The present invention relates to methods and apparatus for well abandonment and slot recovery and in particular, though not exclusively, to a method and apparatus for removing control lines in a well bore during a well abandonment and slot recovery procedure.
When a well has reached the end of its commercial life, the well is abandoned according to strict regulations in order to prevent fluids escaping from the well on a permanent basis. In meeting the regulations it has become good practise to create the cement plug over a predetermined length of the well. In order to achieve this, the production tubing and control lines attached thereto are typically first removed. Cement can then be inserted in casing annulus and between the outermost casing and the formation. Alternatively casing is removed to access the formation or the outermost casing section, on which a cement bond log has been performed to verify the cement bond between the outermost casing and the formation, prior to placing cement to create a plug within the well bore.
These operations require a rig which makes them very expensive for abandonment in subsea wells. Consequently, so-called ‘rig-less’ methods of well abandonment are being developed. These either fall into designing systems to operate from floating vessels which attempt to carry out the same procedures or look at ways to create the cement plug without removing the casing and/or production tubing. A major difficulty in leaving the production tubing in place is in the handling of control lines in the well.
In abandoning a well, control lines cannot simply be cemented in place as they present a potential leak path through the cement plug. Additionally, if the production tubing is removed care must be taken to ensure that control lines are successfully removed to ensure no line is left in the well bore. This can occur as cutting blades may merely push the line out of the path of the blade when the line is not fixed to the outside of the production tubing at the cutting position. The act of pulling the tubing from the well will likely cause the control line to stretch and break at some undetermined location leaving a length of loose control line in the annulus. Unless the breakage point is known, the loose control line needs to be retrieved in a costly fishing exercise as any cement placed in the annulus with the control line present will present a potential leak path.
US2014/0326470 describes a well completion arrangement and method for removing at least a portion of a line running in an annulus between tubing and a casing in a well. The arrangement comprises at least two clamping means spaced apart in the longitudinal direction of the tubing and fixed thereto, the clamping means being configured for fixing the line with respect to tubing, a splitting means for releasing the line from the interval defined by at least an upper clamping means and a lower clamping means of the at least two clamping means, a line manipulator apparatus for activating said release of the line, and a line retrieval apparatus for displacing into the tubing the portion of the line from said interval, thereby removing the line from the annulus. While this arrangement allows for removal of a control line without removal of the production tubing and determines the location of separation, the invention must be in place when the completion is run in the well. Unfortunately this does not provide a solution for older wells which include standard completions.
It is therefore an object of the present invention to provide a method for removing one or more control lines in a well during a well abandonment procedure which obviates or mitigates at least some of the advantages of the prior art.
It is a further object of the present invention to provide a method for removing one or more control lines in a well during a well abandonment procedure which ensures that the control lines are severed and determines the location of separation.
According to a first aspect of the present invention there is provided a method for removing one or more control lines in a well, the control lines running in an annulus behind a tubular in the wellbore, during a well abandonment procedure comprising the steps:
In this way, by securing the control lines to the tubular being cut we can ensure that the control lines will also be cut through.
Here we consider control lines to be any line running in an annulus behind a tubular in the wellbore. Such a line may be a tool control line, a communication line, a chemical injection line or the like. The line may be used to transmit electric or fiber-optic signals, electric power, hydraulic fluid, scale inhibiting chemicals and similar.
The annulus may be between a tubular, such as casing, and the wellbore wall at the formation. Preferably the annulus is between two tubulars. More preferably, the one or more control lines are arranged in the annulus between the production tubing and casing.
The self-supporting settable composition may be a resin. The self-supporting settable composition may be a gel. In an embodiment, the self-supporting settable composition is a Thermatek™ rigid setting fluid available from Halliburton Corporation, USA. The method may comprise deploying an injection tool to displace a pre-determined amount of self-supporting settable composition through the perforations into the annulus.
The method may include displacing the self-supporting settable composition into the annulus as a foam. In this way, fluids which are typically not self-supporting may be arranged to be so.
The method may comprise running a perforating tool through the tubular to a predetermined and/or desired depth.
The method may comprise perforating the tubular using explosive charges or a perforating tool. The method may comprise perforating the tubular using a tubing punch.
The method may comprise providing a tubing cutter to cut a circumferential slot through a wall of the tubular to sever the tubular and the one or more control lines. The method may then comprise pulling the cut section of tubular with the severed one or more control lines attached from the well. This could be done using a rig.
The method may comprise deploying a milling tool to mill away a longitudinal section of the tubular and the corresponding portion of the one or more control lines. The method may comprise milling in an upward or downward direction. The method may comprise milling away the tubular up to the top of the self-supporting settable composition. This allows abandonment to be performed without having to pull the tubular and thus a rigless well abandonment operation can be achieved.
The method may comprise soaking the set self-supporting settable composition as part of the washing step. The method may comprise using an acid wash to remove the set self-supporting settable composition.
The method may comprise washing the annulus prior to displacing self-supporting settable composition. This may help the self-supporting settable composition to adhere to the walls of the tubular(s).
The method may comprise performing a cement bond log on an exposed outer tubular bounding the annulus. The method may further comprise deploying a cement plug to set against the exposed outer tubular. Thus the method can be used to form a cement plug in well abandonment if the cement bond is of good quality.
The method may comprise repeating the steps at a shallower depth in the wellbore. This may be needed if the tubular and one or more control lines are stuck and cannot be pulled or if, following milling, the CBL finds the cement bond to be of poor quality.
Preferably, the steps (a) to (e) are performed in order. The steps may be performed on separate trips into the well. Alternatively two or more steps may be performed on the same trip into the well.
In the description that follows, the drawings are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in the interest of clarity and conciseness. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce the desired results.
Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. Use of terms such as “upper” and “lower” are considered relative and though the well bore is drawn in the ideal vertical orientation, it will be appreciated that this may be deviated. Language such as “including,” “comprising,” “having,” “containing,” or “involving,” and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term “comprising” is considered synonymous with the terms “including” or “containing” for applicable legal purposes.
All numerical values in this disclosure are understood as being modified by “about”. All singular forms of elements, or any other components described herein including (without limitations) components of the apparatus are understood to include plural forms thereof.
There will now be described, by way of example only, various embodiments of the invention with reference to the drawings, of which:
Reference is initially made to
In the production tubing 7 there may be located permanent downhole gauges 16 such would be required for measuring pressure and temperature. These gauges 16 are connected to and controlled from the surface via a control line 15. The control line 15 may be a single cable or a bundle of cables which are attached via couplings 17 to the production tubing 7 at intervals along its length. While the control line 15 is described as a gauge control line, it will be appreciated that the control line 15 may be any line running in an annulus 18 behind a tubular 7 in the wellbore 1,4,12. Such a line may be a tool control line, a communication line, a chemical injection line or the like. The line may be used to transmit electric or fiber-optic signals, electric power, hydraulic fluid, scale inhibiting chemicals and similar.
When the time comes to abandon the well, in a first embodiment, the production tubing 7 is removed from the well.
In
As the composition 21 enters the annulus 18 it will move around and cover the control line 15 effectively embedding it in the composition 21.
The composition 21 is then allowed to set hard, thus securing the tubing 7 and control line 15 rigidly in preparation for the next operations. The composition 21 is selected such that, when set, it provides a suitable compressive strength both to hold the tubing 7 and control lines 15 and be cut through without movement. In
The production tubing 7 and control line 15 are now entirely severed at the slot 31. Thus the location of the point of cutting the control line 15 is known.
The next step is to wash away the composition 21. This is typically done by locating a washing tool 26 over the holes 20 at the slot 31. A fluid capable of dissolving and/or dispersing the composition 21 is pumped through the holes 20 and slot 21. An acid wash is typically used with the composition 21 being acid soluble and permeable. This is illustrated in
With the composition 21 removed, the severed production tubing 7 can be pulled. The cut section of control line 15 will be pulled with the severed section of production tubing 7. This leaves a production tubing stub 27 with a control line 15 whose location is known and will not interfere with any operations carried out above the production tubing stub 27.
Casing 5 is now exposed and a cement bond log (CBL) can be performed using a cement bond logging tool 36 deployed through the tubing 7 to assess the quality of the cement 6 in the annulus 29 behind the casing 5. This is illustrated in
If desired, the method may include the additional step of performing a wash after the perforations have been made. This will clear away any debris and clean the walls of the tubing 7 and casing 5 so that the composition 21 may better adhere when displaced through the holes 20.
Each step in the method described above may be performed as a separate trip into the well. Alternatively, any number of steps can be performed in a single trip by combining the respective tools on the work string.
It will be recognised that the method may be used where the annulus is between a tubular and the borehole 1,4,12. In this arrangement the CBL is not required.
Additionally, if the tubular, once severed, cannot be pulled which may occur particularly when the tubular is production liner or casing, the method can be repeated at increasingly shallower depths in the well until a severed section of tubular can be removed.
Now referring to
The next step is to wash the zone 2. A washing tool (not shown) is inserted through the tubing 7. The tool pumps a wash fluid through the perforations 20a,b while rubber cups both direct fluid through the holes 20a,b and wipe the wall 33 of the production tubing 7. The wash fluid removes dirt, debris and fines which may be in the annulus 18 over the zone 2 (see
In
The composition 21 is then allowed to set hard, thus securing the tubing 7 and control line 15 rigidly in preparation for the next operations. The composition 21 is selected such that, when set, it provides a suitable compressive strength both to hold the tubing 7 and control lines 15 and be cut through without movement. In
The length of tubing 7 and control line 15 milled away is pre-planned and is labelled ‘A’ and might typically be 200 ft. The tubing mill 35 is removed from the well. A layer 34 of set composition 21 may be left adhering on the wall of the casing 5 over the zone 2. This is removed by performing an acid wash. Acid may be circulated to soak through the composition 21 as described hereinbefore with reference to
In
Typically, the cement plug 41 might be 30 m to 60 m thick. If the cement plug 41 is sufficient for well abandonment then the method is complete.
Alternatively, if the cement plug 41 is of insufficient length, then further cement plugs will be required. At the end of the method shown at
The term “upper part” in this context means that this part is closer to the surface than the “lower part”. In general, relative terms such as “upper” and “lower” are used to indicate directions and locations as the apply to the drawings.
If the cement quality at zone 1 is poor, an alternative to pulling the tubing 7e and control lines 15e from the well is to repeat the method as described in
As previously described, a cement bond logging tool now assesses the cement quality and if the cement quality is good, a cementing tool is run to place a cement plug 42 in the lower part of gap ‘C’ as shown in
If the cement quality is poor at zone 3, the cut and drop operation is repeated by moving the cutting tool upward in the wellbore to depths closer to the surface and a further cuts in the tubing and control line are made until a zone with good quality cement is identified and a cement plug may be placed. By applying this cut and drop operation it is not required to provide costly surface equipment such as a drilling rig in order to pull the tubing and perform remedial operations.
It will be appreciated that wells vary in complexity and there may be either more or less zones of interest than described above, however it will also be appreciated that the sequences of operation described heretofore can be applied as many times as are necessary and are not limited to two zones of interest.
Throughout the specification, unless the context demands otherwise, the terms ‘comprise’ or ‘include’, or variations such as ‘comprises’ or ‘comprising’, ‘includes’ or ‘including’ will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers. Furthermore, relative terms such as “upper”, “lower” and the like are used herein to indicate directions and locations as they apply to the appended drawings and will not be construed as limiting the invention and features thereof to particular arrangements or orientations.
The foregoing description of the invention has been presented for the purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise form disclosed. The described embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilise the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore, further modifications or improvements may be incorporated without departing from the scope of the invention as defined by the appended claims.
Number | Date | Country | Kind |
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1721361.2 | Dec 2017 | GB | national |
Filing Document | Filing Date | Country | Kind |
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PCT/GB2018/053672 | 12/19/2018 | WO | 00 |