Thermal insulation coating for drill rod, thermal insulation drill rod and preparation method of thermal insulation drill rod

Abstract

The invention relates to the field of materials, in particular to a heat-insulating coating for a drill rod, a heat-insulating drill rod and a preparation method of the heat-insulating drill rod. The heat insulation coating for the drill rod comprises a first heat insulation layer and a second heat insulation layer which are arranged in a staggered and stacked mode. One or more first heat insulation layers and one or more second heat insulation layers are independently arranged; wherein the material of the first heat insulation layer comprises a first heat insulation material and a binder; the material of the second heat insulation layer comprises a second heat insulation material; the first thermal insulation material comprises at least one of silicon dioxide aerogel and hollow glass microspheres; the second thermal insulation material comprises thermal insulation fibers. The heat-insulating coating for the drill rod has excellent mechanical property and excellent heat-insulating property, and can be applied to a high-temperature drilling environment when being applied to the drill rod.

Description

Technical Field

[0001] The present invention relates to the field of materials, and particularly to a heat-insulating coating for drill pipes, a heat-insulating drill pipe and a preparation method thereof. Background Art

[0002] Heat-insulating drill pipes are important equipment for developing deep oil and gas resources and geothermal resources. In the past hundred years of oil and gas resource production, the reserves of shallow-layer oil and gas resources have been continuously consumed, and the depth of oil and gas drilling has been continuously increased. Moreover, the temperature of the earth's strata increases with the depth. Currently, the international community has begun to massively develop oil and gas reservoirs at 175 - 200 °C, and the development of ultra-deep oil and gas reservoirs faces the problem of high downhole temperatures. For geothermal resources, the formation temperature often reaches above 200 °C, and foreign countries have been researching geothermal development technologies for rock formations at 400 °C.

[0003] For the development of high-temperature oil and gas and geothermal resources, first of all, it is necessary to establish a passage for the flow of substances and information from the ground to the underground target formation, which is usually achieved by drilling. Traditional drilling tools have poor control ability for the drilling wellbore trajectory, while advanced directional drilling tools are difficult to withstand high-temperature environments above 175 °C. High-temperature drilling practice shows that drill pipe heat insulation is an important method and key means to reduce the heat transfer between the fluids inside and outside the drill pipe, and one of the implementation methods is to attach a heat-insulating layer to the inner wall of the drill pipe.

[0004] Currently, the drill pipe heat insulation technology mainly starts from three aspects from the perspective of materials: (1) Filling a heat-insulating layer in the annular space of the drill pipe. This method is to create an annular space inside the drill pipe and fill it with materials having low thermal conductivity to increase the overall thermal resistance of the drill pipe to achieve the heat-insulating effect. This technology originated from oil production pipelines and entered the drilling field around 2002 - 2004, but it has gradually withdrawn from the market as a backward technology. Specifically, the mechanical properties of the heat-insulating material filled in the annular space of the drill pipe are much inferior to those of the steel used to manufacture the drill pipe. In order to meet the mechanical properties required for the drill pipe, it is necessary to thicken the two side walls of the annulus layer. This will result in a reduction in the flow area of the downhole cross-section and affect the flow state of the drilling fluid; (2) Attaching heat-insulating coatings to the inner and outer surfaces of the drill pipe. This method does not modify the drill pipe structure, but sprays heat-insulating materials on the inner and outer walls of the drill pipe to increase the overall thermal resistance of the drill pipe. This technology is the mainstream international drill pipe heat insulation technology, but currently, there is less research and application on the materials used for drill pipe heat insulation, and mostly single materials are used, such as only using alumina-silica aerogel, rare earth tantalate coatings, etc. The above materials have low thermal conductivity, but due to the mechanical properties of the materials, when the drilling fluid flows inside the drill pipe and in the downhole annulus layer, it will wear the materials, and when the drill string collides with the formation, the vibration generated will damage the materials; (3) Manufacturing drill pipes using new composite materials. This method changes the raw materials for manufacturing drill pipes to reduce the thermal conductivity of the drill pipe material itself to increase the thermal resistance. However, this technology has a high cost and has a great impact on the mechanical properties of the drill pipe, and has not been widely applied. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the present invention provides a heat-insulating coating for drill pipes, a heat-insulating drill pipe and a preparation method thereof. The heat-insulating coating for drill pipes has both excellent mechanical properties and excellent heat-insulating properties, and when applied to drill pipes, it is applicable to high-temperature drilling environments.

[0006] To this end, in a first aspect of the present invention, there is provided a heat-insulating coating for drill pipes, the heat-insulating coating for drill pipes comprising a first heat-insulating layer and a second heat-insulating layer which are alternately stacked; the first heat-insulating layer and the second heat-insulating layer are each independently one or more;

[0007] wherein, the material of the first heat-insulating layer comprises a first heat-insulating material and a binder;

[0008] the material of the second heat-insulating layer comprises a second heat-insulating material;

[0009] the first heat-insulating material comprises at least one of silica aerogel and hollow glass microspheres;

[0010] the second heat-insulating material comprises heat-insulating fibers.

[0011] To solve the deficiencies in the prior art, the present invention starts from the heat-insulating coating for drill pipes and solves the technical problem that the mechanical properties of the materials in the prior art do not meet the requirements by selecting heat-insulating materials and arranging multiple heat-insulating layers. The present invention prepares a heat-insulating coating based on the first heat-insulating material and the second heat-insulating material, which can have both excellent mechanical properties and excellent heat-insulating properties. When applied to drill pipes, the temperature in the well can be reduced by 50-120 °C relative to the formation temperature.

[0012] According to an embodiment of the present invention, the thickness of the first heat-insulating layer is 0-20 mm and is not 0 mm.

[0013] According to an embodiment of the present invention, the thickness of the second heat-insulating layer is 0-50 mm and is not 0 mm.

[0014] According to an embodiment of the present invention, the binder comprises at least one of sodium silicate, polyurethane and epoxy resin.

[0015] According to an embodiment of the present invention, the binder contains additives, and the additives comprise nano-silica and / or heat-insulating fibers.

[0016] According to an embodiment of the present invention, the mass ratio of the additives in the binder is 0-90 wt%.

[0017] According to an embodiment of the present invention, the heat-insulating fibers comprise at least one of basalt fibers and glass fibers.

[0018] According to an embodiment of the present invention, the number of the first heat insulation layers is 1-10, and the number of the second heat insulation layers is 1-10.

[0019] In a second aspect of the present invention, there is provided a heat-insulated drill pipe, which includes a drill pipe body and the heat-insulating coating for drill pipes described in the first aspect.

[0020] Wherein, the heat-insulating coating is provided on the outer wall and / or inner wall of the drill pipe body, and the first heat insulation layer or the second heat insulation layer of the heat insulation unit close to the drill pipe body is in contact with the outer wall and / or inner wall of the drill pipe body.

[0021] Thus, the heat-insulated drill pipe has both excellent mechanical properties and excellent heat insulation properties, and can reduce the temperature in the well by 50-120°C relative to the formation temperature.

[0022] In a third aspect of the present invention, there is provided a preparation method for the heat-insulated drill pipe described in the second aspect. The preparation method includes alternately stacking the first heat insulation layer and the second heat insulation layer on the outer wall and / or inner wall of the drill pipe body to obtain the heat-insulated drill pipe.

[0023] The additional aspects and advantages of the present invention will be partly given in the following description, partly become obvious from the following description, or be understood through the practice of the present invention. Detailed Embodiments

[0024] The embodiments of the present invention will be described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as a limitation to the present invention.

[0025] It should be noted that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Further, in the description of the present invention, unless otherwise specified, "a plurality of" means two or more.

[0026] The endpoints and any values disclosed in this article for a range are not limited to the exact range or value. These ranges or values should be understood to include values close to these ranges or values. For a numerical range, between the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this article.

[0027] To facilitate a better understanding of the present invention, certain technical and scientific terms are specifically defined below. Unless otherwise clearly defined elsewhere in this document, all other technical and scientific terms used herein shall have the meanings commonly understood by those of ordinary skill in the art to which the present invention pertains.

[0028] As used herein, the term "comprising" or "including" is an open-ended expression, meaning it includes the content specified in the present invention but does not exclude other aspects.

[0029] As used herein, the terms "optionally", "optional", or "option" generally refer to the subsequent events or conditions that may or may not occur, and this description includes the cases where such events or conditions occur and the cases where they do not occur.

[0030] As used herein, the term "plurality" refers to more than two (including two), and similarly, "multiple times" refers to more than two times (including two times).

[0031] According to an embodiment of the present invention, a heat-insulating coating for drill pipes is provided in a first aspect of the present invention. The heat-insulating coating for drill pipes includes a first heat-insulating layer and a second heat-insulating layer that are alternately stacked; the first heat-insulating layer and the second heat-insulating layer are independently one or more;

[0032] Wherein, the material of the first heat-insulating layer includes a first heat-insulating material and a binder;

[0033] The material of the second heat-insulating layer includes a second heat-insulating material;

[0034] The first heat-insulating material includes at least one of silica aerogel and hollow glass microspheres;

[0035] The second heat-insulating material includes heat-insulating fibers.

[0036] The present invention prepares a heat-insulating coating for drill pipes based on the first heat-insulating material and the second heat-insulating material. The first heat-insulating material includes at least one of silica aerogel and hollow glass microspheres, which has excellent heat-insulating performance; the second heat-insulating material includes heat-insulating fibers, which has excellent mechanical properties and heat-insulating performance. The present invention combines the first heat-insulating material and the second heat-insulating material, making the coating have both an extremely low thermal conductivity and good mechanical properties.

[0037] According to specific embodiments of the present invention, the number of the first heat insulation layer and the second heat insulation layer is not particularly limited and may be one or more, for example, 1-20, preferably 1-10. Those skilled in the art can select according to the heat insulation situation. Specifically, the number of the first heat insulation layer and the second heat insulation layer may be the same or different, as long as they are arranged in an alternating and stacked manner. When the number of the first heat insulation layer and the second heat insulation layer is the same, it may be an alternating structure of one layer of the first heat insulation layer and one layer of the second heat insulation layer; when the number of the first heat insulation layer and the second heat insulation layer is different, it may be an alternating structure of one layer of the first heat insulation layer, one layer of the second heat insulation layer, and finally one layer of the first heat insulation layer, or it may be an alternating structure of one layer of the second heat insulation layer, one layer of the first heat insulation layer, and finally one layer of the second heat insulation layer.

[0038] According to specific embodiments of the present invention, the material of the first heat insulation layer is not particularly limited and includes, but is not limited to, a first heat insulation material and a binder.

[0039] Specifically, the first heat insulation material includes at least one of silica aerogel and hollow glass microspheres. Among them, silica aerogel is a porous functional material with both solid-phase particles and pores in the nanometer scale. Silica aerogel has an extremely low thermal conductivity (0.0012-0.002 W / (m·K)) at room temperature. Therefore, silica aerogel is an excellent heat insulation material, and only a very small thickness is required to achieve a good heat insulation effect. Although silica aerogel has excellent heat insulation performance, it has defects of high brittleness and low strength, which greatly limit its practical application. In the present invention, the aerogel is compounded or cross-linked with a binder to prepare a composite aerogel material with good mechanical and heat insulation properties.

[0040] Specifically, the type of the binder is not particularly limited, as long as it can bond the first heat insulation layer and the second heat insulation layer at the working environment temperature. Those skilled in the art can select according to the situation, including but not limited to sodium silicate, polyurethane, high-temperature resistant epoxy resin glue, etc. Since the first heat insulation material is a porous material, the binder can enter the pores to generate strong bonding ability.

[0041] Specifically, it is preferred that the binder contains additives, including but not limited to nano-silica and / or heat insulation fibers. Among them, nano-silica and heat insulation fibers have a relatively high porosity, which further promotes the binder to enter the pores to form strong bonding ability. At the same time, when the binder includes sodium silicate, the silica skeleton formed after its condensation and curing has a relatively low thermal conductivity, but it lacks toughness and seismic resistance. On this basis, heat insulation fibers, such as basalt fiber rovings, can be introduced, which can improve the mechanical properties of the silica skeleton. In addition, introducing nano-silica particles into the binder can further reduce the thermal conductivity of the binder.

[0042] Specifically, the mass ratio of the additive in the binder is not particularly limited. As some specific limitations, the mass ratio of the additive in the binder is 0-90 wt%, such as 0 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt%, etc.

[0043] Specifically, the mass ratio of the first heat-insulating material to the binder is not particularly limited, as long as good adhesion and heat-insulating performance can be achieved.

[0044] According to a specific embodiment of the present invention, the material of the second heat-insulating layer includes a second heat-insulating material, and the second heat-insulating material includes heat-insulating fibers. The type of the heat-insulating fibers is not particularly limited, including but not limited to basalt fibers and glass fibers. Specifically, the form of the heat-insulating fibers is also not particularly limited, and it can exist in the form of fibers or fiber cloth. Among them, basalt fibers are continuous fibers formed by melting basalt stone materials and then high-speed drawing through a wire-drawing die plate. The main components are silicon dioxide, aluminum oxide, calcium oxide, magnesium oxide, etc. They have high tensile strength, high temperature resistance, acid and alkali corrosion resistance, and good insulation properties, and are one of the four key-developed fibers. Basalt fiber cloth is a thin sheet product made by orienting continuous filaments or chopped filaments and binding them together through chemical binders or mechanical action. Basalt fiber cloth has high tensile strength and compressive strength, can still ensure the strength and integrity of the material under a certain deformation, has a low friction coefficient, and at the same time, it is measured that the basalt fiber cloth with a braiding density of 2655 kg / m 3 has a thermal conductivity of 1.46 W / (m·K) at 200 °C. It can be seen that basalt fiber cloth has excellent heat-insulating performance. The same is true for glass fibers.

[0045] According to a specific embodiment of the present invention, the thicknesses of the first heat-insulating layer and the second heat-insulating layer are not particularly limited. Since the first heat-insulating layer and the second heat-insulating layer provided by the present invention take into account extremely low thermal conductivity and good mechanical properties, the first heat-insulating layer and the second heat-insulating layer can be set to extremely low thicknesses. For example, the thickness of the first heat-insulating layer is 0-20 mm and not 0 mm, and the thickness of the second heat-insulating layer is 0-50 mm and not 0 mm, and the influence on the flow area and fluid flow state of the inner and outer walls of the drill pipe can be ignored.

[0046] According to an embodiment of the present invention, in a second aspect of the present invention, a heat-insulating drill pipe is provided, and the heat-insulating drill pipe includes a drill pipe body and the heat-insulating coating for drill pipes described in the first aspect;

[0047] Among them, the heat-insulating coating is provided on the outer wall and / or inner wall of the drill pipe body, and the first heat-insulating layer or the second heat-insulating layer of the heat-insulating unit close to the drill pipe body is in contact with the outer wall and / or inner wall of the drill pipe body.

[0048] According to specific embodiments of the present invention, the heat-insulating coating for drill pipes provided by the present invention can be provided on the inner wall of the drill pipe, but is also applicable to the outer wall of the drill pipe, both of which can produce good heat-insulating performance and excellent mechanical properties at the same time.

[0049] According to an embodiment of the present invention, in a third aspect, the present invention provides a method for manufacturing the heat-insulating drill pipe described in the second aspect, including alternately laminating a first heat-insulating layer and a second heat-insulating layer on the outer wall and / or inner wall of the drill pipe body to obtain the heat-insulating drill pipe.

[0050] Thereby, the aforementioned heat-insulating drill pipe is obtained, which has good heat-insulating performance and excellent mechanical properties at the same time.

[0051] According to specific embodiments of the present invention, the manufacturing method may further include:

[0052] Mixing a first heat-insulating material and a binder, and coating the mixture on the outer wall and / or inner wall of the drill pipe body to obtain a first heat-insulating layer;

[0053] Coating a second heat-insulating material on the first heat-insulating layer to obtain the second heat-insulating layer;

[0054] Coating successively according to the required number of the first heat-insulating layer and the second heat-insulating layer, and drying to obtain the heat-insulating drill pipe;

[0055] Or coating the second heat-insulating material on the outer wall and / or inner wall of the drill pipe body to obtain a second heat-insulating layer;

[0056] Mixing a first heat-insulating material and a binder, and coating the mixture on the second heat-insulating layer to obtain a first heat-insulating layer;

[0057] Coating successively according to the required number of the first heat-insulating layer and the second heat-insulating layer, and drying to obtain the heat-insulating drill pipe.

[0058] According to specific embodiments of the present invention, the drying temperature and time in the manufacturing method are not particularly limited, that is, the drying of each heat-insulating layer can be achieved, and those skilled in the art can select according to the situation.

[0059] The following will explain the solution of the present invention in combination with embodiments. Those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the art or according to the product specifications. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0060] Example 1

[0061] This example provides a heat-insulating drill pipe, and the manufacturing method is as follows:

[0062] (1) Mix silica aerogel and water glass containing nano - silica and basalt fiber rovings, and coat it on the inner wall of the drill pipe to obtain a silica aerogel heat - insulating layer with a thickness of 2 mm;

[0063] Among them, the mass ratio of silica aerogel to water glass is 1:10, the mass proportion of nano - silica in water glass is 1%, and the mass proportion of basalt fiber rovings is 5%;

[0064] (2) Coat basalt fiber cloth on the silica aerogel heat - insulating layer with a thickness of 5 mm, and dry it to obtain a heat - insulating drill pipe. This heat - insulating drill pipe can reduce the well - bore temperature by 125 °C relative to the formation temperature.

[0065] Example 2

[0066] This example provides a heat - insulating drill pipe, and the preparation method is as follows:

[0067] (1) Mix hollow glass microspheres and water glass containing nano - silica and basalt fiber rovings, and coat it on the inner wall of the drill pipe to obtain a hollow glass microsphere heat - insulating layer with a thickness of 2 mm;

[0068] Among them, the mass ratio of hollow glass microspheres to water glass is 1:5, the mass proportion of nano - silica in water glass is 1%, and the mass proportion of basalt fiber rovings is 5%;

[0069] (2) Coat glass fiber on the hollow glass microsphere heat - insulating layer with a thickness of 5 mm, and dry it to obtain a heat - insulating drill pipe. This heat - insulating drill pipe can reduce the well - bore temperature by 110 °C relative to the formation temperature.

[0070] Example 3

[0071] This example provides a heat - insulating drill pipe, and the preparation method is as follows:

[0072] (1) Mix silica aerogel and water glass, and coat it on the inner wall of the drill pipe to obtain a silica aerogel heat - insulating layer with a thickness of 2 mm;

[0073] Among them, the mass ratio of silica aerogel to water glass is 1:10;

[0074] (2) Coat basalt fiber cloth on the silica aerogel heat - insulating layer with a thickness of 5 mm, and dry it to obtain a heat - insulating drill pipe. This heat - insulating drill pipe can reduce the well - bore temperature by 120 °C relative to the formation temperature.

[0075] Example 4

[0076] This example provides a heat - insulating drill pipe, and the preparation method is as follows:

[0077] (1) Mix silica aerogel and water glass containing nano-silica, and coat it on the outer wall of the drill pipe to obtain a silica aerogel thermal insulation layer with a thickness of 2 mm;

[0078] Among them, the mass ratio of silica aerogel to water glass is 1:5, and the mass proportion of nano-silica in water glass is 1%;

[0079] (2) Coat the basalt fiber cloth on the silica aerogel thermal insulation layer with a thickness of 5 mm, and dry it to obtain a heat-insulated drill pipe. This heat-insulated drill pipe can reduce the wellbore temperature by 105 °C relative to the formation temperature.

[0080] Comparative Example 1

[0081] This comparative example provides a heat-insulated drill pipe, and the preparation method is as follows:

[0082] Mix silica aerogel and water glass (the mass ratio of the two is 1:10), coat it on the inner wall of the drill pipe to obtain a silica aerogel thermal insulation layer with a thickness of 10 mm, and dry it to obtain a heat-insulated drill pipe. This heat-insulated drill pipe can reduce the wellbore temperature by 100 °C relative to the formation temperature, but its mechanical properties are poor and it is easy to wear.

[0083] Comparative Example 2

[0084] This comparative example provides a heat-insulated drill pipe, and the preparation method is as follows:

[0085] Coat the basalt fiber cloth on the inner wall of the drill pipe with a thickness of 10 mm, and dry it to obtain a heat-insulated drill pipe. This heat-insulated drill pipe can reduce the wellbore temperature by 80 °C relative to the formation temperature.

[0086] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0087] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A thermal insulation coating for a drill pipe, characterized in that: It comprises a first heat-insulating layer and a second heat-insulating layer which are staggered and stacked; the first heat-insulating layer and the second heat-insulating layer are independently one or more; Wherein, the material of the first heat insulation layer includes a first heat insulation material and a binder; The material of the second thermal insulation layer includes a second thermal insulation material; The first thermal insulation material includes at least one of silica aerogel and hollow glass microspheres; The second thermal insulation material includes thermal insulation fibers.

2. The thermal insulation coating for drill pipe according to claim 1, characterized in that: The thickness of the first heat insulation layer is 0-20 mm, and is not 0 mm.

3. The thermal insulation coating for drill pipe according to claim 1, characterized in that: The thickness of the second heat insulation layer is 0-50 mm, and is not 0 mm.

4. The thermal insulation coating for drill pipe according to claim 1, characterized in that: The adhesive includes at least one of water glass, polyurethane and epoxy resin.

5. The thermal insulation coating for drill pipe according to claim 4, characterized in that: The binder contains additives, which include nano silicon dioxide and / or thermal insulation fibers.

6. The thermal insulation coating for drill pipe according to claim 5, characterized in that: The mass percentage of the additive in the binder is 0-90wt%.

7. The thermal insulation coating for drill pipe according to claim 1, characterized in that: The thermal insulation fiber includes at least one of basalt fiber and glass fiber.

8. The thermal insulation coating for drill pipe according to claim 1, characterized in that: The number of the first heat-insulating layers is 1-10, and the number of the second heat-insulating layers is 1-10.

9. A heat-insulating drill pipe, characterized in that: The heat-insulating drill pipe comprises a drill pipe body and a heat-insulating coating for a drill pipe according to any one of claims 1 to 8; Wherein, the thermal insulation coating is arranged on the outer wall and / or inner wall of the drill rod body, and the first thermal insulation layer or the second thermal insulation layer of the thermal insulation unit close to the drill rod body is in contact with the outer wall and / or inner wall of the drill rod body.

10. A method for preparing the heat-insulating drill pipe according to claim 9, characterized in that: The method comprises staggeredly stacking a first heat insulation layer and a second heat insulation layer on the outer wall and / or the inner wall of a drill rod body to obtain the heat insulation drill rod.