CN111393672B

CN111393672B - Water-in-oil type emulsion film forming liquid, preparation method and application thereof

Info

Publication number: CN111393672B
Application number: CN202010230786.1A
Authority: CN
Inventors: 王星媛; 陆灯云; 袁志平; 吴正良; 孙莉; 景岷嘉; 王兰; 欧翔; 李巍; 曾婷
Original assignee: China National Petroleum Corp; CNPC Chuanqing Drilling Engineering Co Ltd
Current assignee: China National Petroleum Corp; CNPC Chuanqing Drilling Engineering Co Ltd
Priority date: 2020-03-27
Filing date: 2020-03-27
Publication date: 2022-07-29
Anticipated expiration: 2040-03-27
Also published as: CN111393672A

Abstract

The invention provides a water-in-oil type emulsion film-forming liquid, a continuous film, and preparation methods and applications of the water-in-oil type emulsion film-forming liquid and the continuous film. The preparation of the film-forming solution comprises the following steps: uniformly mixing a film forming agent, a film forming auxiliary agent, a film forming connecting agent and nano solid particles to obtain a first solution; uniformly mixing a connecting reactant and a film-forming carrier to obtain a first process solution; uniformly mixing the film-forming continuous phase, the emulsifier and the wetting agent to obtain a second process solution; mixing the first and second process solutions, and uniformly stirring to obtain a second solution; mixing the first solution and the second solution, and stirring to obtain a film forming solution; the water-in-oil type emulsion film-forming solution comprises the film-forming solution obtained by the method. The preparation of the continuous film comprises the following steps: and (3) rolling the film-forming liquid, stirring, and pressing to form a film to obtain the continuous film. The application includes application in the preparation of oil-based drilling fluids. The beneficial effects of the invention include: the preparation method is simple and convenient, the flow is short, the continuous film can repel oil and water, and the high-temperature and high-pressure filtration loss can be greatly reduced.

Description

Water-in-oil type emulsion film forming liquid, preparation method and application thereof

Technical Field

The invention relates to the technical field of oil-based drilling fluids, in particular to a water-in-oil type emulsion forming solution and a preparation method and application thereof.

Background

The drilling fluid plugging property in the exploration and development process mainly has the following requirements: (1) the invasion amount of the drilling fluid to the stratum is small, and the basic premise is to prevent various complex conditions; (2) compatibility of the plugging agent with drilling fluid; (3) the mud cake is formed quickly, and the damage of filtrate and solid phase to a reservoir is reduced; (4) the mud cake has low permeability and does not cause blockage to reservoirs and well completion tools.

At present, the plugging theory in the oil-based drilling fluid mainly takes a particle accumulation theory as a main part, and a plugging formula of an elastic material, a rigid material, a variable material and a fiber material is adopted to form accumulation plugging in stratum rocks or form filling plugging on a mud cake close to a well wall. However, the plugging layer formed in the formation rock has the problem of polluting the formation, and the used solid material must form effective bridges, and if the particle size and the formation pore throat size do not match, an effective plugging effect cannot be formed. According to the research of scanning by an electron microscope, mud cakes formed on a near well wall by the oil-based drilling fluid are of a three-dimensional network structure, cavities with the size of more than 100 microns exist, and the problems of matching degree and probability exist if the mud cakes are plugged and filled according to the particle accumulation theory. If the concentration of the small particle materials is too high, the rheological property of the drilling fluid is often influenced, so that under the condition of particle size matching degree, the addition of the particle materials for plugging the mud cake is small, and each hole of the mud cake cannot be completely plugged, so that the probability of plugging each hole is low. If the solid particles are not embedded in the mud cake, the liquid cannot be effectively blocked, and the solid particles embedded in the mud cake may influence the toughness of the whole mud cake.

In recent years, with the development of a water-based drilling fluid film forming technology, a water-based drilling fluid film forming technology which mainly comprises a semipermeable membrane, an oil film, a surfactant film and the like is formed, the technology does not cause pollution to a reservoir layer and cause blockage of tools, a 'continuous film' can be formed on a mud cake, liquid such as mud, filtrate, oil, water and the like is controlled to enter a stratum from a source, pressure propagation is effectively prevented, stratum pressure fluctuation is reduced, excessive solid particle materials are not needed in a system, and the influence on mud rheology is small. However, most of the current film forming techniques are mainly used in water-based drilling fluids, whereas it is difficult to form a continuous thin film in oil-based drilling fluids.

Disclosure of Invention

In view of the deficiencies in the prior art, it is an object of the present invention to address one or more of the problems in the prior art as set forth above. For example, one of the objectives of the present invention is to provide a water-in-oil type emulsion-forming solution, and a preparation method and application thereof, so as to achieve effective plugging of a mud cake.

In order to achieve the above objects, according to one aspect of the present invention, there is provided a method for preparing a water-in-oil type emulsion-forming solution. The preparation method can comprise the following steps:

preparing a first solution and a second solution, then mixing the first solution and the second solution according to the mass-volume ratio of 0.01-0.04 g/mL, and uniformly stirring to obtain a water-in-oil type emulsion forming solution; wherein the step of preparing the first solution comprises: and (2) mixing the following components in a mass ratio of 30-50: 1.5-2.5: 3-5: 0.25-0.5 of film forming agent, film forming additive, film forming connecting agent and nano solid particles are uniformly mixed to obtain a first solution; the step of preparing the second solution comprises: preparing a first process solution and a second process solution, mixing the first process solution and the second process solution, and uniformly stirring to obtain a second solution; wherein the step of preparing the first process solution comprises: and (2) mixing the following components in a mass ratio of 9-36: uniformly mixing 30-60 parts of a connecting reactant and a film forming carrier to obtain a first process solution; the step of preparing the second process solution comprises: and (2) mixing the following components in a mass ratio of 240-270: 7.5-10.8: 3-4, uniformly mixing the film-forming continuous phase, the emulsifier and the wetting agent to obtain a second process solution, wherein the mass ratio of the film-forming continuous phase to the connecting reactant is 240-270: 9 to 36.

According to one or more exemplary embodiments of the present invention, the film forming agent may include: the emulsion comprises a film-forming agent and a core-shell styrene-acrylic emulsion containing a double-bond unsaturated acid modified group and a double-bond unsaturated hydroxyl modified group, or a copolymerization styrene-acrylic emulsion containing a double-bond unsaturated acid modified group and a double-bond unsaturated hydroxyl modified group, wherein the content of latex particles in the film-forming agent is 20-60%, and the particle size distribution range of the latex is 50-500 nm.

In another aspect, the present invention provides a water-in-oil emulsion-forming solution. The water-in-oil type emulsion-forming solution can comprise the film-forming solution prepared by the preparation method of the water-in-oil type emulsion-forming solution.

In a further aspect, the invention provides the use of a water-in-oil emulsion-forming solution in or for the preparation of an oil-based drilling fluid.

In still another aspect, the present invention provides a method for preparing a continuous thin film using the water-in-oil type emulsion-forming solution. The method may comprise the steps of: mixing the water-in-oil emulsion forming solution, organic soil, oil-soluble asphalt, calcium oxide and barite according to a mass ratio of 250-400: 5-16: 10-24: 7.5-12: 400-800 to obtain a mixture; the mixture is hot rolled, stirred and then pressed into a film to obtain a continuous film.

Alternatively, the method may comprise the steps of: the water-in-oil emulsion forming solution is hot rolled, stirred and pressed into a film to obtain a continuous film.

In yet another aspect of the present invention, a continuous film is provided. The continuous film may include a continuous film prepared by the above-described method for preparing a continuous film using a water-in-oil emulsion.

Compared with the prior art, the beneficial effects of the invention can include: the preparation method is simple and convenient, short in flow and low in cost. The prepared continuous film has oil and water repellency, can bear pressure of 3.5MPa, and can greatly reduce the high-temperature and high-pressure filtration loss.

Drawings

The above and other objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows a schematic view of a continuous film of the present invention;

FIG. 2 shows an electron micrograph of the continuous film from solution D of example 4;

figure 3 shows electron microscope scans of the filter cakes of the blanks and the control.

Detailed Description

Hereinafter, the water-in-oil emulsion-forming liquid of the present invention, its preparation method, use, and preparation method of a continuous thin film will be described in detail with reference to the accompanying drawings and illustrative examples.

The invention provides a preparation method of a water-in-oil type emulsion solution.

In an exemplary embodiment of the method for preparing a water-in-oil emulsion-forming solution of the present invention, the preparation method may comprise the steps of:

s100: a first solution and a second solution are prepared. Wherein, the preparation of the first solution and the second solution is not in sequence.

S200: and mixing the first solution and the second solution according to the mass-volume ratio of 0.01-0.04 g/mL, and uniformly stirring to obtain the water-in-oil type emulsion forming solution. For example, 0.01 to 0.04g of the first solution may be added to 1mL of the second solution.

Wherein,

the step of preparing the first solution may comprise: s110: and (2) mixing the following components in a mass ratio of 30-50: 1.5-2.5: 3-5: 0.25-0.5 of film forming agent, film forming additive, film forming connecting agent and nano solid particles are uniformly mixed to obtain a first solution;

the step of preparing the second solution may comprise: s120: preparing a first process solution and a second process solution, mixing the first process solution and the second process solution, and uniformly stirring to obtain a second solution; wherein, the preparation of the first process solution and the second process solution is not in sequence.

The step of preparing the first process solution may comprise: s121: and (2) mixing the following components in a mass ratio of 9-36: uniformly mixing 30-60 parts of a connecting reactant and a film forming carrier to obtain a first process solution;

The step of preparing the second process solution may comprise: s122: and (2) mixing the following components in a mass ratio of 240-270: 7.5-10.8: 3-4, uniformly mixing the film-forming continuous phase, the emulsifier and the wetting agent to obtain a second process solution, wherein the mass ratio of the film-forming continuous phase to the connecting reactant is 240-270: 9 to 36.

In this embodiment, the film-forming agent may include a core-shell type styrene-acrylic emulsion modified by a double-bond type unsaturated acid monomer (also referred to as a double-bond unsaturated acid monomer) and a double-bond type unsaturated hydroxyl monomer (also referred to as a double-bond unsaturated hydroxyl monomer), or a copolymer type styrene-acrylic emulsion modified by a double-bond type unsaturated acid monomer and a double-bond type unsaturated hydroxyl monomer. The film-forming agent is an emulsion formed by modifying a styrene-acrylate polymer by using a double-bond unsaturated acid monomer and a double-bond unsaturated hydroxyl monomer, the forming method can be divided into a common copolymerization method or a core-shell synthesis method, and finally, the emulsion particles in the produced emulsion are different in shape.

The film forming agent is styrene-acrylic emulsion, wherein the modified monomer accounts for 5-20% of the emulsion.

The content of latex particles in the film forming agent can be 20-60%, and the particle size distribution range of the latex can be 50-500 nm.

In this embodiment, the film-forming binding agent may include sodium alginate.

In this embodiment, the coalescent may include a dodecyl alcohol ester. The film-forming assistant has the main functions of lowering the glass transition temperature of the latex particle polymer, softening the emulsion particles and promoting the emulsion particles to form a film. The film forming mechanism of the latex particles is as follows: after the latex particles deform and contact with each other, the molecular chain segments are wound and fused to finally form a continuous film.

In this embodiment, the nano solid particles may include nano calcium carbonate and/or nano silica.

The particle size of the nano solid particles may be in a nano level and/or a submicron level, for example, the specific particle size of the nano solid particles may be 50 to 400nm, for example, 60nm, 90nm, 120nm, 200nm, and the like, and further, may be 100 to 300 nm. The main purpose of adding the nano-and/or submicron-sized solid particles is: the strength of the finally formed film can be enhanced, and compared with the micron-scale film, the nano solid particles in the nano and/or submicron scale are dispersed more uniformly, and the flatness and the strength of the film are higher.

In this embodiment, the linking reagent may comprise calcium chloride.

In this embodiment, the film-forming carrier can include water.

In this embodiment, the film-forming continuous phase is an oil phase. Further, the film-forming continuous phase may include at least one of white oil, diesel oil, and vegetable oil, but the present invention is not limited thereto.

In this embodiment, the film-forming emulsifier may include fatty acid polyamide type emulsifier and sulfonate type emulsifier, such as a mixture of the two. Wherein the mass ratio of the fatty acid polyamide emulsifier to the sulfonate emulsifier can be 1-3: 6-9.

In this embodiment, the film-forming wetting agent can include a fatty acid amide, a fatty acid imidazoline, and a maleic acid polyamide, such as a mixture of the three. Wherein the mass ratio of the fatty acid amide to the fatty acid imidazoline to the maleic acid polyamide is 10-20: 15-20: 10 to 15.

In another exemplary embodiment of the method for preparing a water-in-oil emulsion-forming solution of the present invention, the preparation method may comprise:

(1) the raw materials by weight portion are:

30-50 parts of a film forming agent;

3-5 parts of film forming connecting agent

1.5-2.5 parts of a film-forming assistant;

0.25-0.5 parts of nano solid particles;

9-36 parts of a connecting reactant;

30-60 parts of a film forming carrier;

240-270 parts of a film-forming continuous phase;

7.5-10.8 parts of an emulsifier;

3-4 parts of a wetting agent.

Wherein the raw material in (1) may be the same kind as that in the previous exemplary embodiment.

(2) Preparing the water-in-oil type emulsion deposition solution according to the raw material ratio in the step (1), wherein the preparation method comprises the following steps:

at normal temperature, the film forming agent, the film forming additive, the film forming connecting agent and the nano solid particles are uniformly mixed to form a solution A (namely a first solution) for later use.

At normal temperature, the linking reagent is added into the film-forming carrier and mixed uniformly to form a solution B (i.e. a first process solution). Wherein, the solution B can be formed by calcium chloride and water and can be used as a carrier of emulsion particles in the solution A, and the calcium chloride can react with sodium alginate.

And (3) uniformly stirring the film-forming continuous phase, the emulsifier and the wetting agent, then adding the solution B, and continuously stirring to form a solution C (namely a second solution). Wherein, the stirring speed of the two times can be 10000-12000 rpm, and the stirring time can be 25-35 min, such as 30 min. Because both the emulsifier and the wetting agent are oil soluble, the emulsifier and the wetting agent need to be uniformly mixed with the oil (i.e., the film-forming continuous phase) so as to be sufficiently and uniformly dispersed in the final system. The addition of the solution B followed by stirring is intended to form a homogeneous emulsion system because the emulsification is enhanced by the oil and water mixing followed by high speed stirring and shearing. The solution C is water-in-oil emulsion, after thermal dispersion, the demulsification voltage of the emulsion at room temperature is more than or equal to 200V, the emulsifying rate after thermal dispersion is more than or equal to 90 percent, and the system is kept still (for example, for 1h) after thermal dispersion without oil-water stratification.

And uniformly stirring the solution A and the solution C to form a solution D (namely the water-in-oil type emulsion forming solution). Namely, the solution D is obtained by mixing water-in-oil emulsion and blocking agent. Wherein, the solution D is kept still (for example, kept still for 1h) at normal temperature and normal pressure, the film forming agent in the system has no precipitation and no precipitation phenomenon, and the whole system has no oil water stratification phenomenon. The solution A can be uniformly dispersed in the solution C by stirring, and the emulsion particles can uniformly contact with the water phase and take water drops as carriers; wherein the stirring speed can be 10000-12000 rpm, and the time can be 8-12 min, such as 11000rpm, 10 min.

In this example, solution a may be considered a blocking agent; solution C was the water-in-oil emulsion formed.

In this embodiment, the solid-to-liquid ratio of the solution a to the solution C is 0.01 to 0.04g/mL, i.e. the ratio of the solution a (mass)/the solution C (volume) is 0.01 to 0.04g/mL, such as 100mL of the solution C, and the amount of the solution a added is 1 to 4 g.

In this example, the mechanism of action of the blocking agent (i.e., solution a): under the premise that the solution A is an oil-based emulsion (namely a solution C, also called a water-in-oil emulsion), a film-forming connecting agent (sodium alginate) in the solution A and a connecting reactant (calcium chloride) in the oil-based emulsion interact, water in the emulsion serves as a carrier, and the emulsion particles can form a film in the water-in-oil emulsion or the oil-based drilling fluid under certain pressure and temperature under the interaction of the emulsion particles, the sodium alginate and the calcium chloride, and the water-in-oil emulsion must contain components of an emulsifier and a wetting agent.

In this example, the membrane-forming linker (i.e., sodium alginate) in solution a is capable of undergoing a rapid ion exchange reaction with divalent metal ions other than magnesiomercury to form an alginate gel. Wherein, the strength of the gel film formed by the film-forming connecting agent and the connecting reactant (calcium chloride) in the solution C is the maximum, and the reaction molecular formula is as follows:

wherein NaAlg is the indicative formula of sodium alginate, Ca (Alg) ₂ Is an illustrative formula of calcium alginate. After the solution A and the solution C are mixed, because the solution A and the solution C are in an oil medium, the contact of the solution A and the solution C is limited to a certain extent, and the contact of the solution A and the solution C is increased due to heat dispersion and high pressure during application, so that the reaction is promoted.

Wherein,

(1) the emulsion particles in solution a can be uniformly dispersed in the system by the water in the emulsion (i.e., solution C).

(2) Gel films formed by sodium alginate and calcium chloride and films formed by emulsion particles under the action of temperature, pressure and a film-forming auxiliary agent can interact with each other, so that the films are formed in water-in-oil emulsion or oil-based drilling fluid, and the action mechanism is mainly physical: firstly, the gel film can be filled and connected among emulsion particles to promote the emulsion particles to approach each other, and the molecules of the emulsion particles can exceed the original interface through diffusion to promote the emulsion particles to form a continuous film; meanwhile, the formed gel film can be used as mutual complement of emulsion particle thickness.

(3) The water-in-oil emulsion (i.e. solution C) can form a layer of oil film on the medium under the action of pressure, especially on the hydrophilic medium surface, and the formed oil film can be stably adsorbed on the medium surface due to the emulsifier, wetting agent and the like contained in the emulsion.

Therefore, the film finally formed by using the solution D in the present invention is a mixed type film.

In another aspect, the present invention provides a water-in-oil emulsion-forming solution. The water-in-oil type emulsion-forming solution may comprise the film-forming solution prepared by the above method.

In a further aspect the invention provides the use of a water-in-oil emulsion in an oil-based drilling fluid, for example in the preparation of an oil-based drilling fluid.

In a further aspect of the invention, there is provided a process for preparing a continuous film using the above water-in-oil emulsion. The method utilizes solution D or an oil-based drilling fluid containing solution D to prepare a continuous film.

The method may comprise the steps of:

hot rolling the solution D or the organic drilling fluid system at a thermal dispersion temperature, and then taking out and stirring; and pressing the film by filter paper under the conditions of film forming temperature and film forming pressure to obtain the continuous film.

Wherein the oil-based drilling fluid system may comprise 250 to 400: 5-16: 10-24: 7.5-12: 400-800 parts of solution D, organic soil, oil-soluble asphalt, calcium oxide and barite. The solution D, the organic soil, the oil-soluble asphalt, the calcium oxide and the barite can be mixed according to the mass ratio to form an oil-based drilling fluid system.

The organic soil is mainly used for forming an internal network structure in the oil-based drilling fluid and enhancing the internal cohesion of the drilling fluid, so that the drilling fluid has strong suspension capacity and shearing dilutability, the organic soil is excessively high, the oil-based drilling fluid is too large in viscosity, poor in rheological property and excessively low in addition, effective internal cohesion cannot be formed, and the effects of suspending barite and rock debris are poor. The oil-soluble asphalt is used as a soft and elastic plugging agent, and has low addition, poor plugging effect, high addition and poor rheological property; the calcium oxide acts to control the alkalinity of the oil-based drilling fluid.

The filter paper may be a filter paper produced as specified in API RP 13B1-2003 water-based drilling fluid field test procedures or API RP 13B2-2005 oil-based drilling fluid field test procedures, such as Fann No.206056(N8800) filter paper.

In this embodiment, the oil-based drilling fluid system is used at 80-150 ℃ and remains liquid after hot rolling; stirring after hot rolling can further enhance the emulsification degree of the emulsion and the uniform dispersion of the emulsion particles and water.

In this embodiment, the heat dispersion temperature may be 80-150 ℃, for example, 110 ± 20 ℃; the hot rolling time can be 14-18 h, such as 16 h.

The stirring speed can be 10000-12000 rpm, and the time is 20-40 min, such as 11000rpm, 30 min.

In this embodiment, the heat dispersion temperature is 80 to 150 ℃, the film forming temperature is 25 to 150 ℃, and the film forming pressure is 0.7 to 3.5 MPa.

The invention utilizes the emulsified water drops as carriers of the hydrophilic nano styrene-acrylic latex particles to solve the problem that the emulsified water drops cannot be stably dispersed in oil, and can form high-concentration aggregation of the hydrophilic nano styrene-acrylic latex particles in an emulsion system; sodium alginate is utilized to be aggregated between latex particles and on the surfaces of the particles, mutual repulsion force between colloidal particles is eliminated, the colloidal particles are further drawn together in the extrusion, deformation and fusion process of the colloidal particles, and simultaneously, a cross-linked body is formed by utilizing the action of the sodium alginate and calcium chloride, and the aggregated latex particles are further cross-linked and form a layer of compact film together with the latex particles in an emulsion; by controlling the addition of the film-forming assistant, the plastic flow and elastic deformation of latex particles are promoted, the softening degree is enhanced, and the coalescence performance is improved.

In the embodiment, the emulsion is thermally dispersed at the temperature of 80-150 ℃, so that the emulsion particles can be more uniformly dispersed on the surface of an emulsified water drop or permeate into the water drop, a high-concentration aggregate can be formed on filter paper or a mud cake by utilizing the film forming pressure and the film forming temperature, and meanwhile, a polymer-shaped continuous film can be formed under the combined action of a film forming auxiliary agent, a film forming connecting agent and a connecting reactant.

The invention can combine the I-type film (semi-permeable film) and the III-type film (oil film, surfactant film and water phase film) in the water-based film forming theory to form a continuous film with high oil repellency and low water repellency. The polymer liquid film formed by the invention comprises a film formed by emulsion particles and a calcium alginate film, both of which are hydrophilic and oleophobic, the effective solvent of the polymer liquid film is water, and according to a semipermeable membrane mechanism, the semipermeable membrane is a film only allowing solvent molecules to permeate, so that the oil repellency rate is high and the water repellency rate is low.

Wherein, type I film: the rock surface is adsorbed and stacked to form a dense polymer aggregation layer, namely a polymer membrane, a rock medium is used as a support body, and the polymer membrane and the adsorbed polymer form a liquid semipermeable membrane with smaller pore size or no pore, wherein the semipermeable membrane refers to a membrane through which small molecular components can pass but large molecular components cannot pass in a dispersion system. The invention can be thermally dispersed at 80-150 ℃, can enable latex particles to be more uniformly dispersed on the surface of emulsified water drops or permeate into the water drops, and can form high-concentration aggregates on a filter medium under the film forming pressure and the film forming temperature, namely an I-type film.

Type iii membranes consist of a continuous phase mobile film, a surfactant film and a drilling fluid aqueous phase film. The type iii film forms a barrier against diffusion of water and solutes, i.e. forms a barrier film ". The oil phase, the water phase and the surfactant (i.e. the film-forming emulsifier and the film-forming wetting agent) in the water-in-oil emulsion or the oil-based drilling fluid are adsorbed or gathered on the filter medium to form a film, namely a type III film.

In still another aspect, the present invention provides a continuous film comprising the continuous film prepared by the above method.

The continuous film prepared by the water-in-oil type emulsion film forming liquid has the advantages that the permeation oil content can be 1.5-15 mL, the permeation water content can be 42-89 mL, and the pressure bearing capacity can reach 2.5MPa at the temperature of 25-150 ℃ and under the pressure of 0.7 MPa.

The oil-based drilling fluid containing the water-in-oil emulsion film-forming liquid can greatly reduce the high-temperature and high-pressure filtration loss, the HTHP reduction rate at 25-150 ℃ is more than or equal to 90 percent, such as 93.75 percent, the permeation loss oil can be 1-5 mL, such as 3.2mL, and the pressure bearing can reach 2.0-3.5 MPa.

FIG. 1 is a schematic view showing the film-forming effect (i.e., the obtained continuous thin film) of the water-in-oil emulsion-forming solution of the present invention. Wherein, the control parameters corresponding to the obtained continuous film are as follows:

O/W is 8: 2, the addition amount of the solution A in the solution C is 4 percent (namely the solution A is added into the solution C according to the mass-volume ratio of 0.04 g/mL), the film forming temperature is 150 ℃, and the film forming pressure is 0.7 MPa. Wherein O/W is the oil-water ratio, namely the oil volume: volume of water.

In order that the above-described exemplary embodiments of the invention may be better understood, further description thereof with reference to specific examples is provided below.

Example 1

Raw materials:

film-forming agent: 30g, solid content of 50% (solid content is latex particle content), 15% of double-bond unsaturated acid modified group and 4% of double-bond unsaturated hydroxyl modified group. Film-forming connecting agent: 3g of sodium alginate. Film-forming auxiliary agent: 1.5g of dodecanol ester. Nano solid particles: 0.3g of nano calcium carbonate. Connecting a reactant: 24g of calcium chloride. Film-forming carrier: 60mL of water. Continuous phase: 240mL of white oil. Emulsifier: 1.5g of fatty acid polyamide, 6g of sulfonate. Wetting agent: 3g of the total weight.

The process comprises the following steps:

the solution A is prepared by utilizing the film forming agent, the film forming connecting agent, the film forming auxiliary agent and the nano solid particles. Solution C was prepared using the linking reagent, film-forming vehicle, film-forming continuous phase, emulsifier and wetting agent described above. Adding the solution A into the solution C according to the mass-to-volume ratio of 0.03g/mL to prepare a solution D.

Example 2

Raw materials:

film-forming agent: 50g, solid content of 45%, the proportion of double-bond unsaturated acid modified groups is 20%, and the proportion of double-bond unsaturated hydroxyl modified groups is 3%. Film-forming connecting agent: 5g of sodium alginate. Film-forming auxiliary agent: 2.5g of dodecanol ester. Nano solid particles: 0.5g of nano calcium carbonate. Connecting a reactant: 9g of calcium chloride. Film-forming carrier: 30mL of water. Continuous phase: 270mL of diesel oil. Emulsifier: 1.5g of fatty acid polyamide, 6g of sulfonate. Wetting agent: 3g of the total weight.

The process comprises the following steps:

the solution A is prepared by utilizing the film forming agent, the film forming connecting agent, the film forming auxiliary agent and the nano solid particles. Solution C was prepared using the linking reagent, film-forming vehicle, film-forming continuous phase, emulsifier and wetting agent described above. Adding the solution A into the solution C according to the mass-to-volume ratio of 0.04g/mL to prepare a solution D.

Example 3

Raw materials:

film-forming agent: 30g, solid content of 45%, the proportion of double-bond unsaturated acid modified groups is 20%, and the proportion of double-bond unsaturated hydroxyl modified groups is 2%. Film-forming connecting agent: 3g of sodium alginate. Film-forming auxiliary agent: 1.5g of dodecanol ester. Nano solid particles: 0.25g of nanosilica. Connecting a reactant: 24g of calcium chloride. Film-forming carrier: 60mL of water. Continuous phase: 240mL vegetable oil. Emulsifier: 2.1g of fatty acid polyamide, 8.7g of sulfonate. Wetting agent: 3g of the total weight.

The process comprises the following steps:

Example 4

Raw materials:

film-forming agent: 40g, solid content is 45%, the proportion of double-bond unsaturated acid modified groups is 18%, and the proportion of double-bond unsaturated hydroxyl modified groups is 5%. Film-forming connecting agent: 4g of sodium alginate. Film-forming auxiliary agent: 1.8g of dodecanol ester. Nano solid particles: 0.4g of nano calcium carbonate. Connecting a reactant: 36g of calcium chloride. Film-forming carrier: 60mL of water. Continuous phase: 240mL of white oil. Emulsifier: 2.1g of fatty acid polyamide, 8.7g of sulfonate. Wetting agent: 4g of the total weight.

The process comprises the following steps:

the solution A is prepared by utilizing the film forming agent, the film forming connecting agent, the film forming auxiliary agent and the nano solid particles. Solution C was prepared using the linking reagent, film-forming vehicle, film-forming continuous phase, emulsifier and wetting agent described above. Solution A was added to solution C at 3% to prepare solution D.

Evaluation of the Properties of the related products in examples 1 to 4

(1) Evaluation of dispersibility of solution D

And (3) performing demulsification voltage measurement on the solution D corresponding to the examples 1-4 by using a FANN 23E demulsification voltage instrument, wherein the measurement temperature is 25 ℃.

The solutions D corresponding to examples 1 to 4 were subjected to the emulsification rate measurement method: pouring the aged solution D at different temperatures (i.e. the thermal dispersion temperatures in Table 1) into a measuring cylinder, standing, observing and reading the volume of the oil phase separated for 2min, and calculating the emulsification rate according to a formula: w ₁ ＝[(V _{Total volume of emulsion} －V)/200]X 100%, wherein W ₁ The emulsification rate,%; v is the volume of the oil layer separated in 5min, mL.

The solutions D corresponding to examples 1 to 4 were thermally dispersed at 100 ℃, 150 ℃ and 80 ℃ for 16 hours, respectively, and then left to stand for 1 hour to observe the state of the solution.

TABLE 1 evaluation of emulsion Properties after thermal Dispersion for 16h

According to the data in the table 1, the film forming agent has better stability in water-in-oil emulsion film forming liquid, the emulsion emulsification rate is 100% after thermal dispersion, the system has no obvious oil-water delamination after standing for 1h, and the film forming agent in the system has no precipitation and precipitation.

(2) Filtration loss, permeation loss and oil loss under the conditions of film forming temperature and film forming pressure

And respectively aiming at the blank sample and the solution D of the example 1-4, preparing a water-in-oil emulsion continuous film by a GGS-42 type high-temperature high-pressure water loss instrument through medium-speed filter paper under the conditions of film forming temperature and film forming pressure, and recording the filtration loss for 30 min.

Wherein, the 30min filtration loss is measured according to GBT 16783.2-2012 oil and gas industry drilling fluid field test part 2: the measurement was carried out according to the high temperature and high pressure measurement protocol specified in oil-based drilling fluids.

Blank sample: the oil-water ratio is 8: 2, the preparation method of the emulsion refers to the preparation method of the solution C, and the formula is as follows: 240mL of white oil +1.5g of primary emulsifier +6g of secondary emulsifier +3g of wetting agent +80mL of 25% calcium chloride brine (80mL of water +20g of calcium chloride).

TABLE 2 fluid loss under the conditions of film-forming temperature and film-forming pressure after thermal dispersion for 16 hours

As can be seen from Table 2, the continuous film prepared at the heat dispersion temperature of 80-150 ℃, the film forming temperature of 80-150 ℃ and the film forming pressure of 0.7-3.5 MPa has a filtration loss of 6.4-23 mL within 30 min.

(3) The film has the oil and water permeability under 0.7MPa

After medium water is filled in a kettle body of the water loss instrument, the filter paper and the continuous film (namely the continuous film corresponding to the example 1-4 in the step (2)) are filled in the water loss instrument again, a water loss permeation test is carried out under the conditions of film forming temperature and film forming pressure, and the water loss permeation quantity is recorded for 30 min; the process of the oil permeability test is the same as the oil permeability test, the test medium is white oil, and the oil permeability loss amount is recorded for 30 min. The results of the experiment are shown in Table 3.

TABLE 3 Permeability loss of water, Permeability loss of oil at test temperature, 0.7MPa

As can be seen from Table 3, the continuous film had 42 to 89mL of water and 1.5 to 15mL of oil, respectively, under the action of 80 to 150 ℃ and 0.7 to 3.5 MPa.

(4) Pressure-bearing capacity test of film

The water-in-oil emulsion type continuous film (namely, the continuous film corresponding to the examples 1-4 in the step (2)) is subjected to pressure-bearing plugging capacity test in different media under certain temperature and pressure conditions by a GGS-42 type high-temperature high-pressure water loss instrument, the filtration loss (mL) is read after each pressure value is stabilized for 5min, then the next pressure value is pressurized for carrying out an experiment, the experiment result is the accumulated filtration loss, and the evaluation result can be shown in a table 4.

TABLE 4 evaluation of pressure-bearing Capacity of emulsion continuous film

As can be seen from Table 4, in the case that the medium is oil, the maximum pressure-bearing capacity can be 2.5MPa, and the accumulated fluid loss can be 13.8-36 mL, for example, 25-36 mL; under the condition that the medium is water, the maximum pressure-bearing capacity is 0.5MPa, and the accumulated filter loss can be 40-53 mL.

(5) Filter membrane electron microscope scanning analysis

The water-in-oil emulsion type continuous film obtained in example 4 was subjected to microscopic morphological analysis by a Quanta 450 type scanning electron microscope.

Fig. 2 shows an electron micrograph of a continuous film of a water-in-oil emulsion obtained using the corresponding solution D of example 4. Wherein (a) shows the full profile of the continuous film; (b) the figure shows the presence of tie crosslinks in the film.

(6) Evaluation of rheological property and high-temperature and high-pressure filtration loss after formation of oil-based drilling fluid

Rheological measurements were performed on the blank and the control. After mixing the solution D corresponding to example 2 with organic soil, oil-soluble asphalt, CaO, and barite to form an oil-based drilling fluid system according to the parameters shown in table 5, thermally dispersing the mixture at 150 ℃ for 16 hours, and then performing high-temperature high-pressure filtration loss (HTHP) and fluid loss evaluation at 150 ℃ and 3.5MPa using a GGS-42 type high-temperature high-pressure water loss instrument, and evaluating the fluid loss of a mud cake using white oil as a filter medium, the evaluation results are shown in tables 6 and 7.

TABLE 5 blank and control formulations

TABLE 6 rheological test data of blank and comparative samples after thermal dispersion for 16h at 150 deg.C

Serial number	φ6	φ3	G’/G”	AV	PV	YP	YP/PV	ES
									Blank sample	11	10	5/15	77	62	15	0.2419	982
Control sample	22	21	12.5/36.9	103	73	30	0.4110	996

Wherein G 'is initial cut, G' is final cut, AV is apparent viscosity, PV is plastic viscosity, YP is dynamic shear force, ES is demulsification voltage, and HTHP is high-temperature high-pressure filtration loss.

As can be seen from Table 6, the emulsibility of the oil-based drilling fluid system formed by compounding the emulsion (i.e., solution D) with the organic soil, the oil-soluble asphalt, the calcium oxide and the barite is better, and the low shear rate reading, the apparent viscosity, the plastic viscosity, the dynamic shear force and the static shear force are all increased compared with those of the blank sample.

TABLE 7 HTHP and oil loss evaluation after thermal dispersion at 150 ℃ for 16h for blanks and comparative samples

From 7, it can be seen from the comparative data in 6 that the oil based drilling fluid mud cake with solution D added has better oil loss capacity with a 60% reduction in HTHP.

(7) Scanning analysis of oil-based drilling fluid film forming electron microscope

The control sample and the blank sample described in table 5 were subjected to HTHP test after hot rolling for 16 hours at 150 ℃, and the pressed mud cake was subjected to microscopic morphological analysis by a Quanta 450 scanning electron microscope, and the analysis results are shown in fig. 3. Wherein (a) and (b) show the microscopic morphology of the blank and the control, respectively. Wherein, the blank has obvious holes on the mud cake, and the hole size is 85-530 μm, such as 86.38 μm, 143.9 μm and 526.9 μm shown in (a) of FIG. 3. As shown in the graph (b) in FIG. 3, a layer of obvious continuous film is formed on the surface of the mud cake of the comparison sample, and large-area effective plugging is carried out on the cavities formed by the mud cake, wherein the cavities are 86.38-526.9 μm, such as 120.6-190.1 μm shown in the graph (a).

In summary, the advantages of the water-in-oil emulsion-forming solution, the continuous thin film, and the methods for preparing both of the present invention may include:

(1) The preparation method is simple and convenient, short in flow and low in cost.

(2) The invention can combine the I-type film and the III-type film to form a continuous film with high oil repellency and low water repellency.

Although the present invention has been described above in connection with exemplary embodiments, it will be apparent to those skilled in the art that various modifications and changes may be made to the exemplary embodiments of the present invention without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A preparation method of a water-in-oil type emulsion forming solution is characterized by comprising the following steps:

preparing a first solution and a second solution, then mixing the first solution and the second solution according to the mass-volume ratio of 0.01-0.04 g/mL, and uniformly stirring to obtain a water-in-oil type emulsion forming solution; wherein,

the step of preparing the first solution comprises: and (2) mixing the following components in a mass ratio of 30-50: 1.5-2.5: 3-5: 0.25-0.5 of film forming agent, film forming additive, film forming connecting agent and nano solid particles are uniformly mixed to obtain a first solution;

the step of preparing the second solution comprises: preparing a first process solution and a second process solution, mixing the first process solution and the second process solution, and uniformly stirring to obtain a second solution; wherein,

The step of preparing the first process solution comprises: and (2) mixing the following components in a mass ratio of 9-36: uniformly mixing 30-60 parts of a connecting reactant and a film forming carrier to obtain a first process solution;

the step of preparing the second process solution comprises: and (2) mixing the following components in a mass ratio of 240-270: 7.5-10.8: 3-4, uniformly mixing the film-forming continuous phase, the emulsifier and the wetting agent to obtain a second process solution, wherein the mass ratio of the film-forming continuous phase to the connecting reactant is 240-270: 9-36;

the film-forming agent comprises: the styrene-acrylic emulsion comprises a core-shell styrene-acrylic emulsion containing double-bond unsaturated acid modified groups and double-bond unsaturated hydroxyl modified groups, or a copolymerization styrene-acrylic emulsion containing double-bond unsaturated acid modified groups and double-bond unsaturated hydroxyl modified groups;

the film-forming connecting agent comprises sodium alginate;

the linking reagent comprises calcium chloride;

the film-forming carrier comprises water, and the film-forming continuous phase is an oil phase.

2. The method for preparing a water-in-oil type emulsion-forming solution according to claim 1, wherein the content of latex particles in the film-forming agent is 20% to 60%, and the particle size distribution range of the latex particles is 50nm to 500 nm.

3. A process for preparing a water-in-oil emulsion solution according to claim 1, wherein said coalescent comprises a dodecanol ester and said nano solid particles comprise at least one of nano calcium carbonate and nano silica.

4. A process for preparing a water-in-oil emulsion-forming solution according to claim 1, wherein said film-forming emulsifier comprises fatty acid polyamide type emulsifier and sulfonate type emulsifier;

the film-forming wetting agent comprises a mixture of fatty acid amide, fatty acid imidazoline, and maleic acid polyamide.

5. A water-in-oil emulsion-forming solution, which comprises a film-forming solution prepared by the method for preparing a water-in-oil emulsion-forming solution according to any one of claims 1 to 4.

6. Use of a water-in-oil emulsion-forming solution according to claim 5 in the preparation of an oil-based drilling fluid.

7. A method for preparing a continuous thin film using a water-in-oil type emulsion-forming solution, comprising the steps of:

mixing the water-in-oil type emulsion-forming solution, the organic soil, the oil-soluble asphalt, the calcium oxide and the barite according to the mass ratio of 250-400: 5-16: 10-24: 7.5-12: 400-800 to obtain a mixture;

the mixture is hot rolled, stirred and then pressed into a film to obtain a continuous film.

8. A method for preparing a continuous thin film using a water-in-oil type emulsion-forming solution, comprising the steps of:

A water-in-oil type emulsion-forming solution according to claim 5, which is subjected to hot rolling, stirring and then press-forming to obtain a continuous film.