CN115305070A - Microgel channeling-preventing fluid loss agent and preparation method and application thereof - Google Patents

Abstract

The invention belongs to the technical field of oilfield chemistry, and relates to a microgel anti-channeling fluid loss agent and a preparation method and application thereof. The microgel anti-channeling water loss agent of the present invention comprises: a PVA microgel and a microgel protective agent with a weight ratio of 1:(0.1-2.0). Compared with the prior art, the microgel anti-channeling water loss agent of the present invention has the following advantages: (1) better fluidity, more suitable for on-site application; (2) stronger film-forming property, water loss reduction performance It has better anti-channeling performance with low temperature; (3) It can control free liquid, and the prepared cement slurry is not easy to generate free water; (4) It has better compatibility with other additives, and when used in combination with other additives, the film-forming property is not easy. affected.

Description

Microgel anti-fluid loss agent and its preparation method and application

technical field

The invention belongs to the technical field of oil field chemistry, and relates to a microgel anti-channeling fluid loss agent and its preparation method and application, in particular to a microgel anti-channeling fluid loss agent suitable for deep water surface cementing and its preparation method.

Background technique

With the continuous advancement of exploration and development of offshore oil and gas resources, deepwater development has gradually become an important battlefield for international oil and gas exploration and development. In the process of deepwater drilling and completion, low temperature and shallow flow/gas are two common problems in cementing operations. At present, the anti-channeling cement slurry mainly includes compressible cement slurry technology, impermeable cement slurry technology, thixotropic cement slurry technology and so on.

PVA has good film-forming properties. When the cement slurry loses water, it is easy to form an impermeable film. While preventing the cement slurry from continuing to lose water, it can also prevent gas from invading the slurry. It can be used as an anti-channeling type fluid loss reducer for oil well cement raw materials used. Compared with commonly used AMPS fluid loss reducers, PVA will not produce a retarding effect on the thickening of cement slurry and affect the strength, which is especially important for deep water and low temperature environments. Cross-linking PVA with glutaraldehyde, borax, etc. can further improve the film-forming property of PVA, which is an important method to improve the effect of PVA. Even so, its anti-channeling effect and water loss reduction effect are still insufficient in the face of the deep water cementing problems of deep water low temperature and shallow layer flow/gas.

In order to improve the performance of PVA, scientists in this field have done a lot of research. Such as: the fluid loss reduction mechanism of chemically cross-linked polyvinyl alcohol [J]. Oilfield Chemistry, 2002, 19 (2): 5., the relationship between the cross-linking degree of chemically cross-linked polyvinyl alcohol and the fluid loss reduction performance [J] .Drilling Fluid and Completion Fluid, 2002,19(5):22-24. Performance evaluation of chemically cross-linked polyvinyl alcohol fluid loss reducer[J].Oilfield Chemistry,2012,29(3):6-8 .、Crosslinking degree and properties of chemically crosslinked polyvinyl alcohol fluid loss reducer[J].Chemical Research and Application, 2017,29(007):986-991. Chemical cross-linking was carried out, and the mechanism of fluid loss control and influencing factors of fluid loss control were investigated. However, because when the degree of cross-linking is further increased, the cross-linked PVA is easy to precipitate or the sample cannot flow, and the degree of cross-linking is calculated by the molar ratio of the cross-linking agent to the PVA monomer unit. The degree of cross-linking involved in the above-mentioned documents does not reach 0.1 %. Chinese invention patent CN106085382A cross-links PVA with borax, and then uses ammonium persulfate as a gel breaker to prepare a latex fluid loss reducer. Calculated based on its implementation cases, the degree of cross-linking does not reach 0.1%. Chinese invention patent CN106543994A mixes polyvinyl alcohol, polyvinylpyrrolidone, dispersant, and filler to form a film-forming fluid loss reducer. However, the fluid loss reducer is solid and PVA is not crosslinked.

Therefore, it is still a difficult point in this field to research and develop a microgel type anti-channeling fluid loss agent suitable for deep water and low temperature environment.

Contents of the invention

Aiming at the problems of low temperature and shallow laminar flow/gas in ocean deep water, a microgel anti-channeling fluid loss agent and its preparation method and application are provided. While not affecting the development of low-temperature cement slurry strength, it improves the anti-channeling and water loss reduction effects of cement slurry, and solves the problem that free water is easily produced in cement slurry prepared with PVA fluid loss reducers.

Specifically, the microgel anti-flooding fluid loss agent of the present invention includes: PVA microgel and microgel protective agent in a weight ratio of 1:(0.1-2.0).

In the above-mentioned microgel anti-flooding and water loss agent, the weight ratio of the PVA microgel to the microgel protective agent is 1:(0.5-1.5).

In the aforementioned microgel anti-flooding agent, the weight ratio of the PVA microgel to the microgel protective agent is 1:(0.8-1.2).

The above-mentioned microgel anti-skidding fluid loss agent, the crosslinking agent of the PVA microgel is glutaraldehyde, and the crosslinking degree of the PVA microgel is 0.1-0.8%

In the aforementioned microgel anti-flooding agent, the microgel protective agent is a surfactant with a polar group.

In the aforementioned microgel anti-flooding and fluid loss agent, the microgel protective agent includes styrene derivatives, alkoxylated alcohols, N-alkylpyrrolidones, N-alkyl alcohols, and dodecanol.

On the other hand, the present invention also provides the preparation method of described microgel anti-skidding fluid loss agent, comprising:

(1) Under heating conditions, polyvinyl alcohol is dissolved in deionized water to obtain an aqueous solution of polyvinyl alcohol;

(2) add microgel protective agent in described polyvinyl alcohol aqueous solution, stir;

(3) Adding a cross-linking agent solution, adding acid to adjust the pH value to 3-4, and stirring to obtain a microgel anti-skidding fluid loss agent.

In the preparation method of the above-mentioned microgel anti-skidding fluid loss agent, the heating temperature in step (1) is 60-90°C; the heating temperature in steps (2) and (3) is 40-60°C.

In the preparation method of the above-mentioned microgel anti-skidding fluid loss agent, the concentration of the polyvinyl alcohol aqueous solution is 3-7%; the concentration of the crosslinking agent solution is 15-30%.

In another aspect, the present invention also provides the application of the microgel anti-channeling fluid loss agent in deep water surface layer cementing.

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

Compared with the prior art, the microgel anti-running fluid loss agent of the present invention has four advantages: (1) better fluidity, more suitable for on-site application; (2) stronger film-forming property, lower fluid loss (3) It can control free liquid, and the prepared cement slurry is not easy to produce free water; (4) It has better compatibility with other admixtures. When used in combination with other admixtures, the film-forming Not easily affected.

Detailed ways

In order to fully understand the purpose, features and effects of the present invention, the present invention will be described in detail through the following specific embodiments. Process method of the present invention except following content, all the other all adopt the routine method or device of this field. Unless otherwise specified, the following nouns and terms have the meanings commonly understood by those skilled in the art.

The terms "the", "said", "a" and "an" as used herein do not denote a limitation of quantity but mean that there is at least one of the referred item. The terms "preferred", "more preferred" and the like refer to embodiments of the invention which may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

When a numerical range is disclosed herein, such range is considered continuous and includes the minimum and maximum values of that range and every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum of the range is included. Furthermore, when multiple ranges are provided to describe a feature or characteristics, the ranges may be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein.

The existing technology is mainly PVA and its cross-linked derivatives, the degree of cross-linking is low, the film-forming property has certain limitations, and the effect of reducing water loss and preventing channeling is not good. Poor compatibility with various admixtures, especially when used in combination with some early strength agents and dispersants, its film-forming properties are easily affected, thus losing the functions of reducing water loss and preventing channeling, which may easily cause safety accidents in practical applications. Moreover, the cement slurry prepared with this type of fluid loss reducing agent is prone to produce free water, which leads to the risk of air channeling.

In the first aspect, the present invention provides a microgel type anti-channeling fluid loss agent suitable for low temperature in deep water, aiming at the problem of low temperature and shallow layer flow/air in deep ocean water. The microgel anti-running fluid loss agent of the present invention uses PVA as raw material to prepare PVA microgel, and at the same time fully considers its stability and film-forming property in cement slurry to ensure that its film-forming process is not easily affected by other admixtures .

Specifically, the microgel anti-flooding fluid loss agent of the present invention includes: PVA microgel and microgel protective agent in a weight ratio of 1:(0.1-2.0).

In the present invention, by adding a microgel protective agent into the microgel anti-flooding and water loss agent, the PVA forms microgel particles and maintains good stability during the crosslinking process. Although the degree of cross-linking of PVA in the microgel is relatively high, the addition of the microgel protective agent prevents further aggregation between the suspended microgels, so the liquid maintains a good flow state. If no microgel protective agent is added to the microgel anti-fluid loss agent, then when the crosslinking degree of PVA is high, PVA is easy to be precipitated in the form of gel or has poor liquid fluidity, which is not conducive to practical application.

In the microgel anti-skidding fluid loss agent of the present invention, when the weight ratio of the PVA microgel to the microgel protective agent was greater than the maximum value of the above content, the microgel protective agent could not better exert its The protective effect of PVA microgel easily causes the precipitation of PVA microgel due to excessive cross-linking degree; The increase in the amount of protective agent, the increase in the effect is not obvious.

Preferably, the weight ratio of the PVA microgel to the microgel protective agent is 1:(0.5-1.5).

Further preferably, the weight ratio of the PVA microgel to the microgel protective agent is 1:(0.8-1.2).

Preferably, when the PVA microgel is prepared, the crosslinking agent used is glutaraldehyde, and the crosslinking degree of the PVA microgel is 0.1-0.8%.

Wherein, the degree of crosslinking is the molar ratio of the crosslinking agent to the PVA monomer unit.

When the cross-linking degree of the PVA microgel is less than 0.1%, the effect of the microgel is poor; when the cross-linking degree of the PVA microgel is greater than 0.8%, the microgel has the risk of excessive cross-linking and precipitation.

Preferably, the microgel protecting agent is a surfactant with polar groups.

Further preferably, the microgel protective agent includes, but is not limited to: styrene derivatives, alkoxylated alcohols, N-alkylpyrrolidones, N-alkyl alcohols, and dodecanol.

Compared with the prior art, the PVA microgel of the invention has a higher cross-linking degree, up to 0.8%, and has stable liquid and good flow state. This is due to the addition of the microgel protective agent, the PVA forms microgel particles and maintains good stability during the crosslinking process. The degree of crosslinking of PVA in the microgel is high, but the microgel protective agent makes the suspension There is no further aggregation between the microgels, so the liquid maintains a good flow state. When the cement paste loses water, the microgel particles aggregate rapidly and form a PVA film more quickly. Therefore, the PVA microgel of the present invention has better dehydration and air channeling resistance.

On the other hand, the present invention provides the preparation method of described microgel anti-skidding fluid loss agent, comprising the following steps:

(1) Under heating conditions, polyvinyl alcohol is dissolved in deionized water to obtain an aqueous solution of polyvinyl alcohol;

(2) add microgel protective agent in described polyvinyl alcohol aqueous solution, stir;

(3) Adding a cross-linking agent solution, adding acid to adjust the pH value to 3-4, and stirring to obtain a microgel anti-skidding fluid loss agent.

Preferably, in step (1), the heating temperature is 60-90° C., and the concentration of the polyvinyl alcohol aqueous solution is 3-7%.

Further preferably, in step (1), the heating temperature is 80° C., and the concentration of the polyvinyl alcohol aqueous solution is 5%.

Preferably, the heating temperature in step (2) and step (3) is 40-60°C, more preferably 50°C.

Preferably, the concentration of the crosslinking agent solution is 15-30%, more preferably 25%.

Wherein, the acid is one or more of hydrochloric acid, sulfuric acid, acetic acid, nitric acid, etc., preferably hydrochloric acid.

Wherein, in the preparation method of the microgel anti-sleeping fluid loss agent of the present invention, the types and proportions of the various components involved are all described in the microgel anti-sliding fluid loss agent of the first aspect. A detailed introduction will not be repeated here.

In another aspect, the present invention also provides the application of the microgel anti-channeling fluid loss agent in deep water surface layer cementing.

Example

The present invention is further illustrated below by means of examples, but the present invention is not limited to the scope of the examples. For the experimental methods not indicating specific conditions in the following examples, follow conventional methods and conditions. The raw materials used in the following examples are all commercially available.

In a water bath at 80°C, 5 g of commercial polyvinyl alcohol with a degree of hydrolysis of 88% and a molecular weight of 100,000 was dissolved in 95 g of deionized water to prepare polyvinyl alcohol with a mass fraction of 5%. Lower the temperature to 50°C, add microgel protective agent, and continue stirring for 15 minutes. Afterwards, add 0.23g concentration and be 25% glutaraldehyde, continue to stir, simultaneously, add a small amount of hydrochloric acid and make its pH value maintain between 3-4, obtain the microgel that crosslinking degree is 0.5%. agent.

Each embodiment weighs several raw materials according to the content in Table 1, and the preparation method is the same as above.

Each embodiment raw material of table 1 and consumption statistical table

It can be seen from the above examples that after adding the microgel protective agent, the viscosity of the product can be significantly reduced, and its viscosity is related to the selected microgel protective agent and the amount added. The lower viscosity is more conducive to the on-site application of the product, especially for deep water cementing, the amount of surface cement slurry is huge, if the product viscosity is low, it can be better suitable for the LAS system (liquid feeding system), greatly reducing on-site labor Strength and improve the efficiency of on-site slurry mixing.

Performance Testing

A cement slurry with a density of 1.90 g·cm ^-3 and a water-cement ratio of 0.44 was prepared using the microgel fluid loss reducer prepared in the above examples. Free liquid, water loss, transition time and other indicators are measured in accordance with the provisions of GB-T 19139-2012 "Oil Well Cement Test Methods", the test temperature is 50 ° C, and the dispersant used is sulfonated aldehyde ketone dispersant, polycarboxylate acid dispersant.

Table 2 Experimental Examples 1 to 5 Cement slurry dehydration, free liquid results statistical table

Note: cement slurry formula: 100 parts by weight of G grade cement + 5 parts by weight of fluid loss reducer (experimental example 1-5) + 1 part by weight of dispersant (sulfonated aldehyde and ketone dispersant, polycarboxylic acid dispersant) + 1 part by weight All defoamers, dispersants and defoamers are produced by COSL Chemical Co., Ltd.

It can be seen from the data in Table 2 that after the cement slurry is prepared by using Example 1 without adding a microgel protective agent, the effect of reducing water loss is not good, and there are many free liquids, especially when the polycarboxylic acid dispersant is used. more obvious. However, after the fluid loss reducing agent added with the microgel protective agent (Experimental Example 3-7) was formulated into cement slurry, the effect of reducing fluid loss was significantly improved. Using dodecylpyrrolidone as the microgel protective agent (Experimental Example 3-6), the free liquid was significantly reduced. However, using lauryl alcohol as the microgel protective agent (Experimental Example 7), although the effect of reducing water loss has been improved to a certain extent, its effect on reducing free liquid is not good. From the above results, it can be seen that the selection and addition of microgel protective agent have a great influence on the water loss and free fluid performance of this type of fluid loss reducer. Transition time can reflect the ability of cement slurry to prevent air channeling. The shorter the transition time, the stronger the anti-air channeling ability. It can be seen from Table 2 that the transition time can be shortened by adding microgel protective agent (experimental example 3-7). Improve the ability of slurry to prevent gas channeling.

The early strength agent is a common admixture in the construction of cement slurry formula. In the actual application process, the early strength agent should have good compatibility with the fluid loss reducer. Commonly used CaCl ₂ is used as the early strength agent, and the formula is constructed for experimental measurement. The experimental temperature is 10°C, and the properties are shown in the table below.

Table 3 Statistical table of experimental examples 8 to 10 cement slurry dehydration and free liquid results

Experimental example fluid loss agent Dispersant Dehydration (mL) Free liquid (mL) 8 Example 1 Polycarboxylate Dispersant 184 1.2 9 Example 1 Sulfonated Aldehyde and Ketone Dispersant 103 0.8 10 Example 2 Polycarboxylate Dispersant 32 0 11 Example 2 Sulfonated Aldehyde and Ketone Dispersant 26 0

Note: Cement slurry formula: 100 parts by weight of grade G cement + 5 parts by weight of fluid loss reducer (experimental example 1-2) + 1 part by weight of dispersant (sulfonated aldehyde and ketone dispersant, polycarboxylic acid dispersant) + 1 part by weight 1 part of CaCl ₂ + 1 part by weight of defoamer, dispersant and defoamer are all produced by COSL Chemical Co., Ltd.

It can be seen from the data in Table 3 that when the cement slurry formula is constructed with the early strength agent CaCl ₂ , the addition of microgel protective agents (experimental examples 10-11) can significantly reduce the water loss and free liquid of the cement slurry.

Compared with the common AMPS fluid loss reducer, the invention has no negative influence on the strength development of cement slurry at low temperature, and thus has stronger applicability in deep water low temperature surface layer cementing. Using the fluid loss reducer of the present invention and AMPS fluid loss reducer commonly used by COSL to prepare cement slurry with a density of 1.90 g·cm ^-3 , the performance comparison is shown in the table below.

Table 4 Statistical table of experimental examples 12 to 15 cement slurry loss of water, free liquid, thickening time, compressive strength and transition time

Note: Cement slurry formula: 100 parts by weight of G grade cement + 5 parts by weight of water loss reducer + 1 part by weight of dispersant (sulfonated aldehyde ketone dispersant) + 1 part by weight of defoamer, AMPS water loss reducer, dispersant , defoamer are produced by COSL Chemical Co., Ltd.

It can be seen from Table 4 that under the condition of similar performance of water loss and free liquid, the thickening time of the cement slurry prepared by the fluid loss reducing agent of the present invention is shorter, the compressive strength is higher, and the transition time is shorter. Under different temperature conditions, the 24h compressive strength of the cement slurry prepared by the fluid loss reducer of the present invention has different degrees of improvement compared with the AMPS fluid loss reducer: at 20°C, it increased by nearly 26%; at 10°C, it increased nearly 44%. The transition time of the cement slurry prepared by the fluid loss reducer of the present invention is shorter at different temperatures, which indicates that it has a stronger ability to prevent gas channeling at low temperatures. To sum up, compared with the AMPS fluid loss reducer, the fluid loss reducer of the present invention is more suitable for deep water surface low temperature environment and deep water environment with shallow air flow.

Based on the above experiments, compared with the commonly used PVA fluid loss reducing agent, the microgel type fluid loss reducing agent of the present invention has the following four advantages: ① better fluidity, more suitable for on-site application; ② better film forming Strong, more excellent water loss reduction and low temperature channeling resistance; ③It can control free liquid, and the prepared cement slurry is not easy to produce free water. ④Compatibility with other admixtures is better, and when used in combination with other admixtures, the film-forming property is not easily affected. Compared with AMPS fluid loss reducer, it has the following two advantages: ①Higher compressive strength at low temperature; ②Excellent anti-channeling performance.

The present invention has been disclosed above with preferred embodiments, but those skilled in the art should understand that these embodiments are only used to describe the present invention, and should not be construed as limiting the scope of the present invention. It should be noted that all changes and replacements equivalent to these embodiments should be considered as falling within the scope of the claims of the present invention. Therefore, the protection scope of the present invention should be determined by the scope defined in the claims.

Claims (10)

1. A microgel channeling-preventing fluid loss agent is characterized by comprising: the weight ratio of the PVA microgel to the microgel protective agent is 1 (0.1-2.0).

2. The microgel channeling-preventing and fluid loss reducing agent as claimed in claim 1, wherein the weight ratio of the PVA microgel to the microgel protective agent is 1 (0.5-1.5).

3. The microgel channeling-preventing and fluid loss reducing agent as claimed in claim 2, wherein the weight ratio of the PVA microgel to the microgel protective agent is 1 (0.8-1.2).

4. The microgel channeling-preventing and reducing agent according to any one of claims 1 to 3, wherein the crosslinking agent of the PVA microgel is glutaraldehyde, and the degree of crosslinking of the PVA microgel is 0.1 to 0.8%.

5. The microgel channeling-preventing and fluid-loss-reducing agent according to any one of claims 1 to 3, wherein the microgel protecting agent is a surfactant having a polar group.

6. The microgel channeling-preventing fluid loss additive as claimed in claim 5, wherein the microgel protective agent comprises styrene derivatives, alkoxylated alcohols, N-alkylpyrrolidones, N-alkyl alcohols, dodecanol.

7. The method for preparing a microgel channeling-preventing fluid loss additive as set forth in any one of claims 1 to 6, which comprises:

(1) Under the heating condition, dissolving polyvinyl alcohol in deionized water to obtain a polyvinyl alcohol aqueous solution;

(2) Adding a micro-gel protective agent into the polyvinyl alcohol aqueous solution, and stirring;

(3) Adding a cross-linking agent solution, adding acid to adjust the pH value to 3-4, and stirring to obtain the microgel channeling-preventing fluid loss agent.

8. The method for preparing a microgel channeling-preventing fluid loss additive according to claim 7, wherein the heating temperature in step (1) is 60-90 ℃; the heating temperature in the steps (2) and (3) is 40-60 ℃.

9. The method for preparing a microgel channeling-preventing fluid loss additive according to claim 7, wherein the concentration of the polyvinyl alcohol aqueous solution is 3-7%; the concentration of the cross-linking agent solution is 15-30%.

10. Use of a microgel channeling-preventing fluid loss additive as defined in any one of claims 1 to 9 in deep water surface cementing.