High-temperature-resistant salt-calcium-resistant water-in-oil emulsion polymer filtrate reducer as well as preparation method and application thereof

Abstract

The invention discloses a high-temperature-resistant salt-calcium-resistant water-in-oil emulsion polymer filtrate reducer as well as a preparation method and application thereof. The high-temperature-resistant salt-calcium-resistant water-in-oil emulsion polymer filtrate reducer comprises a continuous phase containing a non-polar dispersion medium and a dispersion phase which is dispersed in the continuous phase and contains a water-soluble polymer, the water-soluble polymer has a structure as shown in a formula (1). The high-temperature-resistant salt-calcium-resistant fluid loss reducer has the beneficial effects that the high-temperature-resistant salt-calcium-resistant fluid loss reducer contains the water-soluble polymer with a rigid structure, can resist high temperature of 200 DEG C, saturated NaCl pollution and 5% CaCl2 pollution while effectively reducing the fluid loss of the water-based drilling fluid, has excellent temperature-resistant salt-calcium-resistant fluid loss reduction performance, is suitable for deep water-based drilling fluid fluid loss reduction, and is simple in production process, low in cost and suitable for industrial production. Compared with the conventional powder polymer filtrate reducer commonly used in the oil field, the filtrate reducer does not need to be further dried and crushed during use, and is good in dispersity, high in solid content and good in reservoir stability; # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield chemistry, and particularly relates to a high temperature and salt resistant calcium water-in-oil emulsion polymer fluid loss reducer, a preparation method and application thereof. Background Art

[0002] With the development of economy, the global demand for energy resources is increasing, the exploration and development of oil and gas resources in deep and complex formations is becoming more and more intense, and the requirements for high-temperature and salt-resistant calcium drilling fluid fluid loss reducers are getting higher and higher. Calcium ions interact with drilling fluid fluid loss reducers at high temperatures, which can cause the fluid loss reducers to fail. In addition, conventional polymer fluid loss reducers are also prone to degradation and failure at high temperatures, resulting in unstable drilling fluid performance at high temperatures, which seriously affects the exploration and development of deep formation oil and gas resources. In addition, most of the polymer fluid loss reducers commonly used in oil fields are powders, which need to be dried and crushed during the production process, and the dosage requirements are high during the on-site preparation of drilling fluids, and the dispersion time is long. Summary of the invention

[0003] In view of the deficiencies of the prior art, the present invention provides a high temperature resistant, salt resistant, calcium resistant, oil-in-water emulsion polymer fluid loss reducer, a preparation method and an application thereof. The fluid loss reducer of the present invention has excellent high temperature resistant, salt resistant, and calcium resistant fluid loss reducing performance, does not require further drying and crushing when used, has good dispersibility, high solid content, and good reservoir stability, and has long-term practical value and economic benefits for the exploration and development of oil and gas resources in formations with severe salt and calcium invasion.

[0004] The first aspect of the present invention provides a high temperature and salt resistant calcium water-in-oil emulsion polymer fluid loss reducer, which comprises a continuous phase comprising a non-polar dispersion medium, and a dispersed phase comprising a water-soluble polymer dispersed in the continuous phase; the water-soluble polymer has a structure shown in formula (1);

[0005]

[0006] Wherein, R1 and R2 are each independently selected from H or a C1-C16 alkyl group;

[0007] R3 is selected from one of C4-C6 alkyl sulfonic acid or its salt, C4-C6 alkyl sulfonic acid ester or its salt;

[0008] n, m, l, p are molar numbers and n:m:l:p=4~6.5:1.5~2:1~2:1~2.

[0009] According to a specific embodiment of the present invention, R1 and R2 are each independently selected from H or a C1-C6 alkyl group.

[0010] According to a specific embodiment of the present invention, R3 is selected from one of dimethylpropane sulfonate, methyl butyl methane sulfonate, and methyl amyl sulfonic acid; preferably, R3 is selected from one of sodium dimethylpropane sulfonate, sodium methyl butyl methane sulfonate, and methyl amyl sulfonic acid.

[0011] The second aspect of the present invention provides a method for preparing the aforementioned high temperature and salt resistant calcium water-in-oil emulsion polymer fluid loss reducer, comprising: in the presence of a base and an initiator, contacting a monomer A having a structural unit a, a monomer B having a structural unit b, a monomer C having a structural unit c, a monomer D having a structural unit d, water, an emulsifier and a non-polar dispersion medium to carry out a reverse emulsion polymerization reaction;

[0012] The structural unit a is a structural unit represented by formula (i); the structural unit b is a structural unit represented by formula (ii); the structural unit c is a structural unit represented by formula (iii); and the structural unit d is a structural unit represented by formula (iv);

[0013]

[0014] Wherein, R1, R2, and R3 are as defined above;

[0015] The molar ratio of monomer A, monomer B, monomer C and monomer D is 5:2:2:1.

[0016] According to a specific embodiment of the present invention, monomer A is selected from at least one of acrylamide, N,N-dimethylacrylamide, N,N-di-n-butylacrylamide, and N,N-di-n-hexylacrylamide; monomer B is 2-acrylamide-2-methylpropanesulfonic acid; monomer C is diallyldimethylammonium chloride; and monomer D is vinyl pyrrolidone.

[0017] According to a specific embodiment of the present invention, the non-polar dispersion medium includes white oil; the emulsifier includes a first emulsifier and a second emulsifier, the first emulsifier is selected from at least one of polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitan monooleate, and the second emulsifier is selected from at least one of sorbitan monooleate, sorbitan monopalmitate, sorbitan monolaurate, and sorbitan monostearate; preferably, the first emulsifier is polyoxyethylene sorbitan monooleate, and the second emulsifier is sorbitan monolaurate; preferably, the mass ratio of the non-polar dispersion medium, the first emulsifier, and the second emulsifier is 100:1:5.

[0018] According to a specific embodiment of the present invention, the initiator is selected from at least one of azobisisobutyronitrile, azobisisobutylimidazoline hydrochloride, azobisisobutylamidine hydrochloride, ammonium persulfate, and potassium persulfate; based on the total weight of the monomers, the amount of the initiator is 0.2-0.4%; preferably, the initiator is azobisisobutyronitrile.

[0019] According to a specific embodiment of the present invention, the reaction temperature is 40 to 70° C., and the reaction time is 3 to 10 hours.

[0020] The third aspect of the present invention provides a drilling fluid, which includes a base slurry and the aforementioned high temperature and salt resistant calcium water-in-oil emulsion polymer fluid loss reducer.

[0021] A fourth aspect of the present invention provides the use of the aforementioned drilling fluid in oil production in an oil field.

[0022] The beneficial effects of the present invention are:

[0023] The present invention is a water-soluble polymer with a rigid structure. Conventional anionic polymer molecules have the same charge and the interaction force is electrostatic repulsion. When salt or calcium is added, Na + or Ca + It will destroy the repulsion between polymer molecules, causing it to change from a stretched state to a curled state and lose its function. Because the polymer molecules of the present invention have zwitterions, the intramolecular force is the attraction between anions and cations, which can better resist the destructive effect of cations in salt. While effectively reducing the filtration loss of water-based drilling fluids, it can resist high temperatures of 200°C, saturated NaCl pollution, and 5% CaCl2 pollution. It has excellent temperature-resistant, salt-resistant, and calcium-resistant filtration loss reduction performance, and is suitable for deep water-based drilling fluid filtration loss reduction. It also has a simple production process and low cost. Compared with the powdered polymer filtration reducers commonly used in existing oil fields, it does not require further drying and crushing when used, has good dispersibility, high solid content, and good reservoir stability. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Example 1

[0026] The monomers (acrylamide monomer: 2-acrylamide-2-methylpropanesulfonic acid monomer: vinyl pyrrolidone: diallyldimethylammonium chloride = 5:2:2:1 (molar ratio)) are prepared into 80g of an aqueous solution with a mass fraction of 60%, the pH value is adjusted to about 7.0 with a NaOH solution, and 1g of an emulsifier polyoxyethylene sorbitan monooleate is added to obtain a monomer aqueous solution; 100g of white oil and 5g of an emulsifier sorbitan monolaurate are added to a 250ml beaker, and the above-mentioned monomer aqueous solution is added. After shearing with a high-speed shear emulsifier for 5min, the emulsion is transferred to a three-necked flask, nitrogen is introduced, 0.15g of an initiator azobisisobutyronitrile is added, and the flask is placed in a constant temperature water bath at 40°C, and reacted at 400r / min for 10h to obtain an emulsion, which is the synthesized fluid loss reducer FL-1.

[0027] Example 2

[0028] The monomers (N, N-dimethylacrylamide monomer: 2-acrylamide-2-methylpropanesulfonic acid monomer: vinyl pyrrolidone: diallyldimethylammonium chloride = 5:2:2:1 (molar ratio)) were prepared into 80 g of an aqueous solution with a mass fraction of 60%, the pH value was adjusted to about 7.0 with a NaOH solution, and 1 g of an emulsifier polyoxyethylene sorbitan monooleate was added to obtain a monomer aqueous solution; 100 g of white oil and 5 g of an emulsifier sorbitan monolaurate were added to a 250 ml beaker, and the above monomer aqueous solution was added. After shearing with a high-speed shear emulsifier for 5 minutes, the emulsion was transferred to a three-necked flask, nitrogen was introduced, 0.15 g of an initiator azobisisobutyronitrile was added, and the flask was placed in a constant temperature water bath at 70°C, and reacted at 400 r / min for 3 hours to obtain an emulsion, which was the synthesized filtrate reducer FL-2.

[0029] Example 3

[0030] The monomers (N,N-di-n-butylacrylamide monomer: 2-acrylamide-2-methylpropanesulfonic acid monomer: vinyl pyrrolidone: diallyldimethylammonium chloride = 5:2:2:1 (molar ratio)) were prepared into 80 g of an aqueous solution with a mass fraction of 60%, the pH value was adjusted to about 7.0 with a NaOH solution, and 1 g of an emulsifier polyoxyethylene sorbitan monooleate was added to obtain a monomer aqueous solution; 100 g of white oil and 5 g of an emulsifier sorbitan monolaurate were added to a 250 ml beaker, and the above monomer aqueous solution was added. After shearing with a high-speed shear emulsifier for 5 minutes, the emulsion was transferred to a three-necked flask, nitrogen was introduced, 0.15 g of an initiator azobisisobutyronitrile was added, and the flask was placed in a constant temperature water bath at 50°C, and reacted for 8 hours at a certain stirring speed to obtain an emulsion, which was the synthesized filtrate reducer FL-3.

[0031] Example 4

[0032] The monomers (N,N-di-n-hexyl acrylamide monomer: 2-acrylamide-2-methylpropanesulfonic acid monomer: vinyl pyrrolidone: diallyldimethylammonium chloride = 5:2:2:1 (molar ratio)) were prepared into 80 g of an aqueous solution with a mass fraction of 60%, the pH value was adjusted to about 7.0 with a NaOH solution, and 1 g of an emulsifier polyoxyethylene sorbitan monooleate was added to obtain a monomer aqueous solution; 100 g of white oil and 5 g of an emulsifier sorbitan monolaurate were added to a 250 ml beaker, and the above monomer aqueous solution was added. After shearing with a high-speed shear emulsifier for 5 minutes, the emulsion was transferred to a three-necked flask, nitrogen was introduced, 0.15 g of an initiator azobisisobutyronitrile was added, and the flask was placed in a constant temperature water bath at 50°C, and reacted at 400 r / min for 8 hours to obtain an emulsion, which was the synthesized filtrate reducer FL-4.

[0033] Example 5

[0034] The monomers (N, N-dimethylacrylamide monomer: 2-acrylamide-2-methylpropanesulfonic acid monomer: vinyl pyrrolidone: diallyldimethylammonium chloride = 5:2:2:1 (molar ratio)) were prepared into 80 g of an aqueous solution with a mass fraction of 60%, the pH value was adjusted to about 7.0 with a NaOH solution, and 1 g of an emulsifier polyoxyethylene sorbitan monooleate was added to obtain a monomer aqueous solution; 100 g of white oil and 5 g of an emulsifier sorbitan monolaurate were added to a 250 ml beaker, and the above monomer aqueous solution was added. After shearing with a high-speed shear emulsifier for 5 minutes, the emulsion was transferred to a three-necked flask, nitrogen was introduced, 0.15 g of an initiator azobisisobutylimidazoline hydrochloride was added, and the flask was placed in a constant temperature water bath at 50°C, and reacted at 400 r / min for 8 hours to obtain an emulsion, which was the synthesized filtrate reducer FL-5.

[0035] Example 6

[0036] The monomers (N, N-dimethylacrylamide monomer: 2-acrylamide-2-methylpropanesulfonic acid monomer: vinyl pyrrolidone: diallyldimethylammonium chloride = 5:2:2:1 (molar ratio)) were prepared into 80 g of an aqueous solution with a mass fraction of 60%, the pH value was adjusted to about 7.0 with a NaOH solution, and 1 g of an emulsifier polyoxyethylene sorbitan monooleate was added to obtain a monomer aqueous solution; 100 g of white oil and 5 g of an emulsifier sorbitan monolaurate were added to a 250 ml beaker, and the above monomer aqueous solution was added. After shearing with a high-speed shear emulsifier for 5 minutes, the emulsion was transferred to a three-necked flask, nitrogen was introduced, 0.15 g of an initiator potassium persulfate was added, and the emulsion was placed in a constant temperature water bath at 60°C and reacted at 400 r / min for 5 hours to obtain an emulsion, which was the synthesized filtrate reducer FL-6.

[0037] Example 7

[0038] The monomers (N, N-dimethylacrylamide monomer: 2-acrylamide-2-methylpropanesulfonic acid monomer: vinyl pyrrolidone: diallyldimethylammonium chloride = 5:2:2:1 (molar ratio)) were prepared into 80 g of an aqueous solution with a mass fraction of 60%, the pH value was adjusted to about 7.0 with a NaOH solution, and 1 g of an emulsifier polyoxyethylene sorbitan monopalmitate was added to obtain a monomer aqueous solution; 100 g of white oil and 5 g of an emulsifier sorbitan monopalmitate were added to a 250 ml beaker, and the above-mentioned monomer aqueous solution was added. After shearing with a high-speed shear emulsifier for 5 minutes, the emulsion was transferred to a three-necked flask, nitrogen was introduced, 0.15 g of an initiator azobisisobutyronitrile was added, and the flask was placed in a constant temperature water bath at 60°C, and reacted for 5 hours at a certain stirring speed to obtain an emulsion, which was the synthesized filtrate reducer FL-7.

[0039] Example 8

[0040] The monomers (N, N-dimethylacrylamide monomer: 2-acrylamide-2-methylpropanesulfonic acid monomer: vinyl pyrrolidone: diallyldimethylammonium chloride = 5:2:2:1 (molar ratio)) were prepared into 80 g of an aqueous solution with a mass fraction of 60%, the pH value was adjusted to about 7.0 with a NaOH solution, and 1 g of an emulsifier polyoxyethylene sorbitan monopalmitate was added to obtain a monomer aqueous solution; 100 g of white oil and 5 g of an emulsifier sorbitan monostearate were added to a 250 ml beaker, and the above-mentioned monomer aqueous solution was added. After shearing with a high-speed shear emulsifier for 5 minutes, the emulsion was transferred to a three-necked flask, nitrogen was introduced, 0.15 g of an initiator azobisisobutyronitrile was added, and the flask was placed in a constant temperature water bath at 60°C, and reacted at 400 r / min for 5 hours to obtain an emulsion, which was the synthesized filtrate reducer FL-8.

[0041] Comparative Example

[0042] The only difference from Example 1 is that diallyldimethylammonium chloride monomer is not added.

[0043] 1. Evaluation of filtration loss reduction effect

[0044] Preparation of base slurry: 4% bentonite and 0.2% sodium carbonate are added to deionized water, stirred at high speed until fully dissolved, and sealed for 24 hours to obtain water-based base slurry. The FL1-8 prepared above were evaluated for filtration loss reduction effect. The drilling fluid formula: 4% bentonite slurry + 5% FL filtration reducer emulsion, and the API filtration loss and rheology were tested. FLAPI aging conditions: 180℃×16h.

[0045]

[0046]

[0047] It can be seen from the table that after adding the FL series fluid loss reducer emulsion to the base slurry, the API fluid loss of the base slurry after hot rolling is significantly reduced, and the fluid loss reduction effect is obvious. Among them, FL-2 has the best fluid loss reduction effect, and FL-6 has the worst fluid loss reduction effect. In addition, after the FL series fluid loss reducer emulsion is added to the water-based drilling fluid base slurry, the apparent viscosity and dynamic shear force will increase. On the one hand, this is because the FL polymer molecular chain increases the viscosity of the water phase after fully stretching, and on the other hand, the functional groups of the polymer fluid loss reducer can be adsorbed on the clay surface. The comparative example does not add cationic monomers, and lacks cationic amine groups compared to the examples. The amine groups can form hydrogen bonds with the hydroxyl groups on the clay surface, enhancing the adsorption of the polymer on the clay surface. Therefore, the comparative example has a poor fluid loss reduction effect.

[0048] 2. Temperature resistance evaluation

[0049] The FL-2, FL-7 and FL-8 prepared above were added into the water-based drilling fluid slurry at 5%, aged for 16 hours at different temperatures, and the rheology and filtration loss were tested.

[0050]

[0051]

[0052] From the table above, it can be seen that after adding FL series fluid loss reducers to the base slurry of water-based drilling fluid, the fluid loss of the base slurry after hot rolling at different temperatures is significantly reduced. Among them, FL-2 has the best temperature resistance, with a fluid loss of only 12.8mL after hot rolling at 200℃ for 16h, and a temperature resistance of 200℃, while FL-7 and FL-8 have slightly poorer temperature resistance. The comparative example does not contain cations and has a poor fluid loss reduction effect.

[0053] 3. Evaluation of salt pollution resistance

[0054] The FL-2, FL-7 and FL-8 prepared above were added to the water-based drilling fluid at 5% and then added with different concentrations of NaCl. The mixture was aged at 180°C for 16 hours and the rheology and filtration properties were tested.

[0055]

[0056] From the above table, we can see that after adding FL series fluid loss reducer to water-based drilling fluid base slurry, the fluid loss and viscosity of water-based drilling fluid base slurry change after being polluted by different concentrations of NaCl. Among them, FL-2 still has good rheology and fluid loss reduction after being polluted by saturated NaCl, indicating that FL-2 can resist saturated salt pollution. The comparative example does not contain cations, and there is only electrostatic repulsion between molecules, which has weak resistance to sodium ions and poor fluid loss reduction effect.

[0057] 4. Evaluation of calcium pollution resistance

[0058] The FL-2, FL-7 and FL-8 prepared above were added into the water-based drilling fluid slurry at 5%, and then different concentrations of CaCl2 were added. The mixture was aged at 180°C for 16 hours, and the rheology and filtration loss properties were tested.

[0059]

[0060] From the above table, we can see that after adding FL series fluid loss reducer to water-based drilling fluid base slurry, the fluid loss and viscosity of water-based drilling fluid base slurry change after being contaminated with different concentrations of CaCl2. Among them, FL-2 still has good rheology and fluid loss reduction after being contaminated with 5% CaCl2, indicating that FL-2 can resist 5% calcium salt pollution. The comparative example does not contain cations, and there is only electrostatic repulsion between molecules. Under the influence of calcium ions, the polymer molecules shrink and the fluid loss reduction effect is poor.

[0061] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

Claims

1. A high temperature and salt resistant calcium water-in-oil emulsion polymer fluid loss reducer, characterized in that: It has a continuous phase containing a non-polar dispersion medium, and a dispersed phase containing a water-soluble polymer dispersed in the continuous phase; the water-soluble polymer has a structure shown in formula (1); Wherein, R1 and R2 are each independently selected from one of H or C1-C16 alkyl; R3 is selected from one of C4-C6 alkyl sulfonic acid or its salt, C4-C6 alkyl sulfonic acid ester or its salt; n, m, l, p are molar numbers and n:m:l:p=4~6.5:1.5~2:1~2:1~2.

2. The high temperature and salt resistant calcium water-in-oil emulsion polymer fluid loss reducer according to claim 1, characterized in that: The R1 and R2 are each independently selected from H or a C1-C6 alkyl group.

3. The high temperature and salt resistant calcium water-in-oil emulsion polymer fluid loss reducer according to claim 1, characterized in that: The R3 is selected from one of dimethyl propane sulfonate, methyl butyl methane sulfonate and methyl pentyl sulfonate.

4. A method for preparing the high temperature and salt resistant calcium water-in-oil emulsion polymer fluid loss reducer according to any one of claims 1 to 3, characterized in that: The preparation method comprises: in the presence of a base and an initiator, bringing a monomer A having a structural unit a, a monomer B having a structural unit b, a monomer C having a structural unit c, a monomer D having a structural unit d, water, an emulsifier and a non-polar dispersion medium into contact to carry out a reverse emulsion polymerization reaction; The structural unit a is a structural unit represented by formula (i); the structural unit b is a structural unit represented by formula (ii); the structural unit c is a structural unit represented by formula (iii); the structural unit d is a structural unit represented by formula (iv); Wherein, R1, R2, and R3 are as defined in claim 1; The molar ratio of monomer A, monomer B, monomer C and monomer D is 5:2::2:

1.

5. The preparation method according to claim 4, characterized in that: The monomer A is selected from at least one of acrylamide, N,N-dimethylacrylamide, N,N-di-n-butylacrylamide, and N,N-di-n-hexylacrylamide; the monomer B is 2-acrylamide-2-methylpropanesulfonic acid; the monomer C is diallyldimethylammonium chloride; and the monomer D is vinyl pyrrolidone.

6. The preparation method according to claim 4, characterized in that: The non-polar dispersion medium includes white oil; The emulsifier comprises a first emulsifier and a second emulsifier, wherein the first emulsifier is selected from at least one of polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate and polyoxyethylene sorbitan monooleate, and the second emulsifier is selected from at least one of sorbitan monooleate, sorbitan monopalmitate, sorbitan monolaurate and sorbitan monostearate.

7. The preparation method according to claim 6, characterized in that: The first emulsifier is polyoxyethylene sorbitan monooleate, and the second emulsifier is sorbitan monolaurate.

8. The preparation method according to claim 6, characterized in that: The mass ratio of the non-polar dispersion medium, the first emulsifier and the second emulsifier is 100:1:

5.

9. The preparation method according to claim 4, characterized in that: The initiator is selected from at least one of azobisisobutyronitrile, azobisisobutylimidazoline hydrochloride, azobisisobutylamidine hydrochloride, ammonium persulfate and potassium persulfate; based on the total weight of the monomers, the amount of the initiator is 0.2-0.4%.

10. The preparation method according to claim 4, characterized in that: The initiator is azobisisobutyronitrile.

11. The preparation method according to claim 4, characterized in that: The reaction temperature is 40-70° C., and the reaction time is 3-10 hours.

12. A drilling fluid, characterized in that: The invention comprises base slurry and the high temperature and salt resistant calcium water-in-oil emulsion polymer fluid loss reducer as claimed in any one of claims 1 to 3.

13. Use of the drilling fluid according to claim 12 in oil production in oil fields.

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