Water-non-dispersible composition, cement slurry comprising same, and preparation method therefor and use thereof

Abstract

A water-non-dispersible composition, cement slurry comprising same, and a preparation method therefor and a use thereof. The water-non-dispersible composition comprises: 0.5-5 parts by weight of a microbial polysaccharide polymer compound, 5-50 parts by weight of an organic polymer compound and 4.5-45 parts by weight of inorganic particles; the organic polymer compound has a number average molecular weight of 100,000-1,000,000 g / mol. The water-non-dispersible composition has good water-non-dispersibility and can be used for preparing cement slurry; and the cement slurry has water-non-dispersibility, can ensure effective filling of the cement slurry in an annulus and structural integrity of a cement sheath, and is suitable for high aquifer formation sealing and thief zone plugging, so as to achieve effective sealing of high aquifer formations and effective plugging of thief zones at different well depths.

Description

Water-insoluble composition and cement slurry containing same, as well as preparation method and application thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application 202310764576.4 filed on June 27, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of well cementing, and in particular to a water-independent composition and cement slurry containing the same, as well as a preparation method and application thereof. Background Art

[0004] During long-term waterflooding and oil recovery, the formation pressure system becomes complex. Multiple pressure systems exist vertically within the same wellbore, especially in structurally complex formations, where cross-flow between layers is common. New wells drilled in these areas are susceptible to formation water damage during the cementing slurry displacement and setting process, leading to water intrusion and channeling, which seriously impacts the cementing quality of the aquifer. The cementing process can also present significant cement slurry losses, resulting in reduced annular displacement efficiency and insufficient cement slurry return depth, leading to leaks in the upper wellbore section, compromising cementing quality.

[0005] The effective isolation of high-aquifer layers and the effective plugging of leakage layers are the key to ensuring the smooth construction of oil and gas wells. During the construction of high-aquifer isolation and leakage layer plugging, when the cementing cement slurry is injected into the high-water annulus or leakage layer, the formation water dissolves, migrates and flushes the ordinary cement slurry, and the solid phase structure of the cement slurry is destroyed, making it impossible to effectively isolate the aquifer and plug the leakage layer, seriously affecting the quality and progress of the project. At present, in order to improve the isolation quality of high-aquifer layers and the plugging effect of leakage layers, it is usually necessary to add water-insoluble materials to ordinary cement slurry to prevent the cement slurry particles from being dispersed by formation water during construction. Traditional water-insoluble materials include polyacrylamide polymers and their copolymers, in addition to natural modified polymer compound materials such as cellulose ethers. Although traditional water-insoluble materials and systems have certain water-insoluble properties, they still have the following shortcomings:

[0006] ① Polyacrylamide is a non-dispersible material when in contact with water. It works best below 80°C, but is prone to decomposition above 80°C, making it impossible to effectively prevent cement slurry particles from being dispersed by water.

[0007] ② Cellulose ethers do not disperse in water and have a good thickening effect at low temperatures, but will gel at 60-90°C, resulting in poor cement slurry construction performance and prone to cementing accidents such as "sausage filling" and annular blockage;

[0008] ③ Conventional water-insoluble cement slurry systems usually do not add high-temperature strength stabilizers, which can easily cause cement stone strength degradation under high temperature conditions.

[0009] Therefore, it is necessary to seek a cement slurry that does not disperse in water over a wide temperature range and can ensure the isolation effect of high aquifers and the plugging effect of leakage layers at different well depths when isolating high aquifers and plugging leakage layers.

[0010] Summary of the Invention

[0011] The present invention aims to overcome the problem of cement slurries in the prior art that cement stone strength deteriorates under high temperature conditions. The present invention provides a water-resistant composition, a cement slurry containing the composition, and a preparation method and application thereof. The cement slurry containing the water-resistant composition exhibits excellent water-resistant properties within a temperature range of room temperature to 180°C, ensuring effective filling of the annulus with cement slurry and structural integrity of the cement sheath. It also enables effective isolation of high-aquifer formations at varying well depths and plugging of lost-water zones.

[0012] To achieve the above objectives, the present invention provides a water-resistant composition in a first aspect, comprising: 0.5-5 parts by weight of a microbial polysaccharide polymer compound, 5-50 parts by weight of an organic polymer compound, and 4.5-45 parts by weight of inorganic particles.

[0013] The second aspect of the present invention provides use of the aforementioned non-dispersible composition in water in cement slurry.

[0014] A third aspect of the present invention provides a cement slurry, wherein the cement slurry contains the aforementioned non-dispersible composition when in contact with water.

[0015] A fourth aspect of the present invention provides a method for preparing cement slurry, the method comprising:

[0016] Mixing the G-grade oil well cement, the aforementioned non-dispersible composition when exposed to water, an active material, a high-temperature strength stabilizer, a density regulator, a fluid loss additive, a suspension stabilizer, and a dispersant to obtain a dry mix;

[0017] mixing a retarder, a defoamer, and water to obtain a wet mix;

[0018] The dry mix and the wet mix are mixed at a low stirring rate and then stirred at a high speed to obtain cement slurry.

[0019] A fifth aspect of the present invention provides use of the cement slurry of the third aspect or the cement slurry prepared by the preparation method of the fourth aspect in cementing operations of oil and gas wells.

[0020] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0021] (1) The water-resistant composition of the present invention has good water-resistant properties within the temperature range of room temperature to 180°C, and can be used to prepare cement slurry, thereby ensuring that the particles in the cement slurry are not dispersed by formation water, while having no adverse effect on the conventional properties of the cement slurry, such as rheology, water loss, stability, and cement stone strength.

[0022] (2) The cement slurry of the present invention contains a water-independent composition, which has the characteristic that the cement slurry particles are not dispersed when in contact with water, that is, it is non-dispersible in water, which can ensure the effective filling of the annulus with cement slurry and the structural integrity of the cement annulus.

[0023] (3) The cement slurry of the present invention is suitable for sealing high-aquifer layers and leaking layer plugging. It has good non-dispersibility when exposed to water in the temperature range from room temperature to 180°C, and can effectively isolate high-aquifer layers at different well depths and effectively plug leaking layers, providing good wellbore conditions for oil and gas production and ensuring the efficient exploitation of oil and gas resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a 90°C thickening curve of Example 2+1% retarder;

[0025] FIG2 is a thickening curve of Example 2+1% retarder at 110°C;

[0026] FIG3 is a thickening curve of Example 2 + 1% retarder at 130°C;

[0027] FIG4 is a static gel strength change curve of Example 2 (180° C.×20.7 MPa);

[0028] Figure 5 is a diagram of cement slurry placed in suspension;

[0029] FIG6 is a graph showing the evaluation levels of the non-dispersion performance of cement slurry when exposed to water, where (a) is very poor, (b) is relatively poor, (c) is average, (d) is good, and (e) is very good. DETAILED DESCRIPTION

[0030] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0031] A first aspect of the present invention provides a water-resistant composition, comprising: 0.5-5 parts by weight of a microbial polysaccharide polymer compound, 5-50 parts by weight of an organic polymer compound, and 4.5-45 parts by weight of inorganic particles, wherein the number average molecular weight of the organic polymer compound is 100,000-1,000,000 g / mol.

[0032] Preferably, the water-non-dispersible composition comprises: 1-4 parts by weight of a microbial polysaccharide polymer compound, 10-30 parts by weight of an organic polymer compound, and 10-30 parts by weight of inorganic particles.

[0033] In the present invention, the water-independent composition refers to a mixture that ensures that the cement slurry particles will not be dispersed by water after being mixed with the cement slurry.

[0034] The water-independent composition of the present invention is compounded with microbial polysaccharide polymer compounds, organic polymer compounds and inorganic particles. It utilizes the characteristics of microbial polysaccharide polymer compounds, such as high efficiency, non-toxicity, no secondary pollution, self-degradation and wide applicable temperature range, as well as the flocculation characteristics of organic polymer compounds. Through the synergistic effect of the three, the cement slurry particles are wrapped up to prevent the cement slurry particles from being washed away by formation water when injected into high aquifers and leakage zones. The composition can adapt to different formation temperature conditions and meet the performance requirements of cement slurry for high aquifer isolation and leakage zone plugging operations at different well depths.

[0035] In the present invention, the microbial polysaccharide polymer compound can increase the viscosity of the cement slurry, allowing particulate matter to be evenly suspended in the slurry. It also possesses the characteristics of not decomposing and shear-thinning under high temperature conditions, which can ensure the stability and rheological properties of the cement slurry under high temperature conditions. The organic polymer compound can wrap the particulate matter with the organic polymer long chain, forming a grid structure with a certain strength to prevent it from being dispersed by water. Under the action of the microbial polysaccharide polymer compound, the inorganic particles are evenly suspended in the slurry. At the same time, by combining with the long chain of the organic high-analyte compound, the strength of the grid structure is increased, and the resistance to water impact is enhanced.

[0036] In some embodiments of the present invention, the microbial polysaccharide polymer compound is selected from one or more of xanthan gum, gellan gum, pullulan, trehalose, hyaluronic acid, thermogel, chitosan, curdlan and trehalose.

[0037] In some embodiments of the present invention, the structural skeleton of the microbial polysaccharide polymer compound is connected by chemical bonds of one or more of glucose, glucuronic acid, rhamnose, maltotriose, and acetylglucosamine, and the side chains are connected by chemical bonds of one or more of mannose, rhamnose, and glucuronic acid.

[0038] The microbial polysaccharide macromolecular compound of the present invention has a large number of carboxyl structures and has good hydrophilic properties.

[0039] In some embodiments of the present invention, the organic polymer compound is selected from one or more polymers formed by alkaline hydrolysis of polyethylene oxide, polyvinyl alcohol, polyacrylic acid, sodium polyacrylate, calcium polyacrylate and polyacrylamide; and / or, the organic polymer compound is selected from one or more copolymers formed by styrene sulfonate, wood sulfonate, acrylic acid and methacrylic acid.

[0040] In the present invention, the organic polymer compound is selected from polymers such as polyethylene oxide, polyvinyl alcohol, polyacrylic acid, sodium polyacrylate, calcium polyacrylate, alkaline hydrolyzate of polyacrylamide, and one or more of styrene sulfonate, wood sulfonate, acrylic acid, and methacrylic acid copolymers.

[0041] In the present invention, the microbial polysaccharide polymer compound increases the viscosity of the cement slurry by absorbing water molecules, so that the particulate matter can be evenly suspended in the slurry. At the same time, it has the characteristics of not decomposing at high temperatures and shear thinning, which can ensure that the cement slurry is stable under high temperature conditions and the rheological properties meet the cementing requirements; the molecular structure of the organic polymer compound has a large number of ether bonds and hydrogen bonds, which can be combined with inorganic particles, and the particulate matter of other components in the cement slurry can be wrapped up by the long organic polymer chain to form a grid structure with a certain strength, thereby enhancing the resistance to water impact and avoiding being dispersed by water.

[0042] In some embodiments of the present invention, the inorganic particles are acid-washed quartz sand.

[0043] In some embodiments of the present invention, the average particle size of the inorganic particles is 5-75 μm.

[0044] The water-independent composition of the present invention is prepared by compounding microbial polysaccharide polymer compounds, organic polymer compounds and inorganic particles. The characteristics of the microbial polysaccharide polymer compounds, such as high efficiency, non-toxicity, no secondary pollution, self-degradation, wide applicable temperature range and shear dilution, can be used to increase the viscosity of the cement slurry, so that the particulate matter can be evenly suspended in the slurry within a wide temperature range, and at the same time, the slurry has better rheological properties; the flocculation characteristics of the organic polymer compounds are used to wrap the inorganic particles with high-molecular-weight long chains to form a grid structure with a certain strength. Through the synergistic effect of the three, the cement slurry particles are wrapped to prevent the cement slurry particles from being washed away by formation water when injected into high-aquifer layers and leakage layers. The composition can adapt to different formation temperature conditions and meet the performance requirements of the cement slurry for high-aquifer isolation and leakage layer plugging operations at different well depths.

[0045] The second aspect of the present invention provides use of the aforementioned non-dispersible composition in water in cement slurry.

[0046] A third aspect of the present invention provides a cement slurry, wherein the cement slurry contains the aforementioned non-dispersible composition when in contact with water.

[0047] The cement slurry of the present invention contains a water-independent composition, which has the characteristic that the cement slurry particles are not dispersed when in contact with water, that is, it is water-independent, which can ensure the effective filling of the annulus with cement slurry and the structural integrity of the cement annulus.

[0048] In some embodiments of the present invention, the cement slurry comprises: 100 parts of G-grade oil well cement, 0.5-2 parts of the water-non-dispersible composition, 1-3 parts of active material, 0-50 parts of high-temperature strength stabilizer, 0-100 parts of density regulator, 2-5 parts of fluid loss additive, 0.2-2 parts of suspension stabilizer, 1-3 parts of dispersant, 0.1-2.5 parts of retarder, 0.1-0.5 parts of defoamer and 40-110 parts of water.

[0049] In the present invention, research has found that the amount of the water-independent composition added cannot be too little, less than 0.5 parts, because the water-independent composition cannot effectively wrap up other components in the cement slurry, resulting in poor water-independent dispersibility of the cement slurry and easy dispersion by water when in contact with formation water; the amount of the water-independent composition added cannot be too much, more than 2 parts, because the rheological properties of the cement slurry deteriorate and the consistency is high, making it difficult for cement trucks to inject and replace the cement slurry during the cementing process. The present invention selects a suitable water-independent composition and controls its addition amount to wrap up other components in the cement slurry, thereby preventing the cement slurry components from being dispersed by formation water when injected into high aquifers and leakage zones. It can adapt to different formation temperature conditions and meet the performance requirements of cement slurry for high aquifer isolation and leakage zone plugging operations at different well depths.

[0050] In the present invention, when the ambient temperature is low, there is no problem of high-temperature strength decay, so the amount of high-temperature strength stabilizer added at this time can be zero; when the cement slurry density is the conventional density of 1.90, the density regulator can be zero, which can ensure that the cement slurry density is around the conventional density of 1.90.

[0051] Preferably, the cement slurry comprises: 100 parts of G-grade oil well cement, 0.8-1.5 parts of the water-non-dispersible composition, 1.5-2.5 parts of active material, 10-40 parts of high-temperature strength stabilizer, 20-80 parts of density regulator, 3-4 parts of fluid loss additive, 0.5-1.5 parts of suspension stabilizer, 1.5-2.5 parts of dispersant, 0.5-2 parts of retarder, 0.2-0.4 parts of defoamer and 50-100 parts of water.

[0052] In some embodiments of the present invention, the active material is active microsilicon with an average particle size of 0.1-0.5 μm.

[0053] In the present invention, the active material can improve the consistency of the cement slurry, help the cement slurry to achieve non-dispersibility when encountering water, and enhance the strength of the cement slurry under different temperature conditions.

[0054] In some embodiments of the present invention, the high-temperature strength stabilizer is acid-washed quartz sand, the SiO2 content of which is greater than 99% and the average particle size of which is 5-75 μm.

[0055] In the present invention, the high-temperature strength stabilizer can reduce the Ca(OH)2 content and the calcium-silicon ratio (C / S) in the cement paste, thereby preventing the strength of the cement paste from declining under high-temperature conditions.

[0056] In some embodiments of the present invention, the density regulator includes a weighting material and a lightening material; wherein the weighting material is selected from one or more of iron ore powder, barite and micro-manganese ore powder; and the lightening material is selected from one or more of glass beads, floating beads and fly ash.

[0057] In the present invention, the weighting material and the lightening material are used as density regulators, and the density of the cement slurry system is adjusted by utilizing the density characteristics thereof to meet the density requirements of the cement slurry system under different working conditions.

[0058] Other admixtures used in the present invention, such as suspension stabilizers, retarders, dispersants, and defoamers, are commonly used admixtures in the field. The relevant mechanisms and properties are well known to those skilled in the art and will not be described in detail here.

[0059] In some embodiments of the present invention, the retarder is selected from one or more of AMPS substances and organophosphate substances.

[0060] In some embodiments of the present invention, the fluid loss additive is selected from one or more of AMPS, polymers formed by polymerization of low molecular weight amides and polyhydroxycarboxylic acids, and PVA substances.

[0061] In the present invention, the polymer is formed by polymerizing AMPS, low molecular weight amide and polyhydroxycarboxylic acid substances, and the fluid loss additive is selected from one or more of the polymer and PVA substances.

[0062] In some embodiments of the present invention, the suspension stabilizer is selected from plant gum polymer compounds or cellulose polymer compounds.

[0063] Preferably, the plant gum polymer compound is selected from one or more of guar gum, curdlan gum, carrageenan and locust gum.

[0064] Preferably, the cellulose polymer compound is selected from one or more of lignin fiber, cellulose ether, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose and carboxymethyl cellulose.

[0065] In some embodiments of the present invention, the dispersant is selected from one or more of a condensation product of formaldehyde and acetone, polystyrene sulfonates, and polycarboxylic acids.

[0066] Preferably, the dispersant is selected from one or two of a condensation product of formaldehyde and acetone, a polystyrene sulfonate dispersant and a polycarboxylic acid dispersant.

[0067] In some embodiments of the present invention, the defoaming agent is selected from one or more of tributyl phosphate, polyoxypropylene glycerol and polydimethylsiloxane.

[0068] In some embodiments of the present invention, the density of the cement slurry is 1.2-2.4 g / cm 3 , the applicable temperature range is 10-180℃.

[0069] In some embodiments of the present invention, the fluidity of the cement slurry is greater than 22 cm, the API water loss is less than 50 mL, and the free liquid is 0.

[0070] In some embodiments of the present invention, the density is 1.2 g / cm 3 The cement slurry does not disperse when it comes into contact with water, and its 24h compressive strength is greater than 10MPa.

[0071] In some embodiments of the present invention, the density is 1.9 g / cm 3 The cement slurry does not disperse when it comes into contact with water, and its 24h compressive strength is greater than 20MPa.

[0072] In some embodiments of the present invention, the density is 2.4 g / cm 3 The cement slurry does not disperse when it comes into contact with water, and its 24h compressive strength is greater than 14MPa.

[0073] A fourth aspect of the present invention provides a method for preparing cement slurry, the method comprising:

[0074] Mixing the G-grade oil well cement, the aforementioned non-dispersible composition when in contact with water, an active material, a high-temperature strength stabilizer, a density regulator, a fluid loss additive, a suspension stabilizer, and a dispersant to obtain a dry mix;

[0075] mixing a retarder, a defoamer, and water to obtain a wet mix;

[0076] The dry mix and the wet mix are mixed at a low stirring rate and then stirred at a high speed to obtain cement slurry.

[0077] Specifically, the low stirring rate is 4000±200 r / min, the high-speed stirring rate is 12000±500 r / min, the stirring time is 30-40 s, preferably 35 s, and the obtained cement slurry is a cement slurry that does not disperse in water in a wide temperature range.

[0078] The cement slurry of the present invention has an adjustable density (1.2-2.4 g / cm 3 ), has a wide applicable temperature range (room temperature to 180°C), high compressive strength, and a good linear relationship between thickening time and temperature, density, and retarder dosage.

[0079] A fifth aspect of the present invention provides the use of the cement slurry of the third aspect or the cement slurry prepared by the preparation method of the fourth aspect in oil and gas well aquifer isolation and leakage zone plugging operations.

[0080] The cement slurry of the present invention is suitable for sealing high-aquifer layers and leaking layer plugging. It has good non-dispersibility when exposed to water in the temperature range of room temperature to 180°C, and can effectively isolate high-aquifer layers and effectively plug leaking layer at different well depths, providing good wellbore conditions for oil and gas production and ensuring the efficient exploitation of oil and gas resources.

[0081] The wide temperature range of the present invention does not disperse in water and the density of the cement slurry is adjustable (1.20-2.40g / cm 3 ), applicable temperature range is room temperature - 180 ℃, thickening time has a good linear relationship with temperature, density, retarder dosage, fluidity is greater than 22cm, API water loss is less than 50mL, free liquid is 0, 1.2g / cm 3 The 24h compressive strength of the low-density, water-insoluble cement slurry system is greater than 10MPa and 1.9g / cm 3 The 24h compressive strength of the conventional density non-dispersible cement slurry system is greater than 20MPa, 2.4g / cm 3 The high-density, water-resistant cement slurry system has a 24-hour compressive strength exceeding 14 MPa. The cement slurry exhibits excellent stability under varying temperature conditions. During cementing in high-water-content formations and plugging lost-loop zones, the cement slurry exhibits excellent workability. During construction, the cement slurry particles are not easily dispersed by formation water, ensuring effective annular filling and slurry structural integrity. This effectively isolates high-water-content annular zones and plugs lost-loop zones. This is crucial for improving cementing effectiveness in complex formations and reducing well construction costs.

[0082] The following examples clearly and completely describe the technical solutions of the present invention. Obviously, the described examples are only some of the examples of the present invention, not all of them. Based on the examples of the present invention, all other examples obtained by persons of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0083] In the following examples and comparative examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents and instruments used, if no manufacturer is specified, are commercially available conventional products.

[0084] Experiments were conducted in accordance with the national standard GB / T 19139-2012, "Test Methods for Oil Well Cement," to evaluate the cement slurry's thickening properties, fluidity, API water loss, free water content, stability, and compressive strength. Key experimental instruments included: a 30-60 ribbed agitator; an 8240 high-temperature, high-pressure thickener (from the US company Chandler); a 4265-HT high-temperature, high-pressure static gel strength tester (also from the US company Chandler); and an HH-420 constant-temperature digital display water tank (from Changzhou Yineng Experimental Instrument Factory).

[0085] In the following examples,

[0086] The microbial polysaccharide polymer compound is xanthan gum, produced by Sichuan Kaier Oil and Gas Field Technology Service Co., Ltd.

[0087] The organic polymer compound model is polyethylene oxide with a number average molecular weight of 200,000 g / mol, produced by Shandong Wangtong Chemical Co., Ltd.

[0088] The inorganic particle model is DRB-2S, produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0089] Grade G oil well cement is high sulfate resistance (HSR) Grade G oil well cement, produced by Jiahua Special Cement Co., Ltd.

[0090] The model of high temperature strength stabilizer is DRB-2S, produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0091] The density regulator is glass microspheres (12000Psi) produced by China Steel Group Ma'anshan Mining Institute New Materials Technology Co., Ltd., and refined iron ore powder (6.05g / cm 3 ) is produced by Sichuan Kaier Oil and Gas Field Technology Service Co., Ltd.

[0092] The model of the fluid loss additive is DRF-1S, produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0093] The model of the suspension stabilizer is DRK-3S, produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0094] The model of the dispersant is DRS-1S, produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0095] The retarder model is DRH-1L or DRH-2L, produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0096] The model of the defoaming agent is DRX-1L or DRX-2L, produced by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0097] The water used in the experiment was distilled water.

[0098] The specific operation process of the method for evaluating the non-dispersion performance of cement slurry in contact with water before curing is as follows: prepare two beakers with a volume of 250mL, pour 200mL of distilled water or formation water at room temperature into one beaker (numbered 1-1#), and pour distilled water or formation water heated to a set temperature (maximum 100°C) into the other beaker (numbered 1-2#). Insulate the two beakers separately to ensure that the temperature of the water in the two beakers is constant. According to the preparation method of claim 10, about 600 mL of water-independent cement slurry is prepared and poured into two beakers with a volume of 50 mL (numbered 1-1-1# and 1-2-2#, respectively). The slurry is allowed to stand for a certain time (recommended 10 minutes). Subsequently, the 1-1-1# and 1-2-2# beakers are suspended above the 1-1# and 1-2# beakers at a certain height (recommended 1 cm, as shown in Figure 5), and then poured into the 1-1# and 1-2# beakers at a certain flow rate (recommended 2 mL / s). According to whether the poured cement slurry can be dispersed by water and the turbidity of the water above the 1-1# and 1-2# beakers, the water-independent performance is set to 5 levels, as shown in Figure 6, to evaluate the water-independent property of the cement slurry. The present invention evaluates the non-dispersible line according to the clarity of the upper liquid, with a total of 5 levels from very clear to very turbid. The ratings are shown in Figure 6, namely (a) very good, (b) good, (c) fair, (d) poor and (e) very poor.

[0099] The evaluation method of the non-dispersible performance of cement slurry after curing is as follows: prepare two beakers with a volume of 250mL, pour 200mL of room temperature distilled water or formation water (number 2-1#) into one beaker, and pour distilled water or formation water heated to a set temperature (maximum 100°C) into the other beaker (number 2-2#), and perform heat preservation treatment on the two beakers respectively to ensure that the temperature of the water in the two beakers is at a constant temperature. Then, prepare about 600mL of non-dispersible cement slurry in water according to the preparation method of claim 10, set the curing temperature and pressure as needed, and perform curing for a certain period of time. After the curing is completed, pour in Two beakers with a volume of 50 mL (numbered 2-1-1# and 2-2-2#, respectively) are left to stand for a certain time (recommended 10 minutes). Then, beakers 2-1-1# and 2-2-2# are suspended above beakers 2-1# and 2-2#, respectively, at a certain height (recommended 1 cm, as shown in Figure 5). Then, cement slurry is poured into beakers 2-1# and 2-2#, respectively, at a certain flow rate (recommended 2 mL / s). According to whether the poured cement slurry can be dispersed by water and the turbidity of the water above beakers 2-1# and 2-2#, the water-resistant performance is set to 5 levels, as shown in Figure 6, to evaluate the water-resistant performance of the cement slurry.

[0100] Preparation Example 1

[0101] 2.5 parts by weight of a microbial polysaccharide polymer compound, 30 parts by weight of an organic polymer compound, and 45 parts by weight of inorganic particles were sequentially placed into a mixing device and mixed uniformly to obtain a water-insoluble composition A1.

[0102] Preparation Example 2

[0103] 0.5 parts by weight of a microbial polysaccharide polymer compound, 10 parts by weight of an organic polymer compound and 25 parts by weight of inorganic particles were sequentially placed into a mixing device and mixed evenly to obtain a water-insoluble composition A2.

[0104] Preparation Example 3

[0105] 5 parts by weight of a microbial polysaccharide polymer compound, 50 parts by weight of an organic polymer compound, and 20 parts by weight of inorganic particles were sequentially placed into a mixing device and mixed uniformly to obtain a water-insoluble composition A3.

[0106] Preparation Comparative Example 1

[0107] 30 parts by weight of an organic polymer compound and 45 parts by weight of inorganic particles were sequentially placed into a mixing device and mixed evenly to obtain a water-insoluble composition D1.

[0108] Preparation Comparative Example 2

[0109] 2.5 parts by weight of a microbial polysaccharide polymer compound and 45 parts by weight of inorganic particles were sequentially placed into a mixing device and mixed evenly to obtain a water-insoluble composition D2.

[0110] Preparation Comparative Example 3

[0111] 2.5 parts by weight of a microbial polysaccharide polymer compound and 30 parts by weight of an organic polymer compound were sequentially placed into a mixing device and mixed evenly to obtain a water-insoluble composition D3.

[0112] Example 1

[0113] The cement slurry formula includes the following components in parts by weight: 100 parts of G-grade oil well cement, 1 part of water-insoluble composition A1, 61 parts of density regulator (0.62 g / cm 3 glass microspheres), 2 parts of active microsilica, 30 parts of high temperature strength stabilizer, 1 part of suspension stabilizer, 0.7 parts of retarder, 4.5 parts of fluid loss additive, 2 parts of dispersant, 0.25 parts of retarder, 0.2 parts of defoamer and 103 parts of water, the cement slurry density is 1.2g / cm 3 The test results of conventional properties and non-dispersibility in water are shown in Table 1.

[0114] Example 2

[0115] The cement slurry formula includes the following components in parts by weight: 100 parts of G-grade oil well cement, 1 part of water-resistant composition A2, 35 parts of high-temperature strength stabilizer, 1 part of active microsilica, 0.3 parts of suspension stabilizer, 0.7 parts of retarder, 3.5 parts of fluid loss additive, 2.5 parts of dispersant, 0.2 parts of defoamer and 58 parts of water. The cement slurry density is 1.9 g / cm 3 The results of conventional properties and water-resistant properties are shown in Table 1, and the results of thickening time under different retarder dosages are shown in Table 2.

[0116] Figures 1-3 show the thickening curves of the formulation of Example 2 at 90°C, 110°C, and 130°C and a pressure of 60 MPa. As can be seen from Figures 1-3, there is no obvious abnormality such as bulging in the thickening curves. The thickening times of the cement slurry at the three temperature points are 725 min, 474 min, and 174 min, respectively, indicating that the thickening time changes linearly with increasing temperature.

[0117] FIG4 shows a static gel strength change curve of the formulation of Example 2 at 180° C. and 20.7 MPa. As shown in FIG4 , the formulation of Example 2 begins to develop strength in about 4 hours and exceeds 20 MPa in about 10 hours. The strength then increases slowly and remains above 20 MPa within 168 hours.

[0118] Example 3

[0119] The cement slurry formula includes the following components by weight: 100 parts of G-grade oil well cement, 2 parts of water-insoluble composition A3, 92 parts of density regulator (6.05 g / cm 3 Iron ore powder), 50 parts high temperature strength stabilizer, 1.6 parts suspension stabilizer, 3.2 parts retarder, 3.5 parts fluid loss additive, 1.5 parts dispersant, 0.2 parts defoamer, 68 parts water, cement slurry density is 2.4g / cm 3 The test results of conventional properties and non-dispersibility in water are shown in Table 1.

[0120] Comparative Example 1

[0121] The cement slurry formula includes the following components by weight: 100 parts of G-grade oil well cement, 61 parts of density modifier (0.62 g / cm 3 glass microspheres), 2 parts of active microsilica, 30 parts of high temperature strength stabilizer, 1 part of suspension stabilizer, 0.7 parts of retarder, 4.5 parts of fluid loss additive, 2 parts of dispersant, 0.25 parts of retarder, 0.2 parts of defoamer and 103 parts of water, the cement slurry density is 1.2g / cm 3 The test results of conventional properties and non-dispersibility in water are shown in Table 1.

[0122] Comparative Example 2

[0123] The cement slurry formula includes the following components by weight: 100 parts of G-grade oil well cement, 35 parts of high temperature strength stabilizer, 1 part of active microsilica, 0.3 parts of suspension stabilizer, 0.7 parts of retarder, 3.5 parts of fluid loss additive, 2.5 parts of dispersant, 0.2 parts of defoamer and 58 parts of water. The cement slurry density is 1.9 g / cm 3 The experimental results of conventional performance and non-dispersibility in water are shown in Table 1, and the comparison results of non-dispersibility in water under different salinity conditions are shown in Table 3.

[0124] Comparative Example 3

[0125] The cement slurry formula includes the following components by weight: 100 parts of G-grade oil well cement, 92 parts of density modifier (6.05 g / cm 3 Iron ore powder), 50 parts of high temperature strength stabilizer, 1.6 parts of suspension stabilizer, 3.2 parts of retarder, 3.5 parts of fluid loss additive, 1.5 parts of dispersant, 0.2 parts of defoamer and 68 parts of water, the cement slurry density is 2.4g / cm 3 The experimental results of conventional properties and non-dispersibility in water are shown in Table 1.

[0126] Comparative Example 4

[0127] The cement slurry formula includes the following components in parts by weight: 100 parts of G-grade oil well cement, 1 part of water-insoluble composition D1, 61 parts of density regulator (0.62 g / cm 3 glass microspheres), 2 parts of active microsilica, 30 parts of high temperature strength stabilizer, 1 part of suspension stabilizer, 0.7 parts of retarder, 4.5 parts of fluid loss additive, 2 parts of dispersant, 0.25 parts of retarder, 0.2 parts of defoamer and 103 parts of water, the cement slurry density is 1.2g / cm 3 The test results of conventional properties and non-dispersibility in water are shown in Table 1.

[0128] Comparative Example 5

[0129] The cement slurry formula includes the following components in parts by weight: 100 parts of G-grade oil well cement, 1 part of water-insoluble composition D2, 61 parts of density regulator (0.62 g / cm 3 glass microspheres), 2 parts of active microsilica, 30 parts of high temperature strength stabilizer, 1 part of suspension stabilizer, 0.7 parts of retarder, 4.5 parts of fluid loss additive, 2 parts of dispersant, 0.25 parts of retarder, 0.2 parts of defoamer and 103 parts of water, the cement slurry density is 1.2g / cm 3 The test results of conventional properties and non-dispersibility in water are shown in Table 1.

[0130] Comparative Example 6

[0131] The cement slurry formula includes the following components in parts by weight: 100 parts of G-grade oil well cement, 1 part of water-insoluble composition D3, 61 parts of density regulator (0.62 g / cm 3 glass microspheres), 2 parts of active microsilica, 30 parts of high temperature strength stabilizer, 1 part of suspension stabilizer, 0.7 parts of retarder, 4.5 parts of fluid loss additive, 2 parts of dispersant, 0.25 parts of retarder, 0.2 parts of defoamer and 103 parts of water, the cement slurry density is 1.2g / cm 3 The test results of conventional properties and non-dispersibility in water are shown in Table 1.

[0132] Table 1 Comparison of performance of non-dispersible cement slurry systems with different densities

[0133] Table 1 Comparison of properties of non-dispersible cement slurry systems with different densities (continued)

[0134] Table 2 Thickening time of cement slurry under different retarder dosages in Example 2

[0135] Table 3 Comparison of the non-dispersibility of Example 2 and Comparative Example 2 under different salinity water conditions

[0136] As shown in Table 1, a wide temperature range water-resistant cement slurry system exhibits good water-resistant properties when in contact with room temperature water and 100°C water before and after high temperature and high pressure curing. At the same time, all examples have a fluidity greater than 22 cm, an API water loss less than 50 mL, a free water content of 0, and a stability less than 0.02 g / cm 3 .

[0137] Under the same experimental conditions, the fluidity, API water loss, free water, stability and other data of Example 1, Example 2 and Example 3 are not much different from those of Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5 and Comparative Example 6, indicating that the water-non-dispersible composition has no adverse effect on the conventional properties of the cement slurry.

[0138] The experimental temperature of Example 1, Comparative Example 1, Comparative Example 4, Comparative Example 5, and Comparative Example 6 was all 90°C, and the thickening times were 235 min, 224 min, 239 min, 243 min, and 247 min, respectively. The experimental temperature of Comparative Example 2 and Example 2 was both 110°C, and the thickening times were 291 min and 312 min, respectively. The experimental temperature of Comparative Example 3 and Example 3 was both 150°C, and the thickening times were 201 min and 213 min, respectively. It can be seen that the water-non-dispersible composition has no adverse effect on the thickening time of the cement slurry.

[0139] The compressive strengths of Comparative Example 1 and Example 1 after curing for 24 hours at 110°C and 20.7 MPa were 11.9 MPa and 11.5 MPa, respectively; the compressive strengths of Comparative Example 2 and Example 2 after curing for 24 hours at 130°C and 20.7 MPa were 22.1 MPa and 20.25 MPa, respectively; and the compressive strengths of Comparative Example 3 and Example 3 after curing for 24 hours at 180°C and 20.7 MPa were 18.4 MPa and 16.5 MPa, respectively. It can be seen that the water-non-dispersible composition has no adverse effect on the strength of cement stone.

[0140] The density of the cement slurry in Example 1 is 1.20 g / cm 3 , 24h compressive strength is greater than 10MPa; the cement slurry density of Example 2 is 1.90g / cm 3 , 24h compressive strength is greater than 20MPa; the cement slurry density of Example 3 is 2.40g / cm 3 , the 24h compressive strength is greater than 14MPa. It can be seen that the strength of the cement slurry system that does not disperse when exposed to water meets the requirements of cementing construction.

[0141] Comparative Example 1 did not contain the water-resistant non-dispersible composition, while Example 1 contained one portion of the water-resistant non-dispersible composition. Compared with Comparative Example 1, the cement slurry of Example 1 exhibited excellent water-resistant non-dispersibility when poured into room temperature water and 100°C water before and after high-temperature and high-pressure curing, respectively. This demonstrates that Example 1 exhibits excellent water-resistant non-dispersibility.

[0142] Comparative Example 2 did not contain the water-resistant non-dispersible composition, while Example 2 contained one portion of the water-resistant non-dispersible composition. Compared with Comparative Example 2, the cement slurry of Example 2 exhibited good water-resistant non-dispersibility when poured into room temperature water and 100°C water before and after high-temperature and high-pressure curing, respectively. This indicates that Example 2 exhibits excellent water-resistant non-dispersibility.

[0143] Comparative Example 3 did not contain the water-resistant composition, while Example 3 contained two parts of the water-resistant composition. Compared with Comparative Example 3, the cement slurry of Example 3 exhibited good water-resistant properties when poured into room temperature water and 100°C water before and after high-temperature and high-pressure curing, respectively. This indicates that Example 3 exhibits excellent water-resistant properties.

[0144] Comparative Example 4 did not include the microbial polysaccharide polymer compound in the water-independent composition, while Example 1 was a single portion of the water-independent composition. Compared to Example 1, the water-independent non-dispersibility of the cement slurry in Comparative Example 4 was good to fair when poured into room temperature water and 100°C water, respectively, before high-temperature and high-pressure curing. After high-temperature and high-pressure curing, the water-independent non-dispersibility of the cement slurry in room temperature water and 100°C water was fair. Comparative Example 5 did not include the organic polymer compound in the water-independent composition, while Example 1 was a single portion of the water-independent composition. Compared to Example 1, the water-independent non-dispersibility of the cement slurry in Comparative Example 5 was good to good when poured into room temperature water and 100°C water, respectively, before high-temperature and high-pressure curing. After high-temperature and high-pressure curing, the water-independent non-dispersibility of the cement slurry in room temperature water and 100°C water was fair. Comparative Example 6 did not include the inorganic particles in the water-independent non-dispersibility composition, while Example 1 was a single portion of the water-independent non-dispersibility composition. Compared to Example 1, the cement slurry in Comparative Example 6 exhibited excellent and good water non-dispersibility when poured into room temperature water and 100°C water, respectively, before high-temperature and high-pressure curing. However, after high-temperature and high-pressure curing, the cement slurry exhibited good water non-dispersibility when poured into room temperature water and 100°C water, respectively. However, its 24-hour strength was poor. This indicates that the simultaneous action of the microbial polysaccharide polymer compound, organic polymer compound, and inorganic particles in the water-independent composition results in a cement slurry exhibiting excellent water non-dispersibility.

[0145] As shown in Table 2, Example 2 exhibits adjustable thickening time and a normal thickening curve, with no abnormalities such as "bulging." For Example 2, when the retarder content was 0.7 parts, the thickening times at 90°C, 110°C, and 130°C, and a pressure of 60 MPa, were 432 minutes, 312 minutes, and 145 minutes, respectively. When the retarder content was 1.0 parts, the thickening times at 90°C, 110°C, and 130°C, and a pressure of 60 MPa, were 725 minutes, 474 minutes, and 174 minutes, respectively. When the retarder content was 1.5 parts, the thickening time at 150°C and 60 MPa was 115 minutes. When the retarder content was 2.0 parts, the thickening time at 150°C and 60 MPa was 355 minutes. This indicates that the thickening time of the water-insoluble cement slurry system exhibits a good linear relationship with both retarder content and temperature.

[0146] As shown in Table 3, the thickening curves for Example 2 and Comparative Example 2 were normal during curing, with no abnormalities such as "bulging." For Example 2, after curing, the slurry exhibited excellent water non-dispersibility in water with low, medium, and high salinities. However, for Comparative Example 2, the water non-dispersibility in water with low, medium, and high salinities was poor, very poor, and very poor, respectively. This demonstrates that the water-resistant cement slurry system exhibits excellent water non-dispersibility in water with varying salinities, meeting the operating conditions of formation water with varying salinities.

[0147] Therefore, the wide temperature range water-independent cement slurry system provided by the present invention can ensure that the cement slurry particles are not dispersed by water when in contact with water. It is suitable for cementing high aquifers and plugging lost-water layers in a static temperature range of room temperature to 180°C, and has no adverse effect on conventional properties such as cement slurry rheology, water loss, stability, and cement stone strength. 3 The 24h compressive strength of the low-density, water-insoluble cement slurry system is greater than 10MPa and 1.9g / cm 3 The 24h compressive strength of the conventional density non-dispersible cement slurry system is greater than 20MPa, 2.4g / cm 3 The high-density, water-resistant cement slurry system has a 24-hour compressive strength exceeding 14 MPa, meeting cementing construction requirements. This ensures the slurry's rheological properties, minimizes thixotropy, and avoids "bulging" and "stepping" in the thickening curve. The slurry's thickening time exhibits a strong linear relationship with temperature, density, and retarder dosage. This system effectively fills the annulus, ensuring the structural integrity of the cement sheath and enhancing the isolation of high-aquifer formations and leaking zones under varying temperature conditions. This provides favorable wellbore conditions for oil and gas production and ensures efficient extraction of oil and gas resources.

[0148] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A composition that does not disperse when exposed to water, characterized in that: The water-insoluble composition comprises: 0.5-5 parts by weight of microbial polysaccharide polymer compounds, 5-50 parts by weight of organic polymer compounds and 4.5-45 parts by weight of inorganic particles; wherein the number average molecular weight of the organic polymer compounds is 100,000-1,000,000 g / mol.

2. The water-insoluble composition according to claim 1, wherein: The microbial polysaccharide polymer compound is selected from one or more of xanthan gum, gellan gum, pullulan, trehalose, hyaluronic acid, thermogel, chitosan, curdlan and thermogel.

3. The water-insoluble composition according to claim 2, wherein: The structural skeleton of the microbial polysaccharide polymer compound is connected by one or more of glucose, glucuronic acid, rhamnose, maltotriose and acetylglucosamine through chemical bonds, and the side chain is connected by one or more of mannose, rhamnose and glucuronic acid through chemical bonds.

4. The water-insoluble composition according to claim 1 or 2, wherein: The organic polymer compound is selected from one or more of polyethylene oxide, polyvinyl alcohol, polyacrylic acid, sodium polyacrylate, calcium polyacrylate and a polymer formed by alkaline hydrolysis of polyacrylamide; And / or, the organic polymer compound is selected from one or more of styrene sulfonate, wood sulfonate, and copolymers formed by acrylic acid and methacrylic acid.

5. The water-insoluble composition according to claim 1 or 2, wherein: The inorganic particles are acid-washed quartz sand; And / or, the average particle size of the inorganic particles is 5-75 μm.

6. Use of the water-insoluble composition according to any one of claims 1 to 5 in cement slurry.

7. A cement slurry, characterized in that: The cement slurry contains the water-insoluble composition according to any one of claims 1 to 5.

8. The cement slurry according to claim 7, wherein: The cement slurry comprises: 100 parts of G-grade oil well cement, 0.5-2 parts of the water-insoluble composition, 1-3 parts of active materials, 0-35 parts of high-temperature strength stabilizer, 0-100 parts of density regulator, 2-5 parts of fluid loss reducer, 0.2-0.5 parts of suspension stabilizer, 1-3 parts of dispersant, 0.1-2.5 parts of retarder, 0.1-0.5 parts of defoamer and 40-110 parts of water.

9. The cement slurry according to claim 7 or 8, wherein: The active material is active microsilicon, and the average particle size thereof is 0.1-0.5 μm.

10. The cement slurry according to claim 7 or 8, wherein: The high temperature strength stabilizer is acid washed quartz sand, the SiO2 content of which is greater than 99% and the average particle size of which is 5-75 μm.

11. The cement slurry according to claim 7 or 8, wherein: The density regulator includes a weighting material and a lightening material; wherein the weighting material is selected from one or more of iron ore powder, barite and micro-manganese ore powder; and the lightening material is selected from one or more of glass microbeads, floating beads and fly ash.

12. The cement slurry according to claim 7 or 8, wherein: The retarder is selected from one or more of AMPS substances and organophosphate substances; And / or, the fluid loss reducer is selected from one or more of polymers formed by polymerization of AMPS, low molecular weight amides and polyhydroxycarboxylic acid substances and PVA substances; And / or, the suspension stabilizer is selected from plant gum polymer compounds or cellulose polymer compounds; and / or, the dispersant is selected from one or more of a condensation product of formaldehyde and acetone, polystyrene sulfonates and polycarboxylates; And / or, the defoaming agent is selected from one or more of tributyl phosphate, polyoxypropylene glycerol and polydimethylsiloxane.

13. The cement slurry according to claim 12, wherein: The plant gum polymer compound is selected from one or more of guar gum, curdlan, carrageenan and acacia gum; The cellulose polymer compound is selected from one or more of lignin fiber, cellulose ether, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose and carboxymethyl cellulose.

14. The cement slurry according to claim 7 or 8, wherein: The density of the cement slurry is 1.2-2.4 g / cm 3 ; And / or, the use temperature range of the cement slurry is 10-180°C; And / or, the fluidity of the cement slurry is greater than 22 cm, the API water loss is less than 50 mL, and the free liquid is 0.

15. The cement slurry according to claim 7 or 8, wherein: Density: 1.2g / cm 3 The cement slurry does not disperse when it comes into contact with water, and its 24h compressive strength is greater than 10MPa; and / or, density 1.9 g / cm 3 The cement slurry does not disperse when it comes into contact with water, and its 24h compressive strength is greater than 20MPa; and / or, density 2.4 g / cm 3 The cement slurry does not disperse when it comes into contact with water, and its 24h compressive strength is greater than 14MPa.

16. A method for preparing cement slurry, characterized in that: The preparation method comprises: Mixing the G-class oil well cement, the water-insoluble composition according to any one of claims 1 to 5, an active material, a high temperature strength stabilizer, a density regulator, a fluid loss additive, a suspension stabilizer and a dispersant to obtain a dry mix; mixing a retarder, a defoamer and water to obtain a wet mix; The dry mix and the wet mix are mixed at a low stirring speed and then stirred at a high speed to obtain cement slurry.

17. Use of the cement slurry according to any one of claims 7 to 15 or the cement slurry prepared by the preparation method according to claim 16 in the isolation of aquifers and plugging of lost circulation zones in oil and gas wells.

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