Vigre, Per Gunnar (Fabnavn. 12, Sandnes, N-4325, NO)
CLAIMS
1. Well tool (1) for cleaning the inside of casings and valves, particularly for removing mineral deposits, wherein the tool (1) comprises a main body (9) comprising a drive-member (11 ), a power supply (5), a hydraulic pump (13) and a gripping mechanism (8), characterized in that the tool (1) further comprises a brush-head (10) comprising radially expanding brush-members (16), wherein the tool (1) by means of the drive-member (11) is adapted to clamp the main body (9) to the inside of a casing (2) by means of the gripping mechanism (8), rotate the brush-head (10) and expand the brush-members (16) to a desired outer diameter.
2. Well tool (1 ) according to claim 1 , wherein the drive-member (11) drives a hydraulic pump (13) generating a system pressure, wherein the system pressure is used to activate the gripping mechanism (8), rotate the brush-head (10) and expand the brush-members (16) to the desired outer diameter.
3. Well tool (1 ) according to claim 1 , wherein the drive-member (11 ) is adapted to directly driving tje brush-head (10) comprising the radially expanding brush- members (16), wherein the drive-member (11) further drives a hydraulic pump (13) generating a system pressure, wherein the system pressure is used to activate the gripping mechanism (8) and expand the brush-members (16) to the desired outer diameter.
4. Well tool (1 ) according to any one of the preceding claims, wherein the drive-member (11) comprises an electric motor.
5. Well tool (1) according to any one of the preceding claims, wherein the power supply (5) comprises a battery pack.
6. Well tool (1) according to any one of the preceding claims, wherein the power supply (5) comprises an electric cable (4) from the surface.
7. Well tool (1) according to any one of the preceding claims, wherein the gripping mechanism (8) comprises radially expanding claw-members, wherein the gripping mechanism (8) is adapted to expand radially by means of a hydraulic pressure generated by a hydraulic pump. |
HYDRAULIC BRUSH FOR USE IN DOWNHOLE OPERATIONS
The present invention concerns a well tool for cleaning the inside of casings and valves.
In production of oil and gas, boreholes are drilled and fully or partly lined with casings. Additionally one or more valves are disposed, for example a valve known as a DSV-valve (Downhole Safety Valve), to ensure well control if unforeseen events should occur in the well. A DSV-valve is, as a rule, "fail-safe". This means that it closes automatically if certain parameter values rise or fall out of predetermined intervals. However, with time there will always form an incrustation called scale on the inside of the casing and DSV-valve. Scale can include residues of cement which is used when a casing is fastened in a borehole. Water in the production flow may also contain ions of barium and calcium which can be combined to minerals and deposited in an incrustation or scale of, for example, barium sulphate and calcium carbonate. In addition, the production flow may include substantial amounts of wax, which may combine with e.g. barium sulphate and calcium carbonate to form a stratified scaling, i.e. an incrustation of deposits, which may be very difficult to remove.
This incrustation of deposits may influence the function of the DSV-valve, which is regarded as unacceptable. If the DSV-valve cannot be operated in a safe manner, the well has to be shut down/abandoned, or it must be recompleted (the completion must be performed, and a new well with a new DSV-valve must be installed). In both cases, large economic losses are implied.
Known methods for removing scale comprise using solvents and/or mechanical scraping. Use of solvents implies treatment problems and cost for both solvents and treatment. For removal of cement scales in casings and harder deposits of minerals like barium sulphate and calcium carbonate, common methods include milling and honing. Mechanical scraping using brushes is common as well.
From Norwegian patent NO 320906 B1 an apparatus for cleaning the inside of a casing for scale is known. Rotating cleaning elements are inclined relative to their axis of rotation, and hence oscillate axially against the inner wall of the casing when rotated. Thereby the slow reciprocating movement of prior art is avoided. This apparatus is connected to a pipe, e.g. a drilling string, which both supplies liquid to drive the rotation and oscillation and provides the necessary force required when scale is to be scraped off.
Other cleaning tools for inclusion in a string of pipes are disclosed in NO 316915 B1 , NO 172427 C, US 4.501.322, US 5.947.203 and US 7.255.164 B2. These patents also describe use of liquid supplied though the string of pipes in combination with the brushing/scraping function.
Use of a string of pipes during removal of scale can be complicated, and thus time and cost consuming.
It is an object of the present invention to provide a tool which is capable of cleaning the inside of casings and valves in a simple and cost efficient manner.
It is also an object of the present invention to provide a tool that can clean the inside of casings and valves by means of a "slickline" (which is a wire of typically 3mm (0,125") used to winch equipment and tools down into a well) or "e-line" (wire comprising an electric cable).
These and other objects are obtained by an apparatus that is distinguished by the features of the characterizing part of the appended claims. Further advantageous features and embodiments are apparent from the independent claims.
In the following, a detailed description of a preferred embodiment of the present invention is provided with reference to the accompanying drawings, in which:
Fig. 1 shows a well tool for cleaning the inside of casings and valves according to one embodiment of the present invention, wherein the gripping mechanism and brush-members are in a retracted state,
Fig. 2 shows the well tool of fig. 1, wherein the gripping mechanism and brush- members are in an activated extended state, and
Fig. 3 shows a well tool according to figs. 1 and 2 located in a casing, wherein the gripping mechanism and brush-members are in an activated expanded state and engage a nipple-profile and the DSV-valve respectively.
According to the present invention, a well tool 1 is provided for cleaning the inside of casings 2 and valves 3, which may be run on a slickline 4 or an e-line. If it is run on a slickline 4, it must be provided with a battery pack 5 to supply it with power during operation. Running by means of slickline 4 is regarded as being the least costly well intervention method existing today. If the tool 1 is run on an e-line, power may be supplied from the surface, and the battery pack can be omitted.
According to one embodiment of the present invention, the tool 1 is run on a standard 3mm (0.125") wire 4, in that it is connected to the wire by means of a rope socket 6 and is placed in the sluice pipe. The sluice pipe is pressure tested, whereupon the Christmas tree is opened, and the tool can be lowered into the well until it reaches the DSV-valve 3. The DSV-valve 3 is normally displaced about 50m under the seabed, in that it, in its open position, forms a through path which does not obstruct the access to the lower parts of the well. On the upper parts of the DSV-valve 3, a recess commonly called a "nipple-profile". The nipple-profile forms a point of engagement in the casing 2, which the tool 1 according to the present invention can grip. The tool 1 is lowered down through the DSV-valve 3, whereupon it is pulled slowly upwards until a radially acting gripping mechanism 8 disposed on the tool snaps into the nipple-profile. The tool is caused to grip/clamp the nipple-profile by means of a gripping mechanism 8, comprised by, e.g., claw- members 8 activated by, for example, a tugging movement.
One can also find and activate the claw-members 8 by using optical, magnetic, profile detecting, radioactive or similar sensing means. When the tool 1 is positioned and is properly clamped relative to the DSV-valve 3, the tool is ready to commence and perform the cleaning operation.
The tool according to the present invention comprises, according to one embodiment, a main body 9 and a brush-head 10. The main body 9 comprises, according to one embodiment, the battery pack 5, a drive-member 11 and an actuator 12. The drive-member 11 comprises an electric motor 17 adapted to rotate the brush-head 10 by means of a hydraulic pump 13 and a gear system 18. The drive-member 11 is powered from the battery pack 5, or, alternatively, from the surface through an electrical cable. The hydraulic pump 13 is in communication with a hydraulic system 14, inter alia comprising a hydraulic chamber/reservoir 15, wherein the hydraulic system 14 is used to clamp the tool in the well conduit, and further causes brush-members 16 on the brush head 10 to expand outwardly towards the inside of the well conduit/DSV-valve 3, such that the brush-members 16 engage the well conduit/DSV-valve 3. When the drive-member 11 rotates the brush-head 10 and the brush-members 16 on the brush-head 10 engage the inside of the well conduit/DSV-valve 3, the scaling will be removed quickly and efficiently.
It is understood that the brush-members 16 can comprise brushes of different kinds and design. Instead of brushes, it is in some cases possible to use a honing or milling tool. The honing tool can, for example, be used to ensure that a well conduit is sufficiently cleaned for setting of plugs or for honing of nipples. Similarly, a milling tool can be used to ensure that the well conduit is sufficiently circular, for milling out a window, or for milling out obstructions in the well conduit that should be removed.
The tool 1 according to the present invention can, for example, be activated by performing an "overpuH" on the wire. A sensor or valve will register the extra load represented by the overpull force, whereby the electromotor 17 is caused to start. The electromotor 17 drives, as noted, a hydraulic pump 13, which hydraulic pump
13 causes the pressure in the hydraulic system 14 increases to a desired hydraulic system pressure. Once the desired hydraulic system pressure is achieved, pressure can be applied against the claw-members 8 for further clamping of the tool's main body 9 to the nipple-profile in the well conduit 2, which further will contribute to the tool 1 being properly retained and capable of withstanding the reactive torsion forces arising when the brush-head 10 rotates. At the same time, the brush-head 10 can be caused to rotate by the system pressure along with the brush-members 16 disposed on the brush-head 10 being caused to expand towards the inside of the well conduit. The brush-members 16 are disposed on piston-members causing the brush-members 16 to expand radially outwardly towards the inside of the well conduit. In one embodiment the system pressure will determine how far the brush-members 16 are allowed to expand, such that these are expanded in a controlled manner to a predefined outer diameter (OD) that is adapted to the inner diameter (ID) of the well conduit. Alternatively, the outer diameter of the brush-members 16 can be adjusted in advance by means of mechanical adjusting/stop-members.
According to one embodiment of the present invention, the present well tool may be equipped with devices enabling a reduction of the expansion force on the brush-members 16 when the rotational resistance becomes too large, for example when the rotational velocity becomes too small, or when the electric power consumption becomes too large. One possible way of achieving this, is to employ an electrohydraulic logicsmodule monitoring motor data, and on basis of these monitored data adjusts the hydraulic pressure to the brush-members 16 to a level required to maintain the desired rotational velocity. The electrohydraulic logicsmodule can, for example, be adapted to return pump flow to the chamber/reservoir 15 by means of a varying and adapted restriction, thereby controlling the differential pressure applied to the brush-members 16.
The tool 1 can be adapted to operate sequentially, for example in that the system pressure first causes proper clamping of the claw-members 8, whereafter the brush-head is caused to rotate, and finally the brush-members 16 are radially
expanded outwardly to the intended outer diameter. It is understood that other sequential series also may be chosen.
According to another embodiment, the brush-head 10 may be telescopically designed for performing the cleaning operation of the tool 1 over a greater length of the inside of the well conduit.
According to yet another embodiment, the tool 1 can be designed such that the electromotor 17 directly rotates the brush-head 10, that is, the electromotor 17 causes the brush-head 17 to rotate without detouring through a hydraulic pump 13. The electromotor 17 will additionally drive a hydraulic pump 13 generating a system pressure sufficient to cause the claw-members 8 to clamp properly to the nipple-profile, and expanding the brush-members 16 radially outwards to a desired outer diameter.
Fig. 1 illustrates the tool in one embodiment, wherein the claw-members 8 and brush-members 16 share a common pressure line from the electrohydraulic logicsmodule 19, wherein a pull in the tool 1 provides an impulse to the electrohydraulic logicsmodule 19 from the activating member 12, whereafter the brush-head 10 is activated and the brush-members 16 expand. The brush-head 10 rotates as long as the electric motor 17 is operated. The expansion of the brush- members 16 are then controlled by the electrohydraulic logicsmodule 19 as discussed above.
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