Polyacrylamide coating agent for drilling fluid and preparation method thereof

Abstract

The invention relates to the technical field of drilling fluid treating agents, and provides a polyacrylamide coating agent for drilling fluid and a preparation method of the polyacrylamide coating agent. The polyacrylamide coating agent for the drilling fluid is prepared from the following raw material components in parts by weight: 45 to 85 parts of acrylamide, 25 to 35 parts of methacrylic acid, 15 to 20 parts of disodium ethylene diamine tetraacetate, 10 to 30 parts of potassium phthalimide, 10 to 20 parts of potassium hydroxide, 0.5 to 1.5 parts of initiator, 4 to 18 parts of surfactant, 0.8 to 1.5 parts of chain transfer agent and 150 parts of water. According to the technical scheme, the problem of poor rock debris coating effect of the polyacrylamide coating agent for the drilling fluid in related technologies is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling fluid treatment agents, and specifically, to a polyacrylamide coating agent for drilling fluid and a preparation method thereof. Background Art

[0002] In recent years, with the increasing demand for oil and gas resources, some conventional resources have been exhausted, and the era of unconventional oil and gas resources has arrived. With the increase in the scale of oil and gas exploitation, the exploitation difficulty of oil and gas resources has increased, and the formation conditions encountered have become more complex. The phenomenon of formation hydration often occurs. In these complex situations, the inhibition performance of drilling fluid is particularly important. The coating agent is one of the main additives used in drilling fluid, which can provide inhibition for drilling fluid. The coating agent can be used to inhibit the dispersion of drill cuttings and has a stabilizing effect on the wellbore, maintaining the stability of the drilling fluid and the stability of the drilling operation environment. At present, the coating agents used in drilling fluid are usually some macromolecular polymers, which have good applications under certain conditions but also have defects. The existing coating agents have limited coating effects on cuttings and poor inhibition effects on the hydration of some minerals in the wellbore, and cannot maintain a stable coating effect, thus affecting the overall performance of the drilling fluid. Therefore, improving the coating effect of the coating agent for drilling fluid on cuttings is a technical problem that needs to be solved urgently at present. Summary of the Invention

[0003] The present invention provides a polyacrylamide coating agent for drilling fluid and a preparation method thereof, which solves the problem of poor coating effect of the polyacrylamide coating agent for drilling fluid on cuttings in the related art.

[0004] The technical solution of the present invention is as follows: The present invention provides a polyacrylamide coating agent for drilling fluid, and the raw materials include the following components in parts by weight: 45 - 85 parts of acrylamide, 25 - 35 parts of methacrylic acid, 15 - 20 parts of disodium ethylenediaminetetraacetate, 10 - 30 parts of potassium phthalimide, 10 - 20 parts of potassium hydroxide, 0.5 - 1.5 parts of initiator, 4 - 18 parts of surfactant, 0.8 - 1.5 parts of chain transfer agent, and 150 parts of water.

[0005] As a further technical solution, the weight ratio of acrylamide to potassium phthalimide is 3 - 4:1.

[0006] When the weight ratio of acrylamide to potassium phthalimide is 3 - 4:1, the coating effect of the polyacrylamide coating agent for drilling fluid on cuttings can be further improved.

[0007] As a further technical solution, the raw materials further include 4 - 8 parts of tetrahydrofurfuryl methacrylate.

[0008] The inventors found that in the presence of tetrahydrofurfuryl methacrylate, through the effective action of tetrahydrofurfuryl methacrylate, acrylamide, and potassium phthalimide, the coating effect of the polyacrylamide coating agent for drilling fluid on cuttings can be further improved. It is speculated that the reason may be that tetrahydrofurfuryl methacrylate can further promote the binding of potassium phthalimide and acrylamide, thereby further promoting the adsorption of the polyacrylamide coating agent for drilling fluid on drill cuttings, inhibiting the dispersion of drill cuttings, and further improving the coating effect of the polyacrylamide coating agent for drilling fluid on cuttings.

[0009] As a further technical solution, the weight ratio of the potassium phthalimide to the tetrahydrofurfuryl methacrylate is 4 - 5:1.

[0010] When the weight ratio of the potassium phthalimide to the tetrahydrofurfuryl methacrylate is 4 - 5:1, the coating effect of the polyacrylamide coating agent for drilling fluid on cuttings can be further improved.

[0011] As a further technical solution, the initiator is one or more of potassium persulfate, ammonium persulfate, azobisisobutyramidine hydrochloride, and azobisisobutyramidine hydrochloride.

[0012] As a further technical solution, the surfactant is an anionic surfactant, and the anionic surfactant includes one or two of sodium dodecylbenzenesulfonate and α-olefin sulfonate.

[0013] As a further technical solution, the chain transfer agent is one or more of mercaptoacetic acid, mercaptoethanol, and tert-dodecyl mercaptan.

[0014] The present invention also provides a preparation method of the polyacrylamide coating agent for drilling fluid, comprising the following steps: S1. Mix the remaining components except potassium hydroxide, initiator, and chain transfer agent to obtain a mixed solution; S2. Add the initiator and the chain transfer agent to the mixed solution for blending, carry out a first reaction under a nitrogen atmosphere, add the potassium hydroxide, and carry out a second reaction to obtain the polyacrylamide coating agent for drilling fluid.

[0015] As a further technical solution, in step S2, during the first reaction, the temperature is 50 - 60°C and the time is 2 - 4 h.

[0016] As a further technical solution, in step S2, during the second reaction, the temperature is 60 - 85°C and the time is 1 - 3 h.

[0017] The working principle and beneficial effects of the present invention are as follows: In the present invention, through the effective action of each raw material component, under the action of an initiator and a chain transfer agent, a polyacrylamide coating agent for drilling fluid with good coating effect on drill cuttings is obtained. Among them, potassium phthalimide is introduced. Through the effective action of potassium phthalimide and acrylamide, and by optimizing the combined ratio, the formed polyacrylamide coating agent for drilling fluid can effectively inhibit the dispersion of drill cuttings, thereby maintaining the stability of the drilling fluid and significantly improving the coating effect of the polyacrylamide coating agent for drilling fluid on cuttings. Detailed implementation mode

[0018] The following will combine the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

[0019] Example 1 A polyacrylamide coating agent for drilling fluid, the raw materials include the following components in parts by weight: 45 parts of acrylamide, 25 parts of methacrylic acid, 15 parts of disodium ethylenediaminetetraacetate, 10 parts of potassium phthalimide, 10 parts of potassium hydroxide, 0.5 part of ammonium persulfate, 4 parts of α-olefin sulfonate, 0.8 part of mercaptoethanol, 150 parts of water; Its preparation method includes the following steps: S1. Mix acrylamide, methacrylic acid, disodium ethylenediaminetetraacetate, potassium phthalimide, α-olefin sulfonate and water to obtain a mixed solution; S2. Add ammonium persulfate and mercaptoethanol to the mixed solution and blend. Carry out the first reaction in a nitrogen atmosphere at 50°C for 4 hours. Then add potassium hydroxide and carry out the second reaction at 60°C for 3 hours to obtain the polyacrylamide coating agent for drilling fluid.

[0020] Example 2 A polyacrylamide coating agent for drilling fluid, the raw materials include the following components in parts by weight: 75 parts of acrylamide, 30 parts of methacrylic acid, 18 parts of disodium ethylenediaminetetraacetate, 27 parts of potassium phthalimide, 15 parts of potassium hydroxide, 1 part of ammonium persulfate, 10 parts of α-olefin sulfonate, 1.1 parts of mercaptoethanol, 150 parts of water; Its preparation method includes the following steps: S1. Mix acrylamide, methacrylic acid, disodium ethylenediaminetetraacetate, potassium phthalimide, α-olefin sulfonate and water to obtain a mixed solution; S2. Add ammonium persulfate and mercaptoethanol to the mixed solution and blend them. Conduct the first reaction under a nitrogen atmosphere at 55 °C for 3 h. Then add potassium hydroxide and conduct the second reaction at 70 °C for 2 h to obtain the polyacrylamide coating agent for drilling fluid.

[0021] Example 3 A polyacrylamide coating agent for drilling fluid, the raw materials comprising the following components in parts by weight: 85 parts of acrylamide, 35 parts of methacrylic acid, 20 parts of disodium ethylenediaminetetraacetate, 30 parts of potassium phthalimide, 20 parts of potassium hydroxide, 1.5 parts of ammonium persulfate, 18 parts of α-olefin sulfonate, 1.5 parts of mercaptoethanol, 150 parts of water; Its preparation method comprises the following steps: S1. Mix acrylamide, methacrylic acid, disodium ethylenediaminetetraacetate, potassium phthalimide, α-olefin sulfonate and water to obtain a mixed solution; S2. Add ammonium persulfate and mercaptoethanol to the mixed solution and blend them. Conduct the first reaction under a nitrogen atmosphere at 60 °C for 2 h. Then add potassium hydroxide and conduct the second reaction at 85 °C for 1 h to obtain the polyacrylamide coating agent for drilling fluid.

[0022] Example 4 The difference between this example and Example 2 is only that in this example, the added potassium phthalimide is 15 parts.

[0023] Example 5 The difference between this example and Example 2 is only that in this example, the added potassium phthalimide is 25 parts.

[0024] Example 6 The difference between this example and Example 2 is only that in this example, the added potassium phthalimide is 18.75 parts.

[0025] Example 7 The difference between this example and Example 5 is only that in this example, it further comprises tetrahydrofurfuryl methacrylate, and the added tetrahydrofurfuryl methacrylate is 4 parts; The preparation method of the polyacrylamide coating agent for drilling fluid comprises the following steps: S1. Mix acrylamide, methacrylic acid, disodium ethylenediaminetetraacetate, potassium phthalimide, α-olefin sulfonate, tetrahydrofurfuryl methacrylate and water to obtain a mixed solution; S2. Add ammonium persulfate and mercaptoethanol to the mixed solution, perform a first reaction in a nitrogen atmosphere at 55° C. for 3 hours, add potassium hydroxide, perform a second reaction at 70° C. for 2 hours, and obtain a polyacrylamide coating agent for drilling fluid.

[0026] Example 8 The difference between this embodiment and embodiment 7 is that, in this embodiment, 8 parts of tetrahydrofurfuryl methacrylate are added.

[0027] Example 9 The only difference between this embodiment and embodiment 7 is that in this embodiment, 5 parts of tetrahydrofurfuryl methacrylate are added.

[0028] Example 10 The only difference between this embodiment and embodiment 7 is that in this embodiment, 6.25 parts of tetrahydrofurfuryl methacrylate are added.

[0029] Comparative Example 1 The only difference between this comparative example and Example 1 is that in this comparative example, potassium phthalimide was not added.

[0030] The drilling fluids prepared in Examples 1 to 10 and Comparative Example 1 were subjected to the following performance tests using a polyacrylamide coating agent: ① Cuttings recovery rate: Add the drilling fluid polyacrylamide coating agent sample to water to form a 0.2wt% drilling fluid polyacrylamide coating agent aqueous solution, add 50g cuttings (particle size 10 mesh) to 300mL drilling fluid polyacrylamide coating agent aqueous solution, heat roll at 150℃ for 16h, pass through a 40-mesh sieve, rinse, dry the cuttings, weigh them, and calculate the cuttings recovery rate according to the following formula: Cuttings recovery rate (%) = 40-mesh sieve undersize / 50×100%; ② Core expansion: Bentonite was used to press artificial cores according to the shale expansion test standard requirements, and the shale expansion test was carried out on a shale expansion instrument. The 15h expansion was measured in a sodium chloride brine system with a mass fraction of 10%. The test results are shown in Table 1 below: Table 1 Cuttings recovery rate and expansion test results

[0031] Compared with Comparative Example 1, the cuttings recovery rate of Example 1 is significantly improved and the core expansion is significantly reduced, indicating that when potassium phthalimide is introduced into the polyacrylamide coating agent for drilling fluid, the coating effect of the polyacrylamide coating agent for drilling fluid on cuttings can be significantly improved.

[0032] Compared with Examples 2 and 4, the cuttings recovery rate of Examples 5 to 6 is increased, and the core swelling amount is decreased, indicating that when the weight ratio of acrylamide to potassium phthalimide is 3 to 4:1, the coating effect of the polyacrylamide coating agent for drilling fluid on cuttings can be further improved.

[0033] Compared with Example 5, the cuttings recovery rate of Examples 7 to 10 is increased, and the core swelling amount is decreased, indicating that when the raw material of the polyacrylamide coating agent for drilling fluid further includes tetrahydrofurfuryl methacrylate, through the effective action of tetrahydrofurfuryl methacrylate, acrylamide, and potassium phthalimide, the coating effect of the polyacrylamide coating agent for drilling fluid on cuttings can be further improved. In addition, compared with Examples 7 to 8, the cuttings recovery rate of Examples 9 to 10 is increased, and the core swelling amount is decreased, indicating that when the weight ratio of potassium phthalimide to tetrahydrofurfuryl methacrylate is 4 to 5:1, the coating effect of the polyacrylamide coating agent for drilling fluid on cuttings can be further improved.

[0034] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A polyacrylamide coating agent for drilling fluid, characterized in that The raw materials include the following components in parts by weight: 45 - 85 parts of acrylamide, 25 - 35 parts of methacrylic acid, 15 - 20 parts of disodium ethylenediaminetetraacetate, 10 - 30 parts of potassium phthalimide, 10 - 20 parts of potassium hydroxide, 0.5 - 1.5 parts of initiator, 4 - 18 parts of surfactant, 0.8 - 1.5 parts of chain transfer agent, and 150 parts of water.

2. The polyacrylamide coating agent for drilling fluid according to claim 1, wherein The weight ratio of the acrylamide to the potassium phthalimide is 3 - 4:

1.

3. A polyacrylamide coating agent for drilling fluid according to claim 1, characterized in that, The raw materials further include 4 - 8 parts of tetrahydrofurfuryl methacrylate.

4. The polyacrylamide coating agent for drilling fluid according to claim 3, wherein, The weight ratio of the potassium phthalimide to the tetrahydrofurfuryl methacrylate is 4 - 5:

1.

5. A polyacrylamide coating agent for drilling fluid according to claim 1, characterized in that, The initiator is one or more of potassium persulfate, ammonium persulfate, azodiisobutyramidine hydrochloride, and azodiisobimidazoline hydrochloride.

6. The polyacrylamide coating agent for drilling fluid according to claim 1, characterized in that, The surfactant is an anionic surfactant, and the anionic surfactant includes one or two of sodium dodecylbenzenesulfonate and α-olefin sulfonate.

7. The polyacrylamide coating agent for drilling fluid according to claim 1, characterized in that, The chain transfer agent is one or more of mercaptoacetic acid, mercaptoethanol, and tert-dodecyl mercaptan.

8. The preparation method of a polyacrylamide coating agent for drilling fluid according to any one of claims 1 to 7, characterized in that, It includes the following steps: S1. Mix the remaining components except potassium hydroxide, initiator, and chain transfer agent to obtain a mixed solution. S2. Add the initiator and the chain transfer agent to the mixed solution for blending, conduct a first reaction under a nitrogen atmosphere, add the potassium hydroxide, and conduct a second reaction to obtain a polyacrylamide coating agent for drilling fluid.

9. The preparation method of a polyacrylamide coating agent for drilling fluid according to claim 8, characterized in that, In step S2, during the first reaction, the temperature is 50 - 60°C and the time is 2 - 4 h.

10. The preparation method of a polyacrylamide coating agent for drilling fluid according to claim 8, wherein, In step S2, during the second reaction, the temperature is 60 - 85°C and the time is 1 - 3 h.

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