CA2710830C - The oilwell tubing with coating that prevents buildup, and the method for applying coating - Google Patents
The oilwell tubing with coating that prevents buildup, and the method for applying coating Download PDFInfo
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- CA2710830C CA2710830C CA2710830A CA2710830A CA2710830C CA 2710830 C CA2710830 C CA 2710830C CA 2710830 A CA2710830 A CA 2710830A CA 2710830 A CA2710830 A CA 2710830A CA 2710830 C CA2710830 C CA 2710830C
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- owt
- coating
- polyurethane
- buildup
- inside surface
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Abstract
The invention pertains to the oil production industry, particularly to the field of preventing buildup (asphalt-tar-paraffin, salt, hydrate, etc.) on the inside surface of oil well tubing (OWT); it can be used for coating OWT inside surface, and can be applied with any method for extracting hydrocarbons (oil and gas) regardless of well production conditions and the quality of crude hydrocarbons. The technical result is achieved by pumping polyurethane into the annular cavity formed by the inside OWT
surface and a punch that has a high degree of surface finish and is installed into the OWT, waiting until polyurethane fully hardens, and then extracting the punch from the OWT.
Thereby, full polyurethane adhesion to the OWT wall metal is achieved, as well as a glossy surface and uniform thickness of coating. Depending on polyurethane shrinkage factor, a perforated metal mesh can be installed in the OWT, with the mesh outside diameter equal to the OWT inside diameter. Also, if necessary and based on processing technology for certain polyurethanes, before polyurethane is pumped the OWT is heated to the required temperature using any known method. The use of this design and method for applying coating, combined with the above material, will make it possible to obtain a high-quality homogenized coating layer with the same thickness, a glossy surface, high resistance to corrosive media, high adhesion to OWT inside surface, high abrasion resistance, and high thermal resistance, which will prevent formation of buildup and the related aftereffects, increase the time period between routine repairs and major overhauls of producing wells, and as a result increase OWT
life.
surface and a punch that has a high degree of surface finish and is installed into the OWT, waiting until polyurethane fully hardens, and then extracting the punch from the OWT.
Thereby, full polyurethane adhesion to the OWT wall metal is achieved, as well as a glossy surface and uniform thickness of coating. Depending on polyurethane shrinkage factor, a perforated metal mesh can be installed in the OWT, with the mesh outside diameter equal to the OWT inside diameter. Also, if necessary and based on processing technology for certain polyurethanes, before polyurethane is pumped the OWT is heated to the required temperature using any known method. The use of this design and method for applying coating, combined with the above material, will make it possible to obtain a high-quality homogenized coating layer with the same thickness, a glossy surface, high resistance to corrosive media, high adhesion to OWT inside surface, high abrasion resistance, and high thermal resistance, which will prevent formation of buildup and the related aftereffects, increase the time period between routine repairs and major overhauls of producing wells, and as a result increase OWT
life.
Description
THE OILWELL TUBING WITH COATING THAT PREVENTS BUILDUP, AND THE METHOD FOR
APPLYING COATING
DESCRIPTION OF INVENTION
The invention pertains to the oil industry, particularly to the field of preventing buildup (asphalt-tar-paraffin, salt, hydrate, etc.) on the inside surface of oil well tubing (OWT);
it can be used for coating OWT inside surface and can be applied with any method for extracting hydrocarbons (oil and gas) regardless of well operating conditions and the quality of crude hydrocarbons.
Known is the method for applying coating to the inside surface of a pipeline comprising coating the surface with a single- or multi-layer envelope made, for instance, of a film sheet, by pressing it against the pipeline surface by means of creating pressure differential (see patent RE
2144803, cl. IPC7 F 16 L
58/10, published 04.27.2000).
The method shortcoming is the difficulty of creating uniform coating of the pipe inside surface with a film sheet, low reliability of attaching the sheet to the pipe surface, and low resistance to highly aggressive media.
Known is the method for protecting the inside surface of pipelines with a polymer material comprising application of the latter to the pipeline inside surface by transforming the polymer material to viscous flow state, with subsequent hardening of the material (see patent RF 2118742, cl. IPC7 F 16 L 58/10, published 09.10.98), The invention shortcoming is that because of fast cooling of the melted polymer in a thermomechanical module it is impossible to get a homogenized coating layer and strong polymer bond with the tube surface due to strong heat shrinkage processes in the polymer mass, and movement of the thermomechanical module along the pipe results in changing the length of the coupling between the extruder and the module and changing the conditions of passage of melted polymer through the coupling; this changes the polymer physical state and thus reduces the quality of coating and the strength of polymer adhesion to metal.
APPLYING COATING
DESCRIPTION OF INVENTION
The invention pertains to the oil industry, particularly to the field of preventing buildup (asphalt-tar-paraffin, salt, hydrate, etc.) on the inside surface of oil well tubing (OWT);
it can be used for coating OWT inside surface and can be applied with any method for extracting hydrocarbons (oil and gas) regardless of well operating conditions and the quality of crude hydrocarbons.
Known is the method for applying coating to the inside surface of a pipeline comprising coating the surface with a single- or multi-layer envelope made, for instance, of a film sheet, by pressing it against the pipeline surface by means of creating pressure differential (see patent RE
2144803, cl. IPC7 F 16 L
58/10, published 04.27.2000).
The method shortcoming is the difficulty of creating uniform coating of the pipe inside surface with a film sheet, low reliability of attaching the sheet to the pipe surface, and low resistance to highly aggressive media.
Known is the method for protecting the inside surface of pipelines with a polymer material comprising application of the latter to the pipeline inside surface by transforming the polymer material to viscous flow state, with subsequent hardening of the material (see patent RF 2118742, cl. IPC7 F 16 L 58/10, published 09.10.98), The invention shortcoming is that because of fast cooling of the melted polymer in a thermomechanical module it is impossible to get a homogenized coating layer and strong polymer bond with the tube surface due to strong heat shrinkage processes in the polymer mass, and movement of the thermomechanical module along the pipe results in changing the length of the coupling between the extruder and the module and changing the conditions of passage of melted polymer through the coupling; this changes the polymer physical state and thus reduces the quality of coating and the strength of polymer adhesion to metal.
2 Known is the method for coating pipeline surfaces with a thermoplastic material using injection molding.
The method comprises placing a metal pipe in a mold and feeding thermoplastic material melted to a viscous flow state into the mold while heating the latter, then hardening the material and removing the pipe from the mold (see patent RF 2184903, cl. IPC7 F 16 L 58/10, published 07.10..02).
The invention shortcomings are complexity of the manufacturing process and considerable cost of making the mold, especially for long pipes; it is also impossible to use said method for pipes with the diameter less than 200 mm.
One of the main unsolved problems in the world oil industry is buildup on the walls of OWTs in oil and gas wells for extraction of hydrocarbons (oil and gas). And this process starts from the very first hour of production under any climate conditions and continues up until full plugging of the OWT. The buildup results in rapid wear of pumping equipment, additional expense and lost time for cleaning OWT, as well in pressure loss in OWT due to reduced flow area, which increases the percentage of hydrocarbons shortfall.
Depending on hydrocarbons quality, the time between cleaning OWT at various fields varies from one day to one year.
For instance, in the Buzuluk field, paraffin buildup is cleaned every 1-15 days depending on the well; in Tyumen fields this period is 5-20 days, in Surgut fields it is 7-30 days, and so on.
This is why there is a problem. Having studied the causes of buildup formation on the inside surface of OWT, the design and the method for coating the inside surface of OWT that solve this problem in its totality are being proposed.
There are three main factors that promote formation of buildup on OWT inside surface:
1. Roughness of the OWT inside surface.
2. The presence of static charge on the OWT inside surface during oil movement.
The method comprises placing a metal pipe in a mold and feeding thermoplastic material melted to a viscous flow state into the mold while heating the latter, then hardening the material and removing the pipe from the mold (see patent RF 2184903, cl. IPC7 F 16 L 58/10, published 07.10..02).
The invention shortcomings are complexity of the manufacturing process and considerable cost of making the mold, especially for long pipes; it is also impossible to use said method for pipes with the diameter less than 200 mm.
One of the main unsolved problems in the world oil industry is buildup on the walls of OWTs in oil and gas wells for extraction of hydrocarbons (oil and gas). And this process starts from the very first hour of production under any climate conditions and continues up until full plugging of the OWT. The buildup results in rapid wear of pumping equipment, additional expense and lost time for cleaning OWT, as well in pressure loss in OWT due to reduced flow area, which increases the percentage of hydrocarbons shortfall.
Depending on hydrocarbons quality, the time between cleaning OWT at various fields varies from one day to one year.
For instance, in the Buzuluk field, paraffin buildup is cleaned every 1-15 days depending on the well; in Tyumen fields this period is 5-20 days, in Surgut fields it is 7-30 days, and so on.
This is why there is a problem. Having studied the causes of buildup formation on the inside surface of OWT, the design and the method for coating the inside surface of OWT that solve this problem in its totality are being proposed.
There are three main factors that promote formation of buildup on OWT inside surface:
1. Roughness of the OWT inside surface.
2. The presence of static charge on the OWT inside surface during oil movement.
3. Temperature differential on the OWT wall.
Based on these factors, the requirements to the design and method for coating that prevent buildup have been identified:
1. Coating thickness from 2 to 8 mm, to reduce thermal conductivity and prevent a sharp temperature differential on the OWT wall.
2. A high degree of coating surface finish ¨ a glossy finish.
3. Prevention of static charge accumulation.
In addition to meeting the above requirements, which prevents buildup formation, the coating and the method for applying it shall have:
1. Resistance to corrosive media (acids, alkali, etc.).
2. Integrity, good adhesion to metal, and water repellency - to prevent corrosion of the OWT inside surface.
3. Elasticity, stress cracking resistance under impact and resistance to OWT
deflection at temperatures as low as -600C.
Based on these factors, the requirements to the design and method for coating that prevent buildup have been identified:
1. Coating thickness from 2 to 8 mm, to reduce thermal conductivity and prevent a sharp temperature differential on the OWT wall.
2. A high degree of coating surface finish ¨ a glossy finish.
3. Prevention of static charge accumulation.
In addition to meeting the above requirements, which prevents buildup formation, the coating and the method for applying it shall have:
1. Resistance to corrosive media (acids, alkali, etc.).
2. Integrity, good adhesion to metal, and water repellency - to prevent corrosion of the OWT inside surface.
3. Elasticity, stress cracking resistance under impact and resistance to OWT
deflection at temperatures as low as -600C.
4. Abrasion resistance when exposed to a flow of suspended particles with Mohs hardness of up to 7.
5. Retention of coating characteristics in the temperature range from -600C to + 11000.
The objective of the proposed technical solution is to develop the design and method for coating the OWT inside surface that prevent buildup, with long life, that can be used with any method for extraction of hydrocarbons regardless of operating conditions of the well and the quality of extracted crude hydrocarbons, as well as meeting the above requirements.
By means of research and numerous tests, the material meeting the above retirements has been selected. It is a polyurethane system (thereafter, polyurethane); its parameters are listed in Table 1.
Table 1. Characteristics of Polyurethane Systems Parameter Value Shore hardness DIN 53516 80-95 A
Tensile strength DIN 53504 13-45 N/mm2 Tensile elongation DIN 53504 500-600%
Peel strength DIN 53515 10-50 N/mm Abrasion wear DIN 53516 8-25 pting Compression set 23 C/72 h DIN 53517 11-19%
Compression set 70 C/24 h DIN 53517 30-45%
Rebound elasticity DIN 53512 70-75%
Operating temperature range From -60 C to 110 C
Memory function under impact 100%
The technical result is a high degree of polyurethane adhesion to the OWT
inside surface, a glossy coating surface, and homogenized coating with the specified thickness, as well as meeting the requirements listed above.
Said technical result is achieved by pumping polyurethane into the annular cavity formed by the inside OWT surface and a punch that has a high degree of surface finish and is installed into the OWT by means of mandrels, waiting until polyurethane fully hardens, and then extracting the punch from the OWT. Thereby, complete polyurethane adhesion to the OWT wall metal is achieved, as well as a glossy surface and uniform thickness of coating. Depending on polyurethane shrinkage factor, a perforated metal mesh can be installed in the OWT, with the mesh outside diameter equal to the OWT inside diameter. Also, if necessary and based on processing technology for certain polyurethanes, before polyurethane is pumped the OWT is heated to the required temperature using any known method.
The assembly of the structure and the method for coating comprise the following operations:
1. The OWT inside surface is cleaned from scale, dust and moisture. Then, the surface is degreased.
2. A punch, with its outside surface finish class of at least 9, is installed into the cleaned and degreased OWT; the punch outside diameter shall be such that the clearance between the punch and the OWT
inside wall is equal to coating thickness (coating thickness from 2 to 8 mm).
3. Prior to performing the operation per step 2 the punch outside surface is coated with separating grease, to facilitate subsequent removal of the punch.
4. In addition, prior to performing the operation per step 2, with the shrinkage factor of certain polyurethanes exceeding 2%, a tube made of a perforated metal mesh is installed in the OWT inside cavity; the tube outside diameter is equal to the OWT inside diameter, and its thickness does not exceed 1.5 mm. The mesh prevents polyurethane from shrinking, and thereby a more uniform coating layer with high adhesion to the OWT wall is achieved.
5. Punch (1) is centered by means of mandrels (2) placed on both ends of OWT
(3). One mandrel has fitting (4) for pumping polyurethane (Fig. 1).
The objective of the proposed technical solution is to develop the design and method for coating the OWT inside surface that prevent buildup, with long life, that can be used with any method for extraction of hydrocarbons regardless of operating conditions of the well and the quality of extracted crude hydrocarbons, as well as meeting the above requirements.
By means of research and numerous tests, the material meeting the above retirements has been selected. It is a polyurethane system (thereafter, polyurethane); its parameters are listed in Table 1.
Table 1. Characteristics of Polyurethane Systems Parameter Value Shore hardness DIN 53516 80-95 A
Tensile strength DIN 53504 13-45 N/mm2 Tensile elongation DIN 53504 500-600%
Peel strength DIN 53515 10-50 N/mm Abrasion wear DIN 53516 8-25 pting Compression set 23 C/72 h DIN 53517 11-19%
Compression set 70 C/24 h DIN 53517 30-45%
Rebound elasticity DIN 53512 70-75%
Operating temperature range From -60 C to 110 C
Memory function under impact 100%
The technical result is a high degree of polyurethane adhesion to the OWT
inside surface, a glossy coating surface, and homogenized coating with the specified thickness, as well as meeting the requirements listed above.
Said technical result is achieved by pumping polyurethane into the annular cavity formed by the inside OWT surface and a punch that has a high degree of surface finish and is installed into the OWT by means of mandrels, waiting until polyurethane fully hardens, and then extracting the punch from the OWT. Thereby, complete polyurethane adhesion to the OWT wall metal is achieved, as well as a glossy surface and uniform thickness of coating. Depending on polyurethane shrinkage factor, a perforated metal mesh can be installed in the OWT, with the mesh outside diameter equal to the OWT inside diameter. Also, if necessary and based on processing technology for certain polyurethanes, before polyurethane is pumped the OWT is heated to the required temperature using any known method.
The assembly of the structure and the method for coating comprise the following operations:
1. The OWT inside surface is cleaned from scale, dust and moisture. Then, the surface is degreased.
2. A punch, with its outside surface finish class of at least 9, is installed into the cleaned and degreased OWT; the punch outside diameter shall be such that the clearance between the punch and the OWT
inside wall is equal to coating thickness (coating thickness from 2 to 8 mm).
3. Prior to performing the operation per step 2 the punch outside surface is coated with separating grease, to facilitate subsequent removal of the punch.
4. In addition, prior to performing the operation per step 2, with the shrinkage factor of certain polyurethanes exceeding 2%, a tube made of a perforated metal mesh is installed in the OWT inside cavity; the tube outside diameter is equal to the OWT inside diameter, and its thickness does not exceed 1.5 mm. The mesh prevents polyurethane from shrinking, and thereby a more uniform coating layer with high adhesion to the OWT wall is achieved.
5. Punch (1) is centered by means of mandrels (2) placed on both ends of OWT
(3). One mandrel has fitting (4) for pumping polyurethane (Fig. 1).
6. If necessary, and based on processing technology for certain polyurethanes, the assembled structure is heated to the required temperature, which usually does not exceed 8000, using a circular heater, in an oven or using another known method.
7. To prevent formation of voids in coating the assembled structure is installed in a vertical position with the fitting down, and then polyurethane mass is fed through the fitting until filled.
8. After full polyurethane hardening the punch is removed from the OWT in a horizontal position.
9. Excess flash is removed from OWT ends mechanically.
The use of this design and method for applying coating, combined with the above material, will make it possible to obtain a high-quality homogenized coating layer with the same thickness, a glossy surface, high resistance to corrosive media, high adhesion to the OWT inside surface, high abrasion resistance, and high thermal resistance, which will prevent formation of buildup and the related aftereffects, increase the time period between routine repairs and major overhauls of producing wells, and as a result increase the OWT
life.
In accordance with one aspect of the present invention, there is provided tubing for preventing buildup, comprising: an inside wall coated with a polyurethane coating, wherein the polyurethane coating comprises a cold-cast elastomer in a solidified state, comprising a glossy surface, a high adhesion to metal, a Shore hardness of 50-90 A, a uniform coating width, a high wear resistance to abrasion of up to 25 mg, an elasticity of up to 70-75%, and an operating temperature range of -60 C to 100 C.
The use of this design and method for applying coating, combined with the above material, will make it possible to obtain a high-quality homogenized coating layer with the same thickness, a glossy surface, high resistance to corrosive media, high adhesion to the OWT inside surface, high abrasion resistance, and high thermal resistance, which will prevent formation of buildup and the related aftereffects, increase the time period between routine repairs and major overhauls of producing wells, and as a result increase the OWT
life.
In accordance with one aspect of the present invention, there is provided tubing for preventing buildup, comprising: an inside wall coated with a polyurethane coating, wherein the polyurethane coating comprises a cold-cast elastomer in a solidified state, comprising a glossy surface, a high adhesion to metal, a Shore hardness of 50-90 A, a uniform coating width, a high wear resistance to abrasion of up to 25 mg, an elasticity of up to 70-75%, and an operating temperature range of -60 C to 100 C.
Claims
1. Tubing for preventing buildup, comprising:
an inside wall coated with a polyurethane coating, wherein the polyurethane coating comprises a cold-cast elastomer in a solidified state, comprising a glossy surface, a high adhesion to metal, a Shore hardness of 50-90 A, a uniform coating width, a high wear resistance to abrasion of up to 25 mg, an elasticity of up to 70-75%, and an operating temperature range of -60°C to 100°C.
an inside wall coated with a polyurethane coating, wherein the polyurethane coating comprises a cold-cast elastomer in a solidified state, comprising a glossy surface, a high adhesion to metal, a Shore hardness of 50-90 A, a uniform coating width, a high wear resistance to abrasion of up to 25 mg, an elasticity of up to 70-75%, and an operating temperature range of -60°C to 100°C.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/RU2009/000047 WO2009084987A2 (en) | 2007-12-27 | 2009-02-04 | Tubing with an inner coating protecting it against deposits and a method for applying said coating |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2710830A1 CA2710830A1 (en) | 2009-07-09 |
| CA2710830C true CA2710830C (en) | 2016-05-03 |
Family
ID=42710300
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2710830A Expired - Fee Related CA2710830C (en) | 2009-02-04 | 2009-02-04 | The oilwell tubing with coating that prevents buildup, and the method for applying coating |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2710830C (en) |
-
2009
- 2009-02-04 CA CA2710830A patent/CA2710830C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2710830A1 (en) | 2009-07-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request |
Effective date: 20140130 |
|
| MKLA | Lapsed |
Effective date: 20190204 |