Water non-dispersible compositions and cementitious pastes comprising the same and methods of making the same

Abstract

This invention relates to the field of cementing technology, disclosing a water-indispersible composition, a cement slurry containing the same, its preparation method, and its applications. The water-indispersible composition comprises: 0.5-5 parts by weight of a microbial polysaccharide polymer, 5-50 parts by weight of an organic polymer, and 4.5-45 parts by weight of inorganic particles. The water-indispersible composition of this invention exhibits good water resistance within a temperature range from room temperature to 180°C, and can be used to prepare cement slurries. It ensures that the particles in the cement slurry are not dispersed by formation water, while having no adverse effects on the conventional properties of the cement slurry, such as rheology, water loss, stability, and cement stone strength. This invention also provides a cement slurry containing the water-indispersible composition. This cement slurry exhibits water resistance, ensuring effective filling of the annulus cement slurry and the integrity of the cement sheath structure. It is suitable for sealing high water-cut layers and plugging lost circulation zones, achieving effective sealing of high water-cut layers and effective plugging of lost circulation zones at different well depths.

Description

Technical Field

[0001] This invention relates to the field of cementing technology, and more specifically to water-indispersible compositions and cement slurries containing the same, as well as their preparation methods and applications. Background Technology

[0002] During long-term water-driven oil production, the formation pressure system becomes complex. Vertically, multiple pressure systems exist within the same wellbore, especially in structurally complex formations where cross-contamination between layers is common. If new wells are drilled in these areas, the cement slurry structure is easily disrupted by formation water during the cementing process, leading to water intrusion, channeling, and other problems, severely impacting the cementing quality of the aquifer. Severe cement slurry loss during cementing results in reduced annular displacement efficiency and insufficient cement slurry return depth, causing unsealed upper sections and compromising cementing quality.

[0003] Effective isolation of high-water-cut formations and plugging of lost circulation zones are crucial for the successful construction of oil and gas wells. During the construction of high-water-cut isolation and lost circulation zone plugging operations, when cement slurry is injected into the high-water-cut annulus or lost circulation zone, formation water dissolves, migrates, and scours the ordinary cement slurry, damaging its solid structure and hindering effective isolation of the aquifer and plugging of the lost circulation zone, severely impacting project quality and progress. Currently, to improve the quality of high-water-cut isolation and the effectiveness of lost circulation zone plugging, water-insoluble materials are typically added to the ordinary cement slurry to prevent cement slurry particles from being dispersed by formation water during construction. Traditional water-insoluble materials include polyacrylamide polymers and their copolymers, as well as naturally modified polymers such as cellulose ethers. Although traditional water-insoluble materials and systems possess a certain degree of water resistance, they still have the following shortcomings:

[0004] ① Polyacrylamide-based water-insoluble materials work well below 80°C, but are prone to decomposition above 80°C, and cannot effectively prevent cement slurry particles from being washed away by water.

[0005] ② Cellulose ether water-dispersible materials have a good thickening effect at low temperatures, but they will gel at 60-90℃, resulting in poor cement slurry workability and easy cementing accidents such as "sausage filling" and annular blockage.

[0006] ③ Conventional water-dispersible cement paste systems typically do not contain high-temperature strength stabilizers, which can easily lead to a decline in the strength of cement paste under high-temperature conditions.

[0007] Therefore, there is a need to find a cement slurry that does not disperse water over a wide temperature band, which can ensure the sealing effect of high water-bearing layers and the plugging effect of lost circulation layers at different well depths when sealing high water-bearing layers and plugging lost circulation layers. Summary of the Invention

[0008] The purpose of this invention is to overcome the problem of cement stone strength degradation caused by high-temperature conditions in existing cement slurries, and to provide a water-indispersible composition, a cement slurry containing the same, a method for preparing the same, and its applications. The cement slurry containing this water-indispersible composition exhibits good water-inhibitory properties within a temperature range from room temperature to 180°C, ensuring effective filling of the annulus cement slurry and the integrity of the cement sheath structure, and achieving effective isolation of high-water-bearing layers at different well depths and effective plugging of lost circulation zones.

[0009] To achieve the above objectives, the first aspect of the present invention provides a water-indispersible composition comprising: 0.5-5 parts by weight of a microbial polysaccharide polymer, 5-50 parts by weight of an organic polymer, and 4.5-45 parts by weight of inorganic particles.

[0010] A second aspect of the present invention provides the use of the aforementioned water-indispersible composition in cement slurry.

[0011] A third aspect of the present invention provides a cement slurry containing the aforementioned water-indispersible composition.

[0012] A fourth aspect of the present invention provides a method for preparing cement slurry, the method comprising:

[0013] G-grade oil well cement, the aforementioned water-insoluble composition, active materials, high-temperature strength stabilizer, density regulator, fluid loss reducer, suspension stabilizer and dispersant are mixed to obtain a dry mix;

[0014] The retarder, defoamer and water are mixed to obtain a wet mixture;

[0015] The dry and wet mixtures are mixed at a low stirring rate and then stirred at a high speed to obtain a cement slurry.

[0016] The fifth aspect of the present invention provides the application of the cement slurry prepared by the preparation method of the third aspect or the fourth aspect above in cementing operations of oil and gas wells.

[0017] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0018] (1) The water-insoluble composition of the present invention has good water-insoluble properties in the temperature range of room temperature to 180°C. It can be used to prepare cement slurry, ensuring that the particles in the cement slurry are not dispersed by formation water, and has no adverse effect on the conventional properties of cement slurry such as rheology, water loss, stability, and cement stone strength.

[0019] (2) The cement slurry of the present invention contains a water-insoluble composition, which has the characteristic that the cement slurry particles are not dispersed when in contact with water, that is, it is non-dispersible when in contact with water, which can ensure the effective filling of the annular cement slurry and the integrity of the cement ring structure.

[0020] (3) The cement slurry of the present invention is suitable for sealing high water-bearing layers and plugging lost circulation layers. It has good water non-dispersibility in the temperature range of room temperature to 180°C, and can effectively seal high water-bearing layers at different well depths and effectively plug lost circulation layers, providing good wellbore conditions for oil and gas production and ensuring efficient exploitation of oil and gas resources. Attached Figure Description

[0021] Figure 1 This is the thickening curve at 90°C for Example 2 + 1% retarder;

[0022] Figure 2 This is the thickening curve at 110°C for Example 2 + 1% retarder;

[0023] Figure 3 This is the thickening curve at 130°C for Example 2 + 1% retarder;

[0024] Figure 4 This is the static gel strength variation curve (180℃ × 20.7MPa) of Example 2;

[0025] Figure 5 This is a diagram showing the cement slurry suspended in mid-air.

[0026] Figure 6 This is a chart evaluating the non-dispersibility performance of cement slurry, where (a) is very poor, (b) is poor, (c) is average, (d) is good, and (e) is excellent. Detailed Implementation

[0027] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0028] The first aspect of the present invention provides a water-indispersible composition comprising: 0.5-5 parts by weight of a microbial polysaccharide polymer, 5-50 parts by weight of an organic polymer, and 4.5-45 parts by weight of inorganic particles.

[0029] Preferably, the water-insoluble composition comprises: 1-4 parts by weight of microbial polysaccharide polymer, 10-30 parts by weight of organic polymer and 10-30 parts by weight of inorganic particles.

[0030] In this invention, the water-non-dispersible composition refers to a mixture that, when mixed with cement slurry, ensures that the cement slurry particles will not be dispersed by water.

[0031] The water-indispersible composition of the present invention is a compound of microbial polysaccharide polymers, organic polymers, and inorganic particles. It utilizes the high efficiency, non-toxicity, lack of secondary pollution, self-degradability, and wide applicable temperature range of microbial polysaccharide polymers, as well as the flocculation properties of organic polymers. Through the synergistic effect of the three, the cement slurry particles are encapsulated, preventing them from being dispersed by formation water when injected into high water-bearing and lost circulation zones. This composition can adapt to different formation temperature conditions and meet the performance requirements of cement slurry for sealing high water-bearing and lost circulation zones at different well depths.

[0032] In this invention, microbial polysaccharide polymers can increase the viscosity of cement slurry, allowing particulate matter to be uniformly suspended in the slurry. They also possess the characteristic of not decomposing or shear-diluting under high temperatures, ensuring the stability and rheological properties of the cement slurry under high-temperature conditions. Organic polymers can encapsulate the particulate matter through their long chains, forming a strong network structure that prevents it from being dispersed by water. Inorganic particles are uniformly suspended in the slurry under the action of microbial polysaccharide polymers, and through their combination with the long chains of organic polymers, the strength of the network structure is improved, enhancing resistance to water impact.

[0033] In some embodiments of the present invention, the microbial polysaccharide polymer is selected from one or more of xanthan gum, gellan gum, brevicorpus polysaccharide, trehalose, hyaluronic acid, thermogel, chitosan, gelatin, and hygroscopic gum.

[0034] In some embodiments of the present invention, the structural skeleton of the microbial polysaccharide macromolecule is composed of one or more of glucose, glucuronic acid, rhamnose, maltotriose, and acetylglucosamine linked by chemical bonds, and the side chains are composed of one or more of mannose, rhamnose, and glucuronic acid linked by chemical bonds.

[0035] The microbial polysaccharide polymers of this invention have a large number of carboxyl groups and possess good hydrophilic properties.

[0036] In some embodiments of the present invention, the organic polymer compound is selected from one or more of the polymers formed by the alkaline hydrolysis of polyethylene oxide, polyvinyl alcohol, polyacrylic acid, sodium polyacrylate, calcium polyacrylate, and polyacrylamide; and / or, the organic polymer compound is selected from copolymers formed from one or more of styrene sulfonate, lignosulfonate, acrylic acid, and methacrylic acid.

[0037] In this invention, the organic polymer compound is selected from polymers such as polyethylene oxide, polyvinyl alcohol, polyacrylic acid, sodium polyacrylate, calcium polyacrylate, and alkaline hydrolysate of polyacrylamide, as well as one or more of styrene sulfonate, lignosulfonate, acrylic acid, and methacrylic acid copolymers.

[0038] In this invention, microbial polysaccharide polymers increase the viscosity of cement slurry by adsorbing water molecules, allowing particulate matter to be uniformly suspended in the slurry. They also possess the characteristics of not decomposing at high temperatures and being shear-diluted, ensuring the stability and rheological properties of the cement slurry under high-temperature conditions to meet cementing requirements. The organic polymers have numerous ether and hydrogen bonds in their molecular structure, allowing them to combine with inorganic particles and encapsulate other particulate matter in the cement slurry through their long organic polymer chains, forming a strong network structure that enhances resistance to water impact and prevents the slurry from being washed away.

[0039] In some embodiments of the present invention, the number-average molecular weight of the organic polymer compound is 100,000 to 1,000,000 g / mol.

[0040] In some embodiments of the present invention, the inorganic particles are acid-washed quartz sand.

[0041] In some embodiments of the present invention, the average particle size of the inorganic particles is 5-75 μm.

[0042] The water-indispersible composition of this invention is a compound of microbial polysaccharide polymers, organic polymers, and inorganic particles. Utilizing the high efficiency, non-toxicity, lack of secondary pollution, self-degradability, wide applicable temperature range, and shear dilution properties of microbial polysaccharide polymers, it can increase the viscosity of cement slurry, allowing particulate matter to be uniformly suspended in the slurry over a wide temperature range, while simultaneously giving the slurry good rheological properties. Utilizing the flocculation characteristics of organic polymers, the inorganic particles are encapsulated by long molecular chains, forming a network structure with a certain strength. Through the synergistic effect of these three components, the cement slurry particles are encapsulated, preventing them from being dispersed by formation water when injected into high-water-bearing and lost-loop zones. This allows it to adapt to different formation temperature conditions and meet the performance requirements of cement slurry for high-water-bearing and lost-loop sealing operations at different well depths.

[0043] A second aspect of the present invention provides the use of the aforementioned water-indispersible composition in cement slurry.

[0044] A third aspect of the present invention provides a cement slurry containing the aforementioned water-indispersible composition.

[0045] The cement slurry of the present invention contains a water-insoluble composition, which has the characteristic that the cement slurry particles are not dispersed when in contact with water, that is, it is non-dispersible when in contact with water, which can ensure the effective filling of the annular cement slurry and the integrity of the cement ring structure.

[0046] In some embodiments of the present invention, the cement slurry comprises: 100 parts of Grade G 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 water loss reducer, 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.

[0047] In this invention, research has shown that the amount of water-indispersible composition added cannot be too small, less than 0.5 parts. In this case, the water-indispersible composition cannot effectively encapsulate other components in the cement slurry, resulting in poor water dispersibility and easy dispersibility when in contact with formation water. Conversely, the amount of water-indispersible composition added cannot be too large, more than 2 parts. This leads to poor rheological properties and high consistency in the cement slurry, making it difficult for cement trucks to replace the cement slurry during cementing. This invention, by selecting a suitable water-indispersible composition and controlling its addition amount, encapsulates other components in the cement slurry, preventing them from being dispersed by formation water when the cement slurry is injected into high-water-bearing and lost circulation zones. This allows it to adapt to different formation temperature conditions and meet the performance requirements of cement slurry for high-water-bearing zone isolation and lost circulation zone plugging operations at different well depths.

[0048] In this 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 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 about the conventional density of 1.90.

[0049] Preferably, the cement slurry comprises: 100 parts of Grade G 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 water loss reducer, 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.

[0050] In some embodiments of the present invention, the active material is active microsilica with an average particle size of 0.1-0.5 μm.

[0051] In this invention, the active material can improve the consistency of cement slurry, help the cement slurry achieve non-dispersibility when exposed to water, and enhance the strength of the cement slurry under different temperature conditions.

[0052] In some embodiments of the present invention, the high-temperature strength stabilizer is acid-washed quartz sand with a SiO2 content greater than 99% and an average particle size of 5-75 μm.

[0053] In this invention, the high-temperature strength stabilizer can reduce the Ca(OH)2 content and calcium-silicon ratio (C / S) in cement stone, preventing the cement stone from experiencing strength degradation under high-temperature conditions.

[0054] 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 microspheres, cenospheres, and fly ash.

[0055] In this invention, weighting and lightening materials are used as density regulators. By utilizing their density characteristics, the density of the cement slurry system is adjusted to meet the density requirements of the cement slurry system under different working conditions.

[0056] Other additives used in this invention, such as suspension stabilizers, retarders, dispersants, and defoamers, are commonly used additives in the field. Their mechanisms and properties are well known to those skilled in the art and will not be described in detail here.

[0057] In some embodiments of the present invention, the retarder is selected from one or more of AMPS-type substances and organophosphate-type substances.

[0058] In some embodiments of the present invention, the water loss reducing agent is selected from one or more of AMPS, low molecular weight amides and polyhydroxycarboxylic acid substances polymerized into polymers and PVA substances.

[0059] In this invention, the polymer is formed by polymerizing AMPS, low molecular weight amides and polyhydroxycarboxylic acids, and the water loss reducing agent is selected from one or more of the polymer and PVA-like substances.

[0060] In some embodiments of the present invention, the suspension stabilizer is selected from plant gum polymers or cellulose polymers.

[0061] Preferably, the plant gum polymer is selected from one or more of guar gum, guar gum, carrageenan, and locust gum.

[0062] Preferably, the cellulose polymer is selected from one or more of lignin fiber, cellulose ether, methylcellulose, hydroxypropyl methylcellulose, hydroxyethyl cellulose and carboxymethyl cellulose.

[0063] In some embodiments of the present invention, the dispersant is selected from one or more of formaldehyde and acetone condensates, polystyrene sulfonates, and polycarboxylic acids.

[0064] Preferably, the dispersant is selected from one or two of the following: formaldehyde and acetone condensates, polystyrene sulfonate dispersants, and polycarboxylic acid dispersants.

[0065] In some embodiments of the present invention, the defoamer is selected from one or more of tributyl phosphate, polyoxypropylene glycerol, and polydimethylsiloxane.

[0066] In some embodiments of the present invention, the density of the cement slurry is 1.2-2.4 g / cm³. 3 The applicable temperature range is 10-180℃.

[0067] In some embodiments of the present invention, the flowability of the cement slurry is greater than 22 cm, the API water loss is less than 50 mL, and the free liquid content is 0.

[0068] In some embodiments of the present invention, the density is 1.2 g / cm³. 3 The cement slurry does not disperse when exposed to water, and its compressive strength is greater than 10 MPa after 24 hours.

[0069] In some embodiments of the present invention, the density is 1.9 g / cm³. 3 The cement slurry does not disperse when exposed to water, and its compressive strength is greater than 20 MPa after 24 hours.

[0070] In some embodiments of the present invention, the density is 2.4 g / cm³. 3 The cement slurry does not disperse when exposed to water, and its compressive strength is greater than 14 MPa after 24 hours.

[0071] A fourth aspect of the present invention provides a method for preparing cement slurry, the method comprising:

[0072] G-grade oil well cement, the aforementioned water-insoluble composition, active materials, high-temperature strength stabilizer, density modifier, fluid loss reducer, suspension stabilizer, and dispersant are mixed to obtain a dry mix.

[0073] The retarder, defoamer and water are mixed to obtain a wet mixture;

[0074] The dry and wet mixtures are mixed at a low stirring rate and then stirred at a high speed to obtain a cement slurry.

[0075] Specifically, the low stirring rate is 4000±200 r / min, the high stirring rate is 12000±500 r / min, and the stirring time is 30-40 s, preferably 35 s, resulting in a cement slurry that is non-dispersible in water over a wide temperature range.

[0076] The cement slurry of this invention has an adjustable density (1.2-2.4 g / cm³). 3 It has a wide applicable temperature range (room temperature to 180℃), high compressive strength, and good linear relationship between thickening time and temperature, density, and retarder dosage.

[0077] The fifth aspect of the present invention provides the application of the cement slurry prepared by the method of the third aspect or the fourth aspect above in the sealing of aquifers and plugging of lost circulation zones in oil and gas wells.

[0078] The cement slurry of this invention is suitable for sealing high water-bearing layers and plugging lost circulation zones. It exhibits good water non-dispersibility within a temperature range from room temperature to 180°C, enabling effective sealing of high water-bearing layers at different well depths and effective plugging of lost circulation zones. This provides favorable wellbore conditions for oil and gas production and ensures efficient extraction of oil and gas resources.

[0079] The cement slurry of this invention has a wide temperature range and is non-dispersible in water with adjustable density (1.20-2.40 g / cm³). 3 It has an applicable temperature range of room temperature to 180℃, and exhibits good linearity in thickening time with temperature, density, and retarder dosage. It has a fluidity greater than 22 cm, an API water loss of less than 50 mL, and free liquid content of 0-1.2 g / cm³. 3 The low-density, water-non-dispersible cement paste system has a 24-hour compressive strength greater than 10 MPa and a strength of 1.9 g / cm³. 3 A conventional density cement paste system that does not disperse in water has a compressive strength greater than 20 MPa after 24 hours, and a strength of 2.4 g / cm³. 3 The high-density, water-resistant, non-dispersible cement slurry system exhibits a 24-hour compressive strength greater than 14 MPa. The cement slurry demonstrates excellent stability under varying temperature conditions. During cementing and leak sealing in high-water-content formations, the cement slurry exhibits good workability; the cement slurry particles are not easily dispersed by formation water during construction, ensuring effective annular filling and structural integrity. This enables effective isolation of high-water-content annular layers and effective plugging of leaky zones. It is of great significance for improving cementing effectiveness in complex formations and saving well construction costs.

[0080] The technical solutions of the present invention will be clearly and completely described below through embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0081] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0082] Experiments were conducted according to the national standard GB / T 19139-2012 "Test Methods for Oil Well Cement" to evaluate the thickening properties, fluidity, API water loss, free water, stability, and compressive strength of the cement slurry. The main experimental instruments included: a 30-60 type corrugated agitator, an 8240 type high-temperature and high-pressure thickener (CHANDLER, USA); a 4265-HT type high-temperature and high-pressure static gel strength measuring instrument (CHANDLER, USA); and an HH-420 type constant temperature digital display water tank (Changzhou Yineng Experimental Instrument Factory).

[0083] In the following embodiments,

[0084] The microbial polysaccharide polymer is xanthan gum, produced by Sichuan Kai'er Oil and Gas Field Technology Service Co., Ltd.

[0085] The organic polymer compound is polyethylene oxide with a number average molecular weight of 200,000 g / mol, produced by Shandong Wantong Chemical Co., Ltd.

[0086] The inorganic granules are designated as DRB-2S and are manufactured by China Petroleum Engineering Technology Research Institute Co., Ltd.

[0087] Grade G oil well cement is a high sulfate-resistant (HSR) grade G oil well cement produced by Jiahua Special Cement Co., Ltd.

[0088] The high-temperature strength stabilizer is designated as DRB-2S and is manufactured by China Petroleum Engineering Technology Research Institute Co., Ltd.

[0089] The density regulator, specifically glass microspheres (12000 Psi), is manufactured by Sinosteel Group Maanshan Mining Institute New Materials Technology Co., Ltd., and the concentrate iron ore powder is 6.05 g / cm³. 3 This product was manufactured by Sichuan Kai'er Oil and Gas Field Technology Service Co., Ltd.

[0090] The fluid loss reducer is model DRF-1S and is manufactured by China Petroleum Engineering Technology Research Institute Co., Ltd.

[0091] The suspension stabilizer is designated DRK-3S and is manufactured by China Petroleum Engineering Technology Research Institute Co., Ltd.

[0092] The dispersant is model DRS-1S and is manufactured by China Petroleum Engineering Technology Research Institute Co., Ltd.

[0093] The retarder is designated as DRH-1L or DRH-2L and is manufactured by China Petroleum Engineering Technology Research Institute Co., Ltd.

[0094] The defoamer is model DRX-1L or DRX-2L and is manufactured by China Petroleum Engineering Technology Research Institute Co., Ltd.

[0095] The water used in the experiment was distilled water.

[0096] The evaluation method for the water-insensitive non-dispersible performance of cement slurry before curing is as follows: Prepare two 250mL beakers. Pour 200mL of room temperature distilled water or formation water (numbered 1-1#) into one beaker, and pour distilled water or formation water heated to a set temperature (maximum 100℃) (numbered 1-2#) into the other beaker. Insulate both beakers to ensure that the water temperature in both beakers is constant. Prepare approximately 600mL of water-insensitive non-dispersible cement slurry according to the preparation method described in claim 10, and pour it into two 50mL beakers (numbered 1-1-1# and 1-2-2# respectively). Let it stand for a certain time (recommended 10min). Then, suspend beakers 1-1-1# and 1-2-2# above beakers 1-1# and 1-2-2# respectively at a certain height (recommended 1cm, e.g.) Figure 5 The cement slurry was poured into beakers 1-1# and 1-2# at a certain flow rate (recommended 2 mL / s). Based on whether the poured cement slurry could be dispersed by water and the turbidity of the water at the top of beakers 1-1# and 1-2#, the water non-dispersibility performance was set to 5 levels. Figure 6 As shown, this is used to evaluate the water non-dispersibility of cement slurry. This invention evaluates the non-dispersibility based on the clarity of the supernatant, using a 5-level rating from very clear to very turbid, compared to the control group. Figure 6 The ratings are shown as (a) very good, (b) good, (c) fair, (d) poor and (e) very poor.

[0097] The evaluation method for the water-insoluble performance of cement slurry after curing is as follows: Prepare two 250mL beakers. Pour 200mL of room temperature distilled water or formation water (numbered 2-1#) into one beaker, and pour distilled water or formation water heated to a set temperature (maximum 100℃) (numbered 2-2#) into the other beaker. Insulate both beakers to ensure that the water temperature in both beakers is constant. Then, prepare approximately 600mL of water-insoluble cement slurry according to the preparation method described in claim 10. Set the curing temperature and pressure as needed, and perform curing for a certain period of time. After curing, pour the slurry into two 50mL beakers (numbered 2-1-1# and 2-2-2# respectively) and let it stand for a certain period of time (recommended 10min). Then, suspend beakers 2-1-1# and 2-2-2# above beakers 2-1# and 2-2# respectively at a certain height (recommended 1cm). Figure 5 As shown), then pour the cement slurry into beakers 2-1# and 2-2# at a certain flow rate (recommended 2 mL / s). Based on whether the poured cement slurry can be dispersed by water and the turbidity of the water at the top of beakers 2-1# and 2-2#, set the water non-dispersibility performance to 5 levels, as shown. Figure 6As shown, this is used to evaluate the water non-dispersibility of cement paste.

[0098] Preparation Example 1

[0099] 2.5 parts by weight of microbial polysaccharide polymer, 30 parts by weight of organic polymer and 45 parts by weight of inorganic particles were sequentially placed into a mixing device and mixed evenly to obtain a water-indispersible composition A1.

[0100] Preparation Example 2

[0101] 0.5 parts by weight of microbial polysaccharide polymer, 10 parts by weight of organic polymer and 25 parts by weight of inorganic particles were sequentially placed into a mixing device and mixed evenly to obtain water-indispersible composition A2.

[0102] Preparation Example 3

[0103] Five parts by weight of microbial polysaccharide polymer, 50 parts by weight of organic polymer and 20 parts by weight of inorganic particles were sequentially placed into a mixing device and mixed evenly to obtain water-indispersible composition A3.

[0104] Preparation of Comparative Example 1

[0105] 30 parts by weight of organic polymer and 45 parts by weight of inorganic particles were sequentially placed into a mixing device and mixed evenly to obtain a water-indispersible composition D1.

[0106] Preparation of Comparative Example 2

[0107] 2.5 parts by weight of microbial polysaccharide polymer and 45 parts by weight of inorganic particles were sequentially placed into a mixing device and mixed evenly to obtain water-indispersible composition D2.

[0108] Preparation of Comparative Example 3

[0109] 2.5 parts by weight of microbial polysaccharide polymer and 30 parts by weight of organic polymer were sequentially placed into a mixing device and mixed evenly to obtain water-indispersible composition D3.

[0110] Example 1

[0111] The cement slurry formulation comprises the following components by weight: 100 parts Grade G oil well cement, 1 part water-non-dispersible composition A1, and 61 parts density modifier (0.62 g / cm³). 3 The cement paste contains: 2 parts glass microspheres, 2 parts activated microsilica, 30 parts high-temperature strength stabilizer, 1 part suspension stabilizer, 0.7 parts retarder, 4.5 parts water loss reducer, 2 parts dispersant, 0.25 parts retarder, 0.2 parts defoamer, and 103 parts water. The cement paste density is 1.2 g / cm³. 3 The experimental results of conventional performance and water non-dispersibility are shown in Table 1.

[0112] Example 2

[0113] The cement slurry formulation comprises the following components by weight: 100 parts Grade G oil well cement, 1 part water-indispersible composition A2, 35 parts high-temperature strength stabilizer, 1 part active microsilica, 0.3 parts suspension stabilizer, 0.7 parts retarder, 3.5 parts water loss reducer, 2.5 parts dispersant, 0.2 parts defoamer, and 58 parts water. The cement slurry density is 1.9 g / cm³. 3 The experimental results of conventional performance and water non-dispersibility are shown in Table 1, and the thickening time results under different retarder dosages are shown in Table 2.

[0114] like Figure 1-3 The figures shown are the thickening curves of the formulation in Example 2 at temperatures of 90°C, 110°C, and 130°C and pressures of 60 MPa. Figure 1-3 As can be seen, there are no obvious abnormalities such as bulging in the thickening curve. The thickening times of cement slurry at the three temperature points are 725 min, 474 min and 174 min, respectively, indicating that the thickening time changes linearly with the increase of temperature.

[0115] like Figure 4 The figure shows the static gel strength variation curve of the formulation in Example 2 under conditions of 180°C and 20.7 MPa. Figure 4 It can be seen that the formulation of Example 2 begins to develop strength in about 4 hours and exceeds 20 MPa in about 10 hours. Subsequently, the strength increases slowly and remains above 20 MPa for 168 hours.

[0116] Example 3

[0117] The cement slurry formulation comprises the following components by weight: 100 parts Grade G oil well cement, 2 parts water-non-dispersible composition A3, and 92 parts density modifier (6.05 g / cm³). 3 The ingredients are: refined iron ore powder, 50 parts high-temperature strength stabilizer, 1.6 parts suspension stabilizer, 3.2 parts retarder, 3.5 parts water loss reducer, 1.5 parts dispersant, 0.2 parts defoamer, 68 parts water, and cement paste density of 2.4 g / cm³. 3 The experimental results of conventional performance and water non-dispersibility are shown in Table 1.

[0118] Comparative Example 1

[0119] The cement slurry formulation includes the following components by weight: 100 parts Grade G oil well cement, 61 parts density modifier (0.62 g / cm³). 3 The cement paste contains: 2 parts glass microspheres, 2 parts activated microsilica, 30 parts high-temperature strength stabilizer, 1 part suspension stabilizer, 0.7 parts retarder, 4.5 parts water loss reducer, 2 parts dispersant, 0.25 parts retarder, 0.2 parts defoamer, and 103 parts water. The cement paste density is 1.2 g / cm³. 3The experimental results of conventional performance and water non-dispersibility are shown in Table 1.

[0120] Comparative Example 2

[0121] The cement slurry formulation comprises the following components by weight: 100 parts Grade G oil well cement, 35 parts high-temperature strength stabilizer, 1 part active microsilica, 0.3 parts suspension stabilizer, 0.7 parts retarder, 3.5 parts water loss reducer, 2.5 parts dispersant, 0.2 parts defoamer, and 58 parts water. The cement slurry density is 1.9 g / cm³. 3 The experimental results of conventional performance and water non-dispersibility are shown in Table 1.

[0122] Comparative Example 3

[0123] The cement slurry formulation includes the following components by weight: 100 parts Grade G oil well cement, 92 parts density modifier (6.05 g / cm³). 3 The cement paste contains: 50 parts refined iron ore powder, 1.6 parts high-temperature strength stabilizer, 3.2 parts suspension stabilizer, 3.5 parts retarder, 1.5 parts water loss reducer, 0.2 parts dispersant, and 68 parts defoamer; the cement paste density is 2.4 g / cm³. 3 The experimental results of conventional performance and non-dispersibility in water are shown in Table 1.

[0124] Comparative Example 4

[0125] The cement slurry formulation comprises the following components by weight: 100 parts Grade G oil well cement, 1 part water-dispersible composition D1, and 61 parts density modifier (0.62 g / cm³). 3 The cement paste contains: 2 parts glass microspheres, 2 parts activated microsilica, 30 parts high-temperature strength stabilizer, 1 part suspension stabilizer, 0.7 parts retarder, 4.5 parts water loss reducer, 2 parts dispersant, 0.25 parts retarder, 0.2 parts defoamer, and 103 parts water. The cement paste density is 1.2 g / cm³. 3 The experimental results of conventional performance and water non-dispersibility are shown in Table 1.

[0126] Comparative Example 5

[0127] The cement slurry formulation comprises the following components by weight: 100 parts Grade G oil well cement, 1 part water-dispersible composition D2, and 61 parts density modifier (0.62 g / cm³). 3 The cement paste contains: 2 parts glass microspheres, 2 parts activated microsilica, 30 parts high-temperature strength stabilizer, 1 part suspension stabilizer, 0.7 parts retarder, 4.5 parts water loss reducer, 2 parts dispersant, 0.25 parts retarder, 0.2 parts defoamer, and 103 parts water. The cement paste density is 1.2 g / cm³. 3 The experimental results of conventional performance and water non-dispersibility are shown in Table 1.

[0128] Comparative Example 6

[0129] The cement slurry formulation comprises the following components by weight: 100 parts Grade G oil well cement, 1 part water-dispersible composition D3, and 61 parts density modifier (0.62 g / cm³). 3 The cement paste contains: 2 parts glass microspheres, 2 parts activated microsilica, 30 parts high-temperature strength stabilizer, 1 part suspension stabilizer, 0.7 parts retarder, 4.5 parts water loss reducer, 2 parts dispersant, 0.25 parts retarder, 0.2 parts defoamer, and 103 parts water. The cement paste density is 1.2 g / cm³. 3 The experimental results of conventional performance and water non-dispersibility are shown in Table 1.

[0130] Table 1 Comparison of performance of water-resistant cement paste systems of different densities

[0131]

[0132] Table 1. Comparison of performance results of cement slurry systems with different densities that do not disperse in water (continued)

[0133]

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

[0135]

[0136] As shown in Table 1, a wide-temperature-range water-resistant cement slurry system exhibits good water resistance before and after high-temperature and high-pressure curing, when in contact with room-temperature water and 100°C water. Furthermore, the fluidity of all embodiments is greater than 22 cm, the API water loss is less than 50 mL, the free water content is 0, and the stability is less than 0.02 g / cm³. 3 .

[0137] Under the same experimental conditions, the data on fluidity, API water loss, free water, and stability of Examples 1, 2, and 3 were not significantly different from those of Comparative Examples 1, 2, 3, 4, 5, and 6, indicating that the water-dispersible composition had no adverse effect on the conventional properties of cement paste.

[0138] The experimental temperatures for Examples 1, 1, 4, 5, and 6 were all 90°C, with thickening times of 235 min, 224 min, 239 min, 243 min, and 247 min, respectively. The experimental temperatures for Comparative Example 2 and Example 2 were all 110°C, with thickening times of 291 min and 312 min, respectively. The experimental temperatures for Comparative Example 3 and Example 3 were all 150°C, with thickening times of 201 min and 213 min, respectively. This demonstrates that the water-indispersible 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 at 110℃ and 20.7MPa for 24 hours were 11.9MPa and 11.5MPa, respectively. The compressive strengths of Comparative Example 2 and Example 2 after curing at 130℃ and 20.7MPa for 24 hours were 22.1MPa and 20.25MPa, respectively. The compressive strengths of Comparative Example 3 and Example 3 after curing at 180℃ and 20.7MPa for 24 hours were 18.4MPa and 16.5MPa, respectively. It can be seen that the water-indispersible composition has no adverse effect on the strength of cement stone.

[0140] The density of the cement slurry in Example 1 was 1.20 g / cm³. 3 The 24-hour compressive strength is greater than 10 MPa; the density of the cement paste in Example 2 is 1.90 g / cm³. 3 The 24-hour compressive strength is greater than 20 MPa; the density of the cement paste in Example 3 is 2.40 g / cm³. 3 The 24-hour compressive strength is greater than 14 MPa, which shows that the strength of the water-insoluble cement slurry system meets the requirements for cementing construction.

[0141] Comparative Example 1 was a non-dispersible composition without water, while Example 1 was a 1 part water-dispersible composition. Compared with Comparative Example 1, the cement slurry in Example 1 showed excellent non-dispersibility when poured into room temperature water and 100°C water before and after high temperature and high pressure curing, respectively. Therefore, Example 1 has excellent non-dispersibility when exposed to water.

[0142] Comparative Example 2 was a non-dispersible composition without water, while Example 2 was a water-dispersible composition of 1 part. Compared with Comparative Example 2, the cement slurry in Example 2 showed good non-dispersibility when poured into room temperature water and 100°C water before and after high temperature and high pressure curing, respectively. Therefore, Example 2 has good non-dispersibility when exposed to water.

[0143] Comparative Example 3 was a non-dispersible composition without water, while Example 3 was a water-dispersible composition consisting of 2 parts. Compared to Comparative Example 3, Example 3 showed good water non-dispersibility when the cement slurry was poured into room temperature water and 100°C water before and after high temperature and high pressure curing, respectively. This demonstrates that Example 3 exhibits good water non-dispersibility.

[0144] Comparative Example 4: Microbial polysaccharide polymers in the non-dispersible composition without added water. Example 1 consisted of 1 part of a water-dispersible composition. Compared to Example 1, Comparative Example 4 showed good and moderate non-dispersibility of cement slurry when poured into room temperature water and 100°C water before high-temperature and high-pressure curing, respectively. After high-temperature and high-pressure curing, the non-dispersibility of cement slurry when poured into room temperature water and 100°C water was moderate. Comparative Example 5: Organic polymers in the non-dispersible composition without added water. Example 1 consisted of 1 part of a water-dispersible composition. Compared to Example 1, Comparative Example 5 showed very good and good non-dispersibility of cement slurry when poured into room temperature water and 100°C water before high-temperature and high-pressure curing, respectively. After high-temperature and high-pressure curing, the non-dispersibility of cement slurry when poured into room temperature water and 100°C water was moderate. Comparative Example 6: Inorganic particles in the non-dispersible composition without added water. Example 1 consisted of 1 part of a water-dispersible composition. Compared to Example 1, Comparative Example 6 showed good and good water non-dispersibility when poured into room temperature water and 100°C water before high-temperature and high-pressure curing. After high-temperature and high-pressure curing, the cement slurry showed good water non-dispersibility when poured into room temperature water and 100°C water, but its 24-hour strength was poor. This indicates that good water non-dispersibility in cement slurry requires the simultaneous action of microbial polysaccharide polymers, organic polymers, and inorganic particles in the water-non-dispersible composition.

[0145] As shown in Table 2, the thickening time of Example 2 is adjustable, the thickening curve is normal, and there are no abnormal phenomena such as "bulging". For Example 2, when the retarder is 0.7 parts, the thickening times at circulating temperatures of 90℃, 110℃, and 130℃ and pressure of 60MPa are 432 min, 312 min, and 145 min, respectively; when the retarder is 1.0 part, the thickening times at circulating temperatures of 90℃, 110℃, and 130℃ and pressure of 60MPa are 725 min, 474 min, and 174 min, respectively; when the retarder is 1.5 parts, the thickening time at circulating temperature of 150℃ and pressure of 60MPa is 115 min; and when the retarder is 2.0 parts, the thickening time at circulating temperature of 150℃ and pressure of 60MPa is 355 min. Therefore, the thickening time of the water-non-dispersible cement paste system shows a good linear relationship with the amount of retarder added and the temperature.

[0146] Therefore, the wide-temperature-range, water-resistant cement slurry system provided by this invention ensures that the cement slurry particles are not dispersed by water upon contact. It is suitable for cementing high-water-content formations and sealing lost circulation zones in environments with static temperatures ranging from room temperature to 180°C. It has no adverse effects on the conventional properties of the cement slurry, such as rheology, water loss, stability, and cement stone strength. (1.2 g / cm³) 3 The low-density, water-non-dispersible cement paste system has a 24-hour compressive strength greater than 10 MPa and a strength of 1.9 g / cm³. 3A conventional density cement paste system that does not disperse in water has a compressive strength greater than 20 MPa after 24 hours, and a strength of 2.4 g / cm³. 3 The high-density, water-non-dispersible cement slurry system exhibits a 24-hour compressive strength greater than 14 MPa, meeting the strength requirements for cementing operations. Simultaneously, it ensures the rheological properties of the cement slurry, exhibiting low thixotropy and preventing "bulging" or "stepping" in the thickening curve. The thickening time of the cement slurry system shows a good linear relationship with temperature, density, and the amount of retarder added. It can effectively fill the annulus, ensuring the integrity of the cement sheath structure, improving the sealing effect of high water-cut layers and the plugging effect of lost circulation zones under different temperature conditions, providing favorable wellbore conditions for oil and gas production, and ensuring the efficient exploitation of oil and gas resources.

[0147] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A cement grout, characterized in that, The cement slurry comprises: 100 parts of Grade G oil well cement, 0.5-2 parts of water-insoluble composition, 1-3 parts of active material, 0-35 parts of high-temperature strength stabilizer, 0-100 parts of density regulator, 2-5 parts of water 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; The water-insoluble composition comprises: 0.5-5 parts by weight of microbial polysaccharide polymer, 5-50 parts by weight of organic polymer, and 4.5-45 parts by weight of inorganic particles; The microbial polysaccharide polymers are selected from one or more of xanthan gum, gellan gum, brevicorpus polysaccharide, trehalose, hyaluronic acid, thermogel, chitosan, gelatin, and hygroscopic gum; The organic polymer compound is selected from one or more of the polymers formed by the 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 of the copolymers formed by styrene sulfonate, lignosulfonate, acrylic acid, and methacrylic acid. The number-average molecular weight of the organic polymer is 100,000 to 1,000,000 g / mol; The inorganic particles are acid-washed quartz sand; The suspension stabilizer is selected from plant gum polymers or cellulose polymers.

2. The cement grout according to claim 1, wherein, The structural framework of the microbial polysaccharide macromolecules consists of one or more of glucose, glucuronic acid, rhamnose, maltotriose, and acetylglucosamine linked by chemical bonds, and the side chains consist of one or more of mannose, rhamnose, and glucuronic acid linked by chemical bonds.

3. The cement grout according to claim 1 or 2, wherein, The average particle size of the inorganic particles is 5-75 μm.

4. The cement grout according to claim 1 or 2, wherein, The active material is active microsilicon with an average particle size of 0.1-0.5 μm.

5. The cement grout according to claim 1 or 2, wherein, The high-temperature strength stabilizer is acid-washed quartz sand with a SiO2 content greater than 99% and an average particle size of 5-75 μm.

6. The cement grout according to claim 1 or 2, wherein, The density regulator includes a weighting material and a weight-reducing material; wherein the weighting material is selected from one or more of iron ore powder, barite, and micro-manganese ore powder; and the weight-reducing material is selected from one or more of glass microspheres, cenospheres, and fly ash.

7. The cement grout according to claim 1 or 2, wherein, The retarder is selected from one or more of AMPS-type substances and organophosphates; And / or, the water loss reducing agent is selected from one or more of AMPS, low molecular weight amides and polyhydroxycarboxylic acid polymers and PVA-like substances; And / or, the dispersant is selected from one or more of formaldehyde and acetone condensates, polystyrene sulfonates, and polycarboxylic acids; And / or, the defoamer is selected from one or more of tributyl phosphate, polyoxypropylene glycerol, and polydimethylsiloxane.

8. The cement grout according to claim 1, wherein, The plant gum polymer is selected from one or more of guar gum, guar gum, carrageenan, and locust gum; The cellulose polymeric compound is selected from one or more of lignin fibers and cellulose ethers.

9. The cement grout according to claim 1 or 2, wherein, The density of the cement slurry is 1.2-2.4 g / cm³; And / or, the cement slurry is used in a temperature range of 10-180℃; 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.

10. The cement grout according to claim 1 or 2, wherein, Cement slurry with a density of 1.2 g / cm³ does not disperse when exposed to water and has a compressive strength greater than 10 MPa after 24 hours; And / or, cement paste with a density of 1.9 g / cm³ does not disperse when exposed to water and has a compressive strength greater than 20 MPa after 24 hours; And / or, cement paste with a density of 2.4 g / cm³ does not disperse when exposed to water and has a compressive strength greater than 14 MPa after 24 hours.

11. A method for preparing cement slurry according to any one of claims 1-10, characterized in that, The preparation method includes: G-grade oil well cement, water-indispersible composition, active materials, high-temperature strength stabilizer, density regulator, fluid loss reducer, suspension stabilizer and dispersant are mixed to obtain dry mix; The retarder, defoamer and water are mixed to obtain a wet mixture; The dry and wet mixtures are mixed at a low stirring rate and then stirred at a high speed to obtain a cement slurry.

12. The application of the cement slurry according to any one of claims 1-10 in the sealing of aquifers and plugging of lost circulation zones in oil and gas wells.

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