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

Abstract

The invention relates to a preparation method of a low-density cement paste anti-pollution agent, which comprises the following steps: 1, preparing raw materials: weighing organic phosphonic acid, organic ester and an initiator with preset weight; 2, preparing an organic phosphonic acid solution, dissolving the weighed organic phosphonic acid in water, heating to a preset temperature, and adjusting the pH value of the solution to a preset value; and 3, preparing the anti-pollution agent, namely adding the weighed initiator into the organic phosphonic acid solution, dissolving, adding the weighed organic ester, stirring to dissolve, cooling the solution, and adjusting the pH value to be neutral, thereby obtaining the anti-pollution agent. The low-density cement paste anti-pollution agent has the advantages that the preparation method is simple, the obtained low-density cement paste anti-pollution agent can react with cement hydration products after being added into cement paste, pollution of drilling fluid to the cement paste is prevented, the anti-pollution capacity of the cement paste is improved, the application method is simple and convenient, the well cementation technological process is simplified, and the single well cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of oil well cement admixtures, in particular to a preparation method and application of a low-density cement slurry anti-pollution agent. Background Art

[0002] At present, during cementing construction, cement slurry and drilling fluid often mix and contact contamination occurs. The hazards of contact contamination between cement slurry and drilling fluid are mainly manifested in the decrease of slurry fluidity, which affects the displacement efficiency. At the same time, it may also increase the pump pressure, leak weak formations, and affect the cementing quality; the thickening time of slurry is sharply shortened compared with pure cement slurry, resulting in engineering accidents such as "sausage filling" or "flag pole planting"; the cement hydration process changes, affecting the cement-stone interface bonding, etc.

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

[0004] At present, the third opening of Fuman Oilfield on the south bank of Tahe River in Tarim Oilfield uses methyl polysulfone drilling fluid, and the cement slurry is 1.30-1.40g / cm 3 The low-density cement slurry system in this area has a serious cement slurry pollution problem. The thickening time of the slurry mixed in almost all wells is shorter than the thickening time of the cement slurry, which seriously affects the construction safety. The method to solve the pollution problem in this area is mainly to inject a section of bentonite slurry between the drilling fluid and the isolation fluid, and increase the amount of isolation fluid to ensure the isolation effect; in addition, add retarders, drag reducers and other additives to the isolation fluid to solve the pollution problem.

[0005] However, these solutions all have certain shortcomings and limitations. For example, although bentonite slurry contains fewer admixtures and its performance can meet the requirements during cementing construction, the impact after cementing is unknown. At the same time, increasing the amount of spacer fluid increases the cost of a single well. In addition, adding admixtures such as retarders to the spacer fluid can solve the pollution problem, but it may also lead to problems such as prolonged cement slurry thickening time and slow cement stone strength development after mixing.

[0006] Therefore, from the perspective of the currently commonly used technologies for solving cement slurry drilling fluid contact contamination, the problem is mainly solved from the perspective of process design, but the problem is not fundamentally solved. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention provides a method for preparing a low-density cement slurry anti-pollution agent, comprising:

[0008] Step 1: Prepare raw materials by weighing preset weights of organic phosphonic acid, organic ester and initiator;

[0009] Step 2: preparing an organic phosphonic acid solution, dissolving the weighed organic phosphonic acid in water, heating to a preset temperature, and adjusting the pH value of the solution to a preset value;

[0010] Step three, preparation of the anti-pollution agent, adding the weighed initiator into the organic phosphonic acid solution, adding the weighed organic ester after dissolving, stirring to dissolve, then cooling the solution, adjusting the pH value to neutral, and obtaining the anti-pollution agent.

[0011] Furthermore, the organic phosphonic acid is aminophosphoric acid or alkylphosphonic acid, and the mass fraction of the organic phosphonic acid is 10 parts, and the concentration of the solution is 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 the step 2, the preset temperature is 70-80°C.

[0015] Furthermore, in the step 2, the pH value is 2.0-3.0.

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

[0017] The invention discloses a method for preparing a low-density cement slurry anti-pollution agent. The obtained low-density cement slurry anti-pollution agent has the following beneficial technical effects: the low-density cement slurry anti-pollution agent is added to cement slurry to react with cement hydration products, thereby preventing drilling fluid from polluting the cement slurry and improving the anti-pollution ability of the cement slurry; the low-density cement slurry anti-pollution agent can be directly added to the slurry preparation water, which is convenient to operate and easy to control the amount of addition, greatly facilitating on-site construction; the low-density cement slurry anti-pollution agent is added to the cement slurry, and bentonite slurry does not need to be injected between the spacer fluid and the drilling fluid, while reducing the amount of the spacer fluid, simplifying the cementing process and reducing the cost per well; the low-density cement slurry anti-pollution agent can be applied to cement slurries with a density of less than 1.60 g / cm 3 The cement slurry system has strong compatibility with a variety of admixture systems, does not affect the performance of the cement slurry, and has a wide applicable temperature range, which can be used between 90℃-150℃.

[0018] Another aspect of the present invention discloses the use of a low-density cement slurry anti-pollution agent, wherein the anti-pollution agent prepared by any of the above methods is added to a cement slurry system for cementing.

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

[0020] Furthermore, the low-density cement slurry anti-pollution agent has an applicable temperature range of 90°C-150°C.

[0021] Furthermore, the low-density cement slurry anti-pollution agent is used for cement slurry with a density of less than 1.60 g / cm 3 in cement slurry system.

[0022] In summary, the beneficial technical effects of the present invention are: the low-density cement slurry anti-pollution agent can be applied to cement slurries with a density of less than 1.60 g / cm 3 The cement slurry system has strong compatibility with a variety of admixture systems, does not affect the performance of the cement slurry, and has a wide applicable temperature range, which can be used between 90℃-150℃. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings. The accompanying drawings are only used for the purpose of illustrating the preferred embodiment mode and are not to be considered as limiting the present invention. In addition, the same reference symbols are used to represent the same components throughout the accompanying drawings.

[0024] Figure 1 It is a schematic diagram of the steps of the preparation method of the present invention. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0026] Reference Figure 1The present invention discloses a method for preparing a low-density cement slurry anti-pollution agent, comprising the following steps: step 1, raw material preparation, weighing preset weights of organic phosphonic acid, organic ester and initiator; step 2, organic phosphonic acid solution preparation, dissolving the weighed organic phosphonic acid in water, heating to a preset temperature, and adjusting the pH value of the solution to a preset value; step 3, anti-pollution agent preparation, adding the weighed initiator to the organic phosphonic acid solution, adding the weighed organic ester after dissolution, stirring to dissolve, then cooling the solution, adjusting the pH value to neutral, and obtaining the anti-pollution agent. In this embodiment, the organic phosphonic acid is aminophosphonic acid or alkylphosphonic acid, and the mass fraction of the organic phosphonic acid is 10 parts, and the concentration of its solution is 9%-10%. In this embodiment, the organic ester is oxalate or nitrate, and the 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, in the step 2, the preset temperature is 70-80°C.

[0029] In this embodiment, in the step 2, the pH value is 2.0-3.0.

[0030] In this embodiment, in step 3, the stirring time is 30 minutes.

[0031] On the other hand, this embodiment also discloses the use of a low-density cement slurry anti-pollution agent, in which the anti-pollution agent prepared by any of the above methods is added to a cement slurry system for cementing.

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

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

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

[0035] In summary, the beneficial technical effects of the present invention are: the low-density cement slurry anti-pollution agent can be applied to cement slurries with a density of less than 1.60 g / cm 3 The cement slurry system has strong compatibility with a variety of admixture systems, does not affect the performance of the cement slurry, and has a wide applicable temperature range, which can be used between 90℃-150℃.

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

[0037] Example 1

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

[0039] Example 1 of the present invention, the low-density cement slurry anti-pollution agent is coded as G01, and is added to a cement slurry having a density of less than 1.60 g / cm 3 The anti-pollution performance was evaluated in the cement slurry system. The results are shown in Table 1.

[0040] Table 1G01 Anti-pollution performance evaluation

[0041]

[0042] Example 2

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

[0044] The low-density cement slurry anti-pollution agent of Example 2 of the present invention is coded as G02, and is added to a cement slurry having a density of less than 1.60 g / cm 3 The anti-pollution performance was evaluated in the cement slurry system, and the results are shown in Table 2.

[0045] Table 2G02 Anti-pollution performance evaluation

[0046]

[0047]

[0048] Example 3

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

[0050] The low-density cement slurry anti-pollution agent of Example 3 of the present invention is coded as G03, and is added to a cement slurry having a density of less than 1.60 g / cm 3 The anti-pollution performance was evaluated in the cement slurry system, and the results are shown in Table 3.

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

[0052]

[0053] Example 4

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

[0055] The low-density cement slurry anti-pollution agent of Example 4 of the present invention is coded as G04, and is added to a cement slurry having a density of less than 1.60 g / cm 3 The anti-pollution performance was evaluated in the cement slurry system, and the results are shown in Table 4.

[0056] Table 4G04 Anti-pollution performance evaluation

[0057]

[0058] From the above embodiments, it can be seen that the invention discloses a method for preparing a low-density cement slurry anti-pollution agent, and the obtained low-density cement slurry anti-pollution agent has the following beneficial technical effects: the low-density cement slurry anti-pollution agent is added to the cement slurry, and can react with cement hydration products to prevent the drilling fluid from polluting the cement slurry and improve the anti-pollution ability of the cement slurry; the low-density cement slurry anti-pollution agent can be directly added to the slurry mixing water, which is easy to operate and easy to control the amount of addition, greatly facilitating on-site construction; the low-density cement slurry anti-pollution agent is added to the cement slurry, and bentonite slurry does not need to be injected between the isolation fluid and the 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-pollution agent can be applied to cement slurry systems with a density of less than 1.60g / cm3, has strong compatibility with a variety of admixture systems, does not affect the performance of the cement slurry, and has a wide applicable temperature range, which can be applied between 90°C and 150°C.

[0059] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0060] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

Claims

1. A method for preparing a low-density cement slurry anti-pollution agent, characterized in that: The steps include: Step 1: Prepare raw materials by weighing preset weights of organic phosphonic acid, organic ester and initiator; Step 2: preparing an organic phosphonic acid solution, dissolving the weighed organic phosphonic acid in water, heating to a preset temperature, and adjusting the pH value of the solution to a preset value; Step three, preparation of the anti-pollution agent, adding the weighed initiator into the organic phosphonic acid solution, adding the weighed organic ester after dissolving, stirring to dissolve, then cooling the solution, adjusting the pH value to neutral, and obtaining the anti-pollution agent.

2. The method for preparing the low-density cement slurry anti-pollution agent according to claim 1, characterized in that: The organic phosphonic acid is aminophosphoric acid or alkylphosphonic acid, and the mass fraction of the organic phosphonic acid is 10 parts, and the concentration of the solution is 9%-10%.

3. The method for preparing the low-density cement slurry anti-pollution agent according to claim 1, characterized in that: The organic ester is an oxalate or a nitrate, and the mass fraction of the organic ester is 6-8 parts.

4. The method for preparing the low-density cement slurry anti-pollution agent according to claim 1, characterized in that: The initiator is ammonium persulfate, and its mass fraction is 0.09-0.11 parts.

5. The method for preparing the low-density cement slurry anti-pollution agent according to claim 1, characterized in that: In the step 2, the preset temperature is 70-80°C.

6. The method for preparing the low-density cement slurry anti-pollution agent according to claim 1, characterized in that: In the step 2, the pH value is 2.0-3.

0.

7. The method for preparing the low-density cement slurry anti-pollution agent according to claim 1, characterized in that: In the step 3, the stirring time is 30 minutes.

8. Application of a low-density cement slurry anti-pollution agent, characterized in that: The anti-pollution agent prepared by the method according to any one of claims 1 to 7 is added to a cement slurry system for cementing.

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

10. The use of the low-density cement slurry anti-pollution agent according to claim 8, characterized in that: The low-density cement slurry anti-pollution agent is applicable to a temperature range of 90°C to 150°C.

11. The use of the low-density cement slurry anti-pollution agent according to claim 8, characterized in that: The low-density cement slurry anti-pollution agent is used for cement slurry with a density of less than 1.60 g / cm 3 in cement slurry system.

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