Centrifugal liquid diluent, drilling fluid compounding system and preparation and application thereof

Abstract

The application relates to the field of oil and gas development, in particular to a centrifugal liquid diluent, a drilling fluid compounding system and preparation and application thereof. The centrifugal liquid diluent comprises 90-110 parts of acrylamide, 20-40 parts of 2-acrylamido-2-methylpropanesulfonic acid, 1-20 parts of dimethyldiallylammonium chloride, 50-70 parts of n-hexane, 50-70 parts of Span 80 and 0.5-5 parts of an initiator. The drilling fluid compounding system comprises a drilling fluid centrifugal liquid, a centrifugal liquid diluent and diesel oil, wherein the mass percentage of the centrifugal liquid diluent in the drilling fluid compounding system is 0.3-0.5% based on the mass of the drilling fluid centrifugal liquid, and the mass percentage of the diesel oil is 20-50%. The application can solve the problem of poor high-temperature resistance of the diluent in the prior art.

Description

Technical Field

[0001] This application relates to the technical field of oil and gas development, specifically to a centrifugal fluid diluent, a drilling fluid compounding system, and their preparation and application. Background Technology

[0002] In the drilling fluid industry, centrifuges are typically used to remove small-particle solids from drilling fluids for purification. The working principle utilizes the difference in specific gravity between solids and liquids, amplifying this difference thousands of times through a centrifugal force field. The solid phase settles under the influence of centrifugal force, thus achieving solid-liquid separation. The centrifuged drilling fluid contains a large amount of water and effective reagents, which, as the lighter components of the drilling fluid, can be processed and reused in drilling fluid reprocessing. Currently, simply using centrifuges for solid-liquid separation results in a centrifuged drilling fluid with excessive viscosity and poor flowability. To utilize it in drilling fluid reprocessing and save on technical costs, the centrifuged drilling fluid should be diluted. Summary of the Invention

[0003] To address the problem of poor high-temperature resistance of diluents in existing technologies, this application provides a centrifugal fluid diluent, a drilling fluid compounding system, and its preparation and application.

[0004] In a first aspect, this application relates to a centrifugal liquid diluent comprising the following components in parts by weight: 90-110 parts acrylamide, 20-40 parts 2-acrylamido-2-methylpropanesulfonic acid, 1-20 parts dimethyldiallylammonium chloride, 50-70 parts n-hexane, 50-70 parts Span 80 and 0.5-5 parts initiator.

[0005] In a specific embodiment, optionally, the initiator is a mixture of ammonium persulfate and sodium bisulfite.

[0006] In a specific embodiment, optionally, the ratio of ammonium persulfate to sodium bisulfite in the initiator is in the range of 2:3 to 3:2.

[0007] In a specific embodiment, optionally, the centrifugal liquid diluent contains 100 parts by mass of acrylamide, 30 parts by mass of 2-acrylamido-2-methylpropanesulfonic acid, and 10 parts by mass of dimethyldiallyl ammonium chloride.

[0008] Secondly, this application relates to a method for preparing the aforementioned centrifugal liquid diluent, the method comprising:

[0009] Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and dimethyldiallylammonium chloride were dissolved in water to obtain the first mixed system;

[0010] Hexane and Span 80 were mixed to obtain a second mixed system;

[0011] The second mixture is mixed with the first mixture to obtain a third mixture.

[0012] While maintaining continuous nitrogen purge, an initiator is added to the third mixing system to obtain a centrifugal liquid diluent.

[0013] In a specific embodiment, optionally, after dissolving the acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and dimethyldiallyl ammonium chloride in water to obtain the first mixed system, the method further includes:

[0014] Adjust the pH of the first mixture to 7-8.

[0015] Thirdly, this application relates to the application of the aforementioned centrifugal diluent in oil and gas development.

[0016] Fourthly, this application relates to a drilling fluid compounding system, which includes the aforementioned centrifugal diluent.

[0017] In a specific implementation, optionally, the drilling fluid compounding system also includes drilling fluid centrifuge fluid and diesel oil;

[0018] In the drilling fluid compound system, based on the mass of the drilling fluid centrifuge, the mass percentage of the centrifuge diluent is 0.3-0.5%, and the mass percentage of the diesel fuel is 20-50%.

[0019] Fifthly, this application relates to the application of the aforementioned drilling fluid compounding system in oil and gas development.

[0020] The advantages of this application over the prior art include:

[0021] 1. This application describes a centrifugal fluid diluent developed using acrylamide (AM), anionic monomer 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and cationic monomer dimethyl diallyl ammonium chloride (DMDAAC) as reactants, with the addition of an initiator. Applying this centrifugal fluid diluent to drilling fluid centrifuges effectively reduces the viscosity of the drilling fluid. According to relevant experimental data, for a specific drilling fluid centrifuge, its φ600 value can be reduced to below 90 mPa·s, and the φ6 value and final shear reading are both reduced to below 20 mPa·s. This facilitates the reprocessing of drilling fluid centrifuges into drilling fluid re-mixing, improving the recovery rate of waste drilling fluid. Meanwhile, when the centrifugal diluent in this case is applied to the drilling fluid centrifugal fluid, when the temperature rises to 80°C, the φ600 value, φ6 value and final shear reading of the drilling fluid diluent still show a decreasing trend as the amount of centrifugal diluent increases. This indicates that the centrifugal diluent in this application still has strong stability at high temperatures (above 80°C), can produce a viscosity-reducing effect, and has excellent high-temperature resistance.

[0022] 2. By mixing the centrifugal diluent in this application with drilling fluid centrifugal liquid and diesel oil in a certain proportion, the φ600 value and φ6 value can be further reduced in a temperature environment below 80℃. The resulting drilling fluid compound system has a lower density than the drilling fluid centrifugal liquid.

[0023] 3. The centrifugal liquid diluent in this application is prepared at room temperature and pressure, with mild reaction conditions, low energy consumption and production cost, which is conducive to large-scale production. Detailed Implementation

[0024] Exemplary embodiments will now be described in detail. The implementation methods described in the following exemplary embodiments do not represent all implementation methods consistent with this disclosure.

[0025] The inventors discovered that in existing technologies, waste drilling fluid is typically purified through centrifugation before being reused. However, centrifugation alone results in high viscosity and poor flowability of the centrifuged fluid. Therefore, to reduce the technical costs associated with drilling fluid reprocessing, further treatment of the centrifuged fluid is necessary.

[0026] Current diluents often have poor high-temperature resistance, and the centrifuged drilling fluid obtained after centrifugation usually exhibits a temperature rise. Therefore, it is necessary to improve the stability of diluents at high temperatures.

[0027] Based on the above problems, the inventors conducted further research and development, resulting in this invention.

[0028] The present invention will be described in detail below through specific embodiments and comparative examples:

[0029] 1. Preparation of centrifugal liquid diluent

[0030] Example 1

[0031] At 25°C, 90 parts of acrylamide (AM), 20 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and 1 part of dimethyl diallyl ammonium chloride (DMDAAC) were dissolved in water to obtain a first mixed system. The pH of the first mixed system was adjusted to 8 using NaOH solution.

[0032] Add 50 parts of n-hexane and 50 parts of Span 80 to a three-necked flask and stir until homogeneous to obtain a second mixture. While stirring, add the second mixture to the first mixture to obtain a third mixture. Continue stirring and emulsifying while purging with nitrogen for 30 minutes. While maintaining continuous nitrogen purging, add 0.5 parts of initiator to the first mixture. The initiator is a mixture of ammonium persulfate and sodium bisulfite in a 2:3 ratio. After reacting for 3 hours, a centrifugal diluent is obtained.

[0033] Example 2

[0034] The difference between this embodiment and Example 1 is that 95 parts of acrylamide (AM), 25 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and 5 parts of dimethyl diallyl ammonium chloride (DMDAAC) were dissolved in water to obtain a first mixed system. The pH of the first mixed system was adjusted to 8 using NaOH solution.

[0035] Add 60 parts of n-hexane and 60 parts of Span 80 to a three-necked flask and stir until homogeneous to obtain a second mixture. While stirring, add the second mixture to the first mixture to obtain a third mixture. Continue stirring and emulsifying while purging with nitrogen for 30 minutes. While maintaining continuous nitrogen purging, add 2.5 parts of initiator to the first mixture. The initiator is a mixture of ammonium persulfate and sodium bisulfite in a 2:3 ratio. After reacting for 3 hours, a centrifugal diluent is obtained.

[0036] Example 3

[0037] The difference between this embodiment and Example 1 is that 100 parts of acrylamide (AM), 30 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and 10 parts of dimethyldiallylammonium chloride (DMDAAC) were dissolved in water to obtain a first mixed system. The pH of the first mixed system was adjusted to 8 using NaOH solution.

[0038] Add 65 parts of n-hexane and 65 parts of Span 80 to a three-necked flask and stir until homogeneous to obtain a second mixture. While stirring, add the second mixture to the first mixture to obtain a third mixture. Continue stirring and emulsifying while purging with nitrogen for 30 minutes. While maintaining continuous nitrogen purging, add 5 parts of initiator to the first mixture. The initiator is a mixture of ammonium persulfate and sodium bisulfite in a 2:3 ratio. After reacting for 3 hours, a centrifugal diluent is obtained.

[0039] Example 4

[0040] The difference between this embodiment and Example 1 is that 105 parts of acrylamide (AM), 35 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and 15 parts of dimethyl diallyl ammonium chloride (DMDAAC) were dissolved in water to obtain a first mixed system. The pH of the first mixed system was adjusted to 8 using NaOH solution.

[0041] Add 68 parts of n-hexane and 68 parts of Span 80 to a three-necked flask and stir until homogeneous to obtain a second mixture. While stirring, add the second mixture to the first mixture to obtain a third mixture. Continue stirring and emulsifying while purging with nitrogen for 30 minutes. While maintaining continuous nitrogen purging, add 4 parts of initiator to the first mixture. The initiator is a mixture of ammonium persulfate and sodium bisulfite in a 1:1 ratio. After reacting for 3 hours, a centrifugal diluent is obtained.

[0042] Example 5

[0043] The difference between this embodiment and Example 1 is that 110 parts of acrylamide (AM), 40 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and 20 parts of dimethyldiallylammonium chloride (DMDAAC) were dissolved in water to obtain a first mixed system. The pH of the first mixed system was adjusted to 8 using NaOH solution.

[0044] Add 70 parts of n-hexane and 70 parts of Span 80 to a three-necked flask and stir until homogeneous to obtain a second mixture. While stirring, add the second mixture to the first mixture to obtain a third mixture. Continue stirring and emulsifying while purging with nitrogen for 30 minutes. While maintaining continuous nitrogen purging, add 5 parts of initiator to the first mixture. The initiator is a mixture of ammonium persulfate and sodium bisulfite in a 3:2 ratio. After reacting for 3 hours, a centrifugal diluent is obtained.

[0045] Comparative Example 1

[0046] The difference between this comparative example and Example 1 is that 90 parts of acrylamide (AM), 10 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and 1 part of dimethyldiallylammonium chloride (DMDAAC) were dissolved in water to obtain the first mixed system. All other preparation processes were the same.

[0047] Comparative Example 2

[0048] The difference between this comparative example and Example 1 is that 90 parts of acrylamide (AM), 15 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and 1 part of dimethyldiallylammonium chloride (DMDAAC) were dissolved in water to obtain the first mixed system. The amount of initiator added was 0.4 parts, and the initiator was a mixture of ammonium persulfate and sodium bisulfite in a 2:3 ratio. Other preparation processes were the same.

[0049] Comparative Example 3

[0050] The difference between this comparative example and Example 1 is that 80 parts of acrylamide (AM), 20 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and 1 part of dimethyldiallylammonium chloride (DMDAAC) were dissolved in water to obtain the first mixed system. The amount of initiator added was 5.5 parts, and the initiator was a mixture of ammonium persulfate and sodium bisulfite in a 2:3 ratio. Other preparation processes were the same.

[0051] Comparative Example 4

[0052] The difference between this comparative example and Example 1 is that 90 parts of acrylamide (AM), 10 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and 0.8 parts of dimethyldiallylammonium chloride (DMDAAC) were dissolved in water to obtain the first mixed system. All other preparation processes were the same.

[0053] Comparative Example 5

[0054] The difference between this comparative example and Example 1 is that 120 parts of acrylamide (AM), 45 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and 25 parts of dimethyldiallylammonium chloride (DMDAAC) were dissolved in water to obtain the first mixed system. All other preparation processes were the same.

[0055] Based on the mass percentage of the drilling fluid centrifuge fluid, the centrifuge fluid diluents prepared in Examples 1-5 and Comparative Examples 1-5 were added to the drilling fluid centrifuge fluid at an addition amount of 0.25%. A separate group of drilling fluid centrifuge fluid without added diluent was set up as a blank group. The φ600 value, φ6 value, and final shear reading of each group of drilling fluid centrifuge fluid were measured at 50°C. The results are shown in Table 1. Wherein, φ600 is the reading of the six-speed rotational viscometer at 600 r / min, φ6 is the reading of the six-speed rotational viscometer at 6 r / min, and the final shear reading is the shear force value of the drilling fluid centrifuge fluid after standing for 10 minutes.

[0056] Table 1. φ600 value, φ6 value, and terminal shear reading of drilling fluid centrifuge fluid for each group.

[0057]

[0058] As shown in Table 1, compared to the blank group, the centrifugal fluid diluents in the above examples and comparative examples can all dilute the drilling fluid centrifugal fluid to a certain extent, reducing its viscosity. Furthermore, the centrifugal fluid diluents in Examples 1-5 can reduce the φ600 value of the drilling fluid centrifugal fluid to below 90 mPa·s, and both the φ6 value and the final shear reading to below 20 mPa·s, demonstrating superior viscosity reduction effect and meeting the viscosity reduction requirements.

[0059] In Examples 1-5, the viscosity-reducing effect of the centrifugal liquid diluent phase was better than that of Comparative Examples 1-2, where the amount of AM was less than 20 parts; better than that of Comparative Example 3, where the amount of AM was less than 90 parts; and better than that of Comparative Example 4, where the amount of DMDAAC was less than 1 part. In Comparative Example 5, the amounts of AM, AM, and DMDAAC were greater than 110 parts, 40 parts, and 20 parts, respectively, and the corresponding viscosity-reducing effect tended to decrease compared to Examples 1-5. In summary, in the centrifugal liquid diluent of this application, the amount of AM was determined to be 90-110 parts, the amount of AM was determined to be 20-40 parts, and the amount of DMDAAC was determined to be 1-20 parts.

[0060] Furthermore, in Examples 1-5, the centrifugal fluid diluent in Example 3 can reduce the φ600 value of the drilling fluid centrifugal fluid to 80, the φ6 value to 14, and the final shear reading to 16. This indicates that when the amounts of AM, AMPS, and DMDAAC are 100 parts, 30 parts, and 10 parts, respectively, the viscosity-reducing effect of the centrifugal fluid diluent is further superior to that of the other examples.

[0061] 2. Preparation of Drilling Fluid Compound System

[0062] (1) Evaluation experiment on the effect of centrifugal diluent on the viscosity-temperature characteristics of drilling fluid centrifugal fluid.

[0063] After centrifugation, the liquid phase separated by centrifugation was used as the drilling fluid centrifuge solution for subsequent experiments. The density, oil-water-solid three-phase content, and low-density solids (LGS) content of the drilling fluid centrifuge solution are shown in Table 1.

[0064] Table 2 Drilling fluid centrifugal density, oil-water-solid three-phase content, and low-density solids content

[0065]

[0066] Based on the mass percentage of the drilling fluid centrifuge fluid, centrifuge fluid diluent was added to the drilling fluid centrifuge fluid in (1) at an addition amount of 0.25%. Then, the φ600, φ6 and final shear readings of the drilling fluid centrifuge fluid were measured at 23℃, 35℃, 50℃, 65℃ and 80℃ respectively. The results are shown in Table 3.

[0067] Table 3. φ600, φ6 and terminal shear readings of drilling fluid centrifuge fluid.

[0068]

[0069] As shown in Table 2, with a fixed amount of centrifugal diluent added, the φ600, φ6, and final shear readings of the drilling fluid centrifuge all decreased with increasing temperature. When the room temperature rose to 80℃, the φ600 reading decreased the most, reaching approximately 60%; the φ6 reading decreased by approximately 38%.

[0070] Based on the mass percentage of the drilling fluid centrifuge fluid, centrifuge fluid diluent was added to the drilling fluid centrifuge fluid in (1) at amounts of 0%, 0.1%, 0.3%, 0.5%, and 0.7%. Then, the φ600 value, φ6 value, and final shear reading of the drilling fluid centrifuge fluid were measured at 23℃, 35℃, 50℃, 65℃, and 80℃, respectively. The results are shown in Tables 4 to 6.

[0071] Table 4 shows the relationship between φ600 readings and the amount of centrifugal diluent added and temperature.

[0072]

[0073] Table 5 shows the relationship between φ6 readings and the amount of centrifugal diluent added and temperature.

[0074]

[0075] Table 6. Relationship between terminal reading and centrifugal diluent addition amount and temperature.

[0076]

[0077]

[0078] As shown in Table 4, under the same temperature conditions, the amount of centrifugal diluent added has a relatively small effect on the φ600 value of the drilling fluid centrifuge. When the addition amount is 0.7%, the φ600 value decreases by about 4%. At the same addition amount, the φ600 decreases significantly with increasing temperature. When the temperature increases from 50°C to 80°C, the φ600 value decreases by about 23%.

[0079] As shown in Tables 5 and 6, the centrifugal fluid diluent of this invention has a significant impact on the φ6 reading and final shear of the drilling fluid centrifugal fluid. Under the same temperature conditions, adding 0.7% centrifugal fluid diluent can reduce φ6 by about 60% and the final shear by about 70%. The changes tend to level off after the amount of centrifugal fluid diluent added reaches 0.3%. This indicates that the centrifugal fluid diluent has a significant impact on the structural strength of the drilling fluid centrifugal fluid.

[0080] (2) Experiment on the effect of No. 0 diesel oil on the viscosity-temperature characteristics of drilling fluid centrifugal fluid

[0081] Based on the mass percentage of the drilling fluid centrifuge, No. 0 diesel oil was added to the drilling fluid centrifuge at dosages of 0%, 5%, 10%, 15%, and 20%, respectively. The φ600, φ6, and final shear readings of the drilling fluid centrifuge were measured using a six-speed rotational viscometer at temperatures of 23℃, 35℃, 50℃, 65℃, and 80℃. The results are shown in Tables 7-9.

[0082] Table 7 Relationship between φ600 value and diesel fuel addition amount and temperature

[0083]

[0084] Table 8. Relationship between φ6 value and diesel fuel addition amount and temperature

[0085]

[0086]

[0087] Table 9. Relationship between final cut-off reading and diesel fuel addition amount and temperature.

[0088]

[0089] As shown in Tables 7-9, diesel fuel significantly reduces the φ600, φ6, and final shear readings of the drilling fluid centrifuge fluid. Under the same temperature conditions, as the diesel fuel addition gradually increases within 20%, the φ600, φ6, and final shear readings all decrease significantly. Specifically, when the diesel fuel addition is 20%, φ600 decreases by approximately 51%, φ6 decreases by approximately 68%, and the final shear reading decreases by approximately 67%. Furthermore, at the same diesel fuel addition, the φ600, φ6, and final shear readings also decrease with increasing temperature; when the room temperature rises to 80℃, φ600 decreases by approximately 56%.

[0090] As shown in Tables 7-9, under the same temperature conditions, when the diesel fuel addition is 25%, the values ​​of φ600, φ6, and the final cut-off reading are quite close to those when the diesel fuel addition is 20%, with the φ6 value showing a decreasing trend. This indicates that when the diesel fuel addition is 20% or higher, the changes in the φ600, φ6, and final cut-off readings tend to be gradual.

[0091] (3) Drilling fluid system compounding experiment

[0092] Based on the mass percentage of the drilling fluid centrifuge, centrifuge diluent was added to the drilling fluid centrifuge at amounts of 0%, 0.1%, 0.3%, 0.5%, and 0.7%, respectively. Simultaneously, No. 0 diesel oil was added to the drilling fluid centrifuge at amounts of 0%, 15%, 20%, and 25%, respectively, to form a drilling fluid compound system. One set of drilling fluid centrifuge was set up as a blank group. The density of each drilling fluid compound system was then measured at 25℃ and 65℃. The specific formulations and results are shown in Table 10.

[0093] Table 10. Formulation and density results of drilling fluid compounding systems.

[0094]

[0095]

[0096] As shown in Table 10, when drilling fluid compound systems were prepared using formulations numbered 10, 11, 14, and 15, the resulting systems exhibited low densities at both 25°C and 65°C. Specifically, the density at 65°C was reduced to below 1.1, meeting the inventors' expectations. Therefore, the inventors determined the amount of diesel fuel added to the drilling fluid compound system to be 20–25%, and the amount of centrifugal diluent added to be 0.3–0.5%. Table 10 further shows that, under formulation number 11, when the amount of diesel fuel added to the drilling fluid compound system was 20% and the amount of centrifugal diluent added was 0.5%, the density of the drilling fluid compound system was lower than that of the other formulations, indicating that the viscosity-reducing effect of the centrifugal diluent was further superior to other formulations under this formulation.

[0097] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," just as "comprising" is interpreted as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

Claims

1. A centrifugal liquid diluent, characterized in that, The preparation method of the centrifugal liquid diluent includes the following steps: Dissolve 90-110 parts of acrylamide, 20-40 parts of 2-acrylamido-2-methylpropanesulfonic acid and 1-20 parts of dimethyldiallylammonium chloride in water to obtain a first mixed system; adjust the pH of the first mixed system to 7-8; Mix 50-70 parts of n-hexane with 50-70 parts of Span 80 to obtain a second mixed system; The second mixture is mixed with the first mixture to obtain a third mixture. While maintaining continuous nitrogen purge, 0.5 to 5 parts of initiator are added to the third mixing system to prepare a centrifugal liquid diluent.

2. The centrifugal liquid diluent according to claim 1, characterized in that, The initiator is a mixture of ammonium persulfate and sodium bisulfite.

3. The centrifugal liquid diluent according to claim 2, characterized in that, In the initiator, the mass ratio of ammonium persulfate to sodium bisulfite is in the range of 2:3 to 3:

2.

4. The centrifugal liquid diluent according to claim 1, characterized in that, In the centrifugal liquid diluent, the acrylamide is in the amount of 100 parts by mass, the 2-acrylamido-2-methylpropanesulfonic acid is in the amount of 30 parts by mass, and the dimethyldiallyl ammonium chloride is in the amount of 10 parts by mass.

5. The application of the centrifugal liquid diluent according to any one of claims 1 to 4 in oil and gas development.

6. A drilling fluid compounding system, characterized in that, Includes the centrifugal liquid diluent as described in any one of claims 1 to 4.

7. The drilling fluid compounding system according to claim 6, characterized in that, The drilling fluid compounding system also includes drilling fluid centrifuge fluid and diesel fuel; In the drilling fluid compound system, based on the mass of the drilling fluid centrifuge, the mass percentage of the centrifuge diluent is 0.3-0.5%, and the mass percentage of the diesel fuel is 20-50%.

8. The application of the drilling fluid compounding system according to claim 7 in oil and gas development.

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