Offshore cementing backflowing slurry weak solidification pretreatment agent, preparation method and application thereof

Abstract

The application belongs to the technical field of oilfield development, and particularly relates to a weak solidification pretreatment agent for offshore cementing flowback slurry, a preparation method and application thereof. The weak solidification pretreatment agent for offshore cementing flowback slurry provided by the application comprises, by total weight of 100 parts, modified cellulose 24-36 parts, acrylic acid-acrylamide polymer 9-15 parts, lignin fiber 41-55 parts, and organic carboxylic acid 4-8 parts. The weak solidification pretreatment agent for offshore cementing flowback slurry can realize rapid formation of weak structure solid of flowback slurry, low strength and no free water precipitation, realize bagging, facilitate short-term storage on the platform, and ensure safe transportation of flowback slurry to land for subsequent treatment, thereby avoiding the harm to the environment caused by sea disposal.

Description

Technical Field

[0001] This invention belongs to the field of oilfield development technology, specifically relating to a weak solidification pretreatment agent for offshore cement flowback cement slurry, its preparation method, and its application. Background Technology

[0002] Offshore cementing is a crucial part of the drilling process, serving to support the wellbore, protect the casing, and isolate the formation. During cementing design, to ensure the entire annulus is filled with cement slurry, a certain amount of cement slurry is typically added to the annulus volume calculation. After cementing operations are completed, a certain amount of cement slurry will return from the wellhead. This portion of cement slurry often mixes with a certain amount of mud or separator fluid, collectively referred to as cement flowback fluid. This flowback fluid cannot be reused and needs to be recycled and disposed of.

[0003] With increasingly stringent environmental protection requirements, especially in certain key areas, full recycling of marine waste is required, including cement slurry backflow liquid.

[0004] Current recovery methods primarily involve using cuttings bins or tanks on the platform to collect the backflow fluid, which is then transported back to land by ships for further processing. However, due to the limited space on offshore platforms, the number of cuttings bins or tanks available for recovery is extremely limited, resulting in the occupation of limited platform space resources and hindering the collection of other materials. In addition, the long storage time of the cement slurry can cause damage or render the containers unusable due to solidification. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a weakly solidified pretreatment agent for offshore cementing flowback cement slurry, its preparation method, and its application.

[0006] Specifically, the present invention is achieved through the following technical solutions:

[0007] A weak curing pretreatment agent for offshore cementing flowback cement slurry, comprising, by weight 100 parts: 24-36 parts modified cellulose; 9-15 parts acrylic acid-acrylamide polymer; 41-55 parts lignin fiber; and 4-8 parts organic carboxylic acid.

[0008] The aforementioned marine cementing flowback cement slurry weak curing pretreatment agent, based on a total weight of 100 parts, includes: 30-35 parts modified cellulose; 10-13 parts acrylic acid-acrylamide polymer; 48-54 parts lignin fiber; and 5-7 parts organic carboxylic acid by weight.

[0009] The modified cellulose in the aforementioned offshore cementing flowback slurry weak curing pretreatment agent includes one or more of hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, and hydroxypropyl cellulose.

[0010] The modified cellulose in the aforementioned offshore cementing runoff weak curing pretreatment agent is hydroxyethyl cellulose.

[0011] The aforementioned weak curing pretreatment agent for offshore cementing runoff cement slurry includes lignin fibers comprising poplar sawdust, pine sawdust, or mixtures thereof.

[0012] The aforementioned weak curing pretreatment agent for offshore cementing runoff cement slurry, wherein the lignin fiber is poplar sawdust powder.

[0013] The aforementioned marine cementing flowback cement slurry weak curing pretreatment agent includes one or more of the following organic carboxylic acids: tartaric acid, citric acid, ethylenediaminetetraacetic acid, phenylacetic acid, polyacrylic acid, and maleic acid-acrylic acid copolymer.

[0014] The aforementioned weak curing pretreatment agent for offshore cementing runoff cement slurry, wherein the organic carboxylic acid is citric acid or tartaric acid.

[0015] The aforementioned weak-curing pretreatment agent for offshore cementing flowback slurry, wherein the acrylic-acrylamide polymer is prepared through the following steps:

[0016] (1) Under stirring conditions, add acrylic acid, sodium hydroxide, acrylamide and crosslinking agent to deionized water in sequence and mix well;

[0017] (2) Introduce nitrogen gas and add initiator, raise the temperature to 50℃~60℃, and after the temperature is constant, heat to 65℃~80℃;

[0018] (3) After the reaction is kept at a constant temperature for 1 to 2 hours, stop heating and continue stirring until the reactants cool to room temperature;

[0019] (4) The product is washed, dried and crushed to obtain an acrylic acid-acrylamide polymer.

[0020] The aforementioned marine cementing flowback cement slurry weak curing pretreatment agent uses N,N-methylenebisacrylamide as the crosslinking agent and ammonium persulfate as the initiator.

[0021] The aforementioned marine cementing flowback cement slurry weak curing pretreatment agent has an acrylic acid, sodium hydroxide, acrylamide, crosslinking agent, and initiator in a mass ratio of (7.2-14.4):(2.1-6.4):(7.1-14.2):(0.02-0.04):(0.1-0.2).

[0022] A method for preparing a weakly hardened pretreatment agent for offshore cement flowback slurry, comprising:

[0023] Weigh the modified cellulose, acrylic acid-acrylamide polymer, lignin fiber and organic carboxylic acid according to the specified proportions, and mix them directly until homogeneous.

[0024] The above-mentioned weak curing pretreatment agent for offshore cement flowback cement slurry is used in the treatment of offshore cement flowback cementing fluid.

[0025] In the above applications, the weak solidification pretreatment agent for offshore cementing flowback slurry accounts for 2.0% to 15.0% of the flowback cementing fluid by mass volume.

[0026] The technical solution of the present invention has the following beneficial effects:

[0027] The weak-solidification pretreatment agent for offshore cement flowback slurry of the present invention can enable the flowback cement slurry to quickly form a weak-structured solid with low strength and no free water precipitation. It can be bagged for short-term storage on the platform and ensures the safe transportation of the flowback cement slurry to land for subsequent treatment, thereby avoiding the environmental harm caused by discharge into the sea. Detailed Implementation

[0028] 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 phrases used below have the meanings commonly understood by those skilled in the art.

[0029] When a range of values ​​is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0030] For offshore cement slurry flowback fluid, it is usually treated to meet discharge standards before being discharged into the sea. However, with increasingly stringent environmental regulations, this method of discharge is facing more and more restrictions. Due to the limited processing technology on offshore platforms, it is necessary to temporarily store it in containers and transport it back to land for processing after a certain period. Existing technologies require specialized storage containers, and during long-term storage, the cement slurry may solidify and damage the containers.

[0031] This invention develops a weak curing pretreatment agent for offshore cement flowback cement slurry, comprising: modified cellulose, acrylic-acrylamide polymers, lignin fibers, and organic carboxylic acids.

[0032] The components of this invention complement each other when treating cement flowback slurry. The modified cellulose primarily provides water retention capacity, improves the stability of the weakly solidified body, and can also bind free water. The acrylic acid-acrylamide polymer chains are intertwined, forming a network-interpenetrating high-performance water-retaining agent, which improves the absorption capacity of high-mineralized brine and prevents water from precipitating out of the formed weakly solidified body. The lignin fiber primarily disperses between cement particles, preventing the formation of high strength and facilitating subsequent bagging. The organic carboxylic acid is used to prevent the cement slurry from hydrating too quickly, thus forming higher cement stone strength.

[0033] The following is a detailed description of each component of the weak curing pretreatment agent for offshore cementing flowback cement slurry of the present invention.

[0034] Modified cellulose

[0035] Modified cellulose is a cellulose derivative with special physicochemical properties obtained by appropriately processing natural cellulose to change its original properties in order to meet specific needs.

[0036] In this invention, the modified cellulose plays the role of providing a certain water retention capacity and improving the stability of the weakly solidified body.

[0037] Preferably, the modified cellulose of the present invention includes one or more of hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, and hydroxypropyl cellulose.

[0038] More preferably, the modified cellulose used in this invention is hydroxyethyl cellulose, wherein the degree of polymerization of the hydroxyethyl cellulose is 500 to 800;

[0039] Preferably, based on 100 parts by weight of the weak curing pretreatment agent, the weight of the modified cellulose is 24-36 parts. When the weight of the modified cellulose is less than 24 parts, it cannot provide sufficient water retention for the flowback cementing fluid, resulting in excessive water precipitation; when the weight of the modified cellulose is greater than 36 parts, the flowback cementing slurry rapidly loses its fluidity, and its strength develops too quickly, damaging the treatment container.

[0040] More preferably, the modified cellulose is 30-35 parts by weight, based on 100 parts by weight of the weak curing pretreatment agent.

[0041] Acrylic acid-acrylamide polymers

[0042] Acrylic acid-acrylamide polymers are high molecular weight copolymers of acrylic acid and acrylamide. The polymer chains are intertwined to form a network-interpenetrating high-performance water-retaining agent, which improves the absorption capacity of high-mineralized brine and prevents the precipitation of water from the weakly solidified body.

[0043] Preferably, the acrylic-acrylamide polymer is prepared by the following steps:

[0044] (1) Under stirring conditions, add acrylic acid, sodium hydroxide, acrylamide and crosslinking agent to deionized water in sequence and mix well;

[0045] (2) Introduce nitrogen gas and add initiator, raise the temperature to 50℃~60℃, and after the temperature is constant, heat to 65℃~80℃;

[0046] (3) After the reaction is kept at a constant temperature for 1 to 2 hours, stop heating and continue stirring until the reactants cool to room temperature;

[0047] (4) The product is washed, dried and crushed to obtain an acrylic acid-acrylamide polymer.

[0048] Preferably, the alkali is sodium hydroxide, the initiator is ammonium persulfate, and the crosslinking agent is N,N-methylenebisacrylamide.

[0049] Preferably, the ratio of the acrylic acid, the sodium hydroxide, the acrylamide, the crosslinking agent and the initiator is (7.2-14.4):(2.1-6.4):(7.1-14.2):(0.02-0.04):(0.1-0.2), all of which are mass ratios.

[0050] Preferably, in the process of adding acrylic acid, sodium hydroxide, acrylamide and crosslinking agent, the next component is added only after the previous component has been fully stirred and dissolved.

[0051] Preferably, based on 100 parts by weight of the weak curing pretreatment agent, the acrylic-acrylamide polymer comprises 9-15 parts. When the acrylic-acrylamide polymer comprises less than 9 parts by weight, if the water content in the return cementing fluid is too high, a solidified body cannot be formed in time, prolonging the treatment time. When the acrylic-acrylamide polymer comprises more than 15 parts by weight, if the cement content in the return cementing fluid is too high, cement particles may rapidly aggregate, leading to a rapid increase in the solid phase content of the return cementing slurry and rapid solidification, damaging the treatment container.

[0052] More preferably, the acrylic-acrylamide polymer comprises 10-13 parts per 100 parts by weight of the weak curing pretreatment agent.

[0053] Lignin fibers

[0054] Lignin fiber is an organic fiber obtained from natural wood through chemical treatment.

[0055] In this invention, lignin fibers are dispersed between cement particles to prevent the formation of high strength and facilitate subsequent bagging.

[0056] Preferably, the lignin fibers used in this invention include poplar sawdust, pine sawdust, or a mixture thereof.

[0057] More preferably, the lignin fiber is poplar sawdust.

[0058] The particle size of the lignin fiber in this invention should be ≤0.3mm. If the length is too long, it will cause the weak curing pretreatment agent to be unable to be mixed evenly during production.

[0059] Preferably, the weight of the lignin fiber is 41-55 parts, based on 100 parts by weight of the weak curing pretreatment agent. When the weight of the lignin fiber is less than 41 parts, it cannot ensure sufficient dilution in the solidified body, leading to increased strength of the solidified body; when the weight of the lignin fiber is greater than 55 parts, it will result in a decrease in the content of the other three materials, failing to achieve good suspension and retarding effects.

[0060] More preferably, the weight of the lignin fiber is 48-54 parts, based on 100 parts by weight of the weak curing pretreatment agent.

[0061] Organic carboxylic acids

[0062] Organic carboxylic acids are organic compounds composed of hydrocarbon groups and carboxyl groups linked together.

[0063] In this invention, the main function of organic carboxylic acids is to prevent cement slurry from hydrating too quickly, thus forming higher cement stone strength.

[0064] Preferably, the organic carboxylic acid includes one or more of tartaric acid, citric acid, ethylenediaminetetraacetic acid, phenylacetic acid, polyacrylic acid, and maleic acid-acrylic acid copolymer.

[0065] More preferably, the organic carboxylic acid is citric acid or tartaric acid.

[0066] Preferably, the organic carboxylic acid comprises 4-8 parts by weight of 100 parts of the weak curing pretreatment agent. When the weight of the organic carboxylic acid is less than 4 parts, it cannot ensure sufficient delay of cement hydration, resulting in excessively rapid and excessively high strength development of the consolidated body. When the weight of the organic carboxylic acid is greater than 8 parts, it may lead to a slow cement reaction when the cement content in the return liquid is low, making it impossible to form a weakly consolidated body.

[0067] More preferably, the organic carboxylic acid comprises 5-7 parts by weight of 100 parts of the weak curing pretreatment agent.

[0068] On the other hand, the present invention also provides a method for preparing a weakly solidified pretreatment agent for offshore cementing flowback cement slurry, comprising: weighing modified cellulose, acrylic-acrylamide polymer, lignin fiber and organic carboxylic acid in proportion, and directly mixing them evenly.

[0069] In another aspect, the present invention also provides the application of the above-mentioned weak curing pretreatment agent for offshore cementing flowback cement slurry in the treatment of offshore cementing flowback cementing fluid.

[0070] Preferably, the weak curing pretreatment agent of the offshore cementing flowback cement slurry accounts for 2.0% to 15.0% of the flowback cementing fluid by mass volume.

[0071] In practice, the weak-curing pretreatment agent of this invention has the following advantages in treating offshore cement flowback slurry: 1) Small dosage, approximately 2.0-15.0% of the total flowback slurry; 2) Rapid reaction, after adding the flowback slurry and stirring evenly, initial setting and formation of a weakly solidified body can be achieved within 60 minutes, without occupying cuttings boxes or storage tanks; 3) Final setting time exceeds 12 hours, ensuring sufficient time for bagging; 4) No free water precipitation and low strength, allowing for manual or mechanical bagging; 5) Wide applicability, suitable for materials with a specific strength of 1.2 g / cm³. 3 ~2.2g / cm 3 Various cement slurries can achieve weak curing; 6) It also has a good weak curing effect on flowback cement slurries mixed with isolation fluid and drilling fluid.

[0072] For cementing fluid return waste at sea, which is mainly cementing slurry and contains some flushing fluid and isolation fluid, a weak solidification pretreatment method can be used to make the cementing fluid return waste quickly gel and form a low-strength solidified body, which can then be transported back to land for further processing.

[0073] Example

[0074] 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, are performed according to conventional methods and conditions.

[0075] The raw materials used in each embodiment and comparative example are sourced from the following sources:

[0076] Hydroxyethyl cellulose: The degree of polymerization of the hydroxyethyl cellulose is 500-800, and it was purchased from Renqiu Pengyu Chemical Co., Ltd.

[0077] Poplar sawdust powder: The poplar sawdust powder is a natural wood powder with a particle size ≤0.3mm, purchased from Lingshou County Chengyang Mining Co., Ltd.;

[0078] Acrylic acid-acrylamide polymers: The preparation method of the acrylic acid-acrylamide polymers is as follows:

[0079] 1) Under stirring conditions, add 7.2g acrylic acid, 3.5g sodium hydroxide, 10.5g acrylamide, and 0.03g N,N-methylenebisacrylamide sequentially to 220g deionized water. Add the next ingredient only after each ingredient has fully dissolved.

[0080] 2) After purging with nitrogen for 5 minutes to remove oxygen, add 0.12g of ammonium persulfate as initiator and heat the water bath to 50℃;

[0081] 3) Allow the reaction to proceed naturally for a period of time until the temperature stabilizes, then raise the temperature to 75℃;

[0082] 4) After the reaction is kept at this temperature for 2 hours, stop heating and continue stirring until the reactants cool to room temperature;

[0083] 5) The product is washed, filtered, and thoroughly dried at 120°C. It is then pulverized to a particle size ≤0.3mm to obtain an acrylic acid-acrylamide polymer.

[0084] Example 1

[0085] Preparation of weak curing agent A: Weigh 33 parts of hydroxyethyl cellulose, 11 parts of acrylic acid-acrylamide polymer, 50 parts of poplar sawdust powder, and 6 parts of citric acid by weight, mix them evenly, and set aside for use.

[0086] Example 2

[0087] Preparation of weak curing agent B: Weigh 30 parts of hydroxyethyl cellulose, 13 parts of acrylic acid-acrylamide polymer, 54 parts of poplar sawdust powder, and 3 parts of tartaric acid by weight, mix them evenly, and set aside for use.

[0088] Example 3

[0089] Preparation of weak curing agent C: Weigh 28 parts of hydroxyethyl cellulose, 12 parts of acrylic acid-acrylamide polymer, 53 parts of poplar sawdust powder, and 7 parts of citric acid by weight, mix them evenly, and set aside for use.

[0090] Comparative Example 1

[0091] The only difference between this comparative example and Example 1 is that the amount of hydroxyethyl cellulose used is 10 parts, while the amount and source of other materials and the preparation process of this comparative example are exactly the same as those of Example 1.

[0092] Comparative Example 2

[0093] The only difference between this comparative example and Example 2 is that the amount of acrylic acid-acrylamide polymer used is 5 parts, while the amount and source of other materials and the preparation process of this comparative example are exactly the same as those in Example 2.

[0094] Comparative Example 3

[0095] The only difference between this comparative example and Example 3 is that the amount of citric acid used is 2 parts, while the amount and source of other materials and the preparation process of this comparative example are exactly the same as those of Example 3.

[0096] Test case

[0097] The effects of the weak curing agents in the examples and comparative examples on various slurries were evaluated, and the detailed results are shown in Table 1. This test case involves a comparison of the application performance of the weak curing agents in cement slurry, drilling fluid, release fluid, and their mixtures. The relevant formulations are as follows:

[0098] 1.90g / cm 3 Cement slurry: fresh water + 100g oil well cement + 6.9g water loss reducer PC-G81L + 1.6g retarder PC-H21L + 0.9g defoamer PC-X60L.

[0099] 1.60g / cm 3 High water-cement ratio cement slurry: fresh water + 100g oil well cement + 5g bentonite PC-P50S + 2.0g early strength agent PC-A90S + 0.9g defoamer PC-X60L.

[0100] Separating solution: Fresh water + 1.5g separating agent PC-S11S + 1g organic phosphate defoamer PC-X60L + 100g barite.

[0101] Drilling fluid: Fresh water + 0.3% NaOH + 0.2% Na2CO3 + 0.2% PF-BIOVIS + 1.1% PF-FLOTROL + 0.4% PF-BIOCAP + 2.0% PF-BIOTROL + 1.6% PF-LUBE + 0.2% PF-PAC-LV + 12% NaCl + 15% barite.

[0102] Test pulp A: 100 samples, 1.90 g / cm³ 3 cement grout

[0103] Test slurry B: 100 samples, 1.60 g / cm³ 3 High water-cement ratio cement paste

[0104] Test pulp C: 50 samples, 1.60 g / cm³ 3 High water-cement ratio cement slurry + 25 parts release fluid + 25 parts drilling fluid

[0105] Table 1. Weak curing properties of different test cases

[0106]

[0107]

[0108] The test results show that Examples 1, 2, and 3 can ensure that the initial setting time is less than 60 minutes and the final setting time is greater than 12 hours for cement slurry and mixed slurry of different densities. Moreover, there is no free water after final setting. Compared with the blank control sample, the initial setting time is significantly shortened and the final setting time is extended.

[0109] Compared to Example 1, Comparative Example 1 has a longer initial setting time, and when the cement ratio is high (cement paste and slurry with a water-cement ratio of 1.60), there is more free water.

[0110] Compared to Example 2, Comparative Example 2 has a longer initial setting time, and when the cement ratio is high (1.60 high water-cement ratio cement paste and slurry), there is more free water.

[0111] Compared to Example 3, Comparative Example 3 showed that the final setting time in the cement slurry was too short, resulting in insufficient subsequent processing time, which may have caused damage to the slurry container.

[0112] The present invention has been disclosed above with reference to preferred embodiments. However, those skilled in the art should understand that these embodiments are merely illustrative of the invention and should not be construed as limiting its scope. It should be noted that any variations and substitutions equivalent to these embodiments should be considered to be covered within the scope of the claims. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A weak-curing pretreatment agent for offshore cementing flowback slurry, characterized in that, Based on a total weight of 100 parts, it includes: 24-36 parts modified cellulose; 9-15 parts acrylic acid-acrylamide polymer; 41-55 parts lignin fiber; and 4-8 parts organic carboxylic acids by weight. The modified cellulose includes one or more of hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, and hydroxypropyl cellulose; the lignin fiber includes poplar sawdust, pine sawdust, or a mixture thereof; and the organic carboxylic acid includes one or more of tartaric acid, citric acid, ethylenediaminetetraacetic acid, phenylacetic acid, polyacrylic acid, and maleic acid-acrylic acid copolymer.

2. The weak-curing pretreatment agent for offshore cementing flowback slurry according to claim 1, characterized in that, Based on a total weight of 100 parts, it includes: 30-35 parts modified cellulose; 10-13 parts acrylic acid-acrylamide polymer; 48-54 parts lignin fiber; and 5-7 parts organic carboxylic acid.

3. The weak-curing pretreatment agent for offshore cementing flowback slurry according to claim 1, characterized in that, The modified cellulose is hydroxyethyl cellulose.

4. The weak-curing pretreatment agent for offshore cementing flowback slurry according to claim 1, characterized in that, The lignin fiber is poplar sawdust powder.

5. The weak-curing pretreatment agent for offshore cementing flowback slurry according to claim 1, characterized in that, The organic carboxylic acids are citric acid and tartaric acid.

6. The weak-curing pretreatment agent for offshore cementing flowback slurry according to claim 1 or 2, characterized in that, The acrylic-acrylamide polymer is prepared by the following steps: (1) Under stirring conditions, add acrylic acid, sodium hydroxide, acrylamide and crosslinking agent to deionized water in sequence and mix well; (2) Introduce nitrogen and add initiator, raise the temperature to 50℃~60℃, and after the temperature is constant, heat to 65℃~80℃; (3) After the reaction is kept at a constant temperature for 1 to 2 hours, stop heating and continue stirring until the reactants cool to room temperature; (4) The product is washed, dried and crushed to obtain an acrylic acid-acrylamide polymer.

7. The weak-curing pretreatment agent for offshore cementing flowback slurry according to claim 6, characterized in that, The crosslinking agent is N,N-methylenebisacrylamide, and the initiator is ammonium persulfate.

8. The weak-curing pretreatment agent for offshore cementing flowback slurry according to claim 6, characterized in that, The mass ratio of the acrylic acid, the sodium hydroxide, the acrylamide, the crosslinking agent, and the initiator is (7.2-14.4):(2.1-6.4):(7.1-14.2):(0.02-0.04):(0.1-0.2).

9. The method for preparing the weakly solidified pretreatment agent for offshore cementing flowback slurry according to any one of claims 1-8, characterized in that, include: Weigh the modified cellulose, acrylic acid-acrylamide polymer, lignin fiber and organic carboxylic acid according to the specified proportions, and mix them directly until homogeneous.

10. The application of the weak-curing pretreatment agent for offshore cementing flowback cement slurry according to any one of claims 1-8 in the treatment of offshore cementing flowback cementing fluid.

11. The application according to claim 10, characterized in that, The pre-treatment agent for the weak curing of the cement slurry used in offshore cementing runsoff accounts for 2.0% to 15.0% of the mass volume of the cementing fluid.

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