultra-high temperature of 240°C.In addition, both the 2-day compressive strength and the 28-day compressive strength of the cement paste were higher than those of the Class G oil well cement-sand cement slurry system shown in Comparative Example 2.

[0104] For the high temperature resistant sand-free well cementing slurry system described in Example 3, under the condition of 150°C, the compressive strength of the cement paste cured for 28 days still exceeded 40 MPa, and no degradation in the compressive strength of the cement paste was observed compared with the compressive strength of the cement paste cured for 2 days.

[0105] In Example 2 and Comparative Examples 3 and 4, the weight ratios of Class G oil well cement, low-calcium Portland cement, gypsum, sulfoaluminate cement, and composite additive in the well cementing cement were 43:43:2:8:4, 34:52:4:6:4, and 52:34:5:5:4, respectively. Under the condition of 240°C, Example 2, which used a cement formula with Class G oil well cement, low-calcium Portland cement, gypsum, sulfoaluminate cement, and composite additive in a weight ratio of 43:43:2:8:4, showed the highest compressive strength of the cement stone. In contrast, the compressive strength of the cement paste in each of Comparative Examples 3 and 4, in which the mass ratio of the components in the cement composition was not within the scope of the present invention, was low. In Example 2 and Comparative Examples 3 and 4, the 28-day compressive strength of the cement paste showed no degradation compared to the 2-day compressive strength.This indicates that the well cementing cement made from grade G oil well cement, low-calcium Portland cement, gypsum, sulfoaluminate cement, and a composite additive contributes to improving the mechanical properties of the cement stone under high-temperature conditions and preventing the degradation of the strength of the cement stone at high temperatures. However, the use of the mixing ratio of the components in the cement according to the present invention has the most significant effect on improving the mechanical properties of the cement stone. In addition, the optimal weight ratio of grade G oil well cement, low-calcium Portland cement, gypsum, sulfoaluminate cement, and a composite additive in the high-temperature-resistant well cementing cement according to the present invention was 43:43:2:8:4.

[0106] The composite additive in the high-temperature-resistant well cement of Example 1 was a mixture of carbide slag, phosphorus slag, mussel shell powder, and filter drilling mud at a weight ratio of 10:5:3:1. The composite additive in the well cement of Comparative Example 5 was a mixture of carbide slag, phosphorus slag, and mussel shell powder at a weight ratio of 20:4:2. The well cement of Example 6 did not use the composite additive. Under the condition of 200°C, the compressive strength of the cement stone in Example 1 was the highest, while the compressive strength of the cement stone in Comparative Example 6 was the lowest. In addition, in Example 1 and Comparative Examples 5 and 6, no degradation of the 28-day compressive strength of the cement paste was observed compared to the 2-day compressive strength.The high temperature resistant cement slurry system for well cementing according to Examples 4-7 did not show any strength degradation under the high temperature condition of 200°C; and the 28-day compressive strength of the cement stone in Examples 4-7 was higher than the compressive strength in Comparative Examples 5 and 6.

[0107] The composite additive in the high-temperature-resistant well cement of Example 2 was a mixture of carbide slag, phosphorus slag, mussel shell powder, and filter drilling mud in a weight ratio of 10:5:3:1. The well cement of Example 7 did not use a composite additive. Under 240°C conditions, the compressive strength of the cement stone of Example 2 was significantly higher than that of Example 7.

[0108] Thus, it can be seen that compounding grade G oil well cement, low-calcium Portland cement, gypsum, and sulfoaluminate cement in a weight ratio according to the present invention can achieve a certain effect in preventing high-temperature degradation of cement paste. The composite additive proposed in the present invention has a significant effect on improving the mechanical properties of cement paste.

[0109] In conclusion, the high-temperature-resistant cement for well cementing and the cement slurry system provided by the present invention are applicable to the wellbore circulation temperature in the range of 150°C to 240°C, the compressive strength of the cement stone cured for 28 days in this temperature range is more than 40 MPa (the compressive strength of the cement stone of the sand cement slurry system cured for 28 days is more than 50 MPa), and there is no degradation of the compressive strength of the cement stone compared with the compressive strength of the cement stone cured for 2 days. This solves the problem that the degradation of the strength of the cement stone at 200°C or higher affects high-quality exploration and development.Meanwhile, the high-temperature-resistant cement slurry system for well cementing according to the present invention has a desirable thickening time, eliminating the problem of abnormal cement slurry conditioning performance due to excessively short thickening times. The high-temperature-resistant cement and cement slurry system proposed in accordance with the present invention ensure sealing efficiency and cementing structure safety in high-temperature and ultra-high-temperature conditions in deep wells and ultra-deep wells, thereby improving cementing quality.

[0110] It is obvious that the above examples according to the present invention are merely examples given for the purpose of clearly illustrating the present invention and are not intended to limit the scope of the present invention. Various other variations or modifications can be made by those skilled in the art based on the above description, and it is impossible to exhaustively list all possible embodiments of the invention here. Any changes or modifications that are obvious and arise from the technical solutions according to the present invention still fall within the scope of protection of the present invention.

Claims

1. A high temperature resistant cement for well cementing, comprising by weight: 40-55 parts of class G oil well cement, 40-55 parts of low calcium Portland cement, 1-5 parts of gypsum, 1-10 parts of sulfoaluminate cement and 1-10 parts of a composite additive; wherein the composite additive contains a mixture of carbide slag, phosphorus slag, mussel shell powder and filter drilling mud in a weight ratio of 10-15:5-10:3-6:1-3.

2. The high temperature resistant well cement of claim 1, wherein, based on 100% of the total weight of class G oil well cement, the class G oil well cement contains 95% to 97% Portland cement clinker and 3% to 5% gypsum; wherein, based on 100% of the total weight of the Portland cement clinker, the Portland cement clinker contains 40% to 65% tricalcium silicate, 15% to 25% dicalcium silicate, 10% to 30% tricalcium aluminate and tetracalcium ferroaluminate, 1% to 5% free calcium oxide and free magnesium oxide, and 0% to 0.6% sodium oxide and potassium oxide.

3. The high temperature resistant well cement of claim 1, wherein, based on 100% of the total weight of the low calcium Portland cement, the low calcium Portland cement contains 94% to 99% of low calcium Portland cement clinker and 1% to 6% of gypsum; wherein, based on 100% of the total weight of the low calcium Portland cement clinker, the low calcium Portland cement clinker contains 45% to 70% of dicalcium silicate, 10% to 40% of tricalcium silicate, 10% to 30% of tricalcium aluminate and tetracalcium ferroaluminate, 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 well cementing according to claim 1, characterized in that, based on 100% of the total weight of the sulfoaluminate cement, the sulfoaluminate cement contains 92% to 95% of sulfoaluminate cement clinker and 5% to 8% of gypsum; wherein, based on 100% of the total weight of the sulfoaluminate cement clinker, the sulfoaluminate cement clinker contains 55% to 75% of calcium sulfoaluminate, 8% to 37% of dicalcium silicate, 15% to 35% of tetracalcium ferroaluminate, 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. A high temperature resistant cement for well cementing according to claim 1, characterized in that the gypsum contains one or more of the following: natural dihydrate gypsum, anhydrite and mixed gypsum.

6. High-temperature-resistant cement for well cementing according to claim 1, characterized in that the mass content of Ca(OH)2 in the carbide slag is 70-80%; and the particle size of the carbide slag is 10-15 μm.

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

8. A high-temperature-resistant cement for well cementing according to claim 1, characterized in that the CaCO3 content in the mussel shell powder is 90% - 96%; and the particle size of the mussel shell powder is 200-300 µm.

9. High-temperature-resistant cement for well cementing according to paragraph 1, characterized in that the mass content of CaCO3 in the filter drilling fluid is 55% - 70%.

10. A high temperature resistant well cement slurry system comprising by weight: 100 parts of the high temperature resistant well cement of claim 1, 0-70 parts of quartz sand, 1-6 parts of a suspension stabilizer, 2-9 parts of a fluid loss reducing agent, 0.5-1.5 parts of a dispersant, 1-9 parts of a retarder, 0.1-0.5 parts of an antifoam, and 40-100 parts of water; wherein the high temperature resistant well cement comprises by weight: 40-55 parts of Class G oil well cement, 40-55 parts of low calcium Portland cement, 1-5 parts of gypsum, 1-10 parts of a sulfoaluminate cement, and 1-10 parts of a composite additive; wherein the composite additive contains a mixture of carbide slag, phosphorus slag, mussel shell powder and filter drilling mud in a mass ratio of 10-15:5-10:3-6:1-3.

11. The high temperature resistant cement slurry system for well cementing according to claim 10, characterized in that the quartz sand has a particle size of 50-5000 mesh; and the quartz sand comprises ordinary quartz sand and / or acid washed quartz sand.

12. A high temperature resistant cement slurry system for well cementing according to claim 10, characterized in that the suspension stabilizer comprises an acrylamide polymer suspension stabilizer.

13. The high temperature resistant cement slurry system for well cementing according to claim 12, characterized in that the suspension stabilizer comprises a polymeric suspension stabilizer obtained from 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, diallyldimethylammonium chloride and N-vinylpyrrolidone as monomers.

14. A high temperature resistant cement slurry system for well cementing according to claim 10, characterized in that the fluid loss reducing agent comprises a polymeric fluid loss reducing agent based on 2-acrylamido-2-methylpropanesulfonic acid.

15. A high temperature resistant cement slurry system for well cementing according to claim 14, characterized in that the fluid loss reducing agent comprises a polymeric fluid loss reducing agent obtained from 2-acrylamido-2-methylpropanesulfonic acid, N,N-dimethylacrylamide and an unsaturated carboxylic acid as monomers.

16. A high-temperature-resistant cement slurry system for well cementing according to claim 10, characterized in that the dispersant contains a dispersant based on an aldehyde ketone condensate and / or a dispersant based on a polycarboxylic acid.

17. The high temperature resistant cement slurry system for well cementing according to claim 10, characterized in that the retarder comprises one or more of the following: hydroxyethylidenediphosphonic acid, ethylenediaminetetrakis(methylenephosphonic acid) and ethylenediaminetetrakis(methylenephosphonate).

18. The high temperature resistant cement slurry system for well cementing according to claim 10, characterized in that the defoamer comprises one or more of the following: tributyl phosphate, polyoxypropylene glycerol ether, and polydimethylsiloxane.

19. The method for producing a high-temperature-resistant cement slurry system for well cementing according to claim 10, comprising the steps of: mixing a high-temperature-resistant cement for well cementing, quartz sand, a suspension stabilizer and a dispersant in parts by weight to obtain a dry mixture; mixing a fluid loss reducing agent, a retarder, a defoamer and water in parts by weight to obtain a wet mixture; uniformly pouring the dry mixture into the wet mixture at a rotation speed of 4000 ± 200 rpm; after completely adding the dry mixture to the wet mixture, bringing the rotation speed to 12000 ± 500 rpm and mixing for another 15-35 s to obtain a high-temperature-resistant cement slurry system for well cementing; wherein the high temperature resistant well cement comprises by weight: 40-55 parts of class G oil well cement, 40-55 parts of low calcium Portland cement, 1-5 parts of gypsum, 1-10 parts of sulfoaluminate cement and 1-10 parts of a composite additive; wherein the composite additive comprises a mixture of carbide slag, phosphorus slag, mussel shell powder and filter drilling mud in a weight ratio of 10-15:5-10:3-6:1-3.