CN117757446A - High-temperature-resistant calcium-resistant water-based drilling fluid for shale ultra-deep well and preparation method thereof - Google Patents

Abstract

The invention discloses a high-temperature-resistant and calcium-resistant water-based drilling fluid for a shale ultra-deep well and a preparation method thereof, wherein the high-temperature-resistant and calcium-resistant water-based drilling fluid comprises the following raw materials in parts by weight: water: 1000 parts; sodium bentonite: 30-40 parts; cationic polymer coating agent: 2-4 parts; temperature-resistant and calcium-resistant polymer filtrate reducer: 10-20 parts; clay surface hydration inhibitor: 3-5 parts; sulfonated phenolic resin: 20-30 parts; sulfonated lignite resin: 20-30 parts; low fluorescence cationic asphalt powder: 30-50 parts; biological lubricant: 20-40 parts; solid polymeric alcohol: 15-25 parts; superfine calcium carbonate: 30-50 parts; micro-nano strong plugging agent: 5-15 parts; amphiphilic blocking agent: 10-15 parts; barite: 330-400 parts; the pH value is regulated to 9-10. The drilling fluid can resist high temperature of more than 200 ℃, has strong salt and calcium resistance and 5 percent of calcium chloride pollution resistance, can reduce comprehensive damage to stratum which is easy to collapse due to filtrate, improves stratum bearing capacity, and meets drilling construction requirements.

Description

High-temperature-resistant calcium-resistant water-based drilling fluid for shale ultra-deep well and preparation method thereof

Technical Field

The invention relates to drilling fluid for ultra-deep well operation, in particular to high-temperature-resistant and calcium-resistant water-based drilling fluid for a shale ultra-deep well; the invention also relates to a preparation method of the high-temperature-resistant calcium-resistant water-based drilling fluid for the shale ultra-deep well, and belongs to the technical field of drilling fluids.

Background

In recent years, the development force of domestic oil gas resources is continuously increased, and the oil gas exploration is expanded from shallow layers to middle deep layers and is changed from traditional conventional oil gas exploitation to unconventional oil gas exploitation. Deep wells and unconventional oil and gas face complicated stratum conditions, including extreme factors such as high temperature, high pressure, high calcium, high salt and the like, and the performance requirements on drilling fluid are more severe. How to control the fluid loss performance of the well drilling fluid in deep well drilling is an important index for evaluating the well drilling fluid, the fluid loss additive is used as one of core materials of the well drilling fluid treatment agent, and by combining adsorption and hydration with clay particles, a low-permeability and compact mud cake is formed near the well wall, so that the water phase in the well drilling fluid can be effectively prevented from entering the stratum. The temperature resistance and the calcium resistance of the filtrate reducer are the key for ensuring the stability of the water-based drilling fluid of the calcium-containing stratum in the high-temperature deep well drilling process, and how to maintain the temperature resistance and the stability of the drilling fluid, good rheological property and reasonable high-temperature and high-pressure filtrate loss are all the difficulties of the drilling fluid technology in the ultra-deep well environment.

At present, the domestic temperature-resistant filtrate reducer has various types and can be divided into three main types of natural high molecular materials, synthetic polymers and organic/inorganic composite materials according to the components, wherein the natural high molecular materials have obviously insufficient temperature resistance, and the temperature resistance of the natural high molecular materials can be improved after modification. The synthetic polymer filtrate reducer has the advantages of good thermal stability of molecular chains, strong controllability of molecular structures, multiple types of functional monomers, wide sources, relatively simple synthetic process and the like, and becomes a research hot spot in recent years. The inorganic/organic composite material is prepared by blending and copolymerizing an inorganic material and a polymer, wherein the inorganic material can be used as a filler or a polymer monomer to interact with the polymer to greatly improve the performance of the whole material, and the composite material filtrate reducer mainly comprises silicon dioxide/polymer, graphene/polymer and the like. The filtrate reducer is used in deep wells, especially ultra-deep wells above 5000 meters, has obvious filtrate reducing effect and is widely applied, however, the filtrate reducer has the defect of calcium resistance in ultra-deep wells. The most important problem is that under the influence of high temperature and high calcium, the filtrate reducer molecules curl, so that the filtrate reducer has great influence on the filtrate reducer failure effect and weak calcium resistance. Therefore, the development of the temperature-resistant and calcium-resistant water-based drilling fluid for ultra-deep well operation has become a hot spot for solving the problems of failure of filtrate reducer and the like under the condition of high temperature and high calcium in the ultra-deep well drilling process.

The Chinese patent publication No. CN 102250595B discloses a drilling fluid for active mud shale drilling, which comprises, by weight, 2-6% of bentonite, 0.2-0.5% of coating inhibitor, 0.2-1.0% of flow pattern regulator, 0.2-0.5% of high temperature resistant polymer filtrate reducer, 4-7% of potassium chloride, 1-3% of polyalcohol, 0.5-1.0% of polyamine inhibitor, 0.5-1.0% of anti-balling fast drilling agent and 45-85% of water. The drilling fluid can prevent active mud shale from losing stability of the well wall, dispersion of drill cuttings, mud-packing of drill bit and adhesion and coalescence of mud rock; but cannot be used in high temperature environments for ultra-deep wells above 5000 meters.

Based on the reasons, the high-temperature-resistant and calcium-resistant water-based drilling fluid filtrate reducer with the hyperbranched structure is researched and developed, and a high-temperature-resistant and calcium-resistant water-based drilling fluid system which takes the treating agent as a core and is suitable for ultra-deep wells is formed, so that the filtrate reducer is key to solving a series of problems such as failure of the filtrate reducer under high-temperature and high-calcium conditions in the ultra-deep well drilling operation process.

Disclosure of Invention

The invention aims at overcoming the problems in the prior art and providing the high-temperature-resistant and calcium-resistant water-based drilling fluid for the shale ultra-deep well, which has strong salt-resistant and calcium-resistant capabilities and 5% calcium chloride pollution-resistant capabilities under the high-temperature and high-pressure environment of the ultra-deep well with the temperature exceeding 200 ℃ and more than 5000 meters, can reduce the comprehensive damage of filtrate to the stratum which is easy to collapse, improves the stratum bearing capacity and meets the drilling construction requirements.

In order to solve the technical problems, the high-temperature-resistant and calcium-resistant water-based drilling fluid for the shale ultra-deep well comprises the following raw materials in parts by weight: water: 1000 parts; sodium bentonite: 30-40 parts; cationic polymer coating agent: 2-4 parts; temperature-resistant and calcium-resistant polymer filtrate reducer: 10-20 parts; clay surface hydration inhibitor: 3-5 parts; sulfonated phenolic resin: 20-30 parts; sulfonated lignite resin: 20-30 parts; low fluorescence cationic asphalt powder: 30-50 parts; biological lubricant: 20-40 parts; solid polymeric alcohol: 15-25 parts; superfine calcium carbonate: 30-50 parts; micro-nano strong plugging agent NANOFSEAL: 5-15 parts; amphiphilic blocking agent: 10-15 parts; barite: 330-400 parts; naOH is used for adjusting the pH value to 9-10.

Further, the raw materials comprise the following components in parts by weight: water: 1000 parts; sodium bentonite: 30 parts; cationic polymer coating agent: 2 parts; temperature-resistant and calcium-resistant polymer filtrate reducer: 10 parts; clay surface hydration inhibitor: 3 parts; sulfonated phenolic resin: 20 parts; sulfonated lignite resin: 20 parts; low fluorescence cationic asphalt powder: 30 parts; biological lubricant: 20 parts; solid polymeric alcohol: 15 parts; superfine calcium carbonate: 30 parts; micro-nano strong plugging agent NANOFSEAL:5 parts; amphiphilic blocking agent: 10 parts; barite: 330 parts; the pH was adjusted to 9 with NaOH.

Further, the raw materials comprise the following components in parts by weight: water: 1000 parts; sodium bentonite: 35 parts; cationic polymer coating agent: 3 parts; temperature-resistant and calcium-resistant polymer filtrate reducer: 15 parts; clay surface hydration inhibitor: 4 parts; sulfonated phenolic resin: 25 parts; sulfonated lignite resin: 25 parts; low fluorescence cationic asphalt powder: 40 parts; biological lubricant: 30 parts; solid polymeric alcohol: 20 parts; superfine calcium carbonate: 40 parts; micro-nano strong plugging agent NANOFSEAL:10 parts; amphiphilic blocking agent: 12 parts; barite: 360 parts; the pH was adjusted to 9.5 with NaOH.

Further, the raw materials comprise the following components in parts by weight: water: 1000 parts; sodium bentonite: 40 parts; cationic polymer coating agent: 4 parts; temperature-resistant and calcium-resistant polymer filtrate reducer: 20 parts; clay surface hydration inhibitor: 5 parts; sulfonated phenolic resin: 30 parts; sulfonated lignite resin: 30 parts; low fluorescence cationic asphalt powder: 50 parts; biological lubricant: 40 parts; solid polymeric alcohol: 25 parts; superfine calcium carbonate: 50 parts; micro-nano strong plugging agent NANOFSEAL:15 parts; amphiphilic blocking agent: 15 parts; barite: 400 parts; the pH was adjusted to 10 with NaOH.

The invention further aims to overcome the problems in the prior art, and provides a preparation method of the high-temperature-resistant and calcium-resistant water-based drilling fluid for the shale ultra-deep well, which is strong in salt-resistant and calcium-resistant capabilities and up to 5% in calcium chloride pollution-resistant capabilities under the high-temperature and high-pressure environment of the ultra-deep well with the temperature exceeding 200 ℃ and over 5000 meters, so that the comprehensive damage of filtrate to the stratum which is easy to collapse can be reduced, the stratum bearing capacity is improved, and the drilling construction requirements are met.

In order to solve the technical problems, the preparation method of the high-temperature-resistant calcium-resistant water-based drilling fluid for the shale ultra-deep well, disclosed by the invention, sequentially comprises the following steps of:

a1, firstly mixing 1000 parts of water with 30-40 parts of sodium bentonite, stirring for 30-60 minutes at a stirring speed of 2000-4000 rpm, then stirring for 30-40 minutes at a stirring speed of 6000-10000 rpm, and curing for 24 hours at normal temperature to form a mixture 1;

a2, slowly and uniformly adding 2-4 parts of cationic polymer coating agent into the mixture 1 at a stirring speed of 6000-10000 rpm, uniformly stirring, then adding 10-20 parts of temperature-resistant and calcium-resistant polymer filtrate reducer and 3-5 parts of clay surface hydration inhibitor, and uniformly adding 20-30 parts of sulfonated phenolic resin and 20-30 parts of sulfonated lignite resin while stirring; then evenly adding 30-50 parts of low-fluorescence cationic asphalt powder while stirring, evenly stirring, adding 20-40 parts of biological lubricant, evenly stirring, then adding 15-25 parts of solid polymeric alcohol, evenly stirring, then adding 5-15 parts of micro-nano strong plugging agent NANOFSEAL, evenly stirring, then adding 10-20 parts of amphiphilic plugging agent and 30-50 parts of superfine calcium carbonate to form a mixture 2;

a3, regulating the pH value of the mixture 2 to 9-10 by NaOH to form a mixture 3;

And A4, adding 330-400 parts of barite into the mixture 3, and uniformly stirring to obtain the water-based drilling fluid base slurry.

Further, the preparation method of the high-temperature-resistant calcium-resistant water-based drilling fluid for the shale ultra-deep well sequentially comprises the following steps:

a1, firstly mixing 1000 parts of water with 30 parts of sodium bentonite, stirring for 30 minutes at a stirring speed of 2000rpm, then stirring for 30 minutes at a stirring speed of 6000rpm, and curing for 24 hours at normal temperature to form a mixture 1;

a2, slowly and uniformly adding 2 parts of cationic polymer coating agent into the mixture 1 at a stirring speed of 6000rpm, uniformly stirring, then adding 10 parts of temperature-resistant and calcium-resistant polymer filtrate reducer and 3 parts of clay surface hydration inhibitor, uniformly stirring, then adding 20 parts of sulfonated phenolic resin and 20 parts of sulfonated lignite resin, uniformly stirring, then adding 30 parts of low-fluorescence cationic asphalt powder, uniformly stirring, then adding 20 parts of biological lubricant, uniformly stirring, then adding 15 parts of solid polyalcohol, uniformly stirring, then adding 5 parts of micro-nano strong plugging agent NANOFSEAL, uniformly stirring, then adding 10 parts of amphiphilic plugging agent and 30 parts of superfine calcium carbonate, and forming a mixture 2;

a3, adjusting the pH value of the mixture 2 to 9 by NaOH to form a mixture 3;

And A4, adding 330 parts of weight of crystal stone into the mixture 3, and uniformly stirring to obtain the water-based drilling fluid base slurry.

Further, the preparation method of the high-temperature-resistant calcium-resistant water-based drilling fluid for the shale ultra-deep well sequentially comprises the following steps:

a1, firstly mixing 1000 parts of water with 35 parts of sodium bentonite, stirring for 45 minutes at a stirring speed of 3000rpm, then stirring for 35 minutes at a stirring speed of 8000rpm, and curing for 24 hours at normal temperature to form a mixture 1;

a2, slowly and uniformly adding 3 parts of cationic polymer coating agent into the mixture 1 at a stirring speed of 8000rpm, uniformly stirring, then adding 15 parts of temperature-resistant and calcium-resistant polymer filtrate reducer and 4 parts of clay surface hydration inhibitor, uniformly stirring, then adding 25 parts of sulfonated phenolic resin and 25 parts of sulfonated lignite resin, uniformly stirring, then adding 40 parts of low-fluorescence cationic asphalt powder, uniformly stirring, then adding 30 parts of biological lubricant, uniformly stirring, then adding 20 parts of solid polyalcohol, uniformly stirring, then adding 10 parts of micro-nano strong plugging agent NANOFSEAL, uniformly stirring, then adding 12 parts of amphiphilic plugging agent and 40 parts of superfine calcium carbonate, and forming a mixture 2;

a3, adjusting the pH value of the mixture 2 to 9.5 by NaOH to form a mixture 3;

And A4, adding 360 parts of heavy crystal stone into the mixture 3, and uniformly stirring to obtain the water-based drilling fluid base slurry.

Further, the preparation method of the high-temperature-resistant calcium-resistant water-based drilling fluid for the shale ultra-deep well sequentially comprises the following steps:

a1, firstly mixing 1000 parts of water with 40 parts of sodium bentonite, stirring for 60 minutes at a stirring speed of 4000rpm, then stirring for 40 minutes at a stirring speed of 10000rpm, and curing for 24 hours at normal temperature to form a mixture 1;

a2, slowly and uniformly adding 4 parts of cationic polymer coating agent into the mixture 1 at a stirring speed of 10000rpm, uniformly stirring, then adding 20 parts of temperature-resistant and calcium-resistant polymer filtrate reducer and 5 parts of clay surface hydration inhibitor, uniformly stirring, then adding 30 parts of sulfonated phenolic resin and 30 parts of sulfonated lignite resin, uniformly stirring, then adding 50 parts of low-fluorescence cationic asphalt powder, uniformly stirring, then adding 40 parts of biological lubricant, uniformly stirring, then adding 25 parts of solid polyalcohol, uniformly stirring, then adding 15 parts of micro-nano strong plugging agent NANOFSEAL, uniformly stirring, then adding 20 parts of amphiphilic plugging agent and 50 parts of superfine calcium carbonate, and forming a mixture 2;

a3, adjusting the pH value of the mixture 2 to 10 by NaOH to form a mixture 3;

And A4, adding 400 parts of barite into the mixture 3, and uniformly stirring to obtain the water-based drilling fluid base slurry.

Further, the structural formula of the temperature-resistant and calcium-resistant polymer filtrate reducer is shown as the following formula:

further, the preparation of the temperature-resistant and calcium-resistant polymer filtrate reducer sequentially comprises the following steps:

s1, adding 10 parts by weight of deionized water into a reactor, adding 3-8 parts by weight of triallyl phosphate while stirring, adjusting the pH value of the system to 10-12 by using sodium hydroxide solution, and keeping the temperature at 30+/-3 ℃;

s2, charging nitrogen into the reactor for 30min, removing oxygen in the reactor, and continuously charging nitrogen into the reactor in the reaction process;

s3, taking a solution formed by dissolving dibenzoyl peroxide in water with the mass of 5 times as a primary polymerization initiator;

s4, adding 0.1-0.3 part by weight of primary polymerization initiator into the reactor, and keeping the system temperature at 30+/-3 ℃ for primary polymerization reaction for 0.5 hour;

s5, mixing sodium persulfate and ammonium persulfate according to the proportion of 1:1 mass ratio, and then dissolving the mixture in water with the mass ratio of 5 times as a secondary polymerization initiator;

s6, adding 0.5-1 weight part of secondary polymerization initiator into the reactor, adding 5-15 weight parts of dimethyl diallyl ammonium chloride, and continuing the reaction for 0.5 hour to perform secondary polymerization reaction;

S7, dissolving 10-20 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid, 20-30 parts by weight of acrylamide, 15-35 parts by weight of styrene and 5-15 parts by weight of sodium methacrylate powder monomer in water which is equal to the total mass of the powder, and uniformly stirring;

s8, adding the solution obtained in the step S7 into a reactor, controlling the reaction temperature in the reactor to be 30+/-3 ℃, and carrying out three polymerization reactions for 2 hours;

s9, adding 1 part by weight of a chain transfer agent trichloroethylene into the reactor, and continuing the reaction for 4 hours;

s10, stopping supplying nitrogen into the reactor, blowing air into the reactor, adding 1 part by weight of polymerization inhibitor ferric chloride into the reactor, reacting for 0.5 hour, and terminating the product;

s11, drying the product in the reactor at 100 ℃, and crushing to obtain the product powder of the temperature-resistant and calcium-resistant polymer filtrate reducer.

Compared with the prior art, the invention has the following beneficial effects: 1. the invention uses barite as weighting agent to make the mixture reach the density needed by design, and finally forms suspension type drilling fluid. The advantages of the formed ultra-deep well salt-resistant, calcium-resistant and high-temperature-resistant drilling fluid are represented by the following points: (1) When the complex stratum in the deep well environment is constructed, the combination of the high-temperature inhibitor cationic polymer coating agent and the clay surface hydration inhibitor can greatly improve the overall inhibition of the drilling fluid, effectively prevent the hydration dispersion effect of the shale and synergistically improve the stability of the well wall; (2) The temperature-resistant and calcium-resistant polymer filtrate reducer can obviously reduce the high-temperature and high-pressure filtrate loss of drilling fluid, the drilling fluid is not thickened after being added, the influence on the rheological property of the drilling fluid is small, the high-temperature and high-pressure filtrate loss is still relatively stable and in a lower range after long-time high-temperature action, and the formed drilling fluid filter cake is thin and compact, so that the comprehensive damage of filtrate to the stratum easy to collapse is reduced, and the temperature-resistant and calcium-resistant polymer filtrate reducer not only can improve the filtrate loss performance, but also has good salt and calcium resistance, and can obviously improve the pollution resistance of a drilling fluid system; (3) The combined action of the micro-nano strong plugging agent NANOFSEAL, the amphiphilic plugging agent and the low-fluorescence cationic asphalt powder enables the formed drilling fluid filter cake to be thin, tough and compact, the drilling fluid wall protection effect is stronger, the micro-cracks of the shale stratum which is easy to collapse can be effectively plugged, the stratum bearing capacity can be improved, and the occurrence of underground complex faults caused by the instability of the well wall due to the fact that filtrate enters the stratum can be delayed; (4) The biological lubricant is added to greatly improve the lubricity of the drilling fluid and meet the need of lubrication and anti-seizing. The comprehensive synergistic effect of the above points can greatly reduce the high-temperature high-pressure filtration loss in the deep well environment, various performance indexes of the drilling fluid are stable, the stability of the well wall of the stratum which is easy to collapse by the ultra-deep well shale can be improved, and good technical guarantee can be provided for safe and efficient construction of the ultra-deep well. Therefore, compared with the traditional deep well drilling fluid, the drilling fluid has stable rheological property, strong inhibition, good water loss and wall formation performance, stable control of high-temperature and high-pressure filtration loss, strong and reliable plugging capability, strong salt invasion resistance and calcium invasion resistance, and more stable drilling fluid system performance under the high-temperature condition.

2. The temperature-resistant and calcium-resistant filtrate reducer prepared by the invention is characterized in that triallyl phosphate is polymerized for the first time under the action of dibenzoyl peroxide to form an inner core, the inner core is subjected to secondary polymerization reaction with dimethyl diallyl ammonium chloride under the condition of initiating sodium sulfite and ammonium persulfate, and finally, 2-acrylamide-2-methylpropanesulfonic acid, acrylamide and styrene methacrylic acid are sequentially added for three polymerization reactions, and a monobasic olefin derivative is blocked and a certain molecular chain is properly prolonged, so that a hyperbranched structure is obtained. The carbon-carbon bonds adopted by the inner core of the structure are branched, and the branched carbon-carbon bonds are more stable than carbon-oxygen bonds, carbon-nitrogen bonds and the like, so that the inner core of the molecule has good temperature resistance, and a final product has good temperature resistance; because the polymer has a hyperbranched structure and contains a large amount of hydrophilic groups outside, the polymer has good solubility, is not easy to agglomerate, is more convenient to use, and can play an obvious role at low temperature.

3. Compared with other types of high-temperature resistant drilling fluids existing at present, the drilling fluid has the advantages that: 1) The core treatment agent used by the drilling fluid system is a temperature-resistant and calcium-resistant filtrate reducer, so that the calcium-resistant and salt-resistant pollution capability of the drilling fluid system can be improved, and the temperature-resistant capability of a single agent reaches 230 ℃; 2) The preparation method adopts a three-time polymerization method, and the preparation method has mild and controllable reaction conditions and high reaction speed, and is suitable for industrialized application and popularization.

4. The temperature-resistant and calcium-resistant filtrate reducer has high temperature resistance, salt resistance, calcium resistance and no tackifying, and the synthesized product contains carboxyl, sulfonic acid group, amide group, amino group and ester group, so that the product can well adsorb the surface of clay, has a ring-shaped structure, can enhance the rigidity of molecules and enhances the high temperature resistance of the product; because of the hyperbranched structure and the carboxyl, sulfonic acid group, amido, cyclic and amido contained, the product has very good salt and calcium resistance, and can still have good filtration reducing performance under the environment of high salt and high calcium.

5. Inorganic micro-nano plugging agent and amphiphilic plugging agent are selected for the prepared drilling fluid system, so that the plugging bearing capacity of the drilling fluid to the micro-cracks of the stratum can be improved, and in the two plugging materials, the inorganic micro-nano is a rigid plugging agent, the amphiphilic is a fiber flexible plugging agent, and the two plugging agents are compounded for use, so that the plugging efficiency can be synergistically improved; the composite calcium carbonate particles are used as bridging particles, so that the quality of a filter cake can be obviously improved, and the material is wide in source and low in cost.

Drawings

The invention will now be described in further detail with reference to the drawings and the detailed description, which are provided for reference and illustration only and are not intended to limit the invention.

FIG. 1 is a schematic diagram showing the equations of a one-time polymerization reaction in the preparation process of a filtrate reducer according to the present invention;

FIG. 2 is a schematic diagram showing the equations of the secondary polymerization reaction in the preparation process of the filtrate reducer of the present invention;

FIG. 3 is an equation for three polymerizations during the preparation of a fluid loss additive according to the present invention;

FIG. 4 is a reaction equation for the terminal radical of the tertiary polymerization reaction product of the present invention with a chain transfer agent;

FIG. 5 is a reaction equation of the end groups of the product with the polymerization inhibitor in the present invention;

FIG. 6 is a structural formula of a temperature and calcium resistant polymeric fluid loss additive of the present invention;

fig. 7 is a graph of experimental data of plugging pressure bearing performance of the drilling fluid of the present invention.

Detailed Description

In the following description of the invention, the term "parts" refers to "parts by weight" unless otherwise noted, and "water" is not noted as "deionized water" in the process of preparing the temperature-resistant and calcium-resistant polymer filtrate reducer, and tap water may be used in the process of preparing the drilling fluid.

The invention is further described with reference to the following detailed drawings in order to make the technical means, the creation characteristics, the achievement of the purpose and the effect of the implementation of the invention easy to understand.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

Example 1

The preparation method of the temperature-resistant and calcium-resistant polymer filtrate reducer sequentially comprises the following steps:

s1, adding 10 parts by weight of deionized water into a reactor, adding 3 parts by weight of triallyl phosphate while stirring, adjusting the pH value of the system to 10 by using a sodium hydroxide solution, and keeping the temperature at 27 ℃;

s2, charging nitrogen into the reactor for 30min, removing oxygen in the reactor, and continuously charging nitrogen into the reactor in the reaction process;

s3, taking a solution formed by dissolving dibenzoyl peroxide in water with the mass of 5 times as a primary polymerization initiator, namely a catalyst;

s4, adding 0.1 part by weight of primary polymerization initiator into the reactor, keeping the system temperature at 27 ℃, and carrying out primary polymerization for 0.5 hour, wherein the flow is shown in the figure 1;

s5, mixing sodium persulfate and ammonium persulfate according to the proportion of 1:1 mass ratio, and then dissolving the mixture in water with the mass ratio of 5 times as a secondary polymerization initiator;

s6, adding 0.5 weight part of secondary polymerization initiator into the reactor, adding 5 weight parts of dimethyl diallyl ammonium chloride, and continuing to react for 0.5 hour to perform secondary polymerization, wherein the flow is shown in the figure 2;

s7, dissolving 10 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid, 20 parts by weight of acrylamide, 15 parts by weight of styrene and 5 parts by weight of sodium methacrylate powder monomer in water which is equal to the total mass of the powder, and uniformly stirring;

S8, adding the solution obtained in the step S7 into a reactor, controlling the reaction temperature in the reactor at 27 ℃, and carrying out three polymerization reactions for 2 hours, wherein the flow is shown in a figure 3;

s9, adding 1 part by weight of a chain transfer agent trichloroethylene into the reactor, and continuing the reaction for 4 hours, wherein the aim is to control the molecular weight of the reaction, and the reaction formula of the terminal free radical of the three-time polymerization reaction product and the chain transfer agent is shown in figure 4.

S10, stopping supplying nitrogen into the reactor, blowing air into the reactor, adding 1 part by weight of polymerization inhibitor ferric trichloride into the reactor, and reacting for 0.5 hour to end-cap the product, wherein the reaction formula of the end group of the product and the polymerization inhibitor is shown in figure 5.

S11, drying the product in the reactor at 100 ℃, and crushing to obtain product powder of the temperature-resistant and calcium-resistant polymer filtrate reducer, wherein the structure of the final product is shown in figure 6.

Example 2

The preparation method of the temperature-resistant and calcium-resistant polymer filtrate reducer sequentially comprises the following steps:

s1, adding 10 parts by weight of deionized water into a reactor, adding 6 parts by weight of triallyl phosphate while stirring, adjusting the pH value of the system to 11 by using a sodium hydroxide solution, and keeping the temperature at 30 ℃;

s2, charging nitrogen into the reactor for 30min, removing oxygen in the reactor, and continuously charging nitrogen into the reactor in the reaction process;

S3, taking a solution formed by dissolving dibenzoyl peroxide in water with the mass of 5 times as a primary polymerization initiator;

s4, adding 0.2 part by weight of primary polymerization initiator into the reactor, keeping the system temperature at 30 ℃, and carrying out primary polymerization for 0.5 hour;

s5, mixing sodium persulfate and ammonium persulfate according to the proportion of 1:1 mass ratio, and then dissolving the mixture in water with the mass ratio of 5 times as a secondary polymerization initiator;

s6, adding 0.8 part by weight of secondary polymerization initiator into the reactor, adding 10 parts by weight of dimethyl diallyl ammonium chloride, and continuing to react for 0.5 hour to perform secondary polymerization reaction;

s7, dissolving 15 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid, 25 parts by weight of acrylamide, 25 parts by weight of styrene and 10 parts by weight of sodium methacrylate powder monomer in water which is equal to the total mass of the powder, and uniformly stirring;

s8, adding the solution obtained in the step S7 into a reactor, controlling the reaction temperature in the reactor at 30 ℃, and carrying out three polymerization reactions for 2 hours;

s9, adding 1 part by weight of a chain transfer agent trichloroethylene into the reactor, and continuing the reaction for 4 hours, wherein the aim is to control the molecular weight of the reaction, and the terminal free radical of the three-time polymerization reaction product reacts with the chain transfer agent.

S10, stopping supplying nitrogen into the reactor, blowing air into the reactor, adding 1 part by weight of polymerization inhibitor ferric chloride into the reactor, reacting for 0.5 hour, and carrying out product end capping to react the product end groups with the polymerization inhibitor.

S11, drying the product in the reactor at 100 ℃, and crushing to obtain the product powder of the temperature-resistant and calcium-resistant polymer filtrate reducer.

Example 3

The preparation method of the temperature-resistant and calcium-resistant polymer filtrate reducer sequentially comprises the following steps:

s1, adding 10 parts by weight of deionized water into a reactor, adding 8 parts by weight of triallyl phosphate while stirring, adjusting the pH value of the system to 12 by using a sodium hydroxide solution, and keeping the temperature at 33 ℃;

s2, charging nitrogen into the reactor for 30min, removing oxygen in the reactor, and continuously charging nitrogen into the reactor in the reaction process;

s3, taking a solution formed by dissolving dibenzoyl peroxide in water with the mass of 5 times as a primary polymerization initiator;

s4, adding 0.3 part by weight of primary polymerization initiator into the reactor, keeping the system temperature at 33 ℃, and carrying out primary polymerization for 0.5 hour;

s5, mixing sodium persulfate and ammonium persulfate according to the proportion of 1:1 mass ratio, and then dissolving the mixture in water with the mass ratio of 5 times as a secondary polymerization initiator;

S6, adding 1 part by weight of secondary polymerization initiator into the reactor, adding 15 parts by weight of dimethyl diallyl ammonium chloride, and continuing to react for 0.5 hour to perform secondary polymerization reaction;

s7, dissolving 20 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid, 30 parts by weight of acrylamide, 35 parts by weight of styrene and 15 parts by weight of sodium methacrylate powder monomer in water which is equal to the total mass of the powder, and uniformly stirring;

s8, adding the solution obtained in the step S7 into a reactor, controlling the reaction temperature in the reactor at 33 ℃, and carrying out three polymerization reactions for 2 hours;

s9, adding 1 part by weight of a chain transfer agent trichloroethylene into the reactor, and continuing the reaction for 4 hours, wherein the aim is to control the molecular weight of the reaction, and the terminal free radical of the three-time polymerization reaction product reacts with the chain transfer agent.

S10, stopping supplying nitrogen into the reactor, blowing air into the reactor, adding 1 part by weight of polymerization inhibitor ferric chloride into the reactor, reacting for 0.5 hour, and carrying out product end capping to react the product end groups with the polymerization inhibitor.

S11, drying the product in the reactor at 100 ℃, and crushing to obtain the product powder of the temperature-resistant and calcium-resistant polymer filtrate reducer.

The performance of the high temperature resistant and calcium resistant polymer filtrate reducer is compared and evaluated:

1. evaluation of Property of fresh Water slurry

Fresh water based slurry: taking 350mL of distilled water, adding 14.0g of sodium bentonite and 0.2g of anhydrous sodium carbonate, stirring at a high speed for 20min, and hermetically curing at 25+/-1 ℃ for 24h to obtain the dilute water-based slurry.

Fresh water base slurry was added to 3.5g of the sample, and stirred at high speed for 20 minutes. Transferring into an aging tank, rolling for 16h at a constant temperature (140 ℃ and 180 ℃ and 220 ℃) and taking out the aging tank, cooling to room temperature and stirring for 5 minutes at a high speed; then, the fluid loss and apparent viscosity at the corresponding temperatures were tested as specified in GB/T16783.1-2014 at 25+ -1.

The modified PAC, the terpolymer filtrate reducer and the lignite resin which are conventionally and commonly used are used as comparative examples, and the used modified PAC is a product of Daqingli macro-fine chemical industry Co., ltd, and the terpolymer filtrate reducer and the lignite resin are products of Daoqiao oil technology Co., ltd.

The fluid loss in fresh water base slurry for each sample pair is shown in table 1:

TABLE 1

The apparent viscosity pair of each sample in the fresh water base slurry is shown in table 2:

TABLE 2

As can be seen from tables 1 and 2, the temperature-resistant and calcium-resistant polymer filtrate reducer used in the invention has better effect than the modified PAC, the ternary polymer filtrate reducer and the lignite resin at 140 ℃, 180 ℃ and 220 ℃ under the condition that the addition amount is the same in the fresh water base slurry, and the high-temperature and high-pressure water loss is only 15.6-18.6ml at 220 ℃, so that the high-temperature-resistant performance is shown. The viscosity of the modified PAC and the viscosity of the lignite resin are low at 220 ℃, but the viscosity of the modified PAC and the lignite resin basically have no filtration reducing effect, and the viscosity of the temperature-resistant and calcium-resistant polymer filtration reducing agent used in the invention is low at low temperature and high temperature, and the viscosity of the temperature-resistant and calcium-resistant polymer filtration reducing agent is low, and the change of the temperature-resistant and calcium-resistant polymer filtration reducing agent is low, so that the influence on the slurry performance is small.

2. Evaluation of 5% calcium Water slurry Properties

Taking 350mL of distilled water, sequentially adding 14g of standard evaluation soil, 14g of sodium bentonite and 0.2g of anhydrous sodium carbonate, stirring at a high speed for 20min, and curing at 25+/-1 ℃ for 24h to obtain basic slurry.

Taking 7g of a base slurry, adding 7g of a sample under stirring, adding 5% calcium chloride, stirring at a high speed for 20min, transferring into an aging tank, rolling for 16h at a constant temperature (140 ℃, 180 ℃ and 220 ℃), taking out the aging tank, cooling to room temperature, stirring at a high speed for 5min, and measuring the high-temperature and high-pressure filtration loss and apparent viscosity at a corresponding temperature according to the specification in GB/T16783.1-2014 at 25+/-1 ℃.

The conventional and commonly used modified PAC, terpolymer fluid loss additive and lignite resin were used as comparative examples, and the fluid loss of each sample in 5% calcium water slurry was as shown in table 3:

TABLE 3 Table 3

The apparent viscosity pair ratio of each sample in 5% calcium water slurry is shown in table 4:

TABLE 4 Table 4

As can be seen from the test results in tables 3 and 4, the modified PAC and the lignite resins have poor calcium salt resistance effect at low temperature or high temperature, and are particularly high in Wen Shijun total filtration; the ternary polymer filtrate reducer has certain calcium resistance at low temperature, but at high temperature, the water loss reaches 128ml, the filtrate reduction failure effect is greatly weakened, the high temperature calcium resistance effect is poor, the viscosity is relatively high, and the influence on the viscosity of drilling fluid is large. The temperature-resistant and calcium-resistant polymer filtrate reducer used in the invention has good calcium salt resistance when aged at 220 ℃ and the calcium content is 5%, and the high-temperature and high-pressure filtrate loss is only 24.4-26.4mL, and the viscosity of drilling fluid is low, and the viscosity changes little with temperature, so that the influence of the treating agent on the viscosity of the drilling fluid is small.

From tables 1, 2, 3 and 4, it can be seen that the temperature-resistant and calcium-resistant polymer filtrate reducer used in the invention has good filtrate reducing effect in fresh water slurry, has good filtrate reducing effect when the calcium chloride content reaches 5%, and shows good temperature-resistant and calcium-resistant capabilities at 220 ℃; in the process of preparing drilling fluid, the dissolution speed is high, the drilling fluid is not easy to agglomerate, and the use is more convenient; the influence on the viscosity of the drilling fluid is small, and the viscosity change is small when the temperature is changed, so that the method can be better applied to the field.

Example 4

The invention relates to a preparation method of a high-temperature-resistant calcium-resistant water-based drilling fluid for a shale ultra-deep well, which sequentially comprises the following steps:

a1, firstly mixing 1000 parts of water with 30 parts of sodium bentonite, stirring for 30 minutes at a stirring speed of 2000rpm, then stirring for 30 minutes at a stirring speed of 6000rpm, and curing for 24 hours at normal temperature to form a mixture 1;

a2, slowly and uniformly adding 2 parts of cationic polymer coating agent into the mixture 1 at a stirring speed of 6000rpm, uniformly stirring, then adding 10 parts of the temperature-resistant and calcium-resistant polymer filtrate reducer prepared in the embodiment 1 and 3 parts of clay surface hydration inhibitor, uniformly stirring, adding 20 parts of sulfonated phenolic resin and 20 parts of sulfonated lignite resin, uniformly stirring, then adding 30 parts of low-fluorescence cationic asphalt powder, uniformly stirring, then adding 20 parts of biological lubricant, uniformly stirring, then adding 15 parts of solid polymeric alcohol, uniformly stirring, then adding 5 parts of micro-nano strong plugging agent NANOFSEAL, uniformly stirring, then adding 10 parts of amphiphilic plugging agent and 30 parts of superfine calcium carbonate, and forming a mixture 2;

A3, adjusting the pH value of the mixture 2 to 9 by NaOH to form a mixture 3;

and A4, adding 330 parts of weight of crystal stone into the mixture 3, and uniformly stirring to obtain the water-based drilling fluid base slurry.

Example 5

The invention relates to a preparation method of a high-temperature-resistant calcium-resistant water-based drilling fluid for a shale ultra-deep well, which sequentially comprises the following steps:

a1, firstly mixing 1000 parts of water with 35 parts of sodium bentonite, stirring for 45 minutes at a stirring speed of 3000rpm, then stirring for 35 minutes at a stirring speed of 8000rpm, and curing for 24 hours at normal temperature to form a mixture 1;

a2, slowly and uniformly adding 3 parts of cationic polymer coating agent into the mixture 1 at a stirring speed of 8000rpm, uniformly stirring, then adding 15 parts of the temperature-resistant and calcium-resistant polymer filtrate reducer prepared in the example 2 and 4 parts of clay surface hydration inhibitor, uniformly stirring, then adding 25 parts of sulfonated phenolic resin and 25 parts of sulfonated lignite resin, uniformly stirring, then adding 40 parts of low-fluorescence cationic asphalt powder, uniformly stirring, then adding 30 parts of biological lubricant, uniformly stirring, then adding 20 parts of solid polymeric alcohol, uniformly stirring, then adding 10 parts of micro-nano strong plugging agent NANOFSEAL, uniformly stirring, then adding 12 parts of amphiphilic plugging agent and 40 parts of superfine calcium carbonate, and forming a mixture 2;

A3, adjusting the pH value of the mixture 2 to 9.5 by NaOH to form a mixture 3;

and A4, adding 360 parts of heavy crystal stone into the mixture 3, and uniformly stirring to obtain the water-based drilling fluid base slurry.

Example 6

The invention relates to a preparation method of a high-temperature-resistant calcium-resistant water-based drilling fluid for a shale ultra-deep well, which sequentially comprises the following steps:

a1, firstly mixing 1000 parts of water with 40 parts of sodium bentonite, stirring for 60 minutes at a stirring speed of 4000rpm, then stirring for 40 minutes at a stirring speed of 10000rpm, and curing for 24 hours at normal temperature to form a mixture 1;

a2, slowly and uniformly adding 4 parts of cationic polymer coating agent into the mixture 1 at a stirring speed of 10000rpm, uniformly stirring, then adding 20 parts of the temperature-resistant and calcium-resistant polymer filtrate reducer prepared in the example 3 and 5 parts of clay surface hydration inhibitor, uniformly stirring, adding 30 parts of sulfonated phenolic resin and 30 parts of sulfonated lignite resin, uniformly stirring, then adding 50 parts of low-fluorescence cationic asphalt powder, uniformly stirring, then adding 40 parts of biological lubricant, uniformly stirring, then adding 25 parts of solid polymeric alcohol, uniformly stirring, then adding 15 parts of micro-nano strong plugging agent NANOFSEAL, uniformly stirring, then adding 20 parts of amphiphilic plugging agent and 50 parts of superfine calcium carbonate, and forming a mixture 2;

A3, adjusting the pH value of the mixture 2 to 10 by NaOH to form a mixture 3;

and A4, adding 400 parts of barite into the mixture 3, and uniformly stirring to obtain the water-based drilling fluid base slurry.

3. Drilling fluid filtration performance test

The comparative example was conducted without heating the temperature-resistant, calcium-resistant polymer filtrate reducer, and was otherwise identical to the water-based drilling fluid base slurry of example 5, and was used for the following unnoticed tests.

Drilling fluid base stocks of comparative base stock and examples 4 to 6 are respectively poured into an aging tank, thermally rolled at 200 ℃ for 16 hours, cooled, stirred at high speed for 20 minutes, measured for rheological properties by a six-speed rotational viscometer, and then measured for medium-pressure fluid loss and high-temperature high-pressure fluid loss, and the test results are shown in table 5:

TABLE 5

As can be seen from Table 5, the base slurry comparative examples had normal temperature medium pressure fluid loss of 3.8mL, and examples 4 to 6 had good fluid loss reducing effects at normal temperature with normal temperature medium pressure fluid loss of 3.2mL, 2.4mL, and 2.4 mL. The medium pressure fluid loss of the hot rolled base stock comparative example was 4.4mL, examples 4 to 6 were 3.6mL, 3.0mL; the high-temperature high-pressure fluid loss of the base slurry after the ageing of the comparative example is 18.6mL, the high-temperature high-pressure fluid loss of the examples 4 to 6 are respectively 12.4mL, 9.6mL and 9.4mL, and the high-temperature high-pressure drop fluid loss effect is obvious. Wherein example 5 and example 6 have a high temperature and high pressure water loss of less than 10mL.

After the drilling fluids of examples 4 to 6 were thermally rolled for 16 hours at different temperatures, the drilling fluids were subjected to medium pressure filtration and high temperature and high pressure filtration test under a pressure difference of 3.5MPa, and the high temperature stability performance of the prepared drilling fluid system was evaluated, and the results are shown in Table 6:

TABLE 6

As can be seen from Table 6, after the temperature-resistant and calcium-resistant drilling fluids in examples 4 to 6 are subjected to hot rolling at different temperatures, the high-temperature and high-pressure fluid loss of the system slightly increases along with the rise of the temperature, but the high-temperature and high-pressure fluid loss is controlled in a lower range, and the difference between examples 5 and 6 is not great, and is less than 10mL. Illustrative example 5 meets the requirements for high temperature and high pressure water loss control.

4. Rheological Performance test

The base slurry without the temperature-resistant calcium-resistant filtrate reducer and the high-temperature-resistant calcium drilling fluid in the examples are subjected to rheological property test before and after hot rolling, and the test results are shown in Table 7:

TABLE 7

From Table 7, it can be seen that the drilling fluid is viscous-cut before and after aging, the rheological property is not changed greatly, the drilling fluid system has good temperature stability, no barite is settled before and after aging, the suspension performance is good, and the rheological property of the system is good.

5. Inhibition performance test

The inhibition of the drilling fluid is evaluated by adopting an expansion rate test and a rock debris recovery rate test for the high-temperature-resistant calcium drilling fluid in the base slurry comparative example and the high-temperature-resistant calcium drilling fluid in the examples. Bentonite for experiments is selected from core powder for expansion rate experiments. The recovery rate test adopts core powder (rock scraps particles after large rock blocks are knocked into pieces and pass through a 40-mesh sieve) with high mud rock content in Jiangsu certain well Funing group, the particle size is 30-40 meshes, and the test result is shown in Table 8.

TABLE 8

Experimental group	Linear expansion rate/%	Drill cuttings recovery/%
			Clean water	89.51	49.6
Base slurry	3.47	94.5
			Drilling fluid of example 4	2.30	95.6
Drilling fluid of example 5	2.16	96.1
			Drilling fluid of example 6	2.16	96.4

The expansibility data of the core in the base slurry after high temperature hot rolling is tested and compared with the expansibility in clear water: the expansion of the core in clear water is high, the expansion rate of the core in 8 hours is 89.51%, and the expansion rate of the heat-resistant and calcium-resistant drilling fluid introduced with the heat-resistant and calcium-resistant filtrate reducer in 8 hours and the recovery rate of drilling cuttings in 16 hours are greatly improved. The inhibition and dispersion effects of the temperature-resistant and calcium-resistant drilling fluid are greatly enhanced.

6. Test of sodium salt and calcium resistance

NaCl with different mass fractions is quantitatively weighed and added into the temperature-resistant and calcium-resistant fresh water drilling fluid system of the example 5, and the fresh water drilling fluid system is maintained for 24 hours in a sealed container after being fully stirred.

The temperature-resistant and calcium-resistant fresh water drilling fluid system and the temperature-resistant and calcium-resistant water drilling fluid system are stirred at a high speed for 5 minutes and then are filled into a high-temperature aging tank, and are subjected to rolling heat at 200 ℃ for 16 hours, and the filtration loss of the drilling fluid is measured by using a normal-temperature medium-pressure filtration instrument and a high-temperature high-pressure filtration instrument, and the results are shown in Table 9:

TABLE 9

The data in Table 9 are analyzed, and the salt with different proportions is added into the temperature-resistant and calcium-resistant drilling fluid from small to large, so that the drilling fluid performance after hot rolling is tested, and when the salt content reaches 20% at maximum, the change of the rheological property and the fluid loss of the drilling fluid is small, thus indicating that the system has better salt pollution resistance.

And (3) quantitatively weighing calcium chloride with different mass fractions, adding the calcium chloride into the high-temperature-resistant and calcium-resistant water-based drilling fluid system, fully stirring, and curing in a sealed container for 24 hours.

The temperature-resistant and calcium-resistant fresh water drilling fluid system and the temperature-resistant and calcium-resistant water drilling fluid system are stirred at a high speed for 5 minutes and then are filled into a high-temperature aging tank, and are subjected to rolling heat at 200 ℃ for 16 hours, and the filtration loss of the drilling fluid is measured by using a normal-temperature medium-pressure filtration instrument and a high-temperature high-pressure filtration instrument, and the results are shown in Table 10:

table 10

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The data of the table are analyzed, calcium chloride with different proportions is added into the temperature-resistant and calcium-resistant drilling fluid from small to large, the performance of the drilling fluid after hot rolling is tested, when the maximum calcium chloride reaches 5%, the rheological property and the filtration loss of the drilling fluid change in a small range are small, and the good rheological property and the low filtration loss are still maintained, so that the system has good calcium pollution resistance.

7. Plugging performance test

And a 400mD sand disc is selected for pressure-bearing plugging evaluation experiments. Comparative example base slurry and example 5 drilling fluids were subjected to a sand tray plugging pressure test to evaluate plugging pressure capability. The experiment shows that the pressure is gradually increased from 7MPa, 10MPa, 15MPa, 20MPa and 25MPa to 30MPa at the temperature of 200 ℃, the sand disc filtration loss of the drilling fluid under different pressure conditions is analyzed, the plugging pressure-bearing performance of a 400mD sand disc is evaluated, and the results are shown in Table 11 and FIG. 7.

TABLE 11

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Note that: permeate loss = 2 x 30 min. From the experimental data of Table 11 and the experimental plot of FIG. 7, the example two-base slurry permeation loss was 15.2mL, the example two-drilling fluid permeation loss was 11.2mL, and the average permeation rates were 0.04mL/min and 0.04mL/min, respectively, at 7 MPa. The average permeation rates are 0.04mL/min and 0.02mL/min respectively under the pressure of 30MPa, which shows that the pressure-bearing plugging property of the drilling fluid of the embodiment 5 on a sand disc is obviously better than that of the base slurry of the embodiment 5.

8. Compared with the performance index of the traditional polysulfonate drilling fluid

The drilling fluid of the example 5 and the traditional polysulfonate drilling fluid are subjected to performance index performance test, and the test method is according to the book of modern mud experiment technology published by oil university press in 1999.

Table 12

As can be seen from table 12, the temperature-resistant and calcium-resistant drilling fluid of example 5 is better in rheological property than the conventional polysulfonate drilling fluid under the same density condition, and the temperature-resistant and calcium-resistant drilling fluid is better than the polysulfonate drilling fluid in medium-pressure and high-temperature high-pressure fluid loss control. The traditional polysulfonate drilling fluid comprises the following components: water: 1000 parts; sodium bentonite: 35 parts; sodium hydroxide: 4 parts; cationic polymer coating agent: 3 parts; high temperature sulfonate copolymer filtrate reducer: 20 parts; surface hydration inhibitor: 4 parts; low fluorescence cationic asphalt powder: 40 parts; sulfonated phenolic resin: 40 parts; sulfonated lignite resin: 40 parts; biological lubricant: 30 parts; solid polymeric alcohol: 20 parts; composite calcium carbonate: 25 parts; micro-nano strong plugging agent: 10 parts; amphiphilic blocking agent: 10 parts; barite: 700 parts.

According to the experiment, the temperature resistance of the drilling fluid exceeds 200 ℃, the calcium chloride resistance reaches 5wt%, the salt resistance reaches 20 wt%, the high-temperature high-pressure water loss at 200 ℃ is less than 10mL, the comprehensive damage of filtrate to the stratum which is easy to collapse can be reduced, the stratum bearing capacity is improved, and the drilling construction requirement is met. The high-temperature oil well drilling fluid has good rheological property, fluid loss performance, inhibition, lubricating performance and plugging bearing capacity at high temperature, can meet the requirement of safe drilling in a deep well high-temperature environment, and improves the development benefit of the deep well.

The raw materials used in the invention have the following manufacturers and performance requirements:

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the foregoing description of the preferred embodiments of the present invention illustrates and describes the basic principles, main features and advantages of the present invention, and is not intended to limit the scope of the present invention, as it should be understood by those skilled in the art that the present invention is not limited to the above-described embodiments. In addition to the embodiments described above, other embodiments of the invention are possible without departing from the spirit and scope of the invention. The invention also has various changes and improvements, and all technical schemes formed by adopting equivalent substitution or equivalent transformation fall within the protection scope of the invention. The scope of the invention is defined by the appended claims and equivalents thereof. The technical features of the present invention that are not described may be implemented by or using the prior art, and are not described herein.

Claims (10)

1. The high-temperature-resistant and calcium-resistant water-based drilling fluid for the shale ultra-deep well is characterized by comprising the following raw materials in parts by weight: water: 1000 parts; sodium bentonite: 30-40 parts; cationic polymer coating agent: 2-4 parts; temperature-resistant and calcium-resistant polymer filtrate reducer: 10-20 parts; clay surface hydration inhibitor: 3-5 parts; sulfonated phenolic resin: 20-30 parts; sulfonated lignite resin: 20-30 parts; low fluorescence cationic asphalt powder: 30-50 parts; biological lubricant: 20-40 parts; solid polymeric alcohol: 15-25 parts; superfine calcium carbonate: 30-50 parts; micro-nano strong plugging agent NANOFSEAL: 5-15 parts; amphiphilic blocking agent: 10-15 parts; barite: 330-400 parts; naOH is used for adjusting the pH value to 9-10.

2. The high-temperature-resistant and calcium-resistant water-based drilling fluid for the shale ultra-deep well, according to claim 1, is characterized by comprising the following raw materials in parts by weight: water: 1000 parts; sodium bentonite: 30 parts; cationic polymer coating agent: 2 parts; temperature-resistant and calcium-resistant polymer filtrate reducer: 10 parts; clay surface hydration inhibitor: 3 parts; sulfonated phenolic resin: 20 parts; sulfonated lignite resin: 20 parts; low fluorescence cationic asphalt powder: 30 parts; biological lubricant: 20 parts; solid polymeric alcohol: 15 parts; superfine calcium carbonate: 30 parts; micro-nano strong plugging agent NANOFSEAL:5 parts; amphiphilic blocking agent: 10 parts; barite: 330 parts; the pH was adjusted to 9 with NaOH.

3. The high-temperature-resistant and calcium-resistant water-based drilling fluid for the shale ultra-deep well, according to claim 1, is characterized by comprising the following raw materials in parts by weight: water: 1000 parts; sodium bentonite: 35 parts; cationic polymer coating agent: 3 parts; temperature-resistant and calcium-resistant polymer filtrate reducer: 15 parts; clay surface hydration inhibitor: 4 parts; sulfonated phenolic resin: 25 parts; sulfonated lignite resin: 25 parts; low fluorescence cationic asphalt powder: 40 parts; biological lubricant: 30 parts; solid polymeric alcohol: 20 parts; superfine calcium carbonate: 40 parts; micro-nano strong plugging agent NANOFSEAL:10 parts; amphiphilic blocking agent: 12 parts; barite: 360 parts; the pH was adjusted to 9.5 with NaOH.

4. The high-temperature-resistant and calcium-resistant water-based drilling fluid for the shale ultra-deep well, according to claim 1, is characterized by comprising the following raw materials in parts by weight: water: 1000 parts; sodium bentonite: 40 parts; cationic polymer coating agent: 4 parts; temperature-resistant and calcium-resistant polymer filtrate reducer: 20 parts; clay surface hydration inhibitor: 5 parts; sulfonated phenolic resin: 30 parts; sulfonated lignite resin: 30 parts; low fluorescence cationic asphalt powder: 50 parts; biological lubricant: 40 parts; solid polymeric alcohol: 25 parts; superfine calcium carbonate: 50 parts; micro-nano strong plugging agent NANOFSEAL:15 parts; amphiphilic blocking agent: 15 parts; barite: 400 parts; the pH was adjusted to 10 with NaOH.

5. The preparation method of the high-temperature-resistant calcium-resistant water-based drilling fluid for the shale ultra-deep well is characterized by comprising the following steps in sequence:

a1, firstly mixing 1000 parts of water with 30-40 parts of sodium bentonite, stirring for 30-60 minutes at a stirring speed of 2000-4000 rpm, then stirring for 30-40 minutes at a stirring speed of 6000-10000 rpm, and curing for 24 hours at normal temperature to form a mixture 1;

a2, slowly and uniformly adding 2-4 parts of cationic polymer coating agent into the mixture 1 at a stirring speed of 6000-10000 rpm, uniformly stirring, then adding 10-20 parts of temperature-resistant and calcium-resistant polymer filtrate reducer and 3-5 parts of clay surface hydration inhibitor, uniformly stirring, then adding 20-30 parts of sulfonated phenolic resin and 20-30 parts of sulfonated lignite resin, uniformly stirring, then adding 30-50 parts of low-fluorescence cationic asphalt powder, uniformly stirring, then adding 20-40 parts of biological lubricant, uniformly stirring, then adding 15-25 parts of solid polymeric alcohol, uniformly stirring, then adding 5-15 parts of micro-nano strong plugging agent NANOFSEAL, uniformly stirring, and then adding 10-20 parts of amphiphilic plugging agent and 30-50 parts of superfine calcium carbonate to form a mixture 2;

a3, regulating the pH value of the mixture 2 to 9-10 by NaOH to form a mixture 3;

And A4, adding 330-400 parts of barite into the mixture 3, and uniformly stirring to obtain the water-based drilling fluid base slurry.

6. The method for preparing the high-temperature-resistant calcium-resistant water-based drilling fluid for the shale ultra-deep well, according to claim 5, is characterized by comprising the following steps in sequence:

a1, firstly mixing 1000 parts of water with 30 parts of sodium bentonite, stirring for 30 minutes at a stirring speed of 2000rpm, then stirring for 30 minutes at a stirring speed of 6000rpm, and curing for 24 hours at normal temperature to form a mixture 1;

a2, slowly and uniformly adding 2 parts of cationic polymer coating agent into the mixture 1 at a stirring speed of 6000rpm, uniformly stirring, then adding 10 parts of temperature-resistant and calcium-resistant polymer filtrate reducer and 3 parts of clay surface hydration inhibitor, uniformly stirring, then adding 20 parts of sulfonated phenolic resin and 20 parts of sulfonated lignite resin, uniformly stirring, then adding 30 parts of low-fluorescence cationic asphalt powder, uniformly stirring, then adding 20 parts of biological lubricant, uniformly stirring, then adding 15 parts of solid polyalcohol, uniformly stirring, then adding 5 parts of micro-nano strong plugging agent NANOFSEAL, uniformly stirring, then adding 10 parts of amphiphilic plugging agent and 30 parts of superfine calcium carbonate, and forming a mixture 2;

A3, adjusting the pH value of the mixture 2 to 9 by NaOH to form a mixture 3;

and A4, adding 330 parts of weight of crystal stone into the mixture 3, and uniformly stirring to obtain the water-based drilling fluid base slurry.

7. The method for preparing the high-temperature-resistant calcium-resistant water-based drilling fluid for the shale ultra-deep well, according to claim 5, is characterized by comprising the following steps in sequence:

a1, firstly mixing 1000 parts of water with 35 parts of sodium bentonite, stirring for 45 minutes at a stirring speed of 3000rpm, then stirring for 35 minutes at a stirring speed of 8000rpm, and curing for 24 hours at normal temperature to form a mixture 1;

a2, slowly and uniformly adding 3 parts of cationic polymer coating agent into the mixture 1 at a stirring speed of 8000rpm, uniformly stirring, then adding 15 parts of temperature-resistant and calcium-resistant polymer filtrate reducer and 4 parts of clay surface hydration inhibitor, uniformly stirring, then adding 25 parts of sulfonated phenolic resin and 25 parts of sulfonated lignite resin, uniformly stirring, then adding 40 parts of low-fluorescence cationic asphalt powder, uniformly stirring, then adding 30 parts of biological lubricant, uniformly stirring, then adding 20 parts of solid polyalcohol, uniformly stirring, then adding 10 parts of micro-nano strong plugging agent NANOFSEAL, uniformly stirring, then adding 12 parts of amphiphilic plugging agent and 40 parts of superfine calcium carbonate, and forming a mixture 2;

A3, adjusting the pH value of the mixture 2 to 9.5 by NaOH to form a mixture 3;

and A4, adding 360 parts of heavy crystal stone into the mixture 3, and uniformly stirring to obtain the water-based drilling fluid base slurry.

8. The method for preparing the high-temperature-resistant calcium-resistant water-based drilling fluid for the shale ultra-deep well, according to claim 5, is characterized by comprising the following steps in sequence:

a1, firstly mixing 1000 parts of water with 40 parts of sodium bentonite, stirring for 60 minutes at a stirring speed of 4000rpm, then stirring for 40 minutes at a stirring speed of 10000rpm, and curing for 24 hours at normal temperature to form a mixture 1;

a2, slowly and uniformly adding 4 parts of cationic polymer coating agent into the mixture 1 at a stirring speed of 10000rpm, uniformly stirring, then adding 20 parts of temperature-resistant and calcium-resistant polymer filtrate reducer and 5 parts of clay surface hydration inhibitor, uniformly stirring, then adding 30 parts of sulfonated phenolic resin and 30 parts of sulfonated lignite resin, uniformly stirring, then adding 50 parts of low-fluorescence cationic asphalt powder, uniformly stirring, then adding 40 parts of biological lubricant, uniformly stirring, then adding 25 parts of solid polyalcohol, uniformly stirring, then adding 15 parts of micro-nano strong plugging agent NANOFSEAL, uniformly stirring, then adding 20 parts of amphiphilic plugging agent and 50 parts of superfine calcium carbonate, and forming a mixture 2;

A3, adjusting the pH value of the mixture 2 to 10 by NaOH to form a mixture 3;

and A4, adding 400 parts of barite into the mixture 3, and uniformly stirring to obtain the water-based drilling fluid base slurry.

9. The method for preparing the high-temperature-resistant and calcium-resistant water-based drilling fluid for the shale ultra-deep well according to any one of claims 5 to 8, wherein the structural formula of the temperature-resistant and calcium-resistant polymer filtrate reducer is shown as follows:

10. the method for preparing the high-temperature-resistant and calcium-resistant water-based drilling fluid for the shale ultra-deep well according to any one of claims 5 to 8, wherein the preparation of the temperature-resistant and calcium-resistant polymer filtrate reducer sequentially comprises the following steps:

s1, adding 10 parts by weight of deionized water into a reactor, adding 3-8 parts by weight of triallyl phosphate while stirring, adjusting the pH value of the system to 10-12 by using sodium hydroxide solution, and keeping the temperature at 30+/-3 ℃;

s2, charging nitrogen into the reactor for 30min, removing oxygen in the reactor, and continuously charging nitrogen into the reactor in the reaction process;

s3, taking a solution formed by dissolving dibenzoyl peroxide in water with the mass of 5 times as a primary polymerization initiator;

s4, adding 0.1-0.3 part by weight of primary polymerization initiator into the reactor, and keeping the system temperature at 30+/-3 ℃ for primary polymerization reaction for 0.5 hour;

S5, mixing sodium persulfate and ammonium persulfate according to the proportion of 1:1 mass ratio, and then dissolving the mixture in water with the mass ratio of 5 times as a secondary polymerization initiator;

s6, adding 0.5-1 weight part of secondary polymerization initiator into the reactor, adding 5-15 weight parts of dimethyl diallyl ammonium chloride, and continuing the reaction for 0.5 hour to perform secondary polymerization reaction;

s7, dissolving 10-20 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid, 20-30 parts by weight of acrylamide, 15-35 parts by weight of styrene and 5-15 parts by weight of sodium methacrylate powder monomer in water which is equal to the total mass of the powder, and uniformly stirring;

s8, adding the solution obtained in the step S7 into a reactor, controlling the reaction temperature in the reactor to be 30+/-3 ℃, and carrying out three polymerization reactions for 2 hours;

s9, adding 1 part by weight of a chain transfer agent trichloroethylene into the reactor, and continuing the reaction for 4 hours;

s10, stopping supplying nitrogen into the reactor, blowing air into the reactor, adding 1 part by weight of polymerization inhibitor ferric chloride into the reactor, reacting for 0.5 hour, and terminating the product;

s11, drying the product in the reactor at 100 ℃, and crushing to obtain the product powder of the temperature-resistant and calcium-resistant polymer filtrate reducer.