High-temperature suspending agent for well cementation anti-pollution spacer fluid and preparation method of high-temperature suspending agent

Abstract

The invention relates to the technical field of auxiliary materials for ultra-deep conventional well exploitation, and particularly discloses a high-temperature suspending agent for well cementation anti-pollution spacer fluid and a preparation method of the high-temperature suspending agent. The high-temperature-resistant anti-freezing agent is prepared from sodium p-styrenesulfonate, polyethylene glycol diacrylate, 2-acrylamide-2-methylpropanesulfonic acid, acryloyl, an aldehyde ketone condensate, modified silicon powder particles and a modified imide aromatic heterocycle modified silane coupling agent. The regulator B comprises foamed acid and a retarder; the regulator A and the regulator B are separately prepared and stored, and are used after being mixed together. The invention has the following beneficial effects: the problem is isolated to a certain extent through the micro-powder particles, and the high temperature resistance is improved; in addition, a protective layer is formed on the outer layer of the spacer fluid through decomposition of the auxiliary chain, so that the high temperature resistance is improved.

Description

Technical Field

[0001] The invention relates to the technical field of cementing auxiliary materials for ultra-deep conventional wells and deep shale gas exploration and development, in particular to a high-temperature suspending agent for cementing anti-pollution isolation fluid and a preparation method thereof. Background Art

[0002] As oil and gas exploration advances into deep formations, ultra-deep wells and deep shale gas wells have high well temperatures and pressures, and more and more situations are encountered during well completion, which poses severe technical challenges to drilling fluids, spacer fluids, cement slurries and other well fluids. This is mainly reflected in the higher requirements for the compatibility and stability of various well fluids under high temperature conditions.

[0003] The large-scale application of water-based and oil-based drilling fluids can effectively improve drilling efficiency, protect the environment, and reduce drilling costs. However, during cementing, due to the complex composition of cement in cement slurry and the large number of chemical reactions, especially when the formation temperature is high, the compatibility of drilling fluid and cement slurry is extremely poor. When the two are mixed in a ratio of 3:7 or 1:9, the slurry will flash and flocculate and lose fluidity, which seriously affects the safety of cementing construction.

[0004] In the prior art, in order to ensure the safety of cementing construction and improve the quality of cementing, the usual method is to use isolation fluid or pre-fluid to isolate the drilling fluid and cement slurry to avoid pollution. The solid phase particles in the isolation fluid and drilling fluid are generally inert materials, and various admixtures have good compatibility and good compatibility. The high-temperature resistant isolation fluid system is usually composed of high-temperature suspension stabilizing materials, water loss control materials, surfactants for improving flushing efficiency, and weighting materials for adjusting density. Among them, the suspending agent is the main material and plays a decisive role. However, at the moment when the isolation fluid contacts the cement slurry, due to various reactions and the influence of the suspending agent in the isolation fluid on the cement slurry, the two have poor compatibility and low fluidity. During the construction period, the instantaneous pressure increase leads to well leakage and the subsequent displacement efficiency is reduced, which affects the cementing quality. In order to further ensure the safety of cementing construction and improve the quality of the wellbore, our company has developed a high-temperature suspending agent for anti-fouling isolation fluid for cementing.

[0005] Based on some existing technologies and combined with his own experience, the inventor developed a high-temperature suspension agent for cementing anti-pollution isolation fluid. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a high-temperature suspending agent for cementing anti-pollution isolation fluid and a preparation method thereof, so as to solve the problem that the suspending agent in the existing isolation fluid has poor high-temperature resistance, thereby causing thickening and flocculation of the isolation fluid and cement slurry.

[0007] It should be noted that when cement slurry is injected during cementing, the cement slurry is easily mixed with the drilling fluid. The current solution is to add an isolation fluid between the drilling fluid and the cement slurry to isolate the two. For ordinary oil and gas wells, general suspending agents can be used to prepare isolation fluids for use; but in ultra-deep wells and deep shale gas wells, due to high temperature and high pressure, the suspending agent will decompose at high temperature and lose its original suspension effect, resulting in poor stability of the isolation fluid, and the original isolation effect will be lost due to solid-liquid phase separation. In addition, the decomposed suspending agent will also react with cement particles and Ca in the cement slurry. 2+ etc. and pollute the liquid system.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] In a first aspect, a high temperature suspension agent for anti-pollution isolation fluid for cementing is provided, comprising:

[0010] Regulator A is prepared from sodium styrene sulfonate, polyethylene glycol diacrylate, 2-acrylamide-2-methylpropane sulfonic acid, acryl, aldehyde ketone condensate, modified silicon powder particles, and modified imide aromatic heterocyclic modified silane coupling agent;

[0011] Conditioner B, which includes foaming acid and retarder;

[0012] The regulator A and regulator B are prepared and stored separately, and the two are mixed together before use.

[0013] In some advantageous embodiments, the preparation method of the regulator A is as follows: first, sodium styrene sulfonate, polyethylene glycol diacrylate, 2-acrylamide-2-methylpropane sulfonic acid, and acrylamide are copolymerized, and aldehyde-ketone condensation products are used for dispersion and pH adjustment during the copolymerization to form a copolymer a; the modified silicon powder particles refer to the use of silane grafting to form hydrophobic chains on a portion of the surface of the silicon powder particles; the modified silicon powder is connected to the polymer a through a modified imide aromatic heterocyclic modified silane coupling agent to obtain the regulator A.

[0014] In some advantageous embodiments, in the regulator B, the foaming acid is a mixture of 4-aminopyrrolo[2,1-f][1,2,4]triazine-5-carboxylic acid, carbon dioxide, a foaming agent and a stabilizer.

[0015] In some advantageous embodiments, by weight, 40 to 80 parts of sodium styrene sulfonate; 2 to 10 parts of polyethylene glycol diacrylate; 5 to 10 parts of 2-acrylamide-2-methylpropane sulfonic acid, 1 to 2 parts of acrylamide; 4 to 8 parts of aldehyde-ketone condensate; 8 to 15 parts of modified silicon powder particles, and 8 to 15 parts of modified imide aromatic heterocyclic modified silane coupling agent;

[0016] 1 to 2 parts of foaming acid; 1 to 2 parts of retarder.

[0017] In a second aspect, a method for preparing a high-temperature suspension agent for anti-pollution isolation fluid for cementing is provided, including the preparation of a regulator A and a regulator B.

[0018] When the regulator A is prepared:

[0019] S1. Weigh sodium styrene sulfonate and 2-acrylamide-2-methylpropane sulfonic acid and dissolve them in water, stir them thoroughly to dissolve; then heat them to 60°C to 80°C, add the initiator, stir them well and react them thoroughly to obtain a preliminary copolymer;

[0020] Then, weighed acrylamide and polyethylene glycol diacrylate are added to the preliminary copolymer, and the temperature is maintained at 60°C to 80°C, and a portion of the initiator is added, and the mixture is stirred evenly and reacted fully; after the reaction is fully reacted, an aldehyde-ketone condensate is added to adjust the pH value to 5 to 7, and a copolymer a is obtained;

[0021] S2. The modified silicon powder particles and the modified imide aromatic heterocyclic modified silane coupling agent are mixed, and then added to the copolymer a together, and then uniformly stirred. After a period of time, the mixture is allowed to stand and cooled to finally obtain the finished product of the regulator A.

[0022] In some embodiments, the initiator is an azo compound, and the amount of the azo compound used is 0.05% to 1% of the total weight of sodium styrene sulfonate, polyethylene glycol diacrylate, 2-acrylamide-2-methylpropane sulfonic acid, and acrylamide.

[0023] When preparing the regulator B: directly mix the foam acid and the retarder and stir evenly.

[0024] It should be noted that the molecular shape and structure of organic matter are crucial to its suspension performance. Linear and rigid molecules may be easier to disperse, while molecules with large molecular weight and multiple molecules or ring structures may be difficult to disperse and the suspension effect may be reduced.

[0025] For ease of understanding, the core principles and design points of this solution are explained:

[0026] 1. The suspending agent described in this scheme is applied to ultra-deep wells and deep shale gas formation environments with high temperature and high pressure, and can meet the basic functions required by drilling fluids (suspension, high temperature resistance, and high pressure resistance). The reason is that the regulator A provides a rigid structure and high temperature resistance through sodium styrene sulfonate, increases steric hindrance through polyethylene glycol diacrylate, and then maintains acidic conditions through 2-acrylamide-2-methylpropane sulfonic acid, and it also has the ability to improve suspension stability to a certain extent.

[0027] 2. The core of the suspension agent described in this scheme is the regulator A, which has the following advantages: (1) The optimization of the structure of the regulator A itself: firstly, through the polymerization of sodium styrene sulfonate and 2-acrylamide-2-methylpropanesulfonic acid, it first forms a main chain that is resistant to high temperature and has a spacer effect; then, through acrylamide and polyethylene glycol diacrylate, an auxiliary chain containing an ester bond and also having a spacer effect is grafted on the main chain; then, the modified silicon powder particles are coupled to the main chain and the auxiliary chain through a high temperature resistant coupling agent. (2) Mechanism of action: In a high pressure environment, the modified silicon particles are squeezed and embedded in the gaps between the spacer groups. The high temperature resistance and heat insulation properties of the modified silicon particles themselves can greatly prevent the suspension agent from being decomposed by high temperature. (3) Continuous protection mechanism: If the outer layer of the suspension agent is decomposed by high temperature, the ester bond will break first, causing the auxiliary chain to fall off. After the auxiliary chain is detached, it forms a small molecule, which is still firmly adsorbed to the modified silica powder particles. Due to the hydrophobicity and good fluidity of the modified silica powder particles, the substances combined with the small molecules and the modified silica powder particles can disperse and wrap the suspension agent to form a protective layer. However, it should be pointed out that as time goes on, the auxiliary chain small molecules may also begin to decompose and be consumed, and new isolation liquid needs to be injected at this time.

[0028] The present invention has the following advantages:

[0029] The suspending agent in the isolation fluid can still achieve a good isolation effect under high temperature and high pressure formation environment (specifically, under high pressure environment, the modified silicon powder particles can be squeezed into the gaps between the spacers, and the heat transfer is isolated by the modified silicon powder particles, thereby avoiding the decomposition of the suspension agent; even if the ester bonds in the suspension agent decompose, the small molecules formed can be firmly coupled with the modified silicon powder particles under high temperature and high pressure environment, so that the conjugates formed by the small molecules and the modified silicon particles can be assisted in the outer layer of the suspension agent to play an auxiliary protective role; when the conjugates formed by the small molecules and the modified silicon particles are also decomposed, new isolation fluid needs to be injected). DETAILED DESCRIPTION

[0030] The present invention is further described below, but the protection scope of the present invention is not limited to the following description.

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In the first aspect, a specific embodiment of the present invention discloses a high-temperature suspension agent for cementing anti-pollution isolation fluid, which includes a regulator A and a regulator B, and the regulator A and the regulator B are prepared and stored separately, and the two are mixed together before use;

[0033] Wherein, when the regulator A is prepared, it is prepared from sodium styrene sulfonate, polyethylene glycol diacrylate, 2-acrylamide-2-methylpropane sulfonic acid, acrylamide, aldehyde-ketone condensation product, modified silicon powder particles, and modified imide aromatic heterocyclic modified silane coupling agent; specifically, sodium styrene sulfonate, polyethylene glycol diacrylate, 2-acrylamide-2-methylpropane sulfonic acid, and acrylamide are copolymerized, and during the copolymerization, aldehyde-ketone condensation product is used for dispersion and pH adjustment to form copolymer a; the modified silicon powder particles refer to the hydrophobic chains formed by silane grafting on a part of the surface of the silicon powder particles; the modified silicon powder is connected to the polymer a through the modified imide aromatic heterocyclic modified silane coupling agent to obtain the regulator A;

[0034] The regulator B is a foaming acid and a retarder which are directly mixed and stirred evenly; the foaming acid is a mixture of 4-aminopyrrolo[2,1-f][1,2,4]triazine-5-carboxylic acid, carbon dioxide, a foaming agent and a stabilizer.

[0035] In the second aspect, a specific embodiment of the present invention further discloses a method for preparing a high-temperature suspension agent for anti-pollution isolation fluid for cementing, including the preparation of a regulator A and a regulator B.

[0036] When preparing the regulator A:

[0037] S1. Weigh sodium styrene sulfonate and 2-acrylamide-2-methylpropane sulfonic acid and dissolve them in water, stir them thoroughly to dissolve; then heat them to 60°C to 80°C, add the initiator, stir them well and react them thoroughly to obtain a preliminary copolymer;

[0038] Then, weighed acrylamide and polyethylene glycol diacrylate are added to the preliminary copolymer, and the temperature is maintained at 60°C to 80°C, and a portion of the initiator is added, and the mixture is stirred evenly and reacted fully; after the reaction is fully reacted, an aldehyde-ketone condensate is added to adjust the pH value to 5 to 7, and a copolymer a is obtained;

[0039] It should be noted that the initiator is an azo compound, and the amount of the azo compound is 0.05% to 1% of the total weight of sodium styrene sulfonate, polyethylene glycol diacrylate, 2-acrylamide-2-methylpropane sulfonic acid, and acryl;

[0040] S2. The modified silicon powder particles and the modified imide aromatic heterocyclic modified silane coupling agent are mixed, and then added to the copolymer a together, and then uniformly stirred. After a period of time, the mixture is allowed to stand and cooled to finally obtain the finished product of the regulator A.

[0041] When preparing the regulator B: directly mix the foam acid and the retarder and stir evenly.

[0042] Exemplarily, the embodiments of the present invention are further described below.

[0043] Example 1

[0044] The following components are selected and prepared according to the method of the second aspect: when preparing the regulator A, 80g of sodium styrene sulfonate, 6g of polyethylene glycol diacrylate, 10g of 2-acrylamide-2-methylpropanesulfonic acid, 2g of acrylamide, 8g of aldehyde-ketone condensate, 8g of modified silicon powder particles, 8g of modified imide aromatic heterocyclic modified silane coupling agent, (80+6+10+2)×0.05%g of azobisisobutylimidazoline hydrochloride are selected. The regulator B uses 2g of foam acid and 1g of retarder.

[0045] Example 2

[0046] The following components are selected and prepared according to the method of the second aspect: when preparing the regulator A, 60g of sodium styrene sulfonate, 4g of polyethylene glycol diacrylate, 8g of 2-acrylamide-2-methylpropanesulfonic acid, 1.5g of acrylamide, 6g of aldehyde-ketone condensation product, (60+4+8+1.5)×0.5%g of azobisisobutylimidazoline hydrochloride are selected. The regulator B is composed of 1.5g of foam acid and 1.5g of retarder.

[0047] Example 3

[0048] The following components are selected and prepared according to the method of the second aspect: when preparing the regulator A, 50g of sodium styrene sulfonate, 2g of polyethylene glycol diacrylate, 5g of 2-acrylamide-2-methylpropanesulfonic acid, 1g of acrylamide, 4g of aldehyde-ketone condensation product, (50+2+5+1)×0.1%g of azobisisobutylimidazoline hydrochloride are selected. Regulator B is selected from 1g of foam acid and 2g of retarder.

[0049] Experimental Example 1

[0050] Purpose: To verify the stability of the isolation fluid prepared with high temperature suspension under different temperature conditions.

[0051] Experiment: After the products prepared in Example 1, Example 2, and Example 3 were hydrated, barite powder and microsilicon were added to prepare a 1.88 g / cm3 spacer liquid. After constant temperature stirring for 30 minutes at high temperatures of 120°C and 140°C and 60 MPa in a thickener, the six-turn readings of the spacer liquid were measured at 90°C for stability (upper and lower density difference). The experimental results are shown in Tables 1 and 2.

[0052] Table 1 Performance of the isolation liquid configured in Examples 1, 2, and 3 after being cooled from 140°C to 90°C

[0053]

[0054] Table 2 Performance of the isolation liquid configured in Examples 1, 2, and 3 after being cooled from 120°C to 90°C

[0055]

[0056] Note: All examples are calculated based on drilling fluid power law fluid. K--consistency coefficient, or power law coefficient, unit: Pa·sn, n--fluidity index, or power law index, no unit. K value is a measure of viscosity, the higher the viscosity, the higher the K value. The mud n value is generally better below 0.5.

[0057] From Tables 1 and 2, it can be seen that Example 1 has a higher viscosity value and a smaller density difference than Example 2 and 3, which indicates that the slurry has good stability and fluidity.

[0058] Experimental Example 2

[0059] Purpose: To verify the compatibility of the spacer fluid prepared in Example 1 with cement slurry and drilling fluid at a high temperature of 120°C.

[0060] Experiment: The product of Example 1 was used to prepare a 1.90 g / cm3 spacer fluid according to the conditions in Experimental Example 1. The compatibility of the spacer fluid with the cement slurry and the drilling fluid as well as the compatibility of the three phases were tested. Experimental conditions: The two-phase and three-phase mixed liquids were stirred at a high temperature of 120°C and a pressure of 60 MPa in a viscosifier for 30 minutes, and then the six-turn reading and fluidity were measured at 90°C. The experimental results are shown in Table 3.

[0061] Table 3 Compatibility of the spacer fluid configured in Example 1 with cement slurry and drilling fluid at high temperature 120°C

[0062]

[0063] In Table 3, the cement slurry density is 1.90, the spacer fluid density is 1.88, and the drilling fluid density is 1.85.

[0064] It can be concluded from the data in Table 3 that Example 1 has better rheological properties and excellent fluidity at different slurry ratios, which fully demonstrates that the spacer fluid has good compatibility with the drilling fluid, cement slurry and the three-phase mixture, and can be effectively mixed with different fluids to meet the engineering design requirements.

Claims

1. A high temperature suspending agent for anti-pollution spacer fluid for cementing, characterized in that: include: Regulator A is prepared from sodium styrene sulfonate, polyethylene glycol diacrylate, 2-acrylamide-2-methylpropane sulfonic acid, acryl, aldehyde ketone condensate, modified silicon powder particles, and modified imide aromatic heterocyclic modified silane coupling agent; Conditioner B, which includes foaming acid and retarder; The regulator A and regulator B are prepared and stored separately, and the two are mixed together before use.

2. The high temperature suspending agent for anti-pollution isolation fluid for cementing according to claim 1, characterized in that: The preparation method of the regulator A: Firstly, sodium styrene sulfonate, polyethylene glycol diacrylate, 2-acrylamide-2-methylpropane sulfonic acid and acrylamide are copolymerized, and during the copolymerization, aldehyde-ketone condensation products are used for dispersion and pH adjustment to form a copolymer a; The modified silicon powder particles refer to the use of silane grafting to form hydrophobic chains on a part of the surface of the silicon powder particles; The modified silicon powder is connected to the polymer a through a modified imide aromatic heterocyclic modified silane coupling agent to obtain a regulator A.

3. A high temperature suspension agent for anti-pollution isolation fluid for cementing according to claim 2, characterized in that: In the regulator B, the foaming acid is a mixture of 4-aminopyrrolo[2,1-f][1,2,4]triazine-5-carboxylic acid, carbon dioxide, a foaming agent and a stabilizer.

4. The high temperature suspension agent for anti-pollution isolation fluid for cementing according to claim 3, characterized in that: By weight, 40 to 80 parts of sodium styrene sulfonate; 2 to 10 parts of polyethylene glycol diacrylate; 5 to 10 parts of 2-acrylamide-2-methylpropane sulfonic acid, 1 to 2 parts of acrylamide; 4 to 8 parts of aldehyde-ketone condensate; 8 to 15 parts of modified silicon powder particles, and 8 to 20 parts of modified imide aromatic heterocyclic modified silane coupling agent; 1 to 2 parts of foaming acid; 1 to 2 parts of retarder.

5. The method for preparing a high temperature suspension agent for anti-pollution spacer fluid for cementing according to any one of claims 1 to 4, characterized in that: The regulator A is prepared as follows: S1. Weigh sodium styrene sulfonate and 2-acrylamide-2-methylpropane sulfonic acid and dissolve them in water, stir them thoroughly to dissolve; then heat them to 60°C to 80°C, add the initiator, stir them well and react them thoroughly to obtain a preliminary copolymer; Then, weighed acrylamide and polyethylene glycol diacrylate are added to the preliminary copolymer, and the temperature is maintained at 60°C to 80°C, and a portion of the initiator is added, and the mixture is stirred evenly and reacted fully; after the reaction is fully reacted, an aldehyde-ketone condensate is added to adjust the pH value to 5 to 7, and a copolymer a is obtained; S2. The modified silicon powder particles and the modified imide aromatic heterocyclic modified silane coupling agent are mixed, and then added to the copolymer a together, and then uniformly stirred. After a period of time, the mixture is allowed to stand and cooled to finally obtain the finished product of the regulator A.

6. The method for preparing a high-temperature suspension agent for anti-pollution spacer fluid for cementing according to claim 5, characterized in that: The initiator is an azo compound, and the amount of the azo compound used is 0.05% to 1% of the total weight of sodium styrene sulfonate, polyethylene glycol diacrylate, 2-acrylamide-2-methylpropane sulfonic acid and acryl.

7. The method for preparing a high temperature suspension agent for anti-pollution spacer fluid for cementing according to claim 5 or 6, characterized in that: The foam acid and the retarder are directly mixed and stirred evenly.

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