Preparation method and application of low-density cement slurry anti-pollution agent

Abstract

This invention relates to a method for preparing a low-density cement slurry antifouling agent, comprising the following steps: 1. Raw material preparation: weighing a predetermined weight of organophosphonic acid, organic ester, and initiator; 2. Organophosphonic acid solution preparation: dissolving the weighed organophosphonic acid in water, heating to a predetermined temperature, and adjusting the pH value of the solution to a predetermined value; 3. Antifouling agent preparation: adding the weighed initiator to the organophosphonic acid solution, dissolving it, then adding the weighed organic ester, stirring to dissolve, subsequently cooling the solution, and adjusting the pH value to neutral to obtain the antifouling agent. The advantages of this invention are: the preparation method is simple; the obtained low-density cement slurry antifouling agent, when added to cement slurry, can react with cement hydration products, preventing drilling fluid from contaminating the cement slurry, improving the antifouling ability of the cement slurry; the application method is convenient, simplifying the cementing process and reducing the cost per well.

Description

Technical Field

[0001] This invention relates to the field of oil well cement admixture technology, and in particular to a method for preparing and applying a low-density cement slurry anti-fouling agent. Background Technology

[0002] Currently, during cementing operations, cement slurry and drilling fluid often mix, leading to contact contamination. The hazards of contact contamination between cement slurry and drilling fluid are mainly manifested in the following ways: reduced slurry fluidity, affecting displacement efficiency; increased pump pressure, potentially causing leakage in weak formations and affecting cementing quality; a drastically shortened thickening time compared to pure cement slurry, leading to engineering accidents such as "sausage filling" or "flagpole insertion"; and altered cement hydration process, affecting cement stone interface bonding.

[0003] During cementing operations, the contamination of cement slurry by drilling fluid has seriously affected oil production. How to control and reduce the harm of contact contamination between cement slurry and drilling fluid, especially its impact on thickening time, has become a topic of widespread concern in the petroleum industry.

[0004] Currently, the third phase of the Fuman Oilfield on the south bank of the Tarim River in the Tarim Oilfield uses methyl polysulfonate drilling fluid, and the cement slurry lead is 1.30-1.40 g / cm³. 3 The low-density cement slurry system in this block suffers from severe cement slurry contamination. The thickening time of the mixed slurry in almost all wells is shorter than that of the cement slurry, seriously affecting construction safety. The main solutions to this contamination problem are injecting a section of bentonite slurry between the drilling fluid and the isolation fluid, while simultaneously increasing the amount of isolation fluid to ensure effective isolation; additionally, admixtures such as retarders and drag reducers are added to the isolation fluid to address the contamination issue.

[0005] However, these solutions all have certain drawbacks and limitations. For example, although bentonite slurry contains relatively few additives and its performance can meet the requirements during cementing operations, its impact after cementing is unknown. Furthermore, increasing the amount of placer fluid increases the cost per well. Additionally, while adding retarders and other additives to the placer fluid can solve the contamination problem, it may lead to prolonged cement slurry thickening time and slow cement stone strength development after mixing.

[0006] Therefore, the currently used technologies for solving cement slurry drilling fluid contact contamination mainly address the problem from the perspective of process design, without fundamentally solving the issue. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for preparing a low-density cement slurry anti-fouling agent, comprising:

[0008] Step 1: Raw material preparation, weigh the predetermined weight of organophosphonic acid, organic ester and initiator;

[0009] Step 2: Preparation of organophosphonic acid solution. Dissolve the weighed organophosphonic acid in water, heat to the preset temperature, and adjust the pH value of the solution to the preset value.

[0010] Step 3: Preparation of antifouling agent. The weighed initiator is added to the organophosphonic acid solution and dissolved. Then, the weighed organic ester is added and stirred to dissolve. The solution is then cooled and the pH value is adjusted to neutral to obtain the antifouling agent.

[0011] Furthermore, the organophosphonic acid is an aminophosphonic acid or an alkylphosphonic acid, and the organophosphonic acid has a mass fraction of 10 parts, with a solution concentration of 9%-10%.

[0012] Furthermore, the organic ester is an oxalate or a nitrate, and its mass fraction is 6-8 parts.

[0013] Furthermore, the initiator is ammonium persulfate, and its mass fraction is 0.09-0.11 parts.

[0014] Furthermore, in step two, the preset temperature is 70-80℃.

[0015] Furthermore, in step two, the pH value is 2.0-3.0.

[0016] Furthermore, in step three, the stirring time is 30 minutes.

[0017] The present invention discloses a method for preparing a low-density cement slurry anti-fouling agent. The beneficial technical effects of the obtained low-density cement slurry anti-fouling agent are as follows: When added to cement slurry, the low-density cement slurry anti-fouling agent reacts with cement hydration products, preventing drilling fluid from contaminating the cement slurry and improving its anti-fouling ability; the low-density cement slurry anti-fouling agent can be directly added to the slurry mixing water, making operation convenient and dosage easy to control, greatly facilitating on-site construction; when added to cement slurry, bentonite slurry does not need to be injected between the isolation fluid and drilling fluid, while reducing the amount of isolation fluid, simplifying the cementing process and reducing the cost per well; the low-density cement slurry anti-fouling agent can be applied to areas with a density less than 1.60 g / cm³. 3 The cement slurry system is highly compatible with various admixture systems, does not affect the performance of cement slurry, and has a wide applicable temperature range, applicable between 90℃ and 150℃.

[0018] In another aspect, the present invention discloses the application of a low-density cement slurry anti-fouling agent, wherein the anti-fouling agent prepared by any of the above methods is added to a cement slurry system used for cementing.

[0019] Furthermore, the amount of the low-density cement slurry anti-fouling agent added is 0.5-2.0% of the weight of the cement slurry.

[0020] Furthermore, the applicable temperature range for the low-density cement slurry anti-fouling agent is between 90℃ and 150℃.

[0021] Furthermore, the low-density cement slurry anti-fouling agent is used for cement slurries with a density of less than 1.60 g / cm³. 3 In the cement slurry system.

[0022] In summary, the beneficial technical effects of this invention are as follows: this low-density cement slurry anti-fouling agent can be applied to slurries with a density of less than 1.60 g / cm³. 3 The cement slurry system is highly compatible with various admixture systems, does not affect the performance of cement slurry, and has a wide applicable temperature range, applicable between 90℃ and 150℃. Attached Figure Description

[0023] The above and other objects, features, and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings. The drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0024] Figure 1 This is a schematic diagram of the preparation method of the present invention. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0026] Reference Figure 1The present invention discloses a method for preparing a low-density cement slurry antifouling agent, comprising the following steps: Step 1, raw material preparation: weighing a predetermined weight of organophosphonic acid, organic ester, and initiator; Step 2, organophosphonic acid solution preparation: dissolving the weighed organophosphonic acid in water, heating to a predetermined temperature, and adjusting the pH value of the solution to a predetermined value; Step 3, antifouling agent preparation: adding the weighed initiator to the organophosphonic acid solution, dissolving it, then adding the weighed organic ester, stirring to dissolve, subsequently cooling the solution, and adjusting the pH value to neutral to obtain the antifouling agent. In this embodiment, the organophosphonic acid is aminophosphonic acid or alkylphosphonic acid, and the mass fraction of the organophosphonic acid is 10 parts, with a solution concentration of 9%-10%. In this embodiment, the organic ester is oxalate ester or nitrate ester, and its mass fraction is 6-8 parts.

[0027] In this embodiment, the initiator is ammonium persulfate, and its mass fraction is 0.09-0.11 parts.

[0028] In this embodiment, the preset temperature in step two is 70-80℃.

[0029] In this embodiment, in step two, the pH value is 2.0-3.0.

[0030] In this embodiment, the stirring time in step three is 30 minutes.

[0031] On the other hand, this embodiment also discloses the application of a low-density cement slurry anti-fouling agent, which involves adding the anti-fouling agent prepared by any of the above methods into the cement slurry system used for cementing.

[0032] In this embodiment, the amount of the low-density cement slurry anti-fouling agent added is 0.5-2.0% of the weight of the cement slurry.

[0033] In this embodiment, the applicable temperature range of the low-density cement slurry anti-pollution agent is between 90℃ and 150℃.

[0034] In this embodiment, the low-density cement slurry anti-fouling agent is used for materials with a density less than 1.60 g / cm³. 3 In the cement slurry system.

[0035] In summary, the beneficial technical effects of this invention are as follows: this low-density cement slurry anti-fouling agent can be applied to slurries with a density of less than 1.60 g / cm³. 3 The cement slurry system is highly compatible with various admixture systems, does not affect the performance of cement slurry, and has a wide applicable temperature range, applicable between 90℃ and 150℃.

[0036] The most preferred embodiment of the preparation method of the low-density cement slurry anti-fouling agent of the present invention is as follows:

[0037] Example 1

[0038] Take 10g of aminophosphonic acid, dissolve it in 110g of water to obtain a concentration of 9%, heat it to 70℃, add hydrochloric acid to adjust the pH to 2.0, add 0.1g of ammonium persulfate, and after the ammonium persulfate dissolves, add 8.0g of oxalate while stirring, keep it for 30min, cool it to 30℃, and add sodium hydroxide solution dropwise until the pH is neutralized to 7.0 to obtain a low-density cement slurry anti-pollution agent.

[0039] In Example 1 of this invention, a low-density cement slurry anti-fouling agent, designated G01, is added to an area with a density less than 1.60 g / cm³. 3 The anti-pollution performance of the cement slurry system was evaluated, and the results are shown in Table 1.

[0040] Table 1 Evaluation of G01's anti-pollution performance

[0041]

[0042] Example 2

[0043] Take 10g of aminophosphonic acid, dissolve it in 110g of water to obtain a concentration of 9%, heat it to 70℃, add hydrochloric acid to adjust the pH to 2.0, add 0.1g of ammonium persulfate, and after the ammonium persulfate dissolves, add 7.0g of oxalate while stirring, keep it for 30min, cool it to 30℃, and add sodium hydroxide solution dropwise until the pH is neutralized to 7.0 to obtain a low-density cement slurry anti-pollution agent.

[0044] In Example 2 of this invention, a low-density cement slurry anti-fouling agent, designated G02, is added to an area with a density less than 1.60 g / cm³. 3 The anti-pollution performance of the cement slurry system was evaluated, and the results are shown in Table 2.

[0045] Table 2 Evaluation of the anti-pollution performance of G02

[0046]

[0047]

[0048] Example 3

[0049] Take 10g of aminophosphonic acid, dissolve it in 100g of water to obtain a concentration of 10%, heat it to 70℃, add hydrochloric acid to adjust the pH to 2.0, add 0.1g of ammonium persulfate, and after the ammonium persulfate dissolves, add 6.0g of oxalate while stirring, maintain for 30min, cool down to 30℃, and add sodium hydroxide solution dropwise until the pH is neutralized to 7.0 to obtain a low-density cement slurry anti-pollution agent.

[0050] In Example 3 of this invention, a low-density cement slurry anti-fouling agent, designated G03, is added to an area with a density less than 1.60 g / cm³. 3 The anti-pollution performance of the cement slurry system was evaluated, and the results are shown in Table 3.

[0051] Table 3 Evaluation of the anti-pollution performance of G03

[0052]

[0053] Example 4

[0054] Take 10g of alkylphosphonic acid, dissolve it in 110g of water to obtain a concentration of 9%, heat it to 70℃, add hydrochloric acid to adjust the pH to 3.0, add 0.1g of ammonium persulfate, and after the ammonium persulfate dissolves, add 8.0g of oxalate while stirring, keep it for 30min, cool it to 30℃, and add sodium hydroxide solution dropwise until the pH is neutralized to 7.0 to obtain a low-density cement slurry anti-pollution agent.

[0055] In Example 4 of this invention, a low-density cement slurry anti-fouling agent, designated G04, is added to an area with a density less than 1.60 g / cm³. 3 The anti-pollution performance of the cement slurry system was evaluated, and the results are shown in Table 4.

[0056] Table 4 Evaluation of G04's Anti-pollution Performance

[0057]

[0058] In summary, the above embodiments demonstrate that the preparation method of the low-density cement slurry anti-fouling agent disclosed in this invention has the following beneficial technical effects: When added to cement slurry, the low-density cement slurry anti-fouling agent reacts with cement hydration products, preventing drilling fluid from contaminating the cement slurry and improving its anti-fouling ability; the low-density cement slurry anti-fouling agent can be directly added to the slurry mixing water, making operation convenient and dosage easy to control, greatly facilitating on-site construction; when added to cement slurry, bentonite slurry does not need to be injected between the isolation fluid and drilling fluid, reducing the amount of isolation fluid, simplifying the cementing process, and lowering the cost per well; the low-density cement slurry anti-fouling agent can be applied to cement slurry systems with a density less than 1.60 g / cm³, has strong compatibility with various admixture systems, does not affect cement slurry performance, and has a wide applicable temperature range of 90℃-150℃.

[0059] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0060] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a low-density cement slurry anti-fouling agent, characterized in that, Including the following step: Step 1: Raw material preparation, weigh the predetermined weight of organophosphonic acid, organic ester and initiator; Step 2: Preparation of organophosphonic acid solution. Dissolve the weighed organophosphonic acid in water, heat to the preset temperature, and adjust the pH value of the solution to the preset value. Step 3, preparation of antifouling agent: Add the weighed initiator to the organophosphonic acid solution, dissolve it, then add the weighed organic ester, stir to dissolve, then cool the solution and adjust the pH value to neutral to obtain the antifouling agent; In step one, the mass fractions of the organophosphonic acid, organic ester, and initiator weighed are 10 parts, 6-8 parts, and 0.09-0.11 parts, respectively.

2. The method for preparing the low-density cement slurry anti-fouling agent according to claim 1, characterized in that: The organophosphonic acid is an aminophosphonic acid or an alkylphosphonic acid, and the concentration of its solution is 9%-10%.

3. The method for preparing the low-density cement slurry anti-fouling agent according to claim 1, characterized in that: The organic ester is an oxalate or a nitrate.

4. The method for preparing the low-density cement slurry anti-fouling agent according to claim 1, characterized in that: The initiator is ammonium persulfate.

5. The method for preparing the low-density cement slurry anti-fouling agent according to claim 1, characterized in that: In step two, the preset temperature is 70-80℃.

6. The method for preparing the low-density cement slurry anti-fouling agent according to claim 1, characterized in that, In step two, the pH value is 2.0-3.

0.

7. The method for preparing the low-density cement slurry anti-fouling agent according to claim 1, characterized in that: In step three, the stirring time is 30 minutes.

8. The application of a low-density cement slurry anti-fouling agent, characterized in that, The anti-fouling agent prepared by any one of claims 1-7 is added to the cement slurry system used for cementing.

9. The application of the low-density cement slurry anti-fouling agent according to claim 8, characterized in that: The amount of the low-density cement slurry anti-pollution agent added is 0.5-2.0% of the weight of the cement slurry.

10. The application of the low-density cement slurry anti-fouling agent according to claim 8, characterized in that: The applicable temperature range for the low-density cement slurry anti-fouling agent is between 90℃ and 150℃.

11. The application of the low-density cement slurry anti-fouling agent according to claim 8, characterized in that, The low-density cement slurry anti-fouling agent is used for materials with a density less than 1.60 g / cm³. 3 In the cement slurry system.

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