Ultra-deep well high-temperature-resistant anti-channeling cement paste as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of oilfield chemistry, and particularly relates to ultra-deep well high-temperature-resistant anti-channeling cement paste as well as a preparation method and application thereof. The ultra-deep well high-temperature-resistant anti-channeling cement paste comprises G-grade oil well cement, a high-temperature-resistant declining agent, a high-temperature fluid loss agent, a high-temperature retarder, a retarding auxiliary agent, a high-temperature stabilizer, an anti-gas-channeling agent, a defoaming agent and fresh water. The high-temperature-resistant anti-channeling cement paste for the ultra-deep well is suitable for well cementation at the high temperature of 90-210 DEG C and large temperature difference, the density is adjustable in the range of 1.85-1.95 g / cm < 3 >, the suspension stability is good under the high-temperature condition, the thickening time is adjustable, and the thickening time is easy to prolong.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemical technology, specifically relating to an ultra-deep well high-temperature resistant and anti-channeling cement slurry, its preparation method, and its application. Background Technology

[0002] As oil and gas exploration and development moves towards deeper and more complex formations, the number of deep and ultra-deep wells is increasing. High-temperature and ultra-high-temperature environments pose numerous challenges to cementing slurries, such as poor stability and strength degradation.

[0003] For cementing deep and ultra-deep wells, the well depth typically exceeds 6 kilometers, and the bottom-hole temperature reaches over 150°C. Therefore, the safe working time for cementing operations often exceeds 6 hours. To ensure the cement slurry thickens within the safe working time for tool operations under high and ultra-high temperature conditions, a large amount of high-temperature retarder is often required. Furthermore, since a single retarder is insufficient to achieve the desired retardation effect at ultra-high temperatures, compound retarders are often necessary. Adding a large amount of retarder, thus prolonging the cement slurry thickening time, significantly slows down the strength development of the cement stone at high temperatures and the top strength development under large temperature differences. This not only prolongs the setting time, hindering subsequent construction, but also increases the risk of gas channeling during the setting period.

[0004] There is currently a lot of research on high-temperature cement slurry. In existing technologies, cement slurry suitable for high temperatures mainly consists of the following components: Grade G oil well cement. Anti-fading agents: Primarily silica fume, i.e., high-purity quartz sand, added at 35%-70%, effectively inhibiting strength degradation of cement stone above 110℃. There are also reports of adding fibers, microsilica, magnesium or aluminum-based mineral powders, carbon powder, ceramic powder, glass powder, carbon nanotubes, etc., to effectively enhance the cement stone's resistance to high-temperature fading. Currently reported anti-fading agents typically aim to reduce the strength degradation of cement stone at high temperatures, examining long-term strength development rather than short-term strength development. High-temperature oil well cement admixtures (filtration loss reducers, retarders, stabilizers): Oil well cement admixtures suitable for high temperatures usually use high-molecular polymers, such as AMPS-based polymers, which have good temperature resistance. Current research on high-temperature admixtures, especially high-temperature retarders, usually only examines the retarding effect at high temperatures, with limited research on the short-term strength development and gas channeling prevention capabilities of cement stone at high temperatures. Other functional materials, such as anti-gas channeling agents, can effectively improve the stability and anti-gas channeling ability of cement slurry by adding materials like latex, but they are detrimental to the strength development of cement stone. To ensure a sufficiently long pumping time under high-temperature conditions, ultra-deep well high-temperature resistant cement slurry requires sufficient thickening time. This leads to slow strength development and long static gelation transition time in static states and under large temperature differences, easily resulting in prolonged setting time and increased risk of gas channeling. A review of existing technologies reveals that current high-temperature resistant cement slurries typically suffer from poor high-temperature stability, short thickening time, and high-temperature strength degradation, failing to meet the construction requirements of ultra-deep wells. The problems of slow short-term strength development and long static gelation transition time caused by excessively long thickening times are rarely discussed.

[0005] Therefore, for cementing operations in ultra-deep wells both offshore and onshore, cement slurry must possess multiple properties at high temperatures: it must maintain a relatively long thickening time to ensure proper displacement, and it must rapidly develop early strength after displacement to shorten the setting time and improve subsequent construction efficiency; at the same time, it should achieve rapid short-term strength growth, effectively resist high-temperature strength decay in the long term, and have a relatively short static gelling transition time to meet the requirements for preventing cross-linking. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an ultra-deep well high-temperature resistant and anti-channeling cement slurry, its preparation method, and its application.

[0007] Specifically, the ultra-deep well anti-high temperature and anti-channeling cement slurry provided by the present invention includes: Grade G oil well cement, anti-high temperature degradation agent, high temperature fluid loss reducing agent, high temperature retarder, retarding adjuvant, high temperature stabilizer, anti-gas channeling agent, defoamer, and fresh water.

[0008] The aforementioned ultra-deep well high-temperature resistant and anti-channeling cement slurry, by weight, comprises: 100 parts by weight of G-grade oil well cement; 35-70 parts by weight of anti-high-temperature degradation agent; 5-12 parts by weight of high-temperature fluid loss reducing agent; 1-7 parts by weight of high-temperature retarder; 0.1-3 parts by weight of retarder adjuvant; 1-5 parts by weight of high-temperature stabilizer; 0-15 parts by weight of anti-gas channeling agent; 0.5-3 parts by weight of defoamer; and 30-60 parts by weight of fresh water.

[0009] The aforementioned ultra-deep well high-temperature resistant and anti-channeling cement slurry, by weight, comprises the following high-temperature fading agent: 20-40 parts by weight of quartz powder with a particle size D50 between 20-40 μm; 15-35 parts by weight of quartz powder with a particle size D50 between 0.5-3 μm; and 1-5 parts by weight of ultrafine powder material with a particle size D50 less than 0.1 μm. The ultrafine powder material includes one or more of corundum powder, calcium carbonate powder, and silicon carbide powder.

[0010] The aforementioned ultra-deep well high-temperature resistant and anti-channeling cement slurry is prepared using the following high-temperature water loss reducing agent in parts by weight: 100 parts by weight of deionized water; 10-20 parts by weight of 2-acrylamido-2-methylpropanesulfonic acid; 2-8 parts by weight of N,N-dimethylacrylamide; 0.1-2 parts by weight of maleic anhydride; 2-10 parts by weight of long-side-chain strong adsorption monomer; 0-1 parts by weight of molecular weight regulator; 0.2-2 parts by weight of sodium persulfate; and 2-5 parts by weight of sodium hydroxide.

[0011] The aforementioned ultra-deep well high-temperature resistant and anti-channeling cement slurry contains long-side-chain strong adsorption monomers, which are one or more of tannic acid, potassium humate, sodium humate, and sodium lignosulfonate; and molecular weight regulators, which are one or more of tert-dodecyl mercaptan, isooctyl 3-mercaptopropionate, sodium vinyl sulfonate, sodium methyl methacrylate, and sodium formate.

[0012] The high-temperature retarder in the aforementioned ultra-deep well high-temperature resistant and anti-channeling cement slurry is a polymeric retarder of 2-acrylamido-2-methylpropanesulfonic acid and itaconic acid.

[0013] The aforementioned ultra-deep well high-temperature resistant and anti-channeling cement slurry uses one or more of the retarding additives, namely citric acid, tartaric acid, boric acid, and sodium tetraborate decahydrate.

[0014] The high-temperature stabilizer in the aforementioned ultra-deep well high-temperature resistant and anti-channeling cement slurry is a 2-acrylamido-2-methylpropanesulfonic acid polymer-based high-temperature stabilizer.

[0015] The gas channeling prevention agent in the aforementioned ultra-deep well high-temperature resistant and anti-channeling cement slurry is styrene-butadiene latex.

[0016] The defoamer in the aforementioned ultra-deep well high-temperature resistant and anti-channeling cement slurry is tributyl phosphate.

[0017] The preparation method of ultra-deep well anti-high temperature and anti-channeling cement slurry provided by the present invention includes: mixing G-grade oil well cement, anti-high temperature degradation agent, high temperature fluid loss reducing agent, high temperature retarder, retarding auxiliary agent, high temperature stabilizer, anti-gas channeling agent, defoamer, and fresh water in a certain proportion.

[0018] This invention also provides the application of the above-mentioned ultra-deep well high-temperature resistant and anti-channeling cement slurry in cementing operations.

[0019] Compared with the prior art, the ultra-deep well high-temperature resistant and anti-channeling cement slurry of the present invention has the following beneficial effects: (1) The ultra-deep well anti-high temperature and anti-channeling cement slurry of the present invention uses a high temperature fading agent made of solid particles of different sizes for particle size distribution, which is beneficial to improve the fluidity and high temperature suspension stability of the cement slurry. It has little effect on the thickening time of the cement slurry at high temperature and the thickening time is easy to adjust. It can accelerate the strength development speed of the top and bottom of the cement slurry column and shorten the static gelation transition time under a longer thickening time, while satisfying the requirement of long-term strength not fading at high temperature.

[0020] (2) The ultra-deep well anti-high temperature and anti-channeling cement slurry of the present invention is suitable for cementing wells at high temperatures of 90-210℃ and large temperature differences, with a density of 1.85-1.95 g / cm³. 3 It is adjustable, exhibits good suspension stability under high temperature conditions, and has an adjustable and easily extended thickening time.

[0021] (3) The ultra-deep well anti-high temperature and anti-channeling cement slurry of the present invention can ensure a faster strength development speed and a shorter static gelation transition time under conditions of high temperature or large temperature difference, which is beneficial to shorten the waiting time and prevent gas channeling. At the same time, the cement slurry has low viscosity, good fluidity and suspension stability, high mixing efficiency, and excellent comprehensive performance, which is beneficial to reduce friction during cementing and prevent formation leakage. Detailed Implementation

[0022] To fully understand the purpose, features, and effects of this invention, the following detailed embodiments are provided. Except as described below, the process methods of this invention employ conventional methods or apparatus in the art. Unless otherwise specified, the terms and expressions used below have the meanings commonly understood by those skilled in the art.

[0023] Current high-temperature cement slurry systems suffer from poor high-temperature suspension stability and slow short-term strength development under long high-temperature thickening times. Under high-temperature conditions, the cement slurry exhibits little or no strength after 24 hours, and the static gelation strength transition time is long, increasing the risk of gas channeling during cementing. There is a lack of relevant technical capabilities in this area. In recent years, the number of deep and ultra-deep wells has increased, but existing high-temperature resistant cement slurries and related materials and admixtures have not been specifically developed for short-term strength development and gas channeling prevention. Their performance cannot fully meet the requirements of high-temperature cementing. In particular, anti-strength degradation materials only focus on the long-term strength degradation of the cement stone, which can lead to difficulty in extending the thickening time at high temperatures, requiring the addition of large amounts of retarders, resulting in slow short-term strength development of the cement stone. Furthermore, the sedimentation of solid particles such as silica fume at high temperatures can cause cement slurry instability. Therefore, this invention develops an anti-strength degradation agent and a matching oil well cement admixture suitable for high-temperature conditions in ultra-deep wells. This creates a high-temperature resistant cement slurry system that effectively extends the thickening time, ensures rapid short-term strength development and a short static gelation transition time, and effectively prevents high-temperature sedimentation instability and high-temperature strength degradation.

[0024] Specifically, the present invention provides an ultra-deep well anti-high temperature and anti-channeling cement slurry, comprising: G-grade oil well cement, anti-high temperature degradation agent, high temperature fluid loss reducing agent, high temperature retarder, retarding adjuvant, high temperature stabilizer, anti-gas channeling agent, defoamer, and fresh water.

[0025] In the ultra-deep well anti-high temperature and anti-channeling cement slurry of the present invention, G-grade oil well cement is the main cementitious component in the ultra-deep well anti-high temperature and anti-channeling cement slurry and is the main component that forms high-strength hydration products; the anti-high temperature degradation agent can ensure that the cement hardens effectively resists the strength degradation of cement stone caused by high temperature, while changing the early hydration process of cement at high temperature and adjusting the proportion of hydration products, improving the slow early strength development caused by excessive retarder and the formation of special hydration products of cement at certain sensitive temperatures, and improving the fluidity, high temperature suspension stability and appropriate extension of cement slurry setting time through the principle of particle size distribution and the adsorption effect of enhanced polymer additives; High-temperature water loss reducing agents provide the main viscosity of cement slurry and control its water loss performance, providing suspension stability; high-temperature retarders are used to extend the setting time of cement slurry; retarding adjuvants work synergistically with high-temperature retarders to extend the setting time of cement slurry, while improving the static hydration rate of cement and increasing early strength; high-temperature stabilizers increase the liquid phase viscosity of cement slurry, providing suspension stability; anti-gas channeling agents are mainly used to provide anti-gas channeling performance of cement slurry, and can also work synergistically with high-temperature water loss reducing agents to improve the water loss performance and suspension stability of cement slurry, as well as improve the toughness and corrosion resistance of cement paste; defoamers are used to eliminate air bubbles generated during the mixing process of cement slurry.

[0026] Grade G oil well cement Grade G oil well cement is the core cementing component in ultra-deep well high-temperature resistant and anti-channeling cement slurry.

[0027] The G-grade oil well cement used in this invention is the G-grade oil well cement conventionally used in the field.

[0028] Anti-high temperature degradation agent The main function of anti-high temperature degradation agent is to prevent the strength of cement stone from declining at high temperatures.

[0029] The high-temperature degradation resistant agent is composed of silica of different particle sizes and other powder materials.

[0030] In some preferred embodiments, the high-temperature degradation resistant agent comprises, by weight, 20-40 parts by weight of quartz powder with a particle size D50 between 20-40 μm; 15-35 parts by weight of quartz powder with a particle size D50 between 0.5-3 μm; and 1-5 parts by weight of ultrafine powder material with a particle size D50 less than 0.1 μm.

[0031] The ultrafine powder material includes one or more of corundum powder, calcium carbonate powder, and silicon carbide powder.

[0032] The high-temperature degradation resistant agent of the present invention can improve the suspension stability of cement paste through the particle size distribution effect. At the same time, its specially proportioned components can improve the adsorption effect between the retarder and cement particles, enhance the retarding effect, reduce the amount of retarder, improve the cement hydration efficiency, increase the short-term strength development speed of cement stone at high temperature, and shorten the static cementitious strength transition time.

[0033] In the ultra-deep well anti-high temperature and anti-channeling cement slurry of the present invention, based on 100 parts by weight of G-grade oil well cement, the anti-high temperature degradation agent is 35-70 parts by weight, for example: 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts or 70 parts, or any value between any two values.

[0034] In practice, when the proportion of the anti-high temperature degradation agent is less than 35 parts, the strength of cement stone will decline significantly under high temperature conditions; when the proportion of the anti-high temperature degradation agent is greater than 70 parts, it will affect the suspension stability, water loss performance and strength development of cement paste, and will not have a positive effect on anti-high temperature strength degradation.

[0035] More preferably, the dosage of the anti-high temperature fading agent can be adjusted according to the temperature. When the temperature is below 150°C, the dosage of the anti-high temperature fading agent can be adjusted from 35 to 45 parts by weight according to the requirements and the fluidity of the cement paste. When the temperature is between 150°C and 180°C, the dosage of the anti-high temperature fading agent can be adjusted from 45 to 55 parts by weight. When the temperature is above 180°C, the dosage of the anti-high temperature fading agent can be adjusted from 55 to 65 parts by weight.

[0036] High-temperature dehydration agent The main function of high-temperature water loss reducing agents is to control water loss in cement slurry, increase the liquid phase viscosity of cement slurry, and improve high-temperature suspension stability.

[0037] In some preferred embodiments, the high-temperature water loss reducing agent is prepared from the following raw materials in parts by weight: 100 parts by weight of deionized water; 10-20 parts by weight of 2-acrylamido-2-methylpropanesulfonic acid; 2-8 parts by weight of N,N-dimethylacrylamide; 0.1-2 parts by weight of maleic anhydride; 2-10 parts by weight of long-side-chain strong adsorption monomer; 0-1 parts by weight of molecular weight regulator; 0.2-2 parts by weight of sodium persulfate; and 2-5 parts by weight of sodium hydroxide.

[0038] The high-temperature water loss reducing agent of the present invention can be prepared by existing polymerization reaction methods. For example, the preparation method is as follows: (1) Deionized water, 2-acrylamido-2-methylpropanesulfonic acid, sodium hydroxide, N,N-dimethylacrylamide, maleic anhydride, long side chain strong adsorption monomer and molecular weight regulator are added to the reaction vessel in sequence according to the ratio and stirred and mixed evenly. (2) Place the reaction vessel in a water bath, heat it, and introduce nitrogen gas to replace the oxygen in it; (3) Prepare a sodium persulfate solution and add it dropwise to initiate a polymerization reaction. After the reaction is complete, a high-temperature dehydration agent can be obtained.

[0039] This invention introduces a long-side-chain, strongly adsorbent monomer into a high-temperature water loss control agent. Compared with similar high-temperature water loss control agents, it can improve polymer adsorption, cement slurry mixing efficiency, and flowability, while enhancing stability and high-temperature water loss control capabilities. In some preferred embodiments, the long-side-chain, strongly adsorbent monomer is one or more of tannic acid, potassium humate, sodium humate, and sodium lignosulfonate.

[0040] In some preferred embodiments, the molecular weight regulator is one or more of tert-dodecyl mercaptan, isooctyl 3-mercaptopropionate, sodium vinyl sulfonate, sodium methacrylate, and sodium formate, thereby controlling the molecular weight of the polymer.

[0041] The high-temperature water loss control agent of the present invention has the advantages of low viscosity and strong ability to control water loss at high temperatures. Compared with similar polymer water loss control agents, it has better high-temperature water loss control performance and better fluidity of the cement slurry it is used to prepare.

[0042] In the ultra-deep well anti-high temperature and anti-channeling cement slurry of the present invention, based on 100 parts by weight of G-grade oil well cement, the proportion of the high temperature fluid loss reducing agent is 5-12 parts by weight, for example: 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts or 12 parts, or any value between any two values.

[0043] In practice, when the proportion of high-temperature water loss reducing agent is less than 5 parts, the cement slurry cannot effectively control water loss under high-temperature conditions; when the proportion of high-temperature water loss reducing agent is greater than 12 parts, the liquid phase viscosity is too high, which makes it impossible to mix the cement slurry and reduces its fluidity.

[0044] More preferably, in the ultra-deep well anti-high temperature and anti-channeling cement slurry of the present invention, the high temperature dehydration agent is 5-8 parts by weight, based on 100 parts by weight of G-grade oil well cement.

[0045] High temperature retarder High-temperature retarder is used to extend the thickening time of cement paste. When combined with retarding adjuvants, it can achieve better retarding effect. The two retarding materials are based on different retarding mechanisms, which are conducive to improving the strength development speed of cement stone while extending the thickening time.

[0046] In some preferred embodiments, the high-temperature retarder is a polymeric retarder of 2-acrylamido-2-methylpropanesulfonic acid and itaconic acid.

[0047] More preferably, the high-temperature retarder is a high-temperature retarder conventionally used in the art.

[0048] More preferably, the high-temperature retarder is one or more of retarder C-R40L, C-R41L, and C-R42L.

[0049] For example, the C-R40L can be purchased from Beijing Aokaili Technology Development Co., Ltd.; the C-R41L and C-R42L can be purchased from Blue Ocean Boda Technology Co., Ltd.

[0050] In the ultra-deep well anti-high temperature and anti-channeling cement slurry of the present invention, based on 100 parts by weight of G-grade oil well cement, the proportion of the high temperature retarder is 1-7 parts by weight, for example: 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts or 7 parts, or any value between any two values.

[0051] In practice, when the proportion of high-temperature retarder is less than 1 part, the cement slurry thickening time is shorter; when the proportion of high-temperature retarder is greater than 7 parts, over-retardation is likely to occur, causing the cement slurry to fail to set.

[0052] More preferably, in the ultra-deep well anti-high temperature and anti-channeling cement slurry of the present invention, the proportion of the high temperature retarder is 1-6.5 parts by weight, based on 100 parts by weight of G-grade oil well cement.

[0053] Retarding adjuvants Retarding additives can help extend the thickening time, reduce the amount of polymer retarder used, and at the same time help improve the short-term strength development of cement stone.

[0054] In some preferred embodiments, the retarding agent is one or more of citric acid, tartaric acid, boric acid, and sodium tetraborate decahydrate.

[0055] In the ultra-deep well high-temperature resistant and anti-channeling cement slurry of the present invention, based on 100 parts by weight of G-grade oil well cement, the proportion of the retarding adjuvant is 0.1-3 parts by weight, for example: 0.1 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts or 3 parts, or any value between any two values.

[0056] In practice, when the proportion of retarding admixture is less than 0.1 parts, there is no retarding effect; when the proportion of retarding admixture is greater than 3 parts, it leads to poor fluidity of cement paste and slow strength development.

[0057] More preferably, in the ultra-deep well anti-high temperature and anti-channeling cement slurry of the present invention, the proportion of the retarding adjuvant is 0.1-2 parts by weight, based on 100 parts by weight of G-grade oil well cement.

[0058] More preferably, the ratio of high-temperature retarder to retarding agent should be between 8:1 and 3:1, and the recommended addition temperature for the retarding agent is 150℃-210℃.

[0059] High temperature stabilizer High-temperature stabilizers can improve the suspension stability of cement slurry at high temperatures.

[0060] The high-temperature stabilizer is a conventionally used high-temperature stabilizer in the art.

[0061] In some preferred embodiments, the high-temperature stabilizer is a 2-acrylamido-2-methylpropanesulfonic acid polymer-based high-temperature stabilizer.

[0062] More preferably, the high-temperature stabilizer is one or more of stabilizers C-SSA56, C-SSA60, and C-S30S.

[0063] For example, C-SSA56, C-SSA60, and C-S30S can all be purchased from Blue Ocean Boda Technology Co., Ltd.

[0064] In the ultra-deep well anti-high temperature and anti-channeling cement slurry of the present invention, the proportion of the high temperature stabilizer is 1-5 parts by weight, for example: 1 part, 2 parts, 3 parts, 4 parts or 5 parts, or any value between any two values, based on 100 parts by weight of G-grade oil well cement.

[0065] In practice, when the proportion of high-temperature stabilizer is less than 1 part, it cannot effectively improve the suspension stability of cement slurry; when the proportion of high-temperature stabilizer is greater than 3 parts, the viscosity of the liquid phase increases, resulting in difficulty in mixing cement slurry and poor fluidity.

[0066] More preferably, in the ultra-deep well anti-high temperature and anti-channeling cement slurry of the present invention, the proportion of the high temperature stabilizer is 1-3 parts by weight, based on 100 parts by weight of G-grade oil well cement.

[0067] Anti-gas channeling agent Gas channeling prevention agents can improve the gas channeling prevention of cement slurry and increase its elasticity and toughness. They can be added or not added depending on the requirements for cementing gas channeling prevention and toughening.

[0068] In some preferred embodiments, the anti-gas channeling agent is styrene-butadiene latex.

[0069] In the ultra-deep well anti-high temperature and anti-channeling cement slurry of the present invention, based on 100 parts by weight of G-grade oil well cement, the proportion of the anti-channeling agent is 0-15 parts by weight, for example: 0 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts or 15 parts, or any value between any two values.

[0070] In practice, when the proportion of anti-gas channeling agent is greater than 15 parts, the cement slurry has poor fluidity, is prone to demulsification under high temperature conditions, resulting in loss of fluidity and reduced compressive strength of cement stone.

[0071] More preferably, in the ultra-deep well high-temperature resistant and anti-channeling cement slurry of the present invention, the proportion of the anti-channeling agent is 0-12 parts by weight, based on 100 parts by weight of G-grade oil well cement.

[0072] Defoamer Defoamers are mainly used to eliminate and prevent foaming during the mixing of cement slurry, thereby improving the mixing efficiency of cement slurry.

[0073] In some preferred embodiments, the defoamer is tributyl phosphate.

[0074] In the ultra-deep well anti-high temperature and anti-channeling cement slurry of the present invention, the proportion of the defoamer is 0.5-3 parts by weight, for example: 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts or 3 parts, or any value between any two values, based on 100 parts by weight of G-grade oil well cement.

[0075] In practice, when the proportion of defoamer is less than 0.5 parts, it cannot effectively eliminate the air bubbles generated during the mixing of cement slurry; when the proportion of defoamer is greater than 3 parts, oil-water separation occurs, resulting in poor stability of cement slurry.

[0076] More preferably, in the ultra-deep well anti-high temperature and anti-channeling cement slurry of the present invention, the proportion of the defoamer is 0.5-1.5 parts by weight, based on 100 parts by weight of G-grade oil well cement.

[0077] On the other hand, the present invention also provides a method for preparing ultra-deep well anti-high temperature and anti-channeling cement slurry, which only requires mixing G-grade oil well cement, anti-high temperature degradation agent, high temperature fluid loss reducing agent, high temperature retarder, retarding auxiliary agent, high temperature stabilizer, anti-gas channeling agent, defoamer, and fresh water in a certain proportion.

[0078] The types and proportions of the components involved in the preparation method are consistent with those described in the ultra-deep well anti-high temperature and anti-channeling cement slurry provided in the first aspect of this invention, and will not be repeated here.

[0079] The ultra-deep well high-temperature resistant and anti-channeling cement slurry of the present invention can ensure a fast strength development rate and a short static gelation transition time under conditions of high temperature or large temperature difference, even under long thickening time. This is beneficial to shorten the waiting time for setting and prevent gas channeling. At the same time, the cement slurry has low viscosity, good fluidity and suspension stability, high mixing efficiency, and excellent comprehensive performance. This is beneficial to reduce friction during cementing and prevent formation leakage.

[0080] Example The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments, unless otherwise specified, were performed according to conventional methods and conditions. The raw materials used in the following embodiments were all commercially available.

[0081] The raw materials C-Si300, C-FL80L, C-SSA60, C-R42L, and C-DF60L in the formula were all purchased from Blue Ocean Boda Technology Co., Ltd.

[0082] Example 1: Preparation of an anti-high temperature degradation agent Weigh out quartz powder with a D50 between 20-40μm, quartz powder with a D50 between 0.5-3μm, and silicon carbide powder with a D50 between 0.01-0.1μm in a mass ratio of 3:2:0.3, and mix them evenly to obtain the anti-high temperature degradation agent.

[0083] Example 2: Preparation of an anti-high temperature degradation agent Weigh out quartz powder with a D50 between 20-40μm, quartz powder with a D50 between 0.5-3μm, and corundum powder with a D50 between 0.01-0.1μm according to a mass ratio of 3:1.6:0.2, and mix them evenly to obtain the anti-high temperature degradation agent.

[0084] Example 3: Preparation of a high-temperature dehydration reducing agent (1) Weigh a certain amount of reactants: 200g of deionized water, 38.52g of 2-acrylamido-2-methylpropanesulfonic acid, 9.26g of sodium hydroxide, 6.2g of N,N-dimethylacrylamide, 1.22g of maleic anhydride, 6.8g of potassium humate, and 0.02g of sodium methacrylate sulfonate. Add them to the reaction vessel in sequence, stir and mix evenly, and control the stirring speed at 120 r / min. (2) Place the reaction vessel in a water bath, heat it to 56°C, and purge it with nitrogen for 10 min to replace the oxygen in it; (3) Prepare 12.20g of 10% sodium persulfate solution, add it dropwise to initiate the polymerization reaction. After the reaction temperature stabilizes, raise the temperature to 83℃ and maintain the reaction for 4h to obtain the high temperature dehydration agent.

[0085] Example 4: Application of high-temperature retarders and retarding adjuvants The high-temperature retarder is C-R42L, a polymer retarder of 2-acrylamido-2-methylpropanesulfonic acid and itaconic acid, and the retarding adjuvant is sodium tetraborate decahydrate. The ratio of the two is 5:1.

[0086] Example 5: Preparation of a high-temperature dehydration reducing agent (1) Weigh a certain amount of reactants: 220g of deionized water, 26.86g of 2-acrylamido-2-methylpropanesulfonic acid, 5.48g of sodium hydroxide, 13.52g of N,N-dimethylacrylamide, 3.64g of maleic anhydride, 4.88g of sodium humate, and 0.04g of sodium formate. Add them to the reaction vessel in sequence, stir and mix evenly, and control the stirring speed at 120 r / min. (2) Place the reaction vessel in a water bath, heat it to 54°C, and purge it with nitrogen for 10 min to replace the oxygen in it; (3) Prepare 18.60g of 10% sodium persulfate solution, add it dropwise to initiate the polymerization reaction. After the reaction temperature stabilizes, raise the temperature to 80℃ and maintain the reaction for 4h to obtain the high-temperature dehydration agent.

[0087] Example 6: Preparation of ultra-deep well high-temperature resistant and anti-channeling cement slurry Weigh the solid components: 550g of Grade G oil well cement and 247.5g of high-temperature degradation resistant agent (same as in Example 1); Weigh the following liquid components: 257.9g water, 38.5g high-temperature water loss reducing agent (same as in Example 3), 16.5g high-temperature retarder C-R42L, 2.75g retarder adjuvant sodium tetraborate, 8.25g high-temperature stabilizer C-SSA60, and 2.75g defoamer tributyl phosphate.

[0088] Cement slurry was mixed and prepared according to API standards, yielding a density of 1.9 g / cm³. 3This ultra-deep well high-temperature resistant and anti-channeling cement slurry is suitable for cementing operations at temperatures below 150℃.

[0089] Example 7: Preparation of ultra-deep well high-temperature resistant and anti-channeling cement slurry Weigh the solid components: 400g of G-grade oil well cement and 220g of high-temperature degradation resistant agent (same as in Example 2); Weigh the following liquid components: 160.7g water, 32g high-temperature water loss reducing agent (same as in Example 3), 23.5g high-temperature retarder C-R40L, 4g retarder adjuvant sodium tetraborate, 10g high-temperature stabilizer C-SSA60, 40g anti-gas channeling agent styrene-butadiene latex, and 4g defoamer tributyl phosphate.

[0090] Cement slurry was mixed and prepared according to API standards, yielding a density of 1.88 g / cm³. 3 This ultra-deep well high-temperature resistant and anti-channeling cement slurry is suitable for cementing operations at temperatures between 150-210℃.

[0091] Performance testing To verify the performance of the high-temperature degradation agent, high-temperature fluid loss reducing agent, retarding agent, and ultra-deep well high-temperature anti-channeling cement slurry of the present invention, the inventors conducted performance tests on them. Among them, the static filtration loss, rheological properties, thickening time, compressive strength, and density difference were all measured in accordance with the provisions of GB / T 19139-2012 "Test Methods for Oil Well Cement".

[0092] The performance testing of the high-temperature degradation resistant agent was conducted by comparing the high-temperature degradation resistant agent prepared in Example 1 with the existing conventional anti-degradation agent C-Si300. Cement slurry was prepared according to cement slurry formulations 1 and 2, with formulation 2 serving as a control for formulation 1; the cement slurry density was 1.9 g / cm³. 3 The comparison results are shown in Table 1.

[0093] Formula 1: 100% "G" grade cement + 35% high temperature fading agent + 6% water loss reducer (C-FL80L) + 1% high temperature stabilizer (C-SSA60) + 3% retarder (C-R42L) + 0.5% defoamer (C-DF60L) + 45.7% fresh water; Formula 2: 100% "G" grade cement + 35% anti-fading agent (C-Si300) + 6% water loss reducer (C-FL80L) + 1% high temperature stabilizer (C-SSA60) + 3.5% retarder (C-R42L) + 0.5% defoamer (C-DF60L) + 45.2% fresh water.

[0094] Table 1. Performance Comparison of High-Temperature Degradation Resistant and Anti-Degradation Agent C-Si300

[0095] As shown in Table 1 above, the high-temperature degradation agent of Example 1 of the present invention, compared with the existing conventional anti-degradation agent C-Si300, can improve the adsorption effect between the retarder and cement particles, enhance the retarding effect, reduce the amount of retarder, effectively improve the short-term strength development speed of cement stone under high temperature (150℃) and large temperature difference (top temperature 90℃ / temperature difference 60℃), shorten the static gel strength transition time, improve the anti-channeling performance of cement paste, and effectively improve the suspension stability of cement paste at high temperature.

[0096] The performance testing of the high-temperature water loss reducing agent was conducted by comparing the high-temperature water loss reducing agent prepared in Example 3 with the existing water loss reducing agent C-FL80L. Cement slurry was prepared according to cement slurry formulations 3 and 4, with formulation 4 serving as a control for formulation 3; the cement slurry density was 1.9 g / cm³. 3 The comparison results are shown in Table 2.

[0097] Formula 3: 100% "G" grade cement + 35% anti-fading agent (C-Si300) + 8% high temperature water loss reducing agent (Example 3) + 3% retarder (C-R42L) + 0.5% defoamer (C-DF60L) + 44.7% fresh water; Formula 4: 100% "G" grade cement + 35% anti-fading agent (C-Si300) + 8% water loss reducer (C-FL80L) + 3% retarder (C-R42L) + 0.5% defoamer (C-DF60L) + 44.7% fresh water.

[0098] Table 2. Performance Comparison of High-Temperature Water Loss Control Agent and Water Loss Control Agent C-FL80L

[0099] As can be seen from the results in Table 2 above, the high-temperature water loss reducing agent of Example 3 of the present invention has better mixing efficiency and flowability than the existing conventional water loss reducing agent C-FL80L. Under the same dosage, the high-temperature water loss control performance is significantly improved.

[0100] The performance testing of the retarding additive was conducted using a control experiment comparing the ratio and dosage of the high-temperature retarder and retarding additive in Example 4 with the existing high-temperature retarder C-R42L. Cement slurry was prepared according to cement slurry formulations 5 and 2, with formulation 2 serving as a control for formulation 5; the cement slurry density was 1.9 g / cm³. 3 The comparison results are shown in Table 3.

[0101] Formula 5: 100% "G" grade cement + 35% anti-fading agent (C-Si300) + 6% high-temperature water loss reducer (C-FL80L) + 1% high-temperature stabilizer (C-SSA60) + 3% retarder (C-R42L) + 0.6% retarder adjuvant (sodium tetraborate decahydrate) + 0.5% defoamer (C-DF60L) + 44.7% fresh water; Formula 2: 100% "G" grade cement + 35% anti-fading agent (C-Si300) + 6% water loss reducer (C-FL80L) + 1% high temperature stabilizer (C-SSA60) + 3.5% warm retarder (C-R42L) + 0.5% defoamer (C-DF60L) + 44.7% fresh water.

[0102] Table 3. Performance Comparison of High-Temperature Retarder and Retarding Auxiliary Agent in Combined Use with Retarder C-R42L

[0103] As shown in Table 3 above, the combination of high-temperature retarder and retarding adjuvant can prolong the thickening time and effectively improve the compressive strength of cement stone when the amount of retarder is reduced, compared with the use of retarder C-R42L alone.

[0104] The performance of ultra-deep well high-temperature resistant and anti-channeling cement slurry was tested using the ultra-deep well high-temperature resistant and anti-channeling cement slurry prepared in Examples 6 and 7, respectively, at experimental temperatures of 140℃ and 210℃. The test results are shown in Table 4.

[0105] Table 4 Performance Test of Cement Slurry for High Temperature Resistance and Anti-channeling in Ultra-Deep Wells

[0106] As shown in Table 4 above, the ultra-deep well high-temperature resistant and anti-channeling cement slurry has good application performance, and all performance indicators can meet the field cementing requirements.

[0107] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0108] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0109] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. An ultra-deep well high temperature resistant anti-channeling cement slurry, characterized in that, The application relates to a high-temperature-resistant anti-channeling cement slurry for ultra-deep wells. According to the weight parts, the high-temperature-resistant anti-channeling cement slurry comprises the following components: 100 parts of G-grade oil well cement, 35-70 parts of high-temperature-resistant anti-decay agent, 5-12 parts of high-temperature fluid loss agent, 1-7 parts of high-temperature retarder, 0.1-3 parts of retarder auxiliary agent, 1-5 parts of high-temperature stabilizer, 0-15 parts of anti-channeling agent, 0.5-3 parts of defoaming agent and 30-60 parts of fresh water.

2. The ultra-deep well high temperature resistant anti-channeling cement slurry of claim 1, wherein, According to the weight parts, the high-temperature-resistant anti-channeling cement slurry comprises the following components: 100 parts of G-grade oil well cement, 35-70 parts of high-temperature-resistant anti-decay agent, 5-12 parts of high-temperature fluid loss agent, 1-7 parts of high-temperature retarder, 0.1-3 parts of retarder auxiliary agent, 1-5 parts of high-temperature stabilizer, 0-15 parts of anti-channeling agent, 0.5-3 parts of defoaming agent and 30-60 parts of fresh water.

3. The ultra-deep well high temperature resistant anti-channeling cement slurry of claim 1, wherein, The superfine powder material comprises one or more of corundum powder, calcium carbonate powder and silicon carbide powder. The high-temperature fluid loss agent is prepared from the following raw materials: 100 parts of deionized water, 10-20 parts of 2-acrylamido-2-methylpropane sulfonic acid, 2-8 parts of N,N-dimethyl acrylamide, 0.1-2 parts of maleic anhydride, 2-10 parts of long-side-chain strong adsorption monomer, 0-1 part of molecular weight regulator, 0.2-2 parts of sodium persulfate and 2-5 parts of sodium hydroxide.

4. The ultra-deep well high temperature resistant anti-channeling cement slurry of claim 1, wherein, The long-side-chain strong adsorption monomer is one or more of tannic acid, potassium humate, sodium humate and sodium lignosulfonate; and the molecular weight regulator is one or more of tertiary dodecyl mercaptan, 3-mercapto propionic acid isooctyl ester, sodium vinyl sulfonate, sodium methacryl sulfonate and sodium formate.

5. The ultra-deep well high temperature resistant anti-channeling cement slurry of claim 4, wherein, The high-temperature retarder is a 2-acrylamido-2-methylpropane sulfonic acid and itaconic acid polymer retarder.

6. The ultra-deep well high temperature resistant anti-channeling cement slurry of claim 1, wherein, The retarder auxiliary agent is one or more of citric acid, tartaric acid, boric acid and sodium tetraborate decahydrate.

7. The ultra-deep well high temperature resistant anti-channeling cement slurry of claim 1, wherein, The high-temperature stabilizer is a 2-acrylamido-2-methylpropane sulfonic acid polymer high-temperature stabilizer.

8. The ultra-deep well high temperature resistant anti-channeling cement slurry of claim 1, wherein, The anti-channeling agent is butyl benzene latex.

9. The ultra-deep well high temperature resistant anti-channeling cement slurry of claim 1, wherein, The defoaming agent is tributyl phosphate.

10. The ultra-deep well high temperature resistant anti-channeling cement slurry of claim 1, wherein, The application relates to a high-temperature-resistant anti-channeling cement slurry for ultra-deep wells.

11. A method for preparing the anti-channeling cement slurry for ultra-deep wells at high temperature according to any one of claims 1-10, characterized in that, 12. Application of the high-temperature-resistant anti-channeling cement slurry for ultra-deep wells in cementing operation. ​ ​

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