EA000543B1 - Method for expanding a steel tubing and well with such a tubing - Google Patents

Abstract

1. A method of expanding a steel tubing (4) which is made of a formable steel grade, the method comprising the step of moving an expansion mandrel (5) having a tapering expansion section (6) through the tubing (4) thereby plastically expanding the tubing, characterized in that an at least partly solid tubing (4) is expanded which is made of a formable steel grade which is subject to strain hardening without incurring any necking and ductile fracturing as a result of the expansion process and that the tapering expansion section (6) of the expansion mandrel (5) has a tapering ceramic outer surface. 2. The method of Claim 1, wherein the tubing (4) is made of a formable steel grade having a yield strength-tensile strength ratio which is lower than 0.8 and yield strength of at least 275 MPa. 3. The method of Claim 1 or 2, wherein the tubing (4) is made of a steel having a yield strength-tensile strength ratio which is between 0.6 and 0.7. 4. The method of Claim 1, 2 or 3, wherein the tubing (4) is made of a dual phase (DP) high-strength low alloy (HSLA) steel. 5. The method of Claim 4, wherein the tubing (4) is made of Sollac grade DP55 or DP60 having a tensile strength of at least 550 MPa or Nippon grade SAFH 540 D or SAFH 590 D. 6. The method of Claim 1, 2 or 3 wherein the tubing (4) is made of a formable high-strength steel grade which is selected from the following group of steel grades: - an ASTM A106 high-strength low alloy (HSLA) seamless pipe; - an ASTM A312 austenitic stainless steel pipe, grade TP 304 L; - an ASTM A312 austenitic stainless steel pipe, grade TP 316 L; and - a high-retained austenite high-strength hot rolled steel which is known as TRIP steel. 7. The method of any preceding Claim, wherein the tubing is expanded such that the external diameter of the expanded tubing is at least 20% larger than the external diameter of the unexpanded tubing (4) and wherein the strain hardening exponent n of the formable steel of the tubing (4) is at least 0.16. 8. The method of any preceding Claim, wherein the expansion mandrel (5) comprises a tapering expansion section (6) which has a smooth ceramic outer surface which is oriented at an acute angle A which is between 5 degree and 45 degree with respect to a longitudinal axis of the mandrel (5) and which induces the tubing (4) to expand without inducing any galling of the tubing and such that the average roughness of the inner surface of the tubing (4) decreases as a result of the expansion process. 9. The method of Claim 8, wherein the ceramic outer surface of the tapering expansion section (6) is made of zirconium oxide and is oriented at an acute angle A which is between 15 degree and 30 degree with respect to a longitudinal axis of the mandrel (5). 10. The method of any preceding Claim, wherein the tubing (4) is expanded by pumping the expansion mandrel (5) through the tubing (4). 11. The method of Claim 7 and 10, wherein the expansion mandrel (5) comprises a sealing section (7) which is located at such a distance from the expansion section (6) that when the expansion mandrel (5) is pumped through the tubing (4) the sealing section (7) engages a plastically expanded part of the tubing. 12. The method of Claim 10 or 11, wherein the tubing (4) is expanded inside an underground borehole and the expansion mandrel (5) contains a vent line (8) for venting any fluids that are present in the tubing (4) ahead of the expansion mandrel (5) to the surface. 13. The method of Claim 10 or 11, wherein the tubing (4) is expanded inside an underground borehole such that the outer diameter (D2) of the expanded tubing (4) is slightly smaller than the internal diameter of the borehole or of any casing (2) that is present in the borehole and any fluids that are present in the borehole and tubing (4) ahead of the expansion mandrel are vented to surface via the annular space that remains open around the tubing (4) after the expansion process. 14. The method of any preceding Claim, wherein the tubing (4) is lowered into an underground borehole after reeling the tubing from a reeling drum. 15. A well provided with a tubing (4) which is expanded using the method of any preceding Claim, wherein the tubing (4) serves as a production tubing through which hydrocarbon fluid is transported to the surface and a reelable service and/or kill line passes through at least a substantial part of the length of the interior of the tubing (4), through which line fluid can be pumped towards the bottom of the borehole while hydrocarbon fluid is produced via the surrounding production tubing (4). 16. A well provided with a tubing (4), which is expanded using the method according to any one of Claims 1-12, wherein the tubing is expanded against the inner surface of a casing (2) which is present in the borehole.

Description

The invention relates to the expansion of pipes. More specifically, the invention concerns a method for expanding a steel pipe by moving an expansion mandrel through the pipe.

There are numerous methods and devices for the expansion of pipes.

European Patent 643794 discloses a method for expanding the casing relative to the wall of an underground borehole, in which the casing is made from a ductile material that is preferably capable of plastically deforming at least 25% uniaxial tension, and the casing can be expanded with an expansion mandrel that is injected , dragging or pushing through the casing.

In German Patent No. 1583992 and in US 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 and 5.366.012 describes other methods and devices for expansion.

In many previously known expansion methods, a wavy pipe is used, and in the latter reference material a perforated pipe is used, which expands in a downhole with an expansion mandrel.

The use of corrugated pipes or perforated pipes in the known methods allows to reduce the expanding forces that must be applied to the pipe to create the required expansion.

The method corresponding to the preamble of claim 1 is known from US Pat. No. 5,366.012. In this known method, the perforated pipe is expanded by means of an expansion mandrel having a cone-shaped expansion section.

The object of the present invention is to provide an expansion method, at least partially, of a solid, non-perforated pipe, which requires little effort to expand the pipe, using a pipe having a larger diameter and higher strength than a non-expanded pipe, and which can be made pipe already tubular in shape before expansion.

The method according to the invention comprises the step of moving an expansion mandrel, the cone-shaped expansion section of which has a cone-shaped ceramic outer surface, at least in partly continuous pipe, made of a formable steel grade, which is subjected to strain hardening, without subjecting to any local narrowing and plastic failure. result of the expansion process.

As a result of strain hardening, the pipe becomes more durable during the expansion process, since any additional increase in expansion always requires more significant stress than the previous expansion.

It has been found that the use of a formable steel grade for a pipe in combination with a ceramic cone-shaped outer surface of the expansion mandrel has a synergistic effect, since the resulting expanded pipe has an adequately increased strength, while the expansion efforts remain insignificant. The low yield strength and high ductility of the pipe before expansion allows the use of a pipe in an underground borehole to use a pipe that winds from the reel drum into the borehole.

It has been observed that in the field of metallurgy the terms “strain hardening” and “mechanical hardening” are synonymous, and both are used to denote the increase in strength caused by plastic deformation.

Used in this description, the term "formable steel grade" means that the pipe is able to maintain structural integrity, although it can plastically deform into various forms.

Methods for determining the characteristics of steel forming are described in the Handbook on Metals, 9th edition, Vol. 14, “Forming and Forging”, published by the International AOIM (American Society for Metal Research), published by Metals Pak, Ohio (USA).

The term “local constriction” refers to a geometric effect leading to uneven plastic deformations at a certain area, by means of local compression. From the point of local constriction, continuous hardening in the constricted area no longer compensates for the continuous reduction of the smallest cross section in the constriction, and therefore the ability to withstand the load decreases. With continued loading, almost all further plastic deformation is limited to the area of local contraction, so that a highly uneven deformation develops in the constricted area until a gap occurs.

The term “plastic fracture” means that fracture occurs if the plastic deformation of a section that exhibits plastic properties reaches a limit value so that the section is locally divided into two parts. Nucleation, growth and fusion of internal voids spreads to rupture, leaving a matte fibrous rupture surface. A detailed description of the terms narrowing and ductile fracture is given in the Handbook Destruction of Materials in Mechanical Design by J. A. Collins, second edition, published by John Willie & Sons, New York (USA) in 1993.

The pipe is preferably made of a high-strength steel grade, capable of being molded and having a ratio of yield strength to tensile strength, less than 0.8 and a yield strength of at least 275 MPa. As used herein, the term "high strength steel" means steel with a yield strength of at least 275 MPa.

The pipe is also preferably made of a moldable steel grade, having a yield strength ratio to a tensile stress between 0.6 and 0.7.

Two-phase (DF) high-strength, low-alloyed (VPNL) steels do not have a certain yield strength, which eliminates the formation of Lüders zones during the tubular expansion process, which guarantees a good surface finish of the expanded pipe.

Suitable VPNL biphasic (DF) steels for use in the method according to the invention are the DP55 and DP60 grades developed by Sollak, having a tensile strength of at least 550 MPa, and the Grade 540 D and Grade 590 D grades developed by Nippon Steel a corporation having a tensile strength of at least 540 MPa.

In US patent No. 4.938.266 disclosed method for the production of two-phase steels.

Other suitable steel grades are the following formable high-strength steel grades:

- ASTM A106 (American Society of Testing Materials) steel seamless high-strength low-alloyed (FNL) steel pipe;

- ASTM A312 stainless steel austenitic tube, grade TP 304 L;

- ASTM A312 stainless steel austenitic tube, grade TP 316 L, and

- high-strength hot-rolled steel with high residual austenite (low-alloyed TRIP steel) such brands as SAFH 590 E, SAFH 690 E and SAFH 780 E, developed by Nippon Steel Corporation.

Each of the above-mentioned DFs and other suitable steels has a hardening index n of at least 0.16, which allows the pipe to expand so that the outer diameter of the expanded pipe will be at least 20% larger than the outer diameter of the non-expanded pipe.

A detailed description of the terms "strain hardening", "mechanical hardening" and "hardening rate" n are given in Chapters 3 and 17 of the reference book Mechanics and Metallurgy of Metal Forming, 2nd edition, published by Prentice Hall, New Jersey (USA), 1993 .

Expanding mandrel, respectively, contains an area of expansion, which has a conical ceramic outer surface. In US patent No. 3.901.063 disclosed damming, having a conical ceramic outer surface for use when pulling out the pipe. If the expansion mandrel is injected through a pipe, the mandrel preferably contains a sealing section that is located at such a distance from the conical expansion section that, when the expansion mandrel moves through the pipe through hydraulic pressure behind the mandrel, the sealing section engages the plastically expanded part of the pipe. This is usually achieved if the said distance is at least three times the wall thickness of the expanded pipe.

The use of a ceramic conical surface reduces friction forces during the expansion process and, due to the presence of a sealing section that secures the expanded pipe, eliminates excessive expansion of the pipe under the action of hydraulic forces.

In such a case, it is preferred that the expansion mandrel contains a drain line to ensure that any fluids that are present in the borehole and pipe before the expansion mandrel exit to the surface.

Alternatively, the pipe is expanded so that the outer diameter of the expanded pipe is slightly smaller than the internal diameter of the borehole or any casing that is present in the borehole, and any fluids that are present in the borehole and pipe before the expansion mandrel are produced on surface through the annular space, which remains open around the pipe after the expansion process.

The invention also relates to a borehole with a pipe that is expanded by the method of the invention. In this case, the pipe serves as an elevator pipe, through which the hydrocarbon fluid moves to the surface, and the service line and / or discharge line that can be wound onto the drum passes at least through a substantial part of the pipe length, and a fluid can be pumped through this line. medium to the bottom of the borehole, while hydrocarbon fluid is discharged through the surrounding tubing. The use of such an extended tubular pipe allows the use of an almost complete borehole to transport hydrocarbon fluids so that a relatively narrow borehole can be used to obtain the desired production rate.

Alternatively, the pipe can be expanded to the inner surface of the casing, which is located in the borehole. In such a case, the pipe can either be used as an elevator pipe and / or as a protective coating to protect the casing of the borehole from corrosive fluids from the borehole and damage from tools that can descend into the borehole during maintenance and operation operations.

These and other objectives of the present invention, features and advantages of the borehole method and system will become apparent from the appended claims, abstract and the following detailed description with reference to the attached drawing, in which the figure is a schematic view in longitudinal section of an underground borehole, wherein the pipe expands according to the inventive method.

The figure shows a borehole intersecting an underground formation 1, and a casing 2, which is fixed in a borehole by means of an annular cement mass

3

Lift pipe 4, which is made of two-phase high-strength low-alloyed (VLF) steel or other formable high-strength steel, is suspended inside the casing 2.

The expansion mandrel 5 moves in the longitudinal direction along the pipe 4, thereby expanding the pipe 4 so that its expanded outer diameter is slightly smaller or approximately equal to the internal diameter of the casing 2.

The expansion mandrel 5 is provided with a number of ceramic surfaces 6, which limit the friction forces between the pig and the pipe 4 during the expansion process. The example shows a half upper angle A of a conical ceramic surface that actually expands the pipe by about 25 °. A suitable ceramic material is zirconia, which can be molded into a smooth conical ring. Experiments and simulations have shown that if the half angle of the top of the cone is between 20 and 30 °, the pipe is deformed so that it takes an S-shape and touches the tapering part of the ceramic surface 6 essentially at the outer tip or rim of the said conical part and optionally about half of the conical part.

Experiments have also shown that it is advisable that the expanding pipe 4 be S-shaped, as this reduces the length of the contact surface between the conical part of the ceramic surface 6 and the pipe 4 and thus also reduces the degree of friction between the expansion mandrel 5 and the pipe 4.

Experiments have also shown that if the mentioned half of the upper angle A is less than 15 °, then this leads to relatively high friction forces between the pipe and the pig, whereas if the said upper angle is more than 30 °, this entails excessive plastic work due to plastic bending of pipe 4, which also leads to higher heat dissipation and destruction when the pigs 5 move forward through pipe 4. Therefore, the mentioned value of half the upper angle A is preferably chosen between 15 and 30 ° and this value is allowed between 5 and 45 °.

Experiments have also shown that the conical part of the expansion mandrel 5 should have a non-metallic outer surface in order to avoid abrasion of the pipe during the expansion process. Moreover, the use of a ceramic surface for the conical part of the expansion mandrel causes a decrease in the average roughness of the inner surface of the pipe 4 as a result of the expansion process. Experiments have also shown that the expansion mandrel 5 provided with a ceramic conical surface 6 can expand the pipe 4 made of formable steel so that the outer diameter D2 of the pipe after expansion turns out to be at least 20% larger than the outer diameter D1 of the non-expanded pipe , and that suitable grades of steel to be formed are biphasic (DF) high strength low alloyed (VLF) steels, known as DP55 and DP60; ASTM A106 seamless VPN pipe, ASTM A312 austenitic stainless steel pipes TP 304 L and TPP 316 L and high-strength hot-rolled steel with high residual austenite, known as TRIP steel, manufactured by Nippon Steel Corporation.

The mandrel 5 is provided with a pair of sealing rings 7, which are located at such a distance from the conical ceramic surface 6, that the rings 7 face the plastically expanded section of the pipe 4. The sealing rings serve to avoid the ingress of fluid at high hydraulic pressure between the conical ceramic surface 6 the mandrel 5 and the expanding pipe 4, which could lead to an unevenly large expansion of the pipe 4.

The expansion mandrel 5 is provided with a central ventilation duct which is connected to a ventilation line 8 coiled up in a spiral, through which fluid can reach the surface. After the expansion process is complete, the pig 5 can be pulled to the surface using a vent line and the spiral discharge line and / or maintenance (not shown) can be lowered into the expanded pipe 4 to facilitate the injection of fluid and / or treatment fluid to the inflow zone of hydraulic fluid. environment, which usually passes through the annular gap between the tubing and the casing of the borehole. However, if the pipe 4 is expanded to a smaller diameter, then the residual annular gap between the casing 2 and the expanded pipe 4 can be used to release fluids during the expansion process and to introduce fluids during the production process, in which case there is no need to use line 8 and discharge line and / or service line.

In conventional wells, it is often necessary to use lift pipes that have an outside diameter that is 50% smaller than the inside diameter of the well casing to allow smooth introduction of the pipe, even if the well is deflected and the casing has an uneven internal surface. Therefore, it is obvious that the method of expanding the pipe at the installation site according to the present invention increases the efficient use of the borehole.

Obviously, instead of moving the expansion mandrel through the pipe by means of hydraulic pressure, the mandrel can also be pulled through the pipe with a cable or pushed through the pipe by means of a drill pipe string or drill rod.

The method of the invention can also be used to expand pipes that are used outside the borehole, for example, to expand oil field pipes on surface equipment or to expand existing pipes that are damaged or corroded.

The invention will be further described based on the following comparative experiments.

Experiment 1

An expansion mandrel having a conical ceramic surface (half of the upper angle of the cone = 20 °) was moved through a pipe in a conventional oil field known as an L80 casing with 13% Cr, which is a widely used type of casing with an initial outer diameter of 101, 6 mm (4), the initial wall thickness is 5.75 mm, the pressure at break is 850 bar (85 x 10 ⁶ Pa) and the strain hardening coefficient n = 0.075. The expansion mandrel was designed so that the outer diameter of the expanded pipe was 1 27 mm, so that the diameter increase was 20%. The pipe broke during the expansion process. The analysis showed that the plasticity limit of the material was exceeded, so that plastic failure occurred.

Experiment 2

The experiment was performed with spiral pipes of the QT-800 type, which is more often used as elevator pipes in oil or gas wells. The pipe had an outer diameter of 60.3 mm, a wall thickness of 5.15 mm, a pressure at break of 800 bar (8 x 10 ⁷ Pa) and a strain hardening coefficient n = 0.14. The expansion mandrel was extended through the pipe, and this mandrel contained such a conical ceramic surface that the half-upper angle A of the cone of the envelope of the conical surface was equal to 5 °. It was made so that the outer diameter of the expanded pipe was equal to 73 mm (an increase of approximately 21%). This pipe is broken during the expansion process. Analysis has shown that due to high friction forces, the expansion pressure exceeded the burst pressure of the pipe during the expansion process.

Experiment 3

The experiment was performed on a seamless pipe made of a formable steel grade, known as ASTM 1 06 Grade B. The pipe had an initial outer diameter of 101.6 mm (4), an initial well thickness of 5.75 mm and a strain hardening factor of n = 0.175.

The expansion mandrel was stretched through the pipe, and this mandrel contained such a ceramic conical surface that the half-upper angle A of the cone of the envelope of the conical surface was 20 ° and the outer diameter of the expanded pipe was 127 mm (5) and the outer diameter increased by 21%.

The pipe was successfully expanded and the hydraulic pressure supplied to the mandrel to move through the pipe was between 275 (275 x 10 ⁵ Pa) and 300 bar (3 x 10 ⁷ Pa). The burst pressure of the expanded pipe was between 520 (52 x 10 ⁶ Pa) and 530 bar (53 x 10 ⁶ Pa).

Claims (16)

CLAIM 1. A method of expanding a steel pipe (4) made of a moldable steel grade, comprising the step of moving an expansion mandrel (5) having a cone-shaped expansion portion (6) through the pipe (4), thereby expanding it plastically, characterized in that it is expanded at least partially continuous pipe (4) made of a formable steel grade that undergoes strain hardening without being subjected to any compression and plastic rupture as a result of the expansion process, and the conical expansion part (6) is expansion minutes mandrel (5) has a conical ceramic outer surface. 2. The method according to claim 1, characterized in that the pipe (4) is made of a moldable steel grade having a yield strength to tensile strength lower than 0.8, and a yield strength of at least 275 MPa. 3. The method according to p. 1 or 2, characterized in that the pipe (4) is made of steel having a yield strength to tensile strength ratio between 0.6 and 0.7. 4. The method according to p. 1, 2 or 3, characterized in that the pipe (4) is made of two-phase (DF) high-strength low-alloy (VNL) steel. 5. The method according to claim 4, characterized in that the pipe (4) is made of Sullak steel grade DP55 or DP60, having a tensile strength of at least 550 MPa, or Nippon grade SAFH 540 D or SAFH 590 D. 6. The method according to p. 1, 2 or 3, characterized in that the pipe (4) is made of a moldable high-strength steel grade, which is selected from the following group of steel grades: - high-strength low-alloyed steel (ВПНЛ) ASTM А 106 seamless pipe, austenitic pipe made of ASTM A312 stainless steel, ТР 304 L grade, - austenitic pipe made of stainless steel ASTM A312, grade TP 316 L, and - High strength hot rolled steel with high residual austenite, which is known as TRIP steel. 7. The method according to any one of the preceding paragraphs, characterized in that the pipe is expanded so that the outer diameter of the expanded pipe is at least 20% larger than the outer diameter of the unexpanded pipe (4), while the strain hardening factor n of the pipe steel being molded (4 ) is at least 0.16. 8. A method according to any one of the preceding paragraphs, characterized in that the expansion mandrel (5) comprises a cone-shaped extension part (6) having a smooth ceramic outer surface that is located at an acute angle A between 5 and 45 ° relative to the longitudinal axis of the mandrel ( 5), and causes the expansion of the pipe (4), without causing any abrasion of the pipe, and the average roughness of the inner surface of the pipe (4) decreases as a result of the expansion process. 9. The method according to claim 8, characterized in that the ceramic outer surface of the conical portion (6) of the expansion is made of zirconium oxide and is oriented at an acute angle that is between 15 and 30 ° relative to the longitudinal axis of the mandrel (5). 1 0. A method according to any one of the preceding paragraphs, characterized in that the pipe (4) is expanded by forcing the expansion mandrel (5) through the pipe (4). 11. The method according to claim 7 or 10, characterized in that the expansion mandrel (5) contains a sealing section (7) that is located at such a distance from the expansion part (6) that when the expansion mandrel (5) is pumped through the pipe (4) ), the sealing section (7) closes the plastically expanded part of the pipe. 12. The method according to claim 10 or 11, characterized in that the pipe (4) is expanded inside an underground borehole, and the expansion mandrel (5) contains a vent line (8) for discharging any fluids that are present in the pipe (4) before expansion mandrel (5) to the surface. 13. The method according to claim 10 or 11, characterized in that the pipe (4) is expanded inside an underground borehole so that the outer diameter (D2) of the expanded pipe (4) is slightly smaller than the internal diameter of the borehole or any casing (2), that is present in the borehole, and any fluids present in the borehole and pipe (4) before the expansion mandrel are discharged to the surface through an annular gap that remains open around the pipe (4) after the expansion process. 1 4. A method according to any one of the preceding paragraphs, characterized in that the pipe (4) is lowered into the underground borehole after the pipe is unwound from the winding drum. 15. A well provided with a pipe (4), which is expanded using the method according to any one of the preceding paragraphs, in which the pipe (4) is used as an elevator pipe through which hydrocarbon fluid is brought to the surface, and at least through a significant the length of the inner part of the pipe (4) passes a reel-drawn service and / or injection line through which fluid can be pumped to the base of the borehole, while hydrocarbon fluid is produced through the surrounding elevator pipe (4). 1 6. A well provided with a pipe (4), which is expanded using the method according to any one of claims 1 to 1 2, in which the pipe is expanded relative to the inner surface of the casing (2) present in the borehole.