Temperature-resistant and salt-resistant copolymer with filtration reduction, viscosity increase and lubrication performance, preparation method and application thereof

Abstract

The present application relates to the technical field of oil field chemistry, and provides a temperature-resistant and salt-resistant copolymer with filtration-reducing, viscosity-increasing and lubricating properties, and a preparation method and application thereof.The preparation method of the copolymer comprises: reacting raw material components including natural high molecular material, organic acid anhydride, vinyl-containing sulfonate, anionic monomer, crosslinking monomer and initiator in a solvent to obtain the temperature-resistant and salt-resistant copolymer with filtration-reducing, viscosity-increasing and lubricating properties.The copolymer provided by the present application has excellent temperature resistance and salt resistance, and has good filtration-reducing, viscosity-increasing and lubricating properties.The copolymer provided by the present application is used in a conventional drilling fluid system resistant to 180 DEG C, and under the premise of keeping the performance, the amount of drilling fluid treatment agents such as filtration reducer, viscosity increasing agent and lubricant can be obviously reduced, and the formula of the high-temperature-resistant drilling fluid system is greatly simplified.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oilfield chemical technology, more particularly to a temperature-resistant and salt-resistant copolymer with filtration loss reduction, viscosity increase and lubrication performance, and a preparation method and application thereof. BACKGROUND

[0002] In oil and gas exploration and development, drilling fluid, as the blood of drilling engineering, bears the functions of balancing formation pressure, stabilizing wellbore, carrying cuttings, cooling and lubricating, and transmitting hydrodynamic force. With the gradual expansion of the exploration and development of conventional oil and gas resources to deep formations, in order to meet the performance requirements of temperature resistance, filtration loss control, plugging and anti-sloughing, and lubrication of drilling fluid, poly-sulfonated drilling fluid systems are commonly used in China. This system has the characteristics of good temperature resistance and salt resistance, which promotes the progress of drilling technology in China. However, the shortcomings of this system are also obvious, mainly including two aspects: first, the formula is complex, and there are many types of treatment agents, resulting in complicated treatment and maintenance procedures. For example, in a well in Tahe work area, the poly-sulfonated drilling fluid system formula contains 11 types of treatment agents, with an addition amount of more than 15%, among which there are 6 types of treatment agents such as polymers and resins for filtration loss reduction, with an addition amount of more than 10%. Second, it has high toxicity and high environmental pollution risk, and is difficult to dispose. The core treatment agents such as sulfonated asphalt and SMP in the system are moderately toxic / micro-toxic, with low biodegradation index, and do not meet the environmental protection requirements. The general waste poly-sulfonated drilling fluid EC 50 <1000mg / L, BOD5 / COD Cr <0.1, difficult to biodegrade, difficult to dispose harmlessly.

[0003] In order to overcome the above problems of drilling fluid treatment agents, since the 1990s, a small number of multifunctional products with multiple application effects have been formed by expanding other functions based on the core function of filtration loss reduction. For example, filtration loss reducers also have inhibition and flow pattern control functions, and drilling fluid systems have gradually been simplified.

[0004] Multifunctional drilling fluid treatment agent products generally take filtration loss reduction as the core, and expand other functions to make the filtration loss reducer also have the effects of viscosity reduction / increase and wellbore stabilization. Domestic multifunctional treatment agent products are mostly concentrated in "one agent with two functions". On the basis of filtration loss reduction, other components with functional groups such as amine groups and ester groups are introduced to improve the inhibition and lubrication performance. The existing multifunctional drilling fluid treatment agent products actually achieve the effects of filtration loss reduction, wellbore stabilization and flow pattern adjustment through multi-component compounding, which is actually "one bag" rather than "one agent", and lacks "one agent type" drilling fluid treatment agent products that can efficiently realize multiple functions and effects.

[0005] The conventional polysulfonated drilling fluid with temperature resistance of 180 DEG C can meet the temperature resistance requirement of most drilling operations. The filtration reducer in the polysulfonated drilling fluid system is mainly sulfonated material and polymer, and there are many types and high addition amount. In addition, in order to successfully carry the drilling cuttings out of the wellhead and speed up the drilling speed, the rheological property and lubricating property of the drilling fluid at high temperature are required to be improved. Therefore, it is urgent to develop a 'one-dose' drilling fluid treatment agent product with excellent temperature resistance, good rheological property and lubricating property at high temperature and low addition amount. SUMMARY

[0006] The present application aims to provide a temperature-resistant and salt-resistant copolymer with filtration reduction, viscosity increase and lubricating properties and a preparation method thereof, so as to solve the technical problem of many types and high addition amount of drilling fluid treatment agents in the prior art.

[0007] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0008] In a first aspect, the present application provides a preparation method of a temperature-resistant and salt-resistant copolymer with filtration reduction, viscosity increase and lubricating properties, comprising: reacting raw material components including natural high molecular material, organic acid anhydride, vinyl-containing sulfonate, anionic monomer, crosslinking monomer and initiator in a solvent to obtain the temperature-resistant and salt-resistant copolymer with filtration reduction, viscosity increase and lubricating properties.

[0009] According to some embodiments of the present application, the natural high molecular material is a starch-based natural high molecular material.

[0010] According to some embodiments of the present application, the natural high molecular material includes at least one of corn starch and sweet potato starch.

[0011] According to some embodiments of the present application, the organic acid anhydride includes at least one selected from phthalic anhydride and maleic anhydride.

[0012] According to some embodiments of the present application, the vinyl-containing sulfonate includes at least one of styrene sodium sulfonate and allyl sodium sulfonate.

[0013] According to some embodiments of the present application, the anionic monomer includes 2-acrylamide-2-methylpropane sulfonic acid (AMPS).

[0014] According to some embodiments of the present application, the crosslinking monomer includes at least one of acrylamide and N-hydroxymethyl acrylamide.

[0015] According to some embodiments of the present application, the initiator includes at least one of ammonium persulfate and potassium persulfate.

[0016] According to some embodiments of the present application, the solvent comprises water.

[0017] In the present application, a dendritic copolymer is formed by taking a starch-based natural polymer material as a "central core", and grafting organic acid anhydride, vinyl-containing sulfonate, anionic monomer and crosslinking monomer thereon. The copolymer has excellent temperature resistance and salt resistance, and at the same time has good fluid loss reduction, viscosity increase and lubrication performance.

[0018] According to some embodiments of the present application, the amount of each component comprises:

[0019] Solvent: 100 parts by weight;

[0020] Natural polymer material: 2-3 parts by weight;

[0021] Organic acid anhydride: 10-40 parts by weight;

[0022] Vinyl-containing sulfonate: 4-10 parts by weight;

[0023] Anionic monomer: 20-30 parts by weight;

[0024] Crosslinking monomer: 1-6 parts by weight;

[0025] Initiator: 0.5-1 parts by weight.

[0026] According to some embodiments of the present application, the amount of each component comprises:

[0027] Solvent: 100 parts by weight;

[0028] Natural polymer material: 2-3 parts by weight;

[0029] Organic acid anhydride: 20-30 parts by weight;

[0030] Vinyl-containing sulfonate: 5-8 parts by weight;

[0031] Anionic monomer: 24-26 parts by weight;

[0032] Crosslinking monomer: 3-4 parts by weight;

[0033] Initiator: 0.5-1 parts by weight.

[0034] According to some embodiments of the present application, the preparation method comprises:

[0035] Mixing and stirring the natural polymer material and the solvent; then sequentially adding the organic acid anhydride, the vinyl-containing sulfonate, the anionic monomer and the crosslinking monomer, and stirring to dissolve; then adding the initiator, and stirring and reacting at 60-80°C to obtain the temperature-resistant and salt-resistant copolymer with fluid loss reduction, viscosity increase and lubrication performance.

[0036] According to some embodiments of the present application, the stirring speed is 300-500 r / min.

[0037] According to some embodiments of the present application, the stirring reaction time is 2-8 min.

[0038] According to some embodiments of the present application, the preparation method further comprises drying, crushing and sieving the reaction product.

[0039] According to some embodiments of the present application, the drying temperature is 90-110℃, and the drying time is 16-30 h.

[0040] According to some embodiments of the present application, the sieve size is 0.59 mm.

[0041] In the second aspect, the present application provides a temperature-resistant and salt-resistant copolymer with the properties of fluid loss reduction, viscosity increase and lubrication, which is prepared by the preparation method of the first aspect.

[0042] In the third aspect, the present application provides the use of the temperature-resistant and salt-resistant copolymer with the properties of fluid loss reduction, viscosity increase and lubrication in the second aspect in drilling fluid.

[0043] In the fourth aspect, the present application provides a drilling fluid comprising the temperature-resistant and salt-resistant copolymer with the properties of fluid loss reduction, viscosity increase and lubrication in the third aspect.

[0044] According to some embodiments of the present application, the drilling fluid further comprises water, bentonite and sodium chloride.

[0045] According to some embodiments of the present application, in the drilling fluid, the amount of bentonite is 3-5 parts by weight, the amount of sodium chloride is 20-30 parts by weight, and the amount of the temperature-resistant and salt-resistant copolymer with the properties of fluid loss reduction, viscosity increase and lubrication in the third aspect is 2-4 parts by weight, based on 100 parts by weight of water.

[0046] The present application has at least the following beneficial effects:

[0047] The temperature-resistant and salt-resistant copolymer with the properties of fluid loss reduction, viscosity increase and lubrication provided by the present application has excellent temperature resistance and salt resistance, and good properties of fluid loss reduction, viscosity increase and lubrication. When the temperature-resistant and salt-resistant copolymer with the properties of fluid loss reduction, viscosity increase and lubrication provided by the present application is used in a conventional drilling fluid system resistant to 180℃, the amount of drilling fluid additives such as fluid loss reducer, viscosity enhancer and lubricant can be significantly reduced under the premise of maintaining equivalent performance, greatly simplifying the formula of high-temperature-resistant drilling fluid system and greatly reducing the cost of drilling fluid, which can effectively reduce the construction difficulty and operation intensity. DETAILED DESCRIPTION

[0048] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clear and explicit, the present application will be further described in detail below in combination with specific examples. It should be understood that the specific examples described herein are only used to illustrate the present patent in detail, and do not limit the protection scope of the present application in any way.

[0049] Unless otherwise defined, the technical terms used in the following examples have the same meanings as generally understood by those skilled in the art to which the present application belongs. The reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments and equipment used in the following examples can be purchased on the market or obtained by existing methods; the reagent amount, unless otherwise specified, is the reagent amount in conventional experimental operation; the experimental method, unless otherwise specified, is a conventional method.

[0050] In the various embodiments and comparative examples of the present application, the materials used are all industrial products, and are as follows:

[0051] Corn starch: Zhengzhou Yuhe Food Additive Co., Ltd.

[0052] Sweet potato starch: Zhengzhou Yuhe Food Additive Co., Ltd.

[0053] Phthalic anhydride: Shanghai Guyan Technology Co., Ltd.

[0054] Maleic anhydride: Tianjin Damao Chemical Reagent Factory.

[0055] Sodium styrene sulfonate: Shanghai Maikelin Biochemical Technology Co., Ltd.

[0056] Sodium allyl sulfonate: Guangdong Wengjiang Chemical Reagent Co., Ltd.

[0057] 2-acrylamido-2-methylpropanesulfonic acid (AMPS): Shandong Qicai Chemical Co., Ltd.

[0058] Acrylamide: Zibo Julong Chemical Co., Ltd.

[0059] N-hydroxymethyl acrylamide: Shanghai Gaoming Chemical Co., Ltd.

[0060] Potassium persulfate: Jinan Fengle Chemical Co., Ltd.

[0061] Ammonium persulfate: Jinan Fengle Chemical Co., Ltd.

[0062] In the performance test of the copolymers prepared in the various embodiments and comparative examples of the present application, the test methods used include:

[0063] (1) Filtration loss performance evaluation: 12 g of the copolymer prepared in each example or the comparative example was added to the base slurry under the stirring speed of 11000 r / min in a high-speed mixer, and stirred for 20 min. After aging in a roller oven at 180 °C for 16 h, it was taken out and cooled to room temperature. The high-temperature and high-pressure filtration amount under the condition of 180 °C and 3.5 MPa pressure difference was evaluated according to the provisions in 7.3 of GB / T16783.1.

[0064] (2) Lubrication performance evaluation: 12 g of the copolymer prepared in each example or the comparative example was added to the base slurry under the stirring speed of 11000 r / min in a high-speed mixer, and stirred for 20 min. After aging in a roller oven at 180 °C for 16 h, it was taken out and cooled to room temperature. The API filtration amount was tested using an API filtration instrument, and the mud cake was obtained. The mud cake adhesion coefficient instrument was used to test the adhesion coefficient of the mud cake. The adhesion coefficient reduction rate of the mud cake was calculated according to formula (1).

[0065]

[0066] In the formula:

[0067] P1 - the adhesion coefficient reduction rate of the mud cake, %;

[0068] F v 0 - the adhesion coefficient of the mud cake after aging of the base slurry at 180 °C / 16 h;

[0069] F v - the adhesion coefficient of the mud cake after aging of the base slurry at 180 °C / 16 h after adding the sample.

[0070] (3) Viscosity increasing performance evaluation: 4 g of the copolymer prepared in each example or the comparative example was added to 400 mL of distilled water under the stirring speed of 300 r / min in a low-speed mixer, and stirred for 20 min. The reading value at the speed of 600 r / min was measured using a six-speed rotational viscometer. The apparent viscosity was calculated according to formula (2).

[0071]

[0072] In the formula:

[0073] AV - apparent viscosity, mPa·s;

[0074] R 600 - the reading value of the six-speed rotational viscometer at the speed of 600 r / min.

[0075] The base slurry formula used in the above tests was the same, and the formula was as follows:

[0076] Take 400 mL of distilled water into a cup, add 0.56 g of anhydrous sodium carbonate, 16 g of bentonite, and use a high-speed blender to stir for 20 min at a speed of 11000 r / min. Stop at least twice to scrape off the bentonite adhering to the wall of the container. After 24 h of maintenance at 25℃, add 120 g of sodium chloride at a speed of 11000 r / min, and stir for 20 min to obtain the base slurry.

[0077] It should be noted that the amount of the temperature-resistant and salt-resistant copolymer with filtration loss reduction, viscosity increase, and lubricity performance and other drilling fluid treatment agents provided by the present application added to the drilling fluid is calculated based on the amount of water. For example, 400 mL (400 g) of distilled water is taken to prepare the base slurry, and 12 g of the temperature-resistant and salt-resistant copolymer with filtration loss reduction, viscosity increase, and lubricity performance or other drilling fluid treatment agents is added, and the amount is 3 parts by weight or 3%.

[0078] Example 1

[0079] (1) Always maintain a stirring speed of 300 r / min, add 100 g of water and 2 g of corn starch into a four-necked flask equipped with a stirrer, a dropping funnel, and a thermometer, and stir for 5 min to obtain solution A.

[0080] (2) Always maintain a stirring speed of 300 r / min, add 10 g of phthalic anhydride, 4 g of sodium styrene sulfonate, 20 g of AMPS, and 1 g of acrylamide into solution A in sequence, heat to 40℃, and stir for 30 min to obtain mixture B.

[0081] (3) Always maintain a stirring speed of 300 r / min, heat to 60℃, add 0.5 g of ammonium persulfate dropwise into mixture B, stir for 2 min, pour the solution into a tray, dry at 105℃ for 24 h, crush, sieve (sieve hole 0.59 mm), and obtain the high-performance temperature-resistant and salt-resistant copolymer in the form of dry powder.

[0082] Example 2

[0083] (1) Always maintain a stirring speed of 300 r / min, add 100 g of water and 3 g of corn starch into a four-necked flask equipped with a stirrer, a dropping funnel, and a thermometer, and stir for 5 min to obtain solution A.

[0084] (2) Always maintain a stirring speed of 300 r / min, add 40 g of maleic anhydride, 8 g of sodium styrene sulfonate, 30 g of AMPS, and 6 g of N-hydroxymethyl acrylamide into solution A in sequence, heat to 60℃, and stir for 30 min to obtain mixture B.

[0085] (3) Always keep the stirring speed at 300 r / min, and the temperature rises to 80°C. Add 1 g of potassium persulfate dropwise to the mixture B, stir for 2 min, pour the solution into a tray, dry at 105°C for 24 h, crush, sieve (0.59 mm sieve hole), and obtain a high-performance temperature-resistant and salt-resistant copolymer in the form of dry powder.

[0086] Example 3

[0087] (1) Always keep the stirring speed at 300 r / min. In a four-necked flask equipped with a stirrer, a dropping funnel, and a thermometer, add 100 g of water and 2 g of corn starch, stir for 5 min, and obtain solution A.

[0088] (2) Always keep the stirring speed at 300 r / min. Add 20 g of maleic anhydride, 10 g of sodium styrene sulfonate, 24 g of AMPS, and 3 g of acrylamide to solution A in sequence, heat to 40°C, and stir for 30 min to obtain mixture B.

[0089] (3) Always keep the stirring speed at 300 r / min, and the temperature rises to 80°C. Add 0.5 g of ammonium persulfate dropwise to the mixture B, stir for 2 min, pour the solution into a tray, dry at 105°C for 24 h, crush, sieve (0.59 mm sieve hole), and obtain a high-performance temperature-resistant and salt-resistant copolymer in the form of dry powder.

[0090] Example 4

[0091] (1) Always keep the stirring speed at 300 r / min. In a four-necked flask equipped with a stirrer, a dropping funnel, and a thermometer, add 100 g of water and 3 g of corn starch, stir for 5 min, and obtain solution A.

[0092] (2) Always keep the stirring speed at 300 r / min. Add 30 g of maleic anhydride, 8 g of sodium allyl sulfonate, 26 g of AMPS, and 4 g of acrylamide to solution A in sequence, heat to 60°C, and stir for 30 min to obtain mixture B.

[0093] (3) Always keep the stirring speed at 300 r / min, and the temperature is constant at 60°C. Add 1 g of ammonium persulfate dropwise to the mixture B, stir for 2 min, pour the solution into a tray, dry at 105°C for 24 h, crush, sieve (0.59 mm sieve hole), and obtain a high-performance temperature-resistant and salt-resistant copolymer in the form of dry powder.

[0094] Example 5

[0095] (1) Always keep the stirring speed at 300 r / min. In a four-necked flask equipped with a stirrer, a dropping funnel, and a thermometer, add 100 g of water and 2 g of sweet potato starch, stir for 5 min, and obtain solution A.

[0096] (2) Always keep the stirring speed at 300 r / min, add 10 g of maleic anhydride, 8 g of sodium allyl sulfonate, 20 g of AMPS, and 1 g of N-methylol acrylamide to solution A in sequence, heat to 40 °C, and stir for 30 min to obtain mixture B.

[0097] (3) Always keep the stirring speed at 300 r / min, heat to 60 °C, add 0.5 g of potassium persulfate dropwise to mixture B, stir for 2 min, pour the solution into a tray, dry at 105 °C for 24 h, crush, sieve (screen aperture 0.59 mm), and obtain a high-performance temperature-resistant and salt-resistant copolymer in the form of dry powder.

[0098] Example 6

[0099] (1) Always keep the stirring speed at 300 r / min, add 100 g of water and 2 g of sweet potato starch to a four-necked flask equipped with a stirrer, a dropping funnel, and a thermometer, and stir for 5 min to obtain solution A.

[0100] (2) Always keep the stirring speed at 300 r / min, add 40 g of phthalic anhydride, 10 g of sodium allyl sulfonate, 30 g of AMPS, and 6 g of acrylamide to solution A in sequence, heat to 40 °C, and stir for 30 min to obtain mixture B.

[0101] (3) Always keep the stirring speed at 300 r / min, heat to 80 °C, add 1 g of potassium persulfate dropwise to mixture B, stir for 2 min, pour the solution into a tray, dry at 105 °C for 24 h, crush, sieve (screen aperture 0.59 mm), and obtain a high-performance temperature-resistant and salt-resistant copolymer in the form of dry powder.

[0102] Example 7

[0103] (1) Always keep the stirring speed at 300 r / min, add 100 g of water and 3 g of corn starch to a four-necked flask equipped with a stirrer, a dropping funnel, and a thermometer, and stir for 5 min to obtain solution A.

[0104] (2) Always keep the stirring speed at 300 r / min, add 20 g of maleic anhydride, 9 g of sodium allyl sulfonate, 24 g of AMPS, and 3 g of N-methylol acrylamide to solution A in sequence, heat to 60 °C, and stir for 30 min to obtain mixture B.

[0105] (3) Always keep the stirring speed at 300 r / min, heat to 70 °C, add 0.5 g of initiator dropwise to mixture B, stir for 2 min, pour the solution into a tray, dry at 105 °C for 24 h, crush, sieve (screen aperture 0.59 mm), and obtain a high-performance temperature-resistant and salt-resistant copolymer in the form of dry powder.

[0106] Example 8

[0107] (1) Always keep the stirring speed at 300 r / min, add 100 g of water and 3 g of sweet potato starch into a four-necked flask equipped with a stirrer, a dropping funnel and a thermometer, stir for 5 min to obtain solution A.

[0108] (2) Always keep the stirring speed at 300 r / min, add 30 g of phthalic anhydride, 8 g of sodium allyl sulfonate, 25 g of AMPS and 4 g of acrylamide into solution A in sequence, heat to 60℃, stir for 30 min to obtain mixture B.

[0109] (3) Always keep the stirring speed at 300 r / min, heat to 70℃, add 1 g of ammonium persulfate dropwise into mixture B, stir for 2 min, pour the solution into a tray, dry at 105℃ for 24 h, crush, sieve (screen hole 0.59 mm) to obtain a high-performance temperature-resistant and salt-resistant copolymer in the form of dry powder.

[0110] Example 9

[0111] (1) Always keep the stirring speed at 300 r / min, add 100 g of water and 2 g of sweet potato starch into a four-necked flask equipped with a stirrer, a dropping funnel and a thermometer, stir for 5 min to obtain solution A.

[0112] (2) Always keep the stirring speed at 300 r / min, add 20 g of maleic anhydride, 5 g of sodium allyl sulfonate, 20 g of AMPS and 1 g of acrylamide into solution A in sequence, heat to 40℃, stir for 30 min to obtain mixture B.

[0113] (3) Always keep the stirring speed at 300 r / min, heat to 60℃, add 0.5 g of potassium persulfate dropwise into mixture B, stir for 2 min, pour the solution into a tray, dry at 105℃ for 24 h, crush, sieve (screen hole 0.59 mm) to obtain a high-performance temperature-resistant and salt-resistant copolymer in the form of dry powder.

[0114] Example 10

[0115] (1) Always keep the stirring speed at 300 r / min, add 100 g of water and 2 g of sweet potato starch into a four-necked flask equipped with a stirrer, a dropping funnel and a thermometer, stir for 5 min to obtain solution A.

[0116] (2) Always keep the stirring speed at 300 r / min, add 40 g of maleic anhydride, 10 g of sodium styrene sulfonate, 30 g of AMPS and 6 g of acrylamide into solution A in sequence, heat to 60℃, stir for 30 min to obtain mixture B.

[0117] (3) Always keep the stirring speed at 300 r / min, and raise the temperature to 80°C. Add 1 g of ammonium persulfate dropwise to the mixture B, stir for 2 min, pour the solution into a tray, dry at 105°C for 24 h, crush, sieve (0.59 mm mesh), and obtain the high-performance temperature-resistant and salt-resistant copolymer in the form of dry powder.

[0118] Example 11

[0119] (1) Always keep the stirring speed at 300 r / min. In a four-necked flask equipped with a stirrer, a dropping funnel, and a thermometer, add 100 g of water and 3 g of sweet potato starch, and stir for 5 min to obtain solution A.

[0120] (2) Always keep the stirring speed at 300 r / min. Add 40 g of maleic anhydride, 5 g of sodium styrene sulfonate, 24 g of AMPS, and 3 g of N-methylol acrylamide to solution A in sequence, raise the temperature to 60°C, and stir for 30 min to obtain mixture B.

[0121] (3) Always keep the stirring speed at 300 r / min. Raise the temperature to 70°C. Add 0.5 g of potassium persulfate dropwise to the mixture B, stir for 2 min, pour the solution into a tray, dry at 105°C for 24 h, crush, sieve (0.59 mm mesh), and obtain the high-performance temperature-resistant and salt-resistant copolymer in the form of dry powder.

[0122] Example 12

[0123] (1) Always keep the stirring speed at 300 r / min. In a four-necked flask equipped with a stirrer, a dropping funnel, and a thermometer, add 100 g of water and 3 g of corn starch, and stir for 5 min to obtain solution A.

[0124] (2) Always keep the stirring speed at 300 r / min. Add 30 g of maleic anhydride, 8 g of sodium styrene sulfonate, 26 g of AMPS, and 4 g of N-methylol acrylamide to solution A in sequence, raise the temperature to 40°C, and stir for 30 min to obtain mixture B.

[0125] (3) Always keep the stirring speed at 300 r / min. Raise the temperature to 70°C. Add 1 g of potassium persulfate dropwise to the mixture B, stir for 2 min, pour the solution into a tray, dry at 105°C for 24 h, crush, sieve (0.59 mm mesh), and obtain the high-performance temperature-resistant and salt-resistant copolymer in the form of dry powder.

[0126] Comparative Example 1

[0127] The copolymer is prepared according to Example 8, except that 30 g of phthalic anhydride is not added to solution A in step (2).

[0128] Comparative Example 2

[0129] The copolymer was prepared according to the method of Example 8, except that 8 g of sodium allyl sulfonate was not added to solution A in step (2).

[0130] Comparative Example 3

[0131] The copolymer was prepared according to the method of Example 8, except that 25 g of AMPS was not added to solution A in step (2).

[0132] Comparative Example 4

[0133] The copolymer was prepared according to the method of Example 8, except that 4 g of acrylamide was not added to solution A in step (2).

[0134] Performance evaluation

[0135] (1) The high-temperature high-pressure fluid loss, mud cake viscosity reduction rate, and apparent viscosity of a 1wt% aqueous solution of the copolymers prepared in each of the examples and comparative examples were tested, and commercially available high-performance fluid loss additives DS-II (Shandong Deshengyuan Petroleum Technology Co., Ltd.) and RHPT-2 (Henan Longxiang Petroleum Additive Co., Ltd.) resistant to 180℃ and 30% salt were selected as control samples. DS-II and RHPT-2 are both one-dosage drilling fluid treatment agents, and the amount of each added to the test was the same as that of the copolymers prepared in each of the examples and comparative examples. The performance test results are shown in Table 1.

[0136] Table 1 Performance test results

[0137]

[0138]

[0139] As can be seen from the above performance test results, the copolymer provided by the present application has excellent temperature resistance and salt resistance, and can resist 180℃ and 30% sodium chloride. Moreover, the copolymer provided by the present application has excellent fluid loss reduction, lubrication, and viscosity increasing functions. In particular, the fluid loss reduction performance after high-temperature aging is less than 16 mL, and can even be as low as 8-9 mL after 16 h of rolling aging at 180℃, meeting the requirements of most domestic oilfields for the fluid loss reduction performance of drilling fluid systems resistant to 180℃. At the same time, the copolymer of each example improves the lubrication performance of the system by more than 68%, and has high viscosity increasing performance, meeting the requirements of conventional polysulfonated drilling fluid systems. Although the two commercially available products DS-II and RHPT-2 as control samples can improve the lubrication performance, their fluid loss reduction performance is significantly poorer than the temperature-resistant and salt-resistant copolymer provided by the present application, which has fluid loss reduction, viscosity increasing, and lubrication performance.

[0140] (2) Through the performance evaluation experiment of the drilling fluid system, it can be concluded that in order to achieve the performance equivalent to the temperature-resistant and salt-resistant copolymer provided in Example 8 with the properties of fluid loss reduction, viscosity increase and lubrication, the drilling fluid system formula "4% bentonite + 30% sodium chloride + 1% high-viscosity anionic cellulose + 4% sulfonated lignite + 4% sulfonated phenolic resin + 4% lignite resin + 2% lubricant" needs to be formed. The high-temperature and high-pressure filtration loss of the drilling fluid system is 8.8 mL under the condition of 180 degrees Celsius aging for 16 hours, 180 degrees Celsius and 3.5 MPa pressure difference, and the mud cake viscosity reduction rate is 73.6%.

[0141] It is found through comparison that when the amount of the temperature-resistant and salt-resistant copolymer provided in Example 8 with the properties of fluid loss reduction, viscosity increase and lubrication is 3 parts by weight, the performance improvement of the bentonite slurry containing salt water is basically the same as that of the above-mentioned five drilling fluid treating agents (1% high-viscosity anionic cellulose + 4% sulfonated lignite + 4% sulfonated phenolic resin + 4% lignite resin + 2% lubricant) with the amount of 15 parts by weight. That is, under the premise of keeping the performance equivalent, the addition of the temperature-resistant and salt-resistant copolymer provided in Example 8 with the properties of fluid loss reduction, viscosity increase and lubrication in the conventional drilling fluid system resistant to 180 degrees Celsius can reduce the addition of 4 kinds of drilling fluid treating agents in terms of the types of drilling fluid treating agents, and reduce the total amount of 12 parts by weight in terms of the amount of drilling fluid treating agents.

[0142] Therefore, it can be seen that the temperature-resistant and salt-resistant copolymer provided in the present application can greatly reduce the types and amounts of treating agents in the drilling fluid system, embody the high performance and one agent with multiple functions of the product, greatly simplify the formula of the high-temperature-resistant drilling fluid system, and effectively reduce the construction difficulty and operation intensity.

[0143] It should be noted that the above-described examples are only used to explain the present application and do not constitute any limitation on the present application. The present application is described by referring to typical examples, but it should be understood that the words used therein are descriptive and explanatory words, rather than limiting words. The present application can be modified as specified within the scope of the claims of the present application, and the present application can be revised within the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials and examples, it does not mean that the present application is limited to the specific examples disclosed therein, on the contrary, the present application can be extended to all other methods and applications with the same function.

Claims

1. A method for preparing a temperature-resistant and salt-resistant copolymer with filtration-reducing, viscosity-increasing, and lubricating properties, characterized in that, The application relates to a method for preparing a temperature-resistant and salt-resistant copolymer with filtration-reducing, viscosity-increasing and lubricating properties. The anionic monomer comprises 2-acrylamide-2-methylpropane sulfonic acid. The cross-linking monomer comprises at least one of acrylamide and N-hydroxymethyl acrylamide. The amount of each component comprises: The solvent is 100 parts by weight; The natural polymer material is 2-3 parts by weight; The organic acid anhydride is 10-40 parts by weight; The vinyl-containing sulfonate is 4-10 parts by weight; The anionic monomer is 20-30 parts by weight; The cross-linking monomer is 1-6 parts by weight; The initiator is 0.5-1 part by weight. The natural polymer material is a starch natural polymer material; 2. The production method according to claim 1, characterized by, And / or, the organic acid anhydride comprises at least one selected from phthalic anhydride and maleic anhydride; And / or, the vinyl-containing sulfonate comprises at least one of styrene sodium sulfonate and allyl sodium sulfonate; And / or, the initiator comprises at least one of ammonium persulfate and potassium persulfate; And / or, the solvent comprises water. The natural polymer material comprises at least one of corn starch and sweet potato starch; 3. The preparation method according to claim 1, characterized in that, And / or, the amount of each component comprises: The solvent is 100 parts by weight; The natural polymer material is 2-3 parts by weight; The organic acid anhydride is 20-30 parts by weight; The vinyl-containing sulfonate is 5-8 parts by weight; The anionic monomer is 24-26 parts by weight; The cross-linking monomer is 3-4 parts by weight; The initiator is 0.5-1 part by weight. The preparation method comprises:

4. The production method according to any one of claims 1 to 3, characterized by, The natural polymer material and the solvent are mixed and stirred, then the organic acid anhydride, the vinyl-containing sulfonate, the anionic monomer and the cross-linking monomer are sequentially added and stirred and dissolved, then the initiator is added, and stirring reaction is carried out at 60-80 DEG C to prepare the temperature-resistant and salt-resistant copolymer with filtration-reducing, viscosity-increasing and lubricating properties. The stirring speed is 300-500 r / min; 5. The preparation method according to claim 4, characterized in that, And / or, the stirring reaction time is 2-8 min. The preparation method further comprises drying, crushing and sieving the reaction product.

6. The preparation method according to claim 4, characterized in that, The drying temperature is 90-110 DEG C, and the drying time is 16-30 h.

7. The preparation method according to claim 6, characterized in that, 8. A temperature-resistant and salt-resistant copolymer with filtration-reducing, viscosity-increasing and lubricating properties, which is prepared by the preparation method in any one of claims 1-7.

9. Application of the temperature-resistant and salt-resistant copolymer with filtration-reducing, viscosity-increasing and lubricating properties in claim 8 in a drilling fluid. The drilling fluid comprises the temperature-resistant and salt-resistant copolymer with filtration-reducing, viscosity-increasing and lubricating properties in claim 8.

10. A drilling fluid, characterized by, ​

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