Anti-pollution agent for cementing and preparation method thereof

Abstract

The application relates to the field of oilfield development drilling technology, and discloses a cementing anti-pollution agent and a preparation method thereof. The cementing anti-pollution agent comprises the following components in mass fraction: 30-50 parts of a chelating agent, 1-3 parts of a pH regulator, 1-3 parts of a surfactant, 0.2-0.5 parts of a defoaming agent, 10-20 parts of a methoxy aromatic compound and 100 parts of water. Through the technical scheme, the problem that cement slurry is easily polluted by drilling fluid in cementing engineering in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of oilfield development drilling technology, specifically to a cementing anti-fouling agent and its preparation method. Background Technology

[0002] Cementing is a crucial step in the construction of oil and gas wells, comprising two production processes: casing installation and cementing. The basic cementing process involves cementing and displacement using a double-plug method. After drilling to the predetermined depth, the drill string is retrieved and casing is run to the bottom of the well. At this point, the drilling fluid used to clean cuttings from the drilling fluid remains in the well. During the process of replacing the drilling fluid with cement slurry, the cement slurry comes into contact with the drilling fluid, thus becoming contaminated.

[0003] When cement slurry is contaminated by drilling fluid, it leads to: ① decreased fluidity, increased viscosity and dynamic shear stress; ② the formation of viscous substances that adhere to the casing and wellbore, creating stagnant zones; and ③ a significant decrease in the compressive strength and interfacial bonding strength of the solidified cement paste. Therefore, it is urgent to research an anti-contamination agent to prevent cement slurry from being contaminated by drilling fluid. Summary of the Invention

[0004] This invention proposes an anti-contamination agent for cementing and its preparation method, which solves the problem that cement slurry is easily contaminated by drilling fluid in cementing engineering in related technologies.

[0005] The technical solution of the present invention is as follows: A cementing antifouling agent comprises the following components in parts by weight: 30-50 parts chelating agent, 1-3 parts pH adjuster, 1-3 parts surfactant, 0.2-0.5 parts defoamer, 10-20 parts methoxy aromatic compound, and 100 parts water.

[0006] As a further technical solution, the methoxy aromatic compounds include one or more of 2-methoxythiophene, 3-methoxythiophene, and 1-methoxynaphthalene.

[0007] As a further technical solution, the mass ratio of the chelating agent to the methoxy aromatic compound is 40:12~17.

[0008] This invention limits the mass ratio of chelating agent and methoxy aromatic compound to 40:12~17, which further improves the antifouling ability of the antifouling agent.

[0009] As a further technical solution, the methoxy aromatic compound is 1-methoxynaphthalene.

[0010] As a further technical solution, the chelating agent includes one or more of disodium ethylenediaminetetraacetate, sodium tartrate, and sodium citrate.

[0011] As a further technical solution, the pH adjuster includes one or more of sodium hydroxide, potassium hydroxide, and sodium carbonate.

[0012] As a further technical solution, the surfactant is a nonionic surfactant.

[0013] As a further technical solution, the nonionic surfactant includes one or both of AEO-9 and OP-10.

[0014] As a further technical solution, the defoamer includes one or two of silicone defoamers and polyether defoamers.

[0015] The present invention also proposes a method for preparing an anti-fouling agent for cementing, comprising the following steps: mixing the components in the specified mass fractions evenly to obtain the anti-fouling agent.

[0016] The working principle and beneficial effects of this invention are as follows: 1. This invention provides an anti-fouling agent for cementing, comprising a chelating agent, a pH adjuster, a surfactant, a defoamer, a methoxy aromatic compound, and water. It has good anti-fouling effect and effectively solves the problem of cement slurry being easily contaminated by drilling fluid in cementing engineering in the prior art.

[0017] 2. This invention, by adding methoxy aromatic compounds, delays the thickening time of contaminants and improves their resistance to contamination. The main reason is that the mechanism of cement slurry contamination lies in the production of Ca(OH)₂ during hydration. After dissolving in water, Ca(OH)₂ provides calcium ions. These divalent calcium ions displace monovalent sodium ions adsorbed on the clay surface, converting sodium clay into calcareous clay, which is less prone to dissociation. This reduces the repulsive force between clay particles, leading to clay aggregation and coarsening of the particles. Simultaneously, the degree of hydration decreases, forming viscous, flocculent clumps. The methoxy groups and aromatic structures in methoxy aromatic compounds can adsorb calcium ions, thereby inhibiting the exchange between calcium and sodium ions and preventing the formation of calcareous clay. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] In the following examples and comparative examples, the water loss reducing agent GT-11LH and the silicone defoamer GT-60L were produced by our company.

[0020] Example 1 Mix 30 parts of disodium ethylenediaminetetraacetate, 5 parts of sodium tartrate, 5 parts of sodium citrate, 2 parts of AEO-9, 10 parts of 2-methoxythiophene, and 100 parts of water until homogeneous. Then add 1 part of sodium hydroxide and 1 part of sodium carbonate and continue stirring. Finally, add 0.3 parts of organosilicon defoamer GT-60L and stir until homogeneous to obtain an antifouling agent.

[0021] Example 2 Mix 20 parts of disodium ethylenediaminetetraacetate, 10 parts of sodium tartrate, 1 part of OP-10, 10 parts of 3-methoxythiophene, and 100 parts of water until homogeneous. Add 1 part of potassium hydroxide and continue stirring. Finally, add 0.2 parts of polyether defoamer 571 and stir until homogeneous to obtain the antifouling agent.

[0022] Example 3 Mix 35 parts of disodium ethylenediaminetetraacetate, 15 parts of sodium citrate, 3 parts of OP-10, 6 parts of 2-methoxythiophene, 4 parts of 3-methoxythiophene, and 100 parts of water until homogeneous. Then add 1 part of potassium hydroxide and 2 parts of sodium carbonate and continue stirring. Finally, add 0.5 parts of polyether defoamer 571 and stir until homogeneous to obtain the antifouling agent.

[0023] Example 4 Mix 30 parts of disodium ethylenediaminetetraacetate, 5 parts of sodium tartrate, 5 parts of sodium citrate, 2 parts of AEO-9, 12 parts of 2-methoxythiophene, and 100 parts of water until homogeneous. Then add 1 part of sodium hydroxide and 1 part of sodium carbonate and continue stirring. Finally, add 0.3 parts of organosilicon defoamer GT-60L and stir until homogeneous to obtain an antifouling agent.

[0024] Example 5 Mix 30 parts of disodium ethylenediaminetetraacetate, 5 parts of sodium tartrate, 5 parts of sodium citrate, 2 parts of AEO-9, 15 parts of 2-methoxythiophene, and 100 parts of water until homogeneous. Then add 1 part of sodium hydroxide and 1 part of sodium carbonate and continue stirring. Finally, add 0.3 parts of organosilicon defoamer GT-60L and stir until homogeneous to obtain an antifouling agent.

[0025] Example 6 Mix 30 parts of disodium ethylenediaminetetraacetate, 5 parts of sodium tartrate, 5 parts of sodium citrate, 2 parts of AEO-9, 17 parts of 2-methoxythiophene, and 100 parts of water until homogeneous. Then add 1 part of sodium hydroxide and 1 part of sodium carbonate and continue stirring. Finally, add 0.3 parts of organosilicon defoamer GT-60L and stir until homogeneous to obtain an antifouling agent.

[0026] Example 7 Mix 30 parts of disodium ethylenediaminetetraacetate, 5 parts of sodium tartrate, 5 parts of sodium citrate, 2 parts of AEO-9, 20 parts of 2-methoxythiophene, and 100 parts of water until homogeneous. Then add 1 part of sodium hydroxide and 1 part of sodium carbonate and continue stirring. Finally, add 0.3 parts of organosilicon defoamer GT-60L and stir until homogeneous to obtain an antifouling agent.

[0027] Example 8 Mix 30 parts of disodium ethylenediaminetetraacetate, 5 parts of sodium tartrate, 5 parts of sodium citrate, 2 parts of AEO-9, 15 parts of 1-methoxynaphthalene, and 100 parts of water until homogeneous. Then add 1 part of sodium hydroxide and 1 part of sodium carbonate and continue stirring. Finally, add 0.3 parts of organosilicon defoamer GT-60L and stir until homogeneous to obtain the antifouling agent.

[0028] Comparative Example 1 Mix 30 parts of disodium ethylenediaminetetraacetate, 5 parts of sodium tartrate, 5 parts of sodium citrate, 2 parts of AEO-9, and 100 parts of water until homogeneous. Then add 1 part of sodium hydroxide and 1 part of sodium carbonate and continue stirring. Finally, add 0.3 parts of organosilicon defoamer GT-60L and stir until homogeneous to obtain the antifouling agent.

[0029] Performance testing: While stirring, dissolve 2 parts of carboxymethyl cellulose in 100 parts of water, add 50 parts of 325-mesh iron ore powder, 3 parts of OP-10, GT-11LH (a water loss reducer), and 2 parts of the antifouling agent obtained in Examples 1-8 or Comparative Example 1. Stir at 2000 r / min for 3 min, add 0.3 parts of organosilicon defoamer GT-60L, and continue stirring to mix evenly to obtain the isolation liquid.

[0030] (1) Flushing performance: Remove the rotating outer cylinder of the rotational viscometer and weigh it W0. Rotate the outer cylinder in drilling fluid at 300 rpm for 10 minutes to coat its outer wall with drilling fluid. Let it stand for 1 minute and weigh it again as W1. Immerse the outer cylinder of the rotational viscometer coated with drilling fluid in the isolation fluid and flush it at 300 rpm for 5 minutes. Let it stand for 1 minute and weigh the outer cylinder as W2. The flushing efficiency η is calculated according to the following formula, and 3 sets of parallel tests are conducted and the average value is taken. η=(W2- W0)÷(W1- W0)×100% η - Flushing efficiency; W0 - Mass of the outer cylinder of the rotational viscometer, in grams (g); W1 - The mass of the outer cylinder of the rotational viscometer after it is filled with drilling fluid, in grams (g); W2 - Mass of the outer cylinder of the rotary viscometer after rinsing, in grams (g).

[0031] (2) Thickening time: The prepared isolation fluid, cement slurry, and drilling fluid were mixed at a mass ratio of cement slurry: isolation fluid: drilling fluid = 70:20:10. After curing at normal pressure for 30 min, the rheological parameters of the mixture were measured. The thickening time of the mixture was measured under the conditions of temperature of 80℃, pressure of 40MPa, and heating time of 40 min. The measurement method refers to GB / T 19139-2012.

[0032] When the mass ratio of cement slurry: separator fluid: drilling fluid is 100:0:0, the thickening time is 120 minutes. When the mass ratio of cement slurry:isolator:drilling fluid is 50:0:50, severe flocculation will occur. The results are recorded in Table 1.

[0033] Table 1 Performance Test Results

[0034] As can be seen from Table 1, after adding the anti-fouling agent provided by the present invention, the flushing efficiency is above 96.08%, the thickening time is >284, which delays the thickening time of the cement slurry and drilling fluid system, and greatly ensures the safety of cementing construction, and has a good anti-fouling effect.

[0035] Compared to Comparative Example 1, Examples 1-8 included methoxy aromatic compounds, while Comparative Example 1 did not. The rinsing efficiency and thickening time after adding the antifouling agents provided in Examples 1-8 were higher than those in Comparative Example 1. This indicates that adding methoxy aromatic compounds can delay the thickening time of the contaminant and improve the antifouling ability of the antifouling agent.

[0036] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cementing anti-fouling agent, characterized in that, The product comprises the following components in parts by weight: 30-50 parts chelating agent, 1-3 parts pH adjuster, 1-3 parts surfactant, 0.2-0.5 parts defoamer, 10-20 parts methoxy aromatic compound, and 100 parts water, wherein the methoxy aromatic compound includes one or more of 2-methoxythiophene, 3-methoxythiophene, and 1-methoxynaphthalene.

2. The anti-fouling agent for cementing according to claim 1, characterized in that, The mass ratio of the chelating agent to the methoxy aromatic compound is 40:12~17.

3. The anti-fouling agent for cementing according to claim 2, characterized in that, The methoxy aromatic compound is 1-methoxynaphthalene.

4. The anti-fouling agent for cementing according to claim 1, characterized in that, The chelating agent includes one or more of disodium ethylenediaminetetraacetate, sodium tartrate, and sodium citrate.

5. The anti-fouling agent for cementing according to claim 1, characterized in that, The pH adjuster includes one or more of sodium hydroxide, potassium hydroxide, and sodium carbonate.

6. The anti-fouling agent for cementing according to claim 1, characterized in that, The surfactant is a nonionic surfactant.

7. The anti-fouling agent for cementing according to claim 6, characterized in that, The nonionic surfactant includes one or both of AEO-9 and OP-10.

8. The anti-fouling agent for cementing according to claim 1, characterized in that, The defoamer includes one or both of the following: silicone defoamers and polyether defoamers.

9. A method for preparing a cementing anti-fouling agent according to any one of claims 1 to 8, characterized in that, Includes the following steps: The components in the specified mass fractions are mixed evenly to obtain an anti-fouling agent.

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