Viscosity reducer for CO32-pollution-resistant polymer drilling fluid as well as preparation method and application of viscosity reducer

Abstract

The invention provides a viscosity reducer for a CO3 < 2-> pollution resistant polymer drilling fluid as well as a preparation method and application of the viscosity reducer. The viscosity reducer for the CO3 < 2-> pollution resistant polymer drilling fluid is prepared from the following raw materials in parts by mass: 5 to 20 parts of sulfonated tannin, 5 to 15 parts of 2-acrylamido-2-methylpropanesulfonic acid, 1 to 10 parts of itaconic acid, 40 to 60 parts of isopentenol polyoxyethylene ether, 0.05 to 0.1 part of an initiator, 0.01 to 0.1 part of a chain transfer agent and 100 to 200 parts of water. The viscosity reducer provided by the invention can solve the problems of thickening of drilling fluid, increase of viscosity and shearing force and the like after CO3 < 2-> invasion.

Description

Technical Field

[0001] The present invention belongs to the technical field of drilling fluid treatment agents, and particularly relates to a viscosity reducer for polymer drilling fluid resistant to CO 3 2- pollution, its preparation method and application. Background Art

[0002] With the increasing demand for world oil resources and the continuous exploitation of the proven oil geological reserves, the exploration of complex formations has been continuously strengthened. Due to the complexity of the formations, during the drilling process, various pollutants (H 2 S, CO 2 etc.) from the formations often invade the drilling fluid, causing its performance to change in a manner that does not meet the construction requirements, affecting the rheological properties and filtration properties of the drilling fluid, and exacerbating the damage and corrosion of the drill tools.

[0003] As the "blood" of drilling, drilling fluid plays important roles such as stabilizing the wellbore, suspending cuttings, cooling the drill bit, and increasing the mechanical drilling rate. It is an irreplaceable circulating fluid that satisfies the inside of the drilling. However, when CO 2 invades the drilling fluid, it will increase the concentration of CO 3 2- ions, resulting in a sharp increase in the viscosity and shear force of the drilling fluid, which must be treated in a timely manner. Under normal circumstances, there is currently no fast and effective treatment method for severely contaminated drilling fluid, and it is often treated by replacing the contaminated slurry, which also causes huge losses to the drilling operation. At the same time, the discarded contaminated drilling fluid also brings huge environmental protection pressure.

[0004] At present, there are many reports on viscosity reducers for increasing the viscosity and shear force of drilling fluid. For example, Chinese patent document CN118406476A discloses a viscosity reducer for high-temperature and calcium-resistant drilling fluid. The invention uses block oligomers, hydroxycitrates, sodium hydroxymethyl sulfonate, compound polyols, tetrabutyl titanate, and a co-solvent as raw materials, with a high temperature resistance of over 220°C and excellent calcium resistance. Chinese patent document CN115404053A discloses a preparation method of an organosilicon viscosity reducer. The invention uses 2-acrylamide-2-methylpropanesulfonic acid, hyperbranched polymers, nano-titanium oxide, and condensed water as raw materials, and has excellent viscosity reduction effect in the base slurry aged at 150°C. However, there are few reports on viscosity reducers for drilling fluid under CO 2 pollution conditions.

[0005] Therefore, developing a viscosity reducer for drilling fluid suitable for CO 3 2- pollution conditions is of great significance for the deterioration of the rheological properties of drilling fluid after CO 3 2- pollution. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the present invention provides a viscosity reducer for anti-CO 3 2- polluted polymer drilling fluid and its preparation method and application. The viscosity reducer of the present invention can solve the problems such as the thickening of drilling fluid, the increase of viscosity and shear force after CO 3 2- invasion.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A viscosity reducer for anti-CO 3 2- polluted polymer drilling fluid is prepared from the following raw materials in parts by mass: 5-20 parts of sulfonated tannin (SMT), 5-15 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 1-10 parts of itaconic acid (IA), 40-60 parts of isopentenyl alcohol polyoxyethylene ether, 0.05-0.1 part of initiator, 0.01-0.1 part of chain transfer agent, and 100-200 parts of water.

[0009] Preferably according to the present invention, the viscosity reducer for anti-CO 3 2- polluted polymer drilling fluid is prepared from the following raw materials in parts by mass: 7-15 parts of sulfonated tannin (SMT), 8-12 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 2-7 parts of itaconic acid (IA), 45-50 parts of isopentenyl alcohol polyoxyethylene ether, 0.06-0.08 part of initiator, 0.02-0.03 part of chain transfer agent, and 120-180 parts of water.

[0010] Preferably, the viscosity reducer for anti-CO 3 2- polluted polymer drilling fluid is prepared from the following raw materials in parts by mass: 10 parts of sulfonated tannin (SMT), 10 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 5 parts of itaconic acid (IA), 48 parts of isopentenyl alcohol polyoxyethylene ether, 0.068 part of initiator, 0.024 part of chain transfer agent, and 150 parts of water.

[0011] Preferably according to the present invention, the isopentenyl alcohol polyoxyethylene ether is TPEG-2400, TPEG-3000 or TPEG-4000.

[0012] Preferably according to the present invention, the initiator is azobisisobutyronitrile (AIBN) or azobis(2-methylpropionamidine) dihydrochloride (AIBA).

[0013] Preferably according to the present invention, the chain transfer agent is n-dodecyl mercaptan or 3-mercaptopropionic acid.

[0014] The above anti-CO 3 2- Preparation method of viscosity reducer for polymer drilling fluid contaminated by CO, comprising the following steps:

[0015] Disperse sulfonated tannin (SMT), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), itaconic acid (IA), and isopentenol polyoxyethylene ether in water to obtain a monomer mixture; after heating to the reaction temperature, add an initiator, and add a chain transfer agent dropwise after reacting for 3-5 h. After the dropwise addition is completed, continue to react for 0.5-1 h; after the reaction is completed, adjust the pH to obtain an anti-CO 3 2- Viscosity reducer for polymer drilling fluid contaminated by CO.

[0016] Preferably according to the present invention, the initiator is added dropwise into the system in the form of an initiator aqueous solution, and the dropping rate is 1-2 drops / s; the concentration of the initiator aqueous solution is 2-3 mg / mL.

[0017] Preferably according to the present invention, the reaction temperature is 50-75 °C, and the reaction is carried out under the protection of a protective gas and stirring by a stirrer. Preferably, the protective gas is nitrogen or argon.

[0018] Preferably according to the present invention, the pH is adjusted to 7-9 using an aqueous sodium hydroxide solution with a mass fraction of 15-25%.

[0019] The above anti-CO 3 2- Application of viscosity reducer for polymer drilling fluid contaminated by CO, used as a viscosity reducer in CO 3 2- Contaminated drilling fluid to reduce the viscosity and shear force of the drilling fluid.

[0020] The technical features and beneficial effects of the present invention are as follows:

[0021] 1. The monomers used in the present invention are common, the synthesis process is simple, the reaction conditions are easy to control, and the prepared viscosity reducer

[0022] has a low cost.

[0023] 2. The present invention has a strong viscosity reduction ability in drilling fluid, strong anti-CO 3 2- contamination ability, can compete with CO 3 2- for competitive adsorption, reduce the apparent viscosity, plastic viscosity, etc. of the drilling fluid system, and greatly improve the drilling efficiency.

[0024] 3. 2-Acrylamido-2-methylpropanesulfonic acid added in the present invention can provide sulfonic acid groups and has strong adsorption ability. It reacts with CO 3 2-Competitive adsorption occurs; the addition of itaconic acid and sulfonated tannin improves the temperature resistance of the viscosity reducer, and at the same time, the addition of sulfonated tannin can improve the viscosity reduction performance; the selected isopentenyl alcohol polyoxyethylene ether can improve the hydration and dispersion of clay, and has good rheological regulation and filtration loss reduction properties.

[0025] 4. The 2-acrylamido-2-methylpropanesulfonic acid added in the present invention contains the group -SO 3 Na, which can dissociate in water to form a diffusion double layer, increase the negative charge on the surface of clay particles and increase the thickness of the hydration film, break up the structure formed by clay particles, and play a role in reducing viscosity and shear force.

[0026] 5. The drilling fluid viscosity reducer obtained in the present invention contains sulfonic acid groups and carboxyl groups, etc., which can be adsorbed on the surface of clay through electrostatic adsorption to form a relatively thick hydration film, so that the clay particles repel each other, prevent particle aggregation and flocculation, and form a network structure, which has a certain stabilizing effect on the drilling fluid; and the cyclic structure in the molecular chain has strong thermal stability, so that the viscosity reducer still has good flow stability at high temperatures. Specific embodiments

[0027] The present invention will be further described below through specific examples, but it is not limited thereto.

[0028] The experimental methods described in the examples are all conventional methods unless otherwise specified; the reagents and materials used can be obtained from commercial sources unless otherwise specified.

[0029] The sulfonated tannin used in the examples is available from Guangdong Wengjiang Chemical Reagent Co., Ltd., and the model is PA90843.

[0030] Example 1

[0031] An anti-CO 3 2- Preparation method of viscosity reducer for contaminated polymer drilling fluid, including the following steps:

[0032] 1) Add 10 g of sulfonated tannin, 10 g of 2-acrylamido-2-methylpropanesulfonic acid, 5 g of itaconic acid, 48 g of isopentenyl alcohol polyoxyethylene ether (TPEG-2400) and 120 g of deionized water into a three-necked round-bottom flask and stir to obtain a monomer mixture; heat the above three-necked round-bottom flask to 65 °C and pass nitrogen for 30 min;

[0033] 2) Mix 68 mg of azodiisobutyramidine hydrochloride and 30 mL of deionized water, stir for 10 min to obtain an initiator aqueous solution, and drop it into the three-necked round-bottom flask at a dropping rate of 1 drop per second;

[0034] 3) After the addition of the initiator aqueous solution is completed, under nitrogen protection and at 65 °C, stir and react for 3.5 h, then add 24 mg of 3-mercaptopropionic acid dropwise to the system at a dropping rate of 1 drop per second; after the addition is completed, continue to stir and react for 0.5 h under nitrogen protection and at 65 °C;

[0035] 4) After the reaction is completed and naturally cooled to room temperature, adjust the pH value to 7 using a 20% sodium hydroxide aqueous solution, and the obtained product is the viscosity reducer for anti-CO 3 2- polluted polymer drilling fluid.

[0036] Example 2

[0037] A method for preparing a viscosity reducer for anti-CO 3 2- polluted polymer drilling fluid is as described in Example 1, except that isopentenyl alcohol polyoxyethylene ether TPEG-2400 is replaced with TPEG-3000; other steps or conditions are the same as in Example 1.

[0038] Example 3

[0039] A method for preparing a viscosity reducer for anti-CO 3 2- polluted polymer drilling fluid is as described in Example 1, except that 3-mercaptopropionic acid is replaced with n-dodecyl mercaptan; other steps or conditions are the same as in Example 1.

[0040] Example 4

[0041] A method for preparing a viscosity reducer for anti-CO 3 2- polluted polymer drilling fluid is as described in Example 1, except that the dosage of 3-mercaptopropionic acid is 48 mg; other steps or conditions are the same as in Example 1.

[0042] Comparative Example 1

[0043] A method for preparing a viscosity reducer for anti-CO 3 2- polluted polymer drilling fluid is as described in Example 1, except that in step 3), after the addition of the initiator aqueous solution is completed, add 24 mg of 3-mercaptopropionic acid dropwise to the system at a dropping rate of 1 drop per second, and stir and react for 4 h under nitrogen protection and at 65 °C; other steps or conditions are the same as in Example 1.

[0044] Comparative Example 2

[0045] A method for preparing a viscosity reducer for anti-CO 3 2-The preparation method of the viscosity reducer for contaminated polymer drilling fluid is as described in Example 1, except that: in step 3), 3-mercaptopropionic acid is not added; other steps or conditions are the same as those in Example 1.

[0046] Comparative Example 3

[0047] An anti-CO 3 2- The preparation method of the viscosity reducer for contaminated polymer drilling fluid is as in Example 1, except that: in step 1), 2-acrylamido-2-methylpropanesulfonic acid is replaced by sodium methallylsulfonate; other steps or conditions are the same as those in Example 1.

[0048] Comparative Example 4

[0049] An anti-CO 3 2- The preparation method of the viscosity reducer for contaminated polymer drilling fluid is as described in Example 1, except that: in step 4), sodium hydroxide aqueous solution is not added to adjust the pH; other steps or conditions are the same as those in Example 1.

[0050] Comparative Example 5

[0051] An anti-CO 3 2- The preparation method of the viscosity reducer for contaminated polymer drilling fluid is as in Example 1, except that: in step 1), itaconic acid is replaced by maleic anhydride; other steps or conditions are the same as those in Example 1.

[0052] Comparative Example 6

[0053] An anti-CO 3 2- The preparation method of the viscosity reducer for contaminated polymer drilling fluid is as described in Example 1, except that: sulfonated tannin is replaced by gallic acid; other steps or conditions are the same as those in Example 1.

[0054] Comparative Example 7

[0055] An anti-CO 3 2- The preparation method of the viscosity reducer for contaminated polymer drilling fluid is as described in Example 1, except that: itaconic acid is replaced by benzoic acid; other steps or conditions are the same as those in Example 1.

[0056] Comparative Example 8

[0057] An amphoteric ion viscosity reducer XY27 for industrial use.

[0058] Test Example 1

[0059] The rheological properties of the viscosity reducers prepared in the examples and comparative examples were tested.

[0060] (1) Sample preparation:

[0061] The drilling fluid composition is as follows: Take 400 mL of 4% drilling fluid base slurry (520 g of bentonite and 18.2 g of sodium carbonate added to 1300 mL of water), add 1.2 g of low-viscosity sodium carboxymethyl cellulose, 1.2 g of polyanionic cellulose, 0.6 g of potassium polyacrylate, 500 g of barite, 16 g of sodium carbonate (4%), and 8 g of the viscosity reducer in the example or comparative example to the drilling fluid base slurry, and stir well for 60 min on a high-speed stirrer (rotation speed: 8000 r / min). Use barite to adjust the density of the drilling fluid to 1.8 kg / m 3 , and obtain the sample; test its rheological properties after aging and cooling at room temperature and 180 °C, and use the drilling fluid without adding the viscosity reducer as a comparison at the same time.

[0062] (2) Test method:

[0063] Take a certain amount of the prepared sample and pour it into the test slurry cup, and use an electronic six-speed viscometer to record θ 600 、θ 300 、θ 200 、θ 100 、θ 6 、θ 3 readings.

[0064] Determination of rheology, and the test results are shown in Table 1-2.

[0065] Table 1 Performance test of the viscosity reducer for drilling fluid at room temperature

[0066]

[0067] Table 2 Performance test of the viscosity reducer for drilling fluid at 180 °C

[0068]

[0069]

[0070] It can be seen from the data in Table 1-2 that the viscosity reducer for drilling fluid prepared by the present invention shows good viscosity reduction performance both at room temperature and after aging at 180 °C, and has good temperature resistance.

[0071] In summary, the viscosity reducer for CO 3 2- -polluted polymer-based drilling fluid of the present invention can meet the needs of CO 3 2- pollution.

[0072] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0073] In addition, it should be noted that, in the various specific technical features described in the above specific embodiments, they can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0074] Furthermore, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. Anti-CO3 2- A viscosity reducer for contaminated polymer drilling fluid, characterized in that: The preparation method comprises the following raw materials in parts by weight: 5-20 parts of sulfonated tannin, 5-15 parts of 2-acrylamide-2-methylpropanesulfonic acid, 1-10 parts of itaconic acid, 40-60 parts of isopentanol polyoxyethylene ether, 0.05-0.1 parts of initiator, 0.01-0.1 parts of chain transfer agent and 100-200 parts of water.

2. The method according to claim 1 for resisting CO3 2- A viscosity reducer for contaminated polymer drilling fluid, characterized in that: The anti-CO3 2- A viscosity reducer for contaminated polymer drilling fluid is prepared by including the following raw materials in parts by weight: 7-15 parts of sulfonated tannin, 8-12 parts of 2-acrylamido-2-methylpropanesulfonic acid, 2-7 parts of itaconic acid, 45-50 parts of isopentanol polyoxyethylene ether, 0.06-0.08 parts of initiator, 0.02-0.03 parts of chain transfer agent, and 120-180 parts of water; Preferably, the anti-CO3 2- The viscosity reducer for contaminated polymer drilling fluid is prepared by including the following raw materials in parts by weight: 10 parts of sulfonated tannin, 10 parts of 2-acrylamido-2-methylpropane sulfonic acid, 5 parts of itaconic acid, 48 parts of isopentanol polyoxyethylene ether, 0.068 parts of initiator, 0.024 parts of chain transfer agent and 150 parts of water.

3. The method according to claim 1 for resisting CO3 2- A viscosity reducer for contaminated polymer drilling fluid, characterized in that: The isopentanol polyoxyethylene ether is TPEG-2400, TPEG-3000 or TPEG-4000.

4. The method according to claim 1 for resisting CO3 2- A viscosity reducer for contaminated polymer drilling fluid, characterized in that: The initiator is azobisisobutyronitrile or azobisisobutylamidine hydrochloride.

5. The method of claim 1 for resisting CO3 2- A viscosity reducer for contaminated polymer drilling fluid, characterized in that: The chain transfer agent is n-dodecyl mercaptan or 3-mercaptopropionic acid.

6. The anti-CO3 of claim 1 2- The preparation method of the viscosity reducer for contaminated polymer drilling fluid comprises the following steps: Disperse sulfonated tannin, 2-acrylamido-2-methylpropanesulfonic acid, itaconic acid and isopentanol polyoxyethylene ether in water to obtain a monomer mixture; after heating to the reaction temperature, add an initiator, and dropwise add a chain transfer agent after reacting for 3-5 hours. After the dropwise addition is completed, continue the reaction for 0.5-1 hour; after the reaction is completed, adjust the pH to obtain an anti-CO3 2- Viscosity reducer for contaminated polymer drilling fluids.

7. The method of claim 6 for resisting CO3 2- A method for preparing a viscosity reducer for contaminated polymer drilling fluid, characterized in that: The initiator is added dropwise into the system in the form of an initiator aqueous solution at a dropping rate of 1-2 drops / s; the concentration of the initiator aqueous solution is 2-3 mg / mL.

8. The method of claim 6 for resisting CO3 2- A method for preparing a viscosity reducer for contaminated polymer drilling fluid, characterized in that: The reaction temperature is 50-75° C., and the reaction is carried out under the protection of a protective gas and stirring with a stirrer. Preferably, the protective gas is nitrogen or argon.

9. The method of claim 6 for resisting CO3 2- A method for preparing a viscosity reducer for contaminated polymer drilling fluid, characterized in that: The pH value is adjusted to 7-9 using a sodium hydroxide aqueous solution with a mass fraction of 15-25%.

10. The anti-CO3 of claim 1 2- The application of viscosity reducer for contaminated polymer drilling fluid is characterized in that: Used as a viscosity reducer in CO3 2- Contaminated drilling fluid to reduce the viscosity and shear force of the drilling fluid.

Images