阅读说明：本技术 一种油基钻井液堵漏剂及其应用 (Oil-based drilling fluid plugging agent and application thereof ) 是由 张志磊 焦亚军 程荣超 张永强 冯杰 杨峥 徐进宾 唐守勇 卞维坤 杨洪 于 2020-03-25 设计创作，主要内容包括：本发明提供了一种油基钻井液堵漏剂及其应用。该油基钻井液堵漏剂包括桥接封堵材料、温控膨胀材料和溶胀封堵材料。本发明还提供了上述油基钻井液堵漏剂的随钻应用和在配制堵漏浆中的应用。本发明提供的油基钻井液堵漏剂具有良好的配伍性和较强的封堵能力,具有温度刺激响应和溶剂刺激响应能力,其产生的协同增效机制能够提高堵漏剂对不同孔径分布漏失通道的封堵能力。该油基钻井液堵漏剂可应用于油基钻井液的井漏预防,或在发生井漏后用于对漏层的封堵。(The invention provides an oil-based drilling fluid plugging agent and application thereof. The oil-based drilling fluid plugging agent comprises a bridging plugging material, a temperature control expansion material and a swelling plugging material. The invention also provides the application of the oil-based drilling fluid plugging agent while drilling and the application of the oil-based drilling fluid plugging agent in preparation of plugging slurry. The oil-based drilling fluid plugging agent provided by the invention has good compatibility and strong plugging capability, has temperature stimulation response and solvent stimulation response capabilities, and can improve the plugging capability of the plugging agent on leakage channels with different pore size distributions by a generated synergistic mechanism. The oil-based drilling fluid plugging agent can be applied to the well leakage prevention of oil-based drilling fluid or used for plugging a leakage layer after the well leakage occurs.)

1. The oil-based drilling fluid plugging agent comprises the following components in percentage by mass:

30-90% of bridging plugging material, 1-40% of temperature control expansion material and 1-40% of swelling plugging material, wherein the sum of the percentages of the components is 100%.

2. The oil-based drilling fluid lost circulation agent of claim 1, wherein the oil-based drilling fluid lost circulation agent comprises, in mass percent:

40-80% of bridging plugging material, 2-30% of temperature control expansion material and 2-30% of swelling plugging material, wherein the sum of the percentages of the components is 100%.

3. The oil-based drilling fluid lost circulation agent of claim 1 or 2, wherein the bridging plugging material comprises one or a combination of two or more of calcium carbonate, elastic graphite, powdered asphalt, mica, vermiculite, sepiolite, quartz, glass fiber, basalt fiber, and bamboo fiber.

4. The oil-based drilling fluid plugging agent according to claim 1 or 2, wherein the temperature-controlled swelling material is prepared from a base material and a curing agent through a thermal curing reaction;

preferably, the mass ratio of the base material to the curing agent is 100: (5-40).

5. The oil-based drilling fluid lost circulation agent of claim 4, wherein the temperature controlled swelling material is prepared by a process comprising: heating and melting a base material, adding a curing agent, curing at 60-180 ℃ for 2-8 hours, carrying out hot press molding on a cured product, and carrying out pressure maintaining cooling to obtain the temperature control expansion material;

preferably, the preparation of the temperature control expansion material comprises heating and melting the matrix material, adding the curing agent, curing at 80-100 ℃ for 2-4 hours, heating to 100-150 ℃ for 2-4 hours, hot-pressing and molding the cured product, and cooling under the pressure to obtain the temperature control expansion material.

6. The oil-based drilling fluid lost circulation agent of claim 4 or 5, wherein the matrix material comprises one or a combination of two or more of bisphenol A epoxy, bis (2, 3-epoxycyclopentyl) ether, polyurethane, polyethylene, polyisoprene, polynorbornene, and butadiene-styrene copolymer.

7. The oil-based drilling fluid lost circulation agent of any one of claims 4-6, wherein the curing agent comprises one or a combination of two or more of 4,4 'diaminodiphenylmethane, 4' -diaminodiphenyl sulfone, m-phenylenediamine, phenalkamine, phthalic anhydride, glycerol trimellitate, and diphenyl ether tetracarboxylic dianhydride.

8. The oil-based drilling fluid lost circulation agent of claim 1 or 2, wherein the swelling plugging material comprises one or a combination of two or more of styrene-butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, methacrylate-styrene copolymer, acrylate copolymer and chlorosulfonated polyethylene.

9. The use while drilling of the oil-based drilling fluid lost circulation additive of any of claims 1-8, wherein the oil-based drilling fluid lost circulation additive is added to the oil-based drilling fluid in an amount of 10 to 80 g/L.

10. The use of the oil-based drilling fluid plugging agent of any one of claims 1-8 in the preparation of a plugging slurry, wherein the oil-based drilling fluid plugging agent is added in the base oil in an amount of 100-250 g/L.

Technical Field

The invention relates to the field of oil-based drilling fluid leakage stoppage, in particular to an oil-based drilling fluid leakage stoppage agent and application thereof.

Background

The drilling lost circulation refers to a complex underground working condition that drilling fluid partially or completely leaks into a stratum in the drilling process. Research on the well leakage problem finds that different types of drilling fluids have obvious difference on the leakage loss, and the oil-based drilling fluid is easier to leak than the water-based drilling fluid. At present, along with the deepening of exploration and development of complex strata, the using amount of the oil-based drilling fluid in the domestic unconventional oil and gas field is larger and larger, the problem of well leakage of the oil-based drilling fluid is more and more, and the oil and gas exploration and development process is seriously influenced.

At present, the matching of the oil-based drilling fluid plugging agent in China is not perfect, and related research and development and application achievements are relatively few. CN105441044A discloses a plugging agent for an oil-based drilling fluid, which consists of fibers, walnut shells, oil-absorbing polymer particles and an oil-based core-shell expansion plugging agent. CN105505337A discloses a deformable plugging agent for oil-based drilling fluid and a preparation method thereof, and the deformable plugging agent is prepared by taking orthosilicate as a raw material and adopting an emulsion polymerization method. CN104448136A discloses a preparation method of a while-drilling plugging agent for oil-based drilling fluid, wherein the plugging agent is prepared by emulsion suspension polymerization of propylene water-soluble monomers and inorganic powder materials. CN106634898A discloses a plugging agent while drilling for oil-based drilling fluid, which is formed by combining a sheet material, a particle material and a fiber material. CN105368409A discloses a composite plugging agent for oil-based drilling fluid, which consists of a plugging material, a fiber material, an oil swelling material, an oleophilic ultrafine particle material and an oleophilic sheet material.

The bridging plugging material is a common plugging agent at present, the particle size distribution of the bridging plugging material is relatively fixed, and the bridging plugging material is difficult to effectively plug the leakage passages with different pore size distributions.

The cross-linked consolidation plugging agent material is also a common plugging agent. In the plugging construction, all components in the plugging agent are subjected to chemical reaction underground to form a consolidation body, and an underground leakage passage, drilling fluid and plugging materials in the underground leakage passage are consolidated into a whole to plug the leakage passage. However, the cross-linking consolidation plugging agent generally needs professional personnel and special equipment, and has long operation preparation time and high requirement. Meanwhile, in order to avoid complex accidents such as consolidation drilling tools and the like caused by the fact that the consolidation plugging agent is solidified too fast after entering a well, the consolidation plugging agent needs relatively long waiting time, and the plugging effect can be fully embodied after the consolidation is completed. The plugging agent has high use requirement, long time consumption and relatively high construction risk.

Disclosure of Invention

In order to solve the problems, the invention aims to provide an oil-based drilling fluid plugging agent and application thereof. The oil-based drilling fluid plugging agent is added with the temperature control expansion material and the swelling plugging material to form a synergistic interaction mechanism with the temperature stimulation response and the solvent stimulation response, so that the plugging capability of the bridging plugging material on leakage passages with different pore size distributions is improved.

In order to achieve the purpose, the invention provides an oil-based drilling fluid plugging agent, which comprises the following components in percentage by mass: 30-90% of bridging plugging material, 1-40% of temperature control expansion material and 1-40% of swelling plugging material, wherein the sum of the percentages of the components is 100%.

In the oil-based drilling fluid plugging agent, preferably, the oil-based drilling fluid plugging agent comprises, by mass: 40-80% of bridging plugging material, 2-30% of temperature control expansion material and 2-30% of swelling plugging material, wherein the sum of the percentages of the components is 100%.

In the oil-based drilling fluid plugging agent, preferably, the bridging plugging material comprises one or a combination of more than two of calcium carbonate, elastic graphite, powdered asphalt, mica, vermiculite, sepiolite, quartz, glass fiber, basalt fiber and bamboo fiber.

In the oil-based drilling fluid plugging agent, preferably, the temperature-controlled expansion material is prepared by a base material and a curing agent through a thermosetting reaction.

In a specific embodiment, the temperature-controlled expansion material is a material which contains a stationary phase (i.e. a curing cross-linking point formed by a curing agent) and a reversible phase structure (i.e. a matrix material) and has temperature-responsive deformability. The temperature control expansion material has the capability of thermal expansion, and has a relatively small size at room temperature; after the temperature-controlled expansion material enters a leakage stratum, the reversible phase structure of the temperature-controlled expansion material can be softened at the temperature of 60-100 ℃ and can initiate expansion deformation along with the rise of the temperature of the stratum, and the deformation rate can reach 30-90%. The temperature control expansion material has plugging capability, and after the temperature control expansion material is added into the oil-based drilling fluid plugging agent, the adaptability and plugging capability of the plugging material to different sizes of leakage passages can be further improved.

In the oil-based drilling fluid plugging agent, the mass ratio of the base material to the curing agent is preferably 100: (5-40).

In the oil-based drilling fluid plugging agent, preferably, the preparation process (i.e. the thermal curing reaction) of the temperature-controlled expansion material comprises the following steps: heating and melting the matrix material, adding a curing agent, curing at 60-180 ℃ for 2-8 hours, carrying out hot press molding on the cured product, and cooling under the pressure (generally to room temperature) to obtain the temperature-controlled expansion material.

In the preparation process of the temperature control expansion material, the flexibility of the reversible molecular chain can be gradually enhanced along with the temperature rise in the hot pressing process, and the reversible molecular chain is deformed under the action of pressure. In the pressure maintaining and cooling process, the pressure and the deformation are maintained, the temperature is reduced, the rigidity of the molecular chain in the reversible phase is enhanced, and the stress and the deformation of the molecular chain are frozen. After the temperature control expansion material enters the stratum, the material is heated along with the rise of the temperature of the stratum, the flexibility of the reversible phase molecular chain is enhanced, the stress is released, and the material is subjected to temperature control expansion deformation.

In the preparation of the temperature control expansion material, the curing process can be divided into two temperature gradients, namely the preparation of the temperature control expansion material comprises the steps of heating and melting a matrix material, adding a curing agent, curing at 80-100 ℃ for 2-4 hours, heating to 100-150 ℃ for curing for 2-4 hours, carrying out hot press molding on a cured product, and carrying out pressure maintaining cooling to obtain the temperature control expansion material. In the curing process, the curing speed is greatly influenced by temperature, the curing is slow due to too low temperature, and the curing reaction is accelerated but the performance of a cured product is reduced due to too high temperature. By adopting gradient curing, the curing speed can be higher, and the performance of a cured product can be ensured.

According to the specific embodiment of the invention, the preparation process of the temperature-controlled expansion material can further comprise the steps of carrying out hot-press molding on the solidified product, carrying out granulation and crushing after pressure maintaining and cooling, wherein the size of the crushed particles can be adjusted according to the actual plugging requirement.

In the above oil-based drilling fluid plugging agent, preferably, the matrix material comprises one or a combination of two or more of bisphenol a epoxy resin, bis (2, 3-epoxycyclopentyl) ether, polyurethane, polyethylene, polyisoprene, polynorbornene and butadiene-styrene copolymer.

In the above oil-based drilling fluid plugging agent, preferably, the curing agent comprises one or a combination of two or more of 4,4 'diaminodiphenylmethane, 4' -diaminodiphenyl sulfone, m-phenylenediamine, phenalkamine, phthalic anhydride, glycerol trimellitate, and diphenyl ether tetracarboxylic dianhydride.

In a specific embodiment, the swelling plugging material expands 1-30% in volume after absorbing oil after being soaked in the oil-based drilling fluid due to a similar compatibility principle. The swelling plugging material can play a plugging role, and when the swelling plugging material is added into the oil-based drilling fluid plugging agent, the compactness of a plugging layer can be further improved, and the filling plugging effect is enhanced.

In the oil-based drilling fluid plugging agent, preferably, the swelling plugging material comprises one or a combination of more than two of styrene-butadiene rubber, nitrile-butadiene rubber, hydrogenated nitrile-butadiene rubber, methacrylate-styrene copolymer, acrylate copolymer and chlorosulfonated polyethylene.

According to the specific embodiment of the invention, the oil-based drilling fluid plugging agent can be obtained by directly mixing the bridging plugging material, the temperature control expansion material and the swelling plugging material.

The invention also provides the application of the oil-based drilling fluid plugging agent while drilling, wherein the addition amount of the oil-based drilling fluid plugging agent in the oil-based drilling fluid is 10-80 g/L. In the drilling process, the plugging agent can be dispersed in the drilling fluid for use, so that the oil-based drilling fluid can be effectively prevented from leaking, and the plugging effect on leakage and small leakage is improved.

The invention also provides the application of the oil-based drilling fluid plugging agent in the preparation of plugging slurry, and the oil-based drilling fluid plugging agent can be used for plugging a leaking layer after the well leakage occurs, wherein the addition amount of the oil-based drilling fluid plugging agent in the base oil is 250 g/L.

The invention has the beneficial effects that:

1. the oil-based drilling fluid plugging agent provided by the invention has good compatibility and strong plugging capability.

2. The plugging agent for the oil-based drilling fluid, provided by the invention, has swelling characteristics and temperature regulation and deformation capacity, can fill the framework space of the plugging material under stimulation of various conditions, improves the plugging capacity of the plugging material on leakage channels with different pore sizes, and prevents and inhibits the occurrence of lost circulation.

3. The oil-based drilling fluid plugging agent provided by the invention can be applied to the well leakage prevention of oil-based drilling fluid or used for plugging a leakage layer after the well leakage occurs. The oil-based drilling fluid plugging agent does not generate chemical solidification reaction, does not need to wait for solidification, has low use risk, can save the operation time and improve the efficiency.

Drawings

FIG. 1 shows the results of the soaking experiment of the swelling plugging material of example 4 in an oil-based drilling fluid.

FIG. 2 shows the results of the deformation test of the temperature-controlled expansion material of example 2.

Detailed Description

The technical solutions of the present invention will be described in detail below in order to clearly understand the technical features, objects, and advantages of the present invention, but the present invention is not limited thereto.

Comparative example 1

The comparative example provides an oil-based drilling fluid without a plugging agent, and the specific preparation method comprises the following steps:

400mL of 5# white oil, 16g of organic soil, 18g of emulsifier, 12g of filtrate reducer and 100mLCaCl₂The water solution is stirred and mixed, and the barite weighted drilling fluid is adopted to increase the density to 1.5g/cm³And obtaining the oil-based drilling fluid. Wherein, the emulsifier is prepared by tall oil acid, maleic anhydride and hydroxyethyl ethylene diamine.

Comparative example 2

The comparative example provides an oil-based drilling fluid only added with a bridging plugging material, and the specific preparation method comprises the following steps:

1. and uniformly mixing 60 parts of elastic graphite, 20 parts of powdered asphalt and 20 parts of bamboo fiber to obtain the bridging plugging material.

2. And (3) preparing the oil-based drilling fluid by the same method as the comparative example 1, slowly adding the bridging plugging material into the oil-based drilling fluid according to the addition proportion of 50g/L, and uniformly stirring to obtain an oil-based drilling fluid sample for testing.

Comparative example 3

The comparative example provides an oil-based drilling fluid only added with a bridging plugging material and a swelling plugging material, and the specific preparation method comprises the following steps:

1. and mixing 60 parts of elastic graphite, 20 parts of powdered asphalt, 10 parts of bamboo fiber and 10 parts of nitrile rubber powder to obtain the oil-based drilling fluid plugging agent.

2. And (3) preparing the oil-based drilling fluid by the same method as the comparative example 1, slowly adding the oil-based drilling fluid plugging agent into the oil-based drilling fluid according to the addition proportion of 50g/L, and uniformly stirring to obtain an oil-based drilling fluid sample for testing.

Comparative example 4

The comparative example provides an oil-based drilling fluid only added with a bridging plugging material and a temperature control expansion material, and the specific preparation method comprises the following steps:

1. heating and melting 100 parts of bisphenol A epoxy resin, sequentially adding 15 parts of 4,4' -diaminodiphenylmethane, uniformly stirring, curing at 80 ℃ for 4 hours, then carrying out hot press molding, carrying out pressure maintaining cooling to room temperature, and crushing and granulating to obtain the temperature-controlled expansion material.

2. And (3) mixing 60 parts of elastic graphite, 20 parts of powdered asphalt, 10 parts of bamboo fiber and 10 parts of the temperature control expansion material prepared in the step (1) to obtain the oil-based drilling fluid plugging agent.

3. And (3) preparing the oil-based drilling fluid by the same method as the comparative example 1, slowly adding the oil-based drilling fluid plugging agent into the oil-based drilling fluid according to the addition proportion of 50g/L, and uniformly stirring to obtain an oil-based drilling fluid sample for testing.

Example 1

The embodiment provides an oil-based drilling fluid plugging agent. The preparation process of the oil-based drilling fluid plugging agent comprises the following steps:

1. heating and melting 100 parts of bisphenol A epoxy resin, sequentially adding 15 parts of 4,4' -diaminodiphenylmethane, uniformly stirring, curing at 80 ℃ for 6 hours, then carrying out hot press molding, carrying out pressure maintaining cooling to room temperature, and crushing and granulating to obtain the temperature-controlled expansion material.

2. And (3) mixing 60 parts of elastic graphite, 10 parts of powdered asphalt, 10 parts of bamboo fiber, 10 parts of the temperature control expansion material obtained in the step (1) and 10 parts of nitrile butadiene rubber powder to obtain the oil-based drilling fluid plugging agent.

3. And (3) preparing the oil-based drilling fluid by the same method as the comparative example 1, slowly adding the oil-based drilling fluid plugging agent into the oil-based drilling fluid according to the addition proportion of 50g/L, and uniformly stirring to obtain an oil-based drilling fluid sample for testing.

Example 2

The embodiment provides an oil-based drilling fluid plugging agent. The preparation process of the oil-based drilling fluid plugging agent comprises the following steps:

1. heating and melting 100 parts of bisphenol A epoxy resin, sequentially adding 8 parts of 4,4' -diaminodiphenylmethane and 5 parts of m-phenylenediamine, uniformly stirring, curing at 80 ℃ for 2 hours, heating to 150 ℃ for curing for 4 hours, then carrying out hot press molding, carrying out pressure maintaining cooling to room temperature, and crushing and granulating to obtain the temperature-controlled expansion material.

2. And (3) mixing 60 parts of calcium carbonate, 10 parts of powdered asphalt, 10 parts of bamboo fiber, 10 parts of the temperature control expansion material obtained in the step (1) and 10 parts of nitrile rubber powder to obtain the oil-based drilling fluid plugging agent.

3. And (3) preparing the oil-based drilling fluid by the same method as the comparative example 1, slowly adding the oil-based drilling fluid plugging agent into the oil-based drilling fluid according to the addition proportion of 50g/L, and uniformly stirring to obtain an oil-based drilling fluid sample for testing.

Example 3

The embodiment provides an oil-based drilling fluid plugging agent. The preparation process of the oil-based drilling fluid plugging agent comprises the following steps:

1. heating and melting 100 parts of bisphenol A epoxy resin, sequentially adding 8 parts of m-phenylenediamine, uniformly stirring, curing at 100 ℃ for 6 hours, then carrying out hot press molding, keeping pressure, cooling to room temperature, crushing and granulating to obtain the temperature control expansion material.

2. And (3) mixing 60 parts of calcium carbonate, 10 parts of powdered asphalt, 10 parts of bamboo fiber, 10 parts of the temperature control expansion material obtained in the step (1) and 10 parts of nitrile rubber powder to obtain the oil-based drilling fluid plugging agent.

3. And (3) preparing the oil-based drilling fluid by the same method as the comparative example 1, slowly adding the oil-based drilling fluid plugging agent into the oil-based drilling fluid according to the addition proportion of 50g/L, and uniformly stirring to obtain an oil-based drilling fluid sample for testing.

Example 4

The embodiment provides an oil-based drilling fluid plugging agent. The preparation process of the oil-based drilling fluid plugging agent comprises the following steps:

1. after 50 parts of bisphenol A epoxy resin and 50 parts of bis (2, 3-epoxy cyclopentyl) ether are heated and melted, 18 parts of 4,4' -diaminodiphenylmethane are added successively and stirred uniformly, the mixture is solidified for 2 hours at 100 ℃, the mixture is heated to 150 ℃ and solidified for 4 hours, and then the mixture is hot-pressed and molded, and is cooled to room temperature under the pressure maintaining condition, crushed and granulated to prepare the temperature control expansion material.

2. And (3) mixing 50 parts of calcium carbonate, 20 parts of powdered asphalt, 15 parts of bamboo fiber, 10 parts of the temperature control expansion material obtained in the step (1) and 5 parts of hydrogenated nitrile butadiene rubber powder to obtain the oil-based drilling fluid plugging agent.

3. And (3) preparing the oil-based drilling fluid by the same method as the comparative example 1, slowly adding the oil-based drilling fluid plugging agent into the oil-based drilling fluid according to the addition proportion of 50g/L, and uniformly stirring to obtain an oil-based drilling fluid sample for testing.

Example 5

The embodiment provides an oil-based drilling fluid plugging agent. The preparation process of the oil-based drilling fluid plugging agent comprises the following steps:

1. heating and melting 70 parts of bisphenol A epoxy resin and 30 parts of bis (2, 3-epoxy cyclopentyl) ether, sequentially adding 15 parts of 4,4' -diaminodiphenylmethane, stirring uniformly, curing at 80 ℃ for 4 hours, heating to 100 ℃ for curing for 4 hours, then carrying out hot press molding, maintaining pressure, cooling to room temperature, crushing and granulating to obtain the temperature-controlled expansion material.

2. And (3) mixing 50 parts of calcium carbonate, 10 parts of powdered asphalt, 15 parts of bamboo fiber, 15 parts of the temperature control expansion material obtained in the step (1) and 10 parts of hydrogenated nitrile butadiene rubber powder to obtain the oil-based drilling fluid plugging agent.

3. And (3) preparing the oil-based drilling fluid by the same method as the comparative example 1, slowly adding the oil-based drilling fluid plugging agent into the oil-based drilling fluid according to the addition proportion of 50g/L, and uniformly stirring to obtain an oil-based drilling fluid sample for testing.

Example 6

The embodiment provides an oil-based drilling fluid plugging agent. The preparation process of the oil-based drilling fluid plugging agent comprises the following steps:

1. after 80 parts of bisphenol A epoxy resin and 20 parts of bis (2, 3-epoxy cyclopentyl) ether are heated and melted, 13 parts of 4,4' -diaminodiphenylmethane are added successively and stirred uniformly, the mixture is solidified for 2 hours at 80 ℃, the mixture is heated to 150 ℃ and solidified for 4 hours, and then the mixture is hot-pressed and molded, and is cooled to room temperature under the pressure maintaining condition, crushed and granulated to prepare the temperature control expansion material.

2. And (3) mixing 50 parts of calcium carbonate, 10 parts of powdered asphalt, 10 parts of bamboo fiber, 15 parts of the temperature control expansion material obtained in the step (1) and 15 parts of hydrogenated nitrile butadiene rubber powder to obtain the oil-based drilling fluid plugging agent.

3. And (3) preparing the oil-based drilling fluid by the same method as the comparative example 1, slowly adding the oil-based drilling fluid plugging agent into the oil-based drilling fluid according to the addition proportion of 50g/L, and uniformly stirring to obtain an oil-based drilling fluid sample for testing.

Test example 1

The oil-based drilling fluid samples prepared in examples 1-6 and the oil-based drilling fluid provided in comparative example 1 were tested to evaluate the compatibility of the lost circulation additive provided by the present invention with the oil-based drilling fluid.

The compatibility test process comprises the following steps: the experimental temperature is 100 ℃, the viscosity and the shear force of each sample are measured by adopting a direct-reading viscometer, and the test process and the calculation method refer to GBT 16783.2-2012 section 6 of the 2 nd part of the oil-based drilling fluid field test of the petroleum and natural gas industry drilling fluid. The results of the compatibility tests are summarized in table 1.

As shown in Table 1, after the plugging agent for the oil-based drilling fluid provided by the invention is added, the rheological properties (apparent viscosity, plastic viscosity, dynamic shear force, initial shear force and final shear force) of the oil-based drilling fluid are not obviously changed, the high-temperature and high-pressure filtration loss is reduced, and the demulsification voltage is stable, so that the plugging agent and the oil-based drilling fluid have good compatibility.

TABLE 1

Test example 2 squeeze plugging test

Squeeze plugging tests are carried out on the oil-based drilling fluid samples of examples 1-6 and comparative examples 1-4 by adopting a sand bed plugging evaluation device to evaluate the plugging capability of the plugging agent. The test adopts quartz sand to simulate a leaking layer, the size of the quartz sand is 20-40 meshes, the thickness of a sand bed is 20 cm, and the test temperature is 80 ℃. The test sample is injected into the sand bed sleeve through the pressurization system, along with the increase of the extrusion injection amount, the plugging agent in the oil-based drilling fluid forms a plugging layer in the sand bed, and the extrusion injection pressure is gradually increased. Squeeze pressure of different test samples is recorded, plugging capacity of the plugging agent is represented by comparing the squeeze pressure, and the plugging performance evaluation test result is shown in table 2.

As can be seen from table 2, the bridging lost circulation material has the function of improving the plugging capability of the oil-based drilling fluid, and on the basis, the plugging capability can be further improved by respectively adding the swelling lost circulation material or the temperature-controlled swelling material, but the synergy is not obvious enough under a single action mechanism. From the test results of the samples in examples 1 to 6, it can be seen that the squeeze pressure can be greatly increased from 2.2MPa to 15.2MPa, which indicates that under the dual stimulus response mechanism of the swelling plugging material and the temperature control swelling material, an obvious synergistic effect is generated, the compactness of the plugging layer is further improved, and good plugging capability is shown.

TABLE 2

Name of test sample	Maximum squeeze pressure (MPa)
		Comparative example 1	2.2
Comparative example 2	7
		Comparative example 3	8.6
Comparative example 4	9.2
		Example 1	13
Example 2	13.5
		Example 3	12
Example 4	11.4
		Example 5	14
Example 6	15.2

Test example 3 swelling test

This test example is a soaking experiment of the swelling plugging material of example 4 (i.e., hydrogenated nitrile rubber powder) in an oil-based drilling fluid. The test is carried out according to GB/T528-. In the tensile strength test, the sample is in a 2-type dumbbell shape, and the tensile rate is 500 mm/min; in the volume change test, the test specimen is a type I rectangle.

Figure 1 summarizes the results of a soaking experiment of a swelling plugging material in an oil-based drilling fluid. As can be seen from figure 1, the swelling plugging material expands in volume after being soaked in the oil-based drilling fluid, and gradually increases with the time, and meanwhile, the swelling plugging material has good tensile strength retention rate and good physical properties.

Test example 4 deformation test

The test example is a deformation test of the temperature-controlled expansion material prepared in example 2 at different temperatures, and the specific process is as follows: the thickness of the flaky temperature control expansion material is measured firstly, then the flaky temperature control expansion material is added into the oil-based drilling fluid, the oil-based drilling fluid is respectively subjected to hot rolling for 1 hour at different temperatures, the thickness of the deformed material is measured after cooling, and the thickness of a sample before and after deformation is compared.

FIG. 2 shows the results of the deformation test of the temperature-controlled expansion material. As can be seen from FIG. 2, the deformation rate of the sample gradually increases with the increase of the temperature, and the sample has higher deformation capability in the range of 60-100 ℃.