Carbon dioxide pollution resistant diluent for drilling fluid and preparation method and application thereof

Abstract

The application provides a drilling fluid anti-carbon dioxide pollution diluent and a preparation method and application thereof. The drilling fluid anti-carbon dioxide pollution diluent is prepared from the following raw materials in parts by mass: 10-20 parts of acrylic acid (AA), 5-15 parts of sodium p-styrenesulfonate (SSS), 1-5 parts of N-vinylpyrrolidone (NVP), 45-55 parts of isoamyl alcohol polyoxyethylene ether, 0.01-0.1 parts of an initiator, and 100-140 parts of water. The diluent can solve the problems of thickening of the drilling fluid, increase of the viscosity and shear force, and increase of the filtration loss after CO2 pollution, and is applied to the CO2-polluted drilling fluid, so that the viscosity and shear force of the CO2-polluted drilling fluid can be effectively reduced, and the filtration loss of the drilling fluid can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of drilling fluid treatment agents, in particular to an anti-carbon dioxide pollution diluent for drilling fluid and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of global economy, the demand for oil and gas resources continues to increase, which makes the global oil and gas exploration and development depth gradually expand from the past medium and shallow layer to deep and ultra-deep layer (burial depth ≥6000m), which also means that the formation to be faced will be more complex. In the process of drilling deep and ultra-deep wells, the problem of CO2 pollution of drilling fluid is often encountered.

[0003] As the "blood" of drilling, drilling fluid has important functions such as stabilizing the well wall, suspending cuttings, cooling the drill bit, and improving the mechanical drilling speed, and is an irreplaceable circulating fluid that meets the internal drilling. However, the invasion of CO2 will make the drilling fluid thicken, and the viscosity and shear force will increase greatly, which can easily cause the pump pressure to be too high, even well leakage, and cause damage to the oil and gas layer; at the same time, it will also affect the quality of the mud cake, forming a thick and loose mud cake on the well wall, increasing the drilling fluid loss, and ultimately leading to wellbore instability and crack leakage.

[0004] At present, there have been many reports on diluents and filtrate reducers for drilling fluid with large viscosity and increased filtration. For example, Chinese patent document CN115160995A discloses a preparation method of a viscosity reducer for drilling fluid. The invention uses methyl acrylamide, 4,4'-diphenylstyrene dicarboxylic acid, 4-vinylbenzoic acid, sodium p-styrene sulfonate and methyl acryloyl ethyl dimethyl benzyl ammonium chloride monomer as raw materials to prepare a diluent. The viscosity reduction effect is good at a temperature of 200-400℃, the viscosity reduction rate is ≥90%, and the apparent viscosity reduction rate is ≥75% at a high temperature of 240℃. Chinese patent document CN107418528A discloses a preparation method of a filtrate reducer. The invention uses acrylic acid, sodium p-styrene sulfonate and allyl alcohol polyoxyethylene ether monomer as raw materials to prepare a filtrate reducer, which effectively reduces the filtration loss of drilling fluid in high temperature and high salinity environments. However, the above treatment agents have single function, and there is no report on drilling fluid treatment agents suitable for CO2 pollution conditions.

[0005] Therefore, it is urgent to develop a multifunctional drilling fluid diluent suitable for CO2 pollution conditions to reduce the viscosity, shear force and filtration loss of drilling fluid during drilling. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application provides an anti-carbon dioxide pollution diluent for drilling fluid and a preparation method and application thereof.The diluent of the present application can solve the problems of thickening of drilling fluid, increase of viscosity and shear force, and increase of filtration loss after CO2 pollution, and can be applied to CO2-polluted drilling fluid to effectively reduce the viscosity and shear force of the CO2-polluted drilling fluid and reduce the filtration loss of the drilling fluid.

[0007] To achieve the above-mentioned object, the technical scheme of the present application is as follows:

[0008] An anti-carbon dioxide pollution diluent for drilling fluid is prepared from the following raw materials in mass fraction: acrylic acid (AA) 10-20 parts, sodium p-styrenesulfonate (SSS) 5-15 parts, N-vinylpyrrolidone (NVP) 1-5 parts, iso-pentenyl alcohol polyoxyethylene ether 45-55 parts, initiator 0.01-0.1 parts, and water 100-140 parts.

[0009] According to the present application, preferably, the anti-carbon dioxide pollution diluent for drilling fluid is prepared from the following raw materials in mass fraction: acrylic acid (AA) 12-16 parts, sodium p-styrenesulfonate (SSS) 8-10 parts, N-vinylpyrrolidone (NVP) 2-4 parts, iso-pentenyl alcohol polyoxyethylene ether 48-50 parts, initiator 0.06-0.07 parts, and water 110-130 parts.

[0010] Preferably, the anti-carbon dioxide pollution diluent for drilling fluid is prepared from the following raw materials in mass fraction: acrylic acid (AA) 14.4 parts, sodium p-styrenesulfonate (SSS) 8.4 parts, N-vinylpyrrolidone (NVP) 2.22 parts, iso-pentenyl alcohol polyoxyethylene ether 48 parts, initiator 0.068 parts, and water 120 parts.

[0011] According to the present application, preferably, the iso-pentenyl alcohol polyoxyethylene ether is TPEG-2400 or TPEG-3000.

[0012] According to the present application, preferably, the initiator is azobisisobutyronitrile (AIBN) or azobisisobutylamidine hydrochloride (AIBA).

[0013] The preparation method of the anti-carbon dioxide pollution diluent for drilling fluid comprises the following steps:

[0014] The acrylic acid (AA), sodium p-styrenesulfonate (SSS), N-vinylpyrrolidone (NVP), and iso-pentenyl alcohol polyoxyethylene ether are fully dispersed in water to obtain a monomer mixture; the pH is adjusted to neutral to weak alkaline; the initiator and the acrylic acid mixture are added dropwise, and the anti-carbon dioxide pollution diluent for drilling fluid is obtained through reaction.

[0015] According to the application, preferably, the pH is adjusted to 7-9 by using a sodium hydroxide aqueous solution with a mass concentration of 10-30%.

[0016] According to the application, preferably, the mass ratio of acrylic acid in the monomer mixture to acrylic acid in the initiator-acrylic acid mixture is 0.5-1.5:1.

[0017] According to the application, preferably, the reaction temperature is 55-80 DEG C, the reaction time is 2-6h, and the reaction is carried out under the protection of a protective gas and stirring.

[0018] The drilling fluid anti-carbon dioxide pollution diluent can be used as a diluent for carbon dioxide polluted drilling fluid to reduce the viscosity, shear force and filtration loss of the drilling fluid.

[0019] The technical features and advantages of the application are as follows:

[0020] 1. The preparation process of the application is simple, the synthesis time is moderate, the obtained diluent is safe and environmentally friendly, and has no irritating odor.

[0021] 2. The drilling fluid diluent has strong dilution and viscosity reduction capacity in the drilling base slurry, and has the outstanding feature of strong CO2 pollution resistance, and has the effects of dispersion and viscosity reduction on the drilling fluid system, reduces the shear force and filtration loss, and greatly improves the drilling efficiency.

[0022] 3. The sodium p-styrenesulfonate added in the application can provide sulfonic acid groups to improve the temperature resistance and salt resistance of the diluent; the addition of N-vinylpyrrolidone has the effects of increasing the stability of the drilling fluid and inhibiting shale hydration dispersion; the selected iso-pentenyl alcohol polyoxyethylene ether can improve the hydration dispersion of clay and has good rheological adjustment and filtration loss reduction.

[0023] 4. The drilling fluid diluent obtained by the application contains -SO3 - , -OH and the like, 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 the clay particles from coagulating and flocculating, and form a network structure, which has a stabilizing effect on the drilling fluid; the pyrrolidone ring and sulfonic acid group in the diluent have strong thermal stability and good flow stability at high temperature. At the same time, the sulfonic acid group can also improve the electrolyte pollution resistance and the stability of the drilling fluid.

[0024] 5. The drilling fluid diluent obtained by this invention has a stronger competitive adsorption capacity compared to CO2, and can be firmly adsorbed on the surface of clay particles to form a thicker hydration film. This inhibits the aggregation and flocculation of clay particles caused by excessive CO2 contamination of the drilling fluid, reducing the viscosity and shear stress of the drilling fluid. Furthermore, it promotes a more reasonable particle size distribution, ultimately forming a dense filter cake and reducing drilling fluid filtration loss. The raw material composition and preparation method of this invention work together as a whole to achieve its excellent effects; any substitution of raw materials, improper proportions, or unsuitable preparation conditions will prevent the achievement of these excellent effects. Detailed Implementation

[0025] The present invention will be further described below through specific embodiments, but is not limited thereto.

[0026] Unless otherwise specified, the experimental methods described in the examples are conventional methods; the reagents and materials used are commercially available unless otherwise specified.

[0027] Example 1

[0028] A method for preparing a carbon dioxide-resistant diluent for drilling fluids, comprising the following steps:

[0029] 1) Add 7.2g acrylic acid, 8.4g sodium p-styrene sulfonate, 2.22g N-vinylpyrrolidone, 48g isopentenyl alcohol polyoxyethylene ether (TPEG-2400) and 120mL deionized water to a three-necked round-bottom flask and stir to obtain a mixed solution;

[0030] 2) Add a 20wt% sodium hydroxide aqueous solution to the above mixed solution to adjust the pH to 7;

[0031] 3) Heat the above three-necked round-bottom flasks in a water bath at 65°C and purge with nitrogen for 30 minutes;

[0032] 4) Dissolve 68 mg of azobisisobutyronitrile in 7.2 g of acrylic acid. After stirring and dissolving, add the solution dropwise to the above mixture. Stir and react for 4 h under nitrogen protection at 65 °C. After the reaction is complete, the product obtained is the anti-carbon dioxide pollution diluent.

[0033] Example 2

[0034] A method for preparing a carbon dioxide-resistant diluent for drilling fluids, comprising the following steps:

[0035] 1) Add 7.2g acrylic acid, 8.4g sodium p-styrene sulfonate, 3.33g N-vinylpyrrolidone, 48g isopentenyl alcohol polyoxyethylene ether (TPEG-2400) and 120mL deionized water to a three-necked round-bottom flask and stir to obtain a mixed solution;

[0036] 2) In the above mixed solution, add 20wt% sodium hydroxide solution to adjust pH to 7;

[0037] 3) The above three round-bottom flask is heated in water bath at 65℃, and nitrogen is passed for 30min;

[0038] 4) Dissolve 68mg of azobisisobutyronitrile into 7.2g of acrylic acid, after stirring and dissolving, add it drop by drop into the above mixed solution, stir and react under nitrogen protection at 65℃ for 4h, after the reaction is completed, the obtained product is the anti-carbon dioxide pollution diluent.

[0039] Example 3

[0040] A method for preparing an anti-carbon dioxide pollution diluent for drilling fluid, comprising the steps of:

[0041] 1) Put 7.2g of acrylic acid, 9.4g of sodium p-styrenesulfonate, 2.22g of N-vinyl pyrrolidone, 48g of isoamyl alcohol polyoxyethylene ether (TPEG-2400) and 120mL of deionized water into three round-bottom flasks respectively for stirring to obtain a mixed solution;

[0042] 2) In the above mixed solution, add 20wt% sodium hydroxide solution to adjust pH to 7;

[0043] 3) The above three round-bottom flask is heated in water bath at 65℃, and nitrogen is passed for 30min;

[0044] 4) Dissolve 68mg of azobisisobutyronitrile into 7.2g of acrylic acid, after stirring and dissolving, add it drop by drop into the above mixed solution, stir and react under nitrogen protection at 65℃ for 4h, after the reaction is completed, the obtained product is the anti-carbon dioxide pollution diluent.

[0045] Example 4

[0046] A method for preparing an anti-carbon dioxide pollution diluent for drilling fluid, comprising the steps of:

[0047] 1) Put 7.2g of acrylic acid, 8.4g of sodium p-styrenesulfonate, 2.22g of N-vinyl pyrrolidone, 50g of isoamyl alcohol polyoxyethylene ether (TPEG-2400) and 120mL of deionized water into three round-bottom flasks respectively for stirring to obtain a mixed solution;

[0048] 2) In the above mixed solution, add 20wt% sodium hydroxide solution to adjust pH to 7;

[0049] 3) The above three round-bottom flask is heated in water bath at 65℃, and nitrogen is passed for 30min;

[0050] 4) Dissolve 68 mg of azobisisobutyronitrile into 7.2 g of acrylic acid, after stirring and dissolving, add it into the above mixed solution drop by drop with a dropper, stir and react under nitrogen protection at 65℃ for 4 h, after the reaction is completed, the obtained product is the anti-carbon dioxide pollution diluent.

[0051] Example 5

[0052] A preparation method of an anti-carbon dioxide pollution diluent for drilling fluid, as described in Example 1, except that iso-pentenyl alcohol polyoxyethylene ether is TPEG-3000; and other steps or conditions are the same as in Example 1.

[0053] Example 6

[0054] A preparation method of an anti-carbon dioxide pollution diluent, as described in Example 1, except that azobisisobutyronitrile is replaced by azobisisobutylamidine hydrochloride; and other steps or conditions are the same as in Example 1.

[0055] Comparative Example 1

[0056] A preparation method of an anti-carbon dioxide pollution diluent, as described in Example 1, except that sodium p-styrenesulfonate is replaced by 2-acrylamido-2-methylpropanesulfonic acid; and other steps or conditions are the same as in Example 1.

[0057] Comparative Example 2

[0058] A preparation method of an anti-carbon dioxide pollution diluent, as described in Example 1, except that sodium p-styrenesulfonate is replaced by sodium methacrylsulfonate; and other steps or conditions are the same as in Example 1.

[0059] Comparative Example 3

[0060] A preparation method of an anti-carbon dioxide pollution diluent, as described in Example 1, except that no sodium hydroxide aqueous solution is added to adjust the pH; and other steps or conditions are the same as in Example 1.

[0061] The specific steps are as follows:

[0062] 1) Put 7.2 g of acrylic acid, 8.4 g of sodium p-styrenesulfonate, 2.22 g of N-vinylpyrrolidone, 48 g of iso-pentenyl alcohol polyoxyethylene ether (TPEG-2400), and 120 mL of deionized water into a three-necked round-bottom flask for stirring, to obtain a mixed solution;

[0063] 2) Heat the above three-necked round-bottom flask in a water bath at 65℃ for 30 min with nitrogen gas;

[0064] 3) 68 mg of azobisisobutyronitrile was dissolved into 7.2 g of acrylic acid, after it was dissolved by stirring, it was added dropwise into the above mixed solution by using a dropper, and the reaction was stirred at 65°C under nitrogen protection for 4 h, after the reaction was completed, the obtained product was anti-carbon dioxide pollution diluent.

[0065] Comparative Example 4

[0066] A method for preparing an anti-carbon dioxide pollution diluent, as described in Example 1, except that no sodium p-styrenesulfonate was added; other steps or conditions were the same as in Example 1.

[0067] Comparative Example 5

[0068] A method for preparing an anti-carbon dioxide pollution diluent, as described in Example 1, except that no N-vinylpyrrolidone was added; other steps or conditions were the same as in Example 1.

[0069] Comparative Example 6

[0070] A method for preparing an anti-carbon dioxide pollution diluent, as described in Example 1, except that no isopentenyl alcohol polyoxyethylene ether was added; other steps or conditions were the same as in Example 1.

[0071] Comparative Example 7

[0072] A method for preparing an anti-carbon dioxide pollution diluent, as described in Example 1, except that azobisisobutyronitrile was directly added to the system; other steps or conditions were the same as in Example 1.

[0073] Specifically as follows:

[0074] 1) 14.4 g of acrylic acid, 8.4 g of sodium p-styrenesulfonate, 2.22 g of N-vinylpyrrolidone, 48 g of isopentenyl alcohol polyoxyethylene ether (TPEG-2400), and 120 mL of deionized water were respectively added to a three-necked round-bottom flask for stirring to obtain a mixed solution;

[0075] 2) A 20 wt% sodium hydroxide aqueous solution was added to the above mixed solution to adjust the pH to 7;

[0076] 3) The above three-necked round-bottom flask was heated in a water bath at 65°C and nitrogen was passed for 30 min;

[0077] 4) 68 mg of azobisisobutyronitrile was added dropwise into the above mixed solution by using a dropper, and the reaction was stirred at 65°C under nitrogen protection for 4 h, after the reaction was completed, the obtained product was anti-carbon dioxide pollution diluent.

[0078] Comparative Example 8

[0079] A method for preparing an anti-carbon dioxide contamination diluent as described in Example 1, except that the iso-pentenol polyoxyethylene ether is replaced by allyl alcohol polyoxyethylene ether; and the other steps and conditions are the same as in Example 1.

[0080] Test Example 1

[0081] The rheological and fluid loss properties of the diluents in Examples 1-6 and Comparative Examples 1-8 were tested.

[0082] (1) Sample preparation:

[0083] The drilling fluid was prepared as follows: 400 mL of 4% drilling fluid base mud (520 g bentonite and 18.2 g sodium carbonate in 1300 mL water) was prepared, and 2 g of low viscosity sodium carboxymethyl cellulose, 2 g of polyanionic cellulose, 0.6 g of potassium polyacrylate, 580 g of barite (to adjust the drilling fluid density to 1.8 g / cm 3 ) and 8 g of the diluent in Examples or Comparative Examples were added to the drilling fluid base mud, respectively, and stirred well on a high speed stirrer for 30 min. The prepared drilling fluid was placed in a sealed container, and CO2 was bubbled into the drilling fluid for 10 h to obtain a sample. The sample was aged at 180°C for 16 h, and then the rheological and fluid loss properties of the sample before and after aging were tested at room temperature. A control sample without the diluent was also tested.

[0084] (2) Test method:

[0085] 1) A certain amount of the prepared sample was poured into a test mud cup, and a six-speed viscometer was used to record the readings of θ 600 , θ 300 , θ6, and θ3. The relevant rheological parameters were calculated.

[0086] 2) The API fluid loss of the sample was measured using a medium pressure fluid loss instrument (ZNSJ-5A, Qingdao Tongchun Petroleum Instrument Co., Ltd., China) at 100 MPa, and the filtrate volume was recorded after seven and a half minutes. Twice the volume was the API fluid loss.

[0087] The test results are shown in Tables 1-2.

[0088] Table 1 Performance test of drilling fluid diluent before aging

[0089]

[0090] Table 2 Performance test of drilling fluid diluent after aging at 180°C

[0091]

[0092]

[0093] As can be seen from the data in Table 1-2, the drilling fluid diluent prepared by the present application exhibits good viscosity reduction performance at room temperature and after aging at 180 DEG C, and the viscosity reduction effect is remarkable. Meanwhile, the drilling fluid has a large dynamic plastic ratio, so that the drilling fluid has good shear thinning property. And the drilling fluid loss can be effectively reduced.

[0094] In conclusion, the anti-carbon dioxide diluent of the present application can meet the needs of drilling fluid carbon dioxide pollution.

[0095] The above describes the preferred embodiments of the present application in detail, but the present application is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0096] In addition, it should be noted that each specific technical feature described in the above-described specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combinations.

[0097] In addition, various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the idea of the present application, and it should be considered as disclosed content of the present application.

Claims

1. A carbon dioxide-resistant diluent for drilling fluids, characterized in that, It is prepared from the following raw materials in parts by weight: 10-20 parts acrylic acid (AA), 5-15 parts sodium p-styrene sulfonate (SSS), 1-5 parts N-vinylpyrrolidone (NVP), 45-55 parts isopentenyl alcohol polyoxyethylene ether, 0.01-0.1 parts initiator, and 100-140 parts water.

2. The anti-carbon dioxide contamination diluent for drilling fluid according to claim 1, characterized in that, The drilling fluid anti-carbon dioxide contamination diluent is prepared from the following raw materials in parts by weight: 12-16 parts acrylic acid (AA), 8-10 parts sodium p-styrene sulfonate (SSS), 2-4 parts N-vinylpyrrolidone (NVP), 48-50 parts isopentenyl alcohol polyoxyethylene ether, 0.06-0.07 parts initiator, and 110-130 parts water.

3. The anti-carbon dioxide contamination diluent for drilling fluid according to claim 2, characterized in that, The drilling fluid anti-carbon dioxide contamination diluent is prepared from the following raw materials in parts by weight: 14.4 parts acrylic acid (AA), 8.4 parts sodium p-styrene sulfonate (SSS), 2.22 parts N-vinylpyrrolidone (NVP), 48 parts isopentenyl alcohol polyoxyethylene ether, 0.068 parts initiator, and 120 parts water.

4. The anti-carbon dioxide contamination diluent for drilling fluid according to claim 1, characterized in that, The isopentenyl alcohol polyoxyethylene ether is TPEG-2400 or TPEG-3000.

5. The anti-carbon dioxide contamination diluent for drilling fluid according to claim 1, characterized in that, The initiator is azobisisobutyronitrile (AIBN) or azobisisobutyramidine hydrochloride (AIBA).

6. The method for preparing the anti-carbon dioxide contamination diluent for drilling fluid as described in any one of claims 1-5, characterized in that, Including the following steps: Acrylic acid (AA), sodium p-styrene sulfonate (SSS), N-vinylpyrrolidone (NVP), and isopentenyl alcohol polyoxyethylene ether are fully dispersed in water to obtain a monomer mixture; the pH is adjusted to neutral to weakly alkaline; the mixture of initiator and acrylic acid is added dropwise, and a carbon dioxide-resistant diluent for drilling fluid is obtained through reaction.

7. The method for preparing the anti-carbon dioxide contamination diluent for drilling fluid according to claim 6, characterized in that, Adjust the pH to 7-9 using a 10-30% sodium hydroxide aqueous solution.

8. The method for preparing the anti-carbon dioxide contamination diluent for drilling fluid according to claim 6, characterized in that, The mass ratio of acrylic acid in the monomer mixture to that in the initiator and acrylic acid mixture is 0.5-1.5:

1.

9. The method for preparing the anti-carbon dioxide contamination diluent for drilling fluid according to claim 6, characterized in that, The reaction temperature is 55-80℃, the reaction time is 2-6 hours, and the reaction is carried out under the protection of a protective gas and under stirring conditions; the protective gas is nitrogen or argon.

10. The application of the anti-carbon dioxide contamination diluent for drilling fluids as described in any one of claims 1-5, characterized in that, It is used as a diluent in carbon dioxide contaminated drilling fluids to reduce the fluid's viscosity, shear stress, and fluid loss.

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