This application is the U.S. national stage application of International Application No. PCT/NO2008/000008, filed Jan. 9, 2008, which International application was published on Jul. 17, 2008, as International Publication No. WO 2008/085062 A1 in the English language, which application is incorporated herein by reference. The International application claims priority of Norwegian Patent Application No. 20070217, filed Jan. 12, 2007, which application is incorporated herein by reference.
The present invention concerns a cutting device and a method for emergency cutting of a line in a well, for example a hydrocarbon well, injection well or water well.
It should be possible, by means of the present invention, to cut off the line in a controlled manner at an upper portion of the well, for example on or nearby a drilling floor or platform deck for the well. In order to avoid damage to personnel or equipment, the cutting is preferably activated remotely. Typically, such a cutting situation may arise in connection with the running in or pulling out, so-called tripping, of a well string to which said line is connected. For example, the well string may be comprised of a completion string.
Gradually it has become customary, especially in connection with recovery of hydrocarbons, to use various equipment and components being introduced into a well in order to improve the course of recovery in some way. Such downhole well equipment may comprise various measuring apparatuses, actuators, displacable or rotatable sleeves or valve devices, pumping equipment, etc. The present invention, however, does not depend on the type of downhole equipment used in this connection.
Oftentimes said well equipment requires one or several lines to be extended to surface in order to connect the equipment in the well to corresponding equipment on surface. Typically, such lines are used for energy transmission, fluid transmission and signal communication. As such, the lines may comprise optical-fibre or electric cables/lines for transmission of energy or signals, for example control signals and well data. They may also comprise fluid transmission lines/pipes, for example hydraulic lines, coiled tubings or similar, for transmission of energy, control signals and various well treatment fluids. Thus, the present line includes different types of transmission means of different shape and/or material type, and of more or less flexible design.
During said tripping of the well string, at least one such line will be connected to the well string. When running into the well, the line(s) is/are continuously connected to the well string. When pulling out of the well, the line(s) is/are continuously disconnected from the well string. Under both circumstances, the non-connected portion of such a line is spooled off and onto, respectively, a corresponding spooling unit placed at the well's surface or in the vicinity thereof, for example standing on a drilling floor or being suspended from a winch above the wellbore. Normally, such a spooling unit is large and heavy.
During the tripping operation, however, unforeseen events may occur and give rise to the well string unintentionally being dropped or lowered far too fast into the wellbore. By so doing, the line(s) connected to the well string will also accompany the well string in its uncontrolled trip into the wellbore. This will cause the line(s) to be be spooled out in an uncontrolled manner from a spooling unit nearby. In a worst case scenario in a deep well, the well string and the line(s) may drop several thousands of metres. Such an uncontrolled unspooling may cause uncontrolled movement of both the spooling unit(s) and the line(s), which brings about great danger both to personnel and equipment located in the vicinity of this uncontrolled event. Should the line(s) also become torn off in this connection, a fishing operation must be initiated in the well in order to retrieve both the well string and the line(s), which is time-consuming and costly.
On the basis of dangers and disadvantages associated with such an uncontrolled unspooling of one or several line(s), it would therefore prove very advantageous for the the line(s) to be cut off as soon as possible, and in a safe manner for personnel and quipment. Such an endeavour offers the possibility of limiting the harmful effects of the uncontrolled unspooling.
The applicant does not know of any technical solutions for cutting of one or several lines during uncontrolled unspooling thereof into a well. Common practice in such a situation is for personnel to withdraw as soon as possible from the area in which the uncontrolled unspooling takes place.
As background prior art, however, the following publications are mentioned:
Both of these publications relate to cutting devices for controlled cutting of a line in a region down within a well. The cutting is carried out after having placed the line in the well. Moreover, an upwardly directed force must be used to cut off the line for both of these cutting devices.
The primary object of the invention is to provide a technical solution for allowing one or several such well-string-connected lines to be cut off as soon as possible when in an emergency situation.
It is also an object to provide a technical solution allowing said cutting to be carried out in a safe manner preventing damage to personnel and equipment immediately after having cut off the line. For example, such damage may occur in the event that energy inherent in an extended, elastic line suddenly becomes liberated when the line is cut off. Thus, the line located above the cutoff place may bounce back with intense force and cause damage to the surroundings. If the line is comprised of a fluid transmission line, such a sudden cutoff may result in undesirable discharge of fluids and potential harmful effects on the surroundings.
The object is achieved by virtue of features disclosed in the following description and in the subsequent claims.
According to a first aspect of the invention, a cutting device for emergency cutting of at least one line introduced into a well is provided. In the following, this line will only be referred to as one line.
The cutting device is arranged for connection to the well in a suitable position relative to the well. The device is also arranged for incorporation of the line when the device is connected to the well and is located in its position of use. The cutting device comprises the following features:
The distinctive characteristic of the cutting device is that it also comprises:
Upon release, the at least one sliding block will move downward in the direction of the narrow end portion of the guide where the sliding block will force its at least one cutting knife with increasing force against the line until it is cut off. Thereby, the portion of the line located below the cutoff place will drop down into the well. This will prevent a large length of the line to be spooled out and be pulled down into the well, including the time- and cost-related disadvantages associated therewith.
In a first embodiment variant, the tapering guide may be assembled from at least two axially extending and non-parallel face elements, for example in the form of plates. Such a guide structure is easy to incorporate into or assemble with other borehole-related equipment used at the upper end of the well, for example on a drilling floor or platform deck at the surface of the borehole, or at the upper end of a riser or similar connected to the borehole, as in an offshore situation. For example, such borehole-related equipment may comprise a borehole slips or a borehole bushing typically used on a drilling floor.
In a second embodiment variant, the tapering guide may be comprised of a conical funnel, which may have e.g. a circular or other suitable cross-section. This guide structure may be formed as an enclosing unit, for example a housing. Such a form may be advantageous should it prove desirable to assemble the present cutting device with external borehole-related equipment, which for example is placed on, at or above a drilling floor or platform deck and in vicinity of the well. Thus, the cutting device may be assembled with, for example, a sheave wheel connected to a drawworks or a winch, or assembled with a spool or drum for the line in question.
The present cutting device may include only one sliding block. Upon release, the sliding block will force its at least one cutting knife with increasing force against one side of the line, whereas the opposite side of the line is forced in a supporting manner against the guide.
Alternatively, the cutting device may include at least two sliding block. Upon release, the sliding blocks will move downward and force its cutting knives with increasing force against the line. Preferably, the the cutting knives are arranged in scissor configuration for clipping off the line.
Yet further, a sliding side of the sliding block may be provided with at least one axially extending guide track arranged for cooperation with at least one axially extending guide strip provided at an inside of the guide.
Alternatively, a sliding side of the sliding block may be provided with at least one axially extending guide strip arranged for cooperation with at least one axially extending guide track provided at an inside of the guide.
A gripping side of the sliding block may include an axially extending gripping face bevelled toward an inside of the guide in the direction of its wide end portion. Advantageously, this gripping face may form an angle which, relative to a longitudinal axis through the guide, is larger than that of a corresponding angle formed by the inside of the guide. The latter feature ensures optimum force transmission to the cutting knives during the cutting. In order to intensify the cutting effect, the sliding block may also include at least one weight for gravity-assisted movement of the sliding block upon release thereof.
The sliding block may also include a magnet-affectable material. Thereby, the releasable holding mechanism of the cutting device may be comprised of an electromagnet for releasable standby holding of the magnet-affectable sliding block.
Advantageously, the releasable holding mechanism may be connected to a remote control device for remotely controlled release of the holding mechanism.
As mentioned above, a portion of the line located above the cutoff place, and also any sliding blocks, may bounce back after the cutting and cause damages to the surroundings. Yet further, the cutting of a potential fluid transmission line may also result in undesirable discharge of fluids from the line. It is therefore advantageous for both the overlying line portion and the at least one sliding block to be held tight at the cutoff place after the cutting. Preferably, this is carried out by keeping said sliding block and its cutting knife forced against the overlying line portion until a controlled liberation thereof may be carried out. Such a squeezing and fixing will also prevent a potential fluid discharge.
For example, this fixing may be carried out by arranging a recoil brake or recoil clutch, which is separate from the cutting device, around the line at the surface of the well, e.g. on or in vicinity of a drilling floor. The recoil brake/-clutch is activated during the cutting of the line and is squeezed in a braking and locking manner against the line, preferably via remote control or automatic activation.
As an alternative or addition to such a separate brake device, the cutting device may also comprise at least one releasable locking mechanism for locking of the at least one sliding block in a region at the narrow end portion of the guide after cutting off the line.
Preferably, the releasable locking mechanism is arranged for locking engagement between the at least one sliding block and the tapering guide. For example, this may be achieved by virtue of said sliding block being provided with at least one locking dog, whereas the guide is provided with at least one cooperating locking groove. Alternatively, said sliding block may be provided with at least one locking groove, whereas the guide is provided with at least one cooperating locking dog.
Such a locking dog may take on the form of a tooth, knob, pin, pawl or similar protruding element arranged for locking engagement with a suitable locking groove, for example a recess, hollow, tooth bottom, flute or terminal edge.
Preferably, said locking dog is arranged movable relative to the locking groove, for example via reciprocating, linear motion or rotary motion. Alternatively, the locking groove may be arranged movable relative to the locking dog.
Advantageously, the locking dog may be biased in an extended position for engagement with a cooperating locking groove when aligned opposite one another. The locking dog may also take on a form and/or position allowing for locking in the locking groove upon attempts of relative movement in one direction, but allowing for relative movement in the opposite direction, as within a ratchet. For example, a coil spring or gas spring may be used to bias the locking dog in the extended position. Other types of devices may also be used for this purpose, for example electromagnets or pneumatic, hydraulic or electric actuators.
Typically, the latter devices will be arranged for reciprocating movement. Thus, the devices may also be used for releasing the locking dog from locking engagement with a cooperating locking groove, and for moving the locking dog to a retracted, free position. Depending on the specific embodiment of the cutting device, such a device may be provided within, or in connection with, either the tapering guide or the sliding block, and it must also be able to move the locking dog with sufficient force. Such a device may also be used together with a coil spring, gas spring or similar biasing device. For example, a coil spring may thus be used to bias the locking dog in the extended position, whereas an electromagnet may be used to move the locking dog to the rectracted, free position. When the locking dog is in the free position, the at least one sliding block and the overlying line portion may be liberated from the guide, whereby the liberated line portion may be pulled out of the well in a controlled manner.
Thus, said axially extending guide strip at the inside of the guide may be provided with transverse flutes, whereas the sliding block may be provided with a spring-loaded and movable locking knob extending inwards toward said axially extending guide track in the sliding block for engagement with said flutes on the guide strip. Alternatively, the guide strip of the guide may be provided with a spring-loaded and movable locking knob/locking pawl arranged in a manner allowing it to spring out behind the upper terminal end of the sliding block after having been led past the knob/pawl during the cutting, as in a catch lock.
As an alternative to the above-mentioned, releasable locking mechanisms, the inside of the tapering guide may be formed with Morse taper for self-locking of the at least one sliding block when being forced against the guide during cutting of the line. In connection with manufacturing of tools and machine parts in drilling- and cutting machines, it is common to use Morse taper in fastening parts for such machines, for example in a so-called Morse taper sleeve or tool taper. Preferably, this locking mechanism comprises a release device, for example in the form of a pull rod, push rod or launching wedge, which is used to liberate the sliding block from the self-locking engagement with the guide. Such a release device may be provided within, or in connection with, the guide. For example, the release device may be driven by virtue of an electromagnet or a pneumatic, hydraulic or electric actuator.
Yet further, the releasable locking mechanism is preferably connected to a remote control device for remotely controlled release thereof subsequent to said locking of the at least one sliding block in a region at the narrow end portion of the guide.
In its position of use by the well, the cutting device may be incorporated in a borehole slips, for example a spider-type borehole slips.
The cutting device may also be incorporated in a borehole bushing.
As a further alternative, the cutting device may be connected to a sheave wheel for use in connection with spooling of the line. Normally, such a sheave wheel is connected to a winch or a drawworks.
According to a second aspect of the invention, a method for emergency cutting of a line in a well is provided, the method comprising the following steps:
The distinctive characteristic of the method is that it further comprises the following steps:
After being released, the sliding block will move downward in the direction of the narrow end portion of the guide where it will force its at least one cutting knife with increasing force against the line until it is cut off.
According to the method, said holding mechanism may be released by means of remote control.
According to the method, a cutting device which also comprises at least one releasable locking mechanism for locking of the at least one sliding block in a region at the narrow end portion of the guide after cutting off the line, may also be used. Preferably, said locking mechanism may be released by means of remote control after locking of the at least one sliding block at the narrow end portion of the guide.
Yet further, a recoil brake or recoil clutch, which is separate from the cutting device, may be arranged around the line at the surface of the well.
Moreover, the cutting device may be incorporated in a borehole slips, for example a spider-type borehole slips.
The cutting device may also be incorporated in a borehole bushing.
As a further alternative, the cutting device may also be connected to a sheave wheel for spooling of the line.
In connection with the present method, reference is also made to details described hereinbefore in connection with the present cutting device.
In the following, different embodiment examples of the present invention will be shown, in which:
a-3d are perspective drawings showing structural features of the cutting device and also four instant situations thereof whilst mounted in its position of use and having said electric line inserted therethrough, in which
The figures are schematic and may be somewhat distorted with respect to relative size and relative placement of components being part of the embodiment examples of the invention. In general, identical or corresponding details of the figures will be denoted with the same or similar reference numerals in the following.
Embodiment Examples of the Invention
a-3d show four instant situations of the cutting device as it will appear whilst mounted in its operational position in the borehole bushing 4, and having the electric line 12 inserted therethrough. For the sake of clarity, only the cutting device 2 and the line 12 are shown in the figures.
a-3d also show significant structural features of the cutting device 2. Thus, the cutting device 2 comprises a tapering guide having, in this embodiment example, the form of a conical box 18, which includes a narrow end portion 20 and and overlying, wide end portion 22 for feed-through of the line 12. The conical box 18 is assembled from two axially extending and non-parallel side plates 24, 26 mounted perpendicular onto a support plate 28. The box 18 is open vis-à-vis the support plate 28 and outwardly toward the centre of the borehole bushing 4.
The cutting device 2 also comprises two sliding blocks 30, 32 arranged axially movable within the conical box 18 and each along a side plate 24, 26 of their own. The sliding blocks 30, 32 are aligned opposite one another, whereby the line 12 is located therebetween.
On their gripping sides 34 and 36, the sliding blocks 30, 32 are provided each with a cutting knife 38, 40 directed inwards toward the centre of the conical box 18 and against the line 12. In order to achieve an efficient scissor configuration when clipping off the line 12, one cutting knife 38 is placed at a somewhat lower position than that of the other cutting knife 40. Yet further, and in order to achieve an efficient grip against the line 12 during emergency cutting, the gripping sides 34, 36 of the sliding block 30, 32 are provided each with an axially extending and fluted gripping face 42, 44 positioned opposite the respective cutting knife 38, 40. In this embodiment example, each gripping face 42, 44 is bevelled toward the inside of the box 18 in the direction of its wide end portion 22. See the dashed lines in
On their sliding sides 46 and 48, the sliding block 30, 32 are provided each with an axially extending guide track 50, 52. Such a guide track 50 is shown best in
Yet further, the cutting device 2 comprises at least one releasable holding mechanism (see
Upon release, the sliding blocks 30, 32 will move downward in the direction of the narrow end portion 20 of the box 18 where they will force their cutting knives 38, 40 with increasing force against the line 12 until being cut off.
In order then to liberate the sliding blocks 30, 32 and thus the line 12, each locking knob 72 must rotate out of engagement with the flutes 80 and to a retracted, free position. If each locking knob 72 and activation pin 78 includes a magnet-affectable material, they advantageously may be connected to an electromagnet (not shown) which, upon activation, pulls both the locking knob 72 and the activation pin 78 back to said free position. For example, such an electromagnet and associated energy source (not shown) may be incorporated into the very sliding block 30, 32 or within said borehole bushing 4, and preferably it is connected to a remote control device for remotely controlled activation of the magnet.
Upon activation, the electromagnet will pull the activation pin 78 into the respective sliding block 30, 32, simultaneously being accompanied by the locking knob 72 rotating out of engagement with the flutes 80 onto said rectracted, free position. Then the liberated line 12 may be pulled out of the well in a controlled manner.
In order to intensify the cutting effect, the sliding block may also include at least one weight 57a, 57b (see
Number | Date | Country | Kind |
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20070217 | Jan 2007 | NO | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/NO2008/000008 | 1/9/2008 | WO | 00 | 1/29/2010 |
Publishing Document | Publishing Date | Country | Kind |
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WO2008/085062 | 7/17/2008 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
1491610 | Liady | Apr 1924 | A |
1855853 | Gallman et al. | Apr 1932 | A |
1867033 | Spang | Jul 1932 | A |
3962943 | Allen | Jun 1976 | A |
20040089451 | Palmer et al. | May 2004 | A1 |
20080251258 | Bamford | Oct 2008 | A1 |
Number | Date | Country |
---|---|---|
20050511 | Mar 2005 | NO |
WO 2005003504 | Jan 2005 | WO |
Entry |
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International Search Report for parent application PCT/N02008/000008, having a mailing date of Apr. 15, 2008. |
Number | Date | Country | |
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20100139921 A1 | Jun 2010 | US |