JP4289686B2 - Method for extending steel tubing and wells having such tubing - Google Patents

Description

The present invention relates to tubing expansion. In particular, the present invention relates to a method for extending a steel tubing by moving an expansion mandrel through the tubing.
Many methods and apparatus for extending tubing are known.
EP 643794 discloses a method for expanding a casing against the wall of an underground borehole, which casing is made from a malleable material, preferably at least 25%. Non-axially strained plastic deformation is possible and the casing can be expanded by an expansion mandrel that is pumped, pulled or pressed through the casing.
Other expansion methods and devices are described in German Patent Specification No. 1583992, and U.S. Patent Nos. 3,203,483, 3,162,245, 3,167,122, 3,326. , 293, 3,785,193, 3,489,220, 5,014,779, 5,031,699, 5,083,608, 5,366,012 Is disclosed.
Many of the known expansion methods use a corrugated tube from the beginning, while the latter prior art uses a slotted tube that is expanded below the hole by an expansion mandrel. Yes.
The use of corrugated or slotted tubes in a known manner serves to reduce the expansion force required to expand the tube as desired.
A method according to the front part of claim 1 is known from US Pat. No. 5,366,012. In this known method, the slot tube is expanded by an expansion mandrel with a tapered expansion section.
It is an object of the present invention to provide a method for extending non-slot tubing that is at least somewhat robust. In this method, it is required to apply a small force when expanding the tubing, and a tubing having a larger diameter and higher strength than that of the unexpanded tubing is obtained. The method can also be performed by tubing that may already have a tube shape before expansion.
The method according to the present invention includes the step of moving the expansion mandrel through tubing made from a formable steel grade that is at least partly solid and formable . The tapered extension section of the mandrel has a tapered ceramic outer surface. This tubing is strain hardened without any puncture and ductile fracture as a result of the expansion process.
As a result of strain hardening, the tubing becomes stronger during the expansion process. This is because larger extensions require more distortion than the previous extension.
It has been found that using a formable steel grade for tubing in combination with the tapered ceramic outer surface of the expansion mandrel has a synergistic effect. This is because the resulting expanded tubing has a moderately enhanced strength while the expansion force is kept low. If tubing is used in underground wells, tubing wound from the reel drum into the wells can be used due to the low yield strength and high ductility of the tubing before expansion.
In metallurgical technology, the terms strain-hardening and work-hardening are synonymous and both are used to indicate the increase in strength caused by plastic deformation.
As used herein, the formable steel grade means that the tubing can be plastically deformed into various shapes while maintaining its structural integrity.
Methods for determining the forming characteristics of steel are described in Metal Handbook, 9th Edition, Volume 14, Forming and Forging, ASM International, Metals Park, Ohio (USA).
The term necking refers to a geometric effect that causes non-uniform plastic deformation at some location due to the occurrence of local compression. From the marginal point of view, continuous work hardening in the marginal region no longer compensates for the continuous reduction of the smallest cross section in the neck. Therefore, the load carrying capacity of steel is reduced. With continuous loading, in fact all further plastic deformation is confined to the neck region, so that highly non-uniform deformation occurs and develops in the marginal region until failure occurs.
The term ductile fracture means that a defect occurs when the plastic deformation of a component exhibiting ductile properties proceeds so extreme that the component locally breaks into two. Inner void nucleation, growth and condensation proceeds to defects, leaving a dull fibrous bursting surface. For a detailed explanation of the terms shear and ductile fracture, see the handbook “Failure of Materials in Mechanical Design”, J. Am. A. In Collins, 2nd edition, published by John Wiley and Sons, New York (USA), 1993.
Preferably, the tubing is made from a formable high strength steel grade, has a yield strength-tensile strength ratio of less than 0.8, and has a yield strength of at least 275 MPa. The term high strength steel as used herein refers to steel having a yield strength of at least 275 MPa.
It is also preferred that the tubing is made from a formable steel grade with a yield stress / tensile stress ratio of 0.6 to 0.7.
Dual phase (DP) high-strength, low-allow (HSLA) steel is a Luders band during the tube expansion process that ensures a good surface finish of the expanded tube It lacks a clear yield point that eliminates formation.
Suitable HSLA dual phase (DP) steels used in the method according to the invention are grades DP55 and DP60 developed by Sollac and having a tensile strength of at least 550 Mpa, and at least developed by Nippon Steel Corporation. Grades SAFH540 and SAFH590D with a tensile strength of 540 MPa.
It can be seen that U.S. Pat. No. 4,938,266 discloses a method for producing dual phase steel.
Other suitable steels are the following formable high strength steel grades.
-ASTM A106 high strength low alloy (HSLA) seamless pipe,
-ASTM A312 austenitic stainless steel pipe, grade TP304L,
-ASTM A312 austenitic stainless steel pipe, grade TP316L, and-high residual austenitic high strength hot rolled steel (low alloy TRIP steel) such as grades SAFH590E, SAFH690E, SAFH780E developed by Nippon Steel.
The DP and other suitable steels each have a strain hardening index n of at least 0.16 and the tubing is such that the expanded tubing outer diameter is at least 20% greater than the unexpanded tubing outer diameter. Can be expanded.
For a detailed explanation of terms such as strain hardening, work hardening and strain hardening index n, see the handbook “Metal Forming-Mechanics and Metallurgy”, 2nd edition, published by Prentice Hall, New Jersey (USA), 1993. It is done in Chapters 3 and 17 of the year.
Suitably, the expansion mandrel includes an expansion section having a conical ceramic outer surface. U.S. Pat. No. 3,901,063 discloses a plug having a conical ceramic outer surface for use in a tube drawing operation. If the expansion mandrel is pumped through tubing, it is preferred that the mandrel includes a seal section. This seal section is at a distance from the taper extension section such that when the mandrel is moved through the tubing by applying hydraulic pressure behind the extension mandrel, the seal section plastically engages the tubing extension. Be placed. This is generally achieved if the distance is at least three times the wall thickness of the expanded tubing.
By using a conical ceramic surface, the frictional force during the expansion process is reduced, and by providing a seal section that engages the expansion tube, it is avoided that the hydraulic pressure expands the tubing excessively.
In such a case, the expansion mandrel preferably includes a vent line for drawing any fluid present in the wells and tubing in front of the expansion mandrel to the ground.
Alternatively, the tubing is expanded so that the inner diameter of the expanded tubing is slightly smaller than the inner diameter of the well hole or the casing present in the well hole, so that the inside of the tubing in front of the well hole and the expansion mandrel Any fluid present in the water is drawn to the ground via an annular space that remains free around the tubing after the expansion process.
The invention also relates to a well provided with tubing expanded by the method according to the invention. In such cases, the tubing can serve as production tubing that transports hydrocarbon fluids to the surface through the tubing, and the rollable service and / or kill line is at least substantially the tubing length. Hydrocarbon fluid is produced through the surrounding production tubing, while the line fluid can be pumped through the section and toward the bottom of the well hole. By using such expanded production tubing, almost the entire well bore can be used for the transport of hydrocarbon fluids, resulting in a relatively thin to achieve the desired production rate. Well holes are available.
Alternatively, the tubing can be expanded against the inner surface of the casing present in the well bore. In such cases, the tubing can be used as production tubing and / or protective cladding. Protective cladding protects the wells against damage from corrosive well fluids and tools that fall into the wells during maintenance and refurbishment operations.
These and other objects, features and advantages of the method and well system according to the present invention will become apparent from the following detailed description with reference to the appended claims, abstract and accompanying drawings. In the accompanying drawings, FIG. 1 is a longitudinal cross-sectional view of an underground well hole in which tubing is expanded by the method according to the present invention.
Referring to FIG. 1, there is shown a well hole traversing the underground group 1 and a casing 2 fixed in the well hole by an annular main body 3 made of cement.
The production tubing 4 is made from dual phase high strength low alloy (HSLA) steel or other formable high strength steel and is suspended in the casing 2.
The expansion mandrel 5 is moved longitudinally through the tubing 4, thereby expanding the tubing 4 so that the outer diameter of the expansion tubing is slightly less than or approximately equal to the inner diameter of the casing 2.
The expansion mandrel 5 is provided with a series of ceramic surfaces to limit the frictional force between the pig and the tubing 4 during the expansion process. In the example shown, the semi-top angle A of the conical ceramic surface that actually expands the tubing is about 25 °. Zirconium oxide has been found to be a suitable ceramic material that can be formed as a smooth conical ring. Experiments and simulations have shown that if the conical semi-top angle A is 20-30 °, the pipe is essentially at the outer tip or edge of the conical portion, possibly in the middle of the conical portion. Thus, it is shown that it is deformed so as to be S-shaped and contacts the taper portion 6 of the ceramic surface.
Experiments have also shown that it is advantageous for the expanding tubing 4 to be S-shaped. This is because this reduces the length of the contact surface between the tapered portion of the ceramic surface 6 and the tubing 4, thereby reducing the amount of friction between the expansion mandrel 5 and the tubing 4.
According to experiments, if the semi-top angle A is smaller than 15 °, a relatively high frictional force is generated between the pipe and the pig. If the top angle is larger than 30 °, the plasticity of the tubing 4 It has also been shown that extra bending occurs due to the bending of the target, which also causes higher heat dissipation and rupture of the forward movement of the pig 5 through the tubing 4. Therefore, the semi-top angle A is preferably selected between 15 and 30 ° and should always be between 5 and 45 °.
Experiments have also shown that the taper of the expansion mandrel 5 should have a non-metallic outer surface to avoid tube seizure during the expansion process. Further, by using a ceramic surface for the taper portion of the expansion mandrel, the average roughness of the inner surface of the tubing 4 was reduced as a result of the expansion process. Also, according to experiments, the expansion mandrel 5 with the ceramic taper surface 6 expands the tubing 5 made of formable steel so that after expansion the tubing outer diameter D2 is at least 20% larger than the non-expanded tubing outer diameter D1 Suitable formable steels include dual phase (DP) high strength low alloy (HSLA) steels known as DP55 and DP60; ASTM A106 HSLA seamless pipes, ASTM A312 austenitic stainless steel pipes, grades TP304L and TP316L, and Nippon Steel Is a high-residual austenite high-strength hot-rolled steel known as TRIP steel manufactured by
The mandrel 5 comprises a pair of seal rings 7, which are arranged at a distance from the conical ceramic surface 6 so that the ring 7 faces a plastically expanded section of the tubing 4. The seal ring serves to avoid high hydraulic fluids being present between the conical ceramic surface 6 of the mandrel 5 and the expanding tubing 4 causing irregular large expansion of the tubing 4.
The expansion mandrel 5 includes a central vent passage 9 that communicates with the coil vent line 8 through which fluid can be drawn to the ground. After completion of the expansion process, the pig 5 can be pulled up to the ground by a vent line and a coil kill and / or service line (not shown) can be lowered into the expanded tubing 4 toward the hydrocarbon fluid inflow zone. Making it easier to inject kill and / or treatment fluids. This injection is usually done via a ring between the production tubing and the well casing. However, if the tubing 4 is expanded to a smaller diameter, the remaining annular space between the casing 2 and the expanded tubing 4 is used to withdraw fluid during the expansion process and inject fluid during the production process. it can. In this case, it is not necessary to use the vent line 8 and the kill and / or service line.
In conventional wells, production tubing having an outer diameter that is less than 50% of the inner diameter of the well is used to allow smooth insertion into the tubing, even if the well is warped and the casing has an irregular inner surface. It is often necessary to use it. Thus, it is clear that the method of expanding tubing in situ according to the present invention enhances the efficient use of well holes.
It is also understood that instead of moving the expansion mandrel into the tubing by hydraulic pressure, the mandrel can be pulled in the tubing by a cable or pushed in the tubing by a pipe string or rod.
The method according to the invention can be used to expand tubing used outside of a well, for example an oilfield pipe at a ground facility, or to expand a tubing within a damaged or corroded real tubing.
The present invention is further illustrated based on the following comparative experiments.
Experiment 1
An expansion mandrel with a conical ceramic surface (conical semi-top angle A = 20 °) was moved through a conventional oil field pipe known as casing grade L80, 13% Cr. This casing is a widely used casing type with an initial outer diameter of 101.6 mm (4 "), an initial wall thickness of 5.75 mm, a bursting pressure of 850 bar and a strain effect index n = 0.075. The expansion mandrel is designed so that the outer diameter of the expanded tube is 127 mm, thus increasing the diameter by 20% .The tube ruptured during the expansion process. It was overtaken and a ductile fracture occurred.
Experiment 2
Experiments were carried out using type QT-800 coil tubing, which is increasingly used as production tubing in oil or gas wells. Tubing initially has an outer diameter of 60.3 mm, a wall thickness of 5.15 mm, a bursting pressure of 800 bar, and a strain hardening index n = 0.14. The extended mandrel is moved through the tubing, the mandrel includes a conical ceramic surface such that the conical semi-top angle A enveloping the conical surface is 5 °, and the expanded tubing outer diameter is 73 mm. (About 21% increase). This tubing bursts during the expansion process. Analysis revealed that the expansion pressure exceeded the burst pressure of the pipe during the expansion process due to the high frictional force.
Experiment 3
Experiments were conducted using seamless pipes made from a formable steel grade known as ASTM A106 grade B. The pipe initially had an outer diameter of 101.6 mm (4 ″), an initial wall thickness of 5.75 mm, and a strain hardening index n = 0.175.
The expansion mandrel was pumped through the pipe. This mandrel has a conical shape in which the semi-top angle A of the cone enveloping the conical surface is 20 °, the outer diameter of the expanded pipe is 127 mm (5 ″), and the outer diameter is increased by 21%. Including a ceramic surface.
The pipe was successfully expanded and the hydraulic pressure applied to the mandrel to move the mandrel through the pipe was between 275 and 300 bar. The burst pressure of the expanded pipe was between 520 and 530 bar.

Claims (12)

A method of expanding a steel tubing (4) made from a formable steel grade, wherein the tubing is plastically expanded by moving an expansion mandrel (5) having a tapered expansion section (6) through the tubing (4) a method comprising the step of, extended non-waveform and to strain hardening occurs without Segiri and ductile fracture occurs as a result of the process to extend the non-slotted tubing (4), the taper of the expansion mandrel (5) The expansion section (6) has a tapered ceramic outer surface , and the tubing (4) is expanded inside the underground well, and the expansion mandrel (5) is in the tubing (4) in front of the expansion mandrel (5) steel, characterized in that the fluid comprises a vent line (8) for withdrawing the ground How to extend the Yubingu. The method of claim 1, wherein the tubing (4) is made from a formable steel grade having a yield strength-tensile strength ratio of less than 0.8 and a yield strength of at least 275 MPa. The method according to claim 1 or 2, wherein the tubing (4) is made from steel having a yield strength-tensile strength ratio of between 0.6 and 0.7. The method according to claim 1, 2 or 3, wherein the tubing (4) is made from dual phase (DP) high strength low alloy (HSLA) steel. Method according to claim 4, wherein the tubing (4) is made from Sorak grade DP55 or DP60 or Japanese grade SAFH 540 D or SAFH 590 D having a tensile strength of at least 550 MPa. Tubing (4) is a group of the following steel grades:-ASTM A106 high strength low alloy (HSLA) seamless pipe,
-ASTM A312 austenitic stainless steel pipe, grade TP 304L,
ASTM A312 austenitic stainless steel pipe, grade TP 316 L, and high residual austenitic high strength hot rolled steel known as TRIP steel,
4. A method according to claim 1, 2 or 3 made from a formable high strength steel grade selected from. The tubing is expanded such that the outer diameter of the expanded tubing is at least 20% greater than the outer diameter of the unexpanded tubing (4), and the strain hardening index n of the formable steel of the tubing (4) is at least 0. The method according to claim 1, which is 16. The expansion mandrel (5) includes a tapered expansion section (6) having a smooth ceramic outer surface, the ceramic outer surface being at an acute angle A between 5 ° and 45 ° with respect to the longitudinal axis of the mandrel (5). The tubing (4) is expanded without orientation or causing any seizure of the tubing, and the average roughness of the inner surface of the tubing (4) is reduced as a result of the expansion process. The method described. The method according to claim 8, wherein the ceramic outer surface of the tapered extension section (6) is made of zirconium oxide and is oriented at an acute angle A between 15 ° and 30 ° with respect to the longitudinal axis of the mandrel (5). . The method according to any of the preceding claims, wherein the tubing (4) is expanded by pumping the expansion mandrel (5) through the tubing (4). The tubing (4) is expanded so that the outer diameter (D2) of the expanded tubing (4) is slightly smaller than the inner diameter of the well hole or the casing (2) existing in the well hole. and the fluid present in the expansion mandrel in front of the tubing (4) is withdrawn to the surface through the annular space left free around the tubing (4) after the expanding step, the method of claim 1 0. After winding from the winding drum tubing, down the tubing (4) into the well bore underground A method according to any one of claims 1 to 11.

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