Patent Description:
In a downhole well, a casing or well tubular metal structure is inserted into the drilled hole, and the production zone is isolated from, e.g., water-producing zones. Access to the production zone is normally made by a perforation gun using explosives downhole, which is not always allowed and may imply a dangerous situation downhole. <CIT> discloses a downhole machining system. <CIT> discloses wireline-run mills, and <CIT> discloses a perforating apparatus.

It is an object of the present invention to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More specifically, it is an object to provide an improved perforation tool system which does not use explosives to create openings/perforations in the casing/well tubular metal structure.

The above objects, together with numerous other objects, advantages and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention by a perforation tool system for perforating a screen, a sliding sleeve or a casing wall of a casing or another well tubular metal structure in a borehole having a top, comprising:.

wherein the rotation unit comprises a sleeve having a slot engaging a pin of the shaft, the slot comprising a first longitudinal slot part, a second longitudinal slot part and a first guiding slot part connecting the first and second longitudinal slot parts.

Also, the perforation tool system may be a mechanical perforation tool system, i.e., a system not using explosives.

Thus, the rotation unit is provided for rotating the second tool part around the axial extension of the perforation tool system in relation to the first tool part.

Moreover, the perforation tool system may be powered through a wireline, i.e., the perforation tool system may be a perforation wireline tool system.

Further, the perforation tool system may comprise an electric motor powered through a wireline and driving a pump.

In addition, the perforation tool system may further comprise an electronic section for controlling the operation of the perforation tool system.

Furthermore, the perforation tool system may also comprise a compensator for providing overpressure inside the perforation tool system.

The pump may drive the axial actuator to move the shaft back and forth along the axial extension.

Also, the first longitudinal slot part may have a first part and a second part, the guiding slot part being connected to the first longitudinal slot part between the first part and the second part.

Moreover, the second longitudinal slot part may have a first part and a second part, the guiding slot part being connected to the second longitudinal slot part between the first part and the second part.

Further, the pin may be in a first position when the pin is arranged in the first part of the first longitudinal slot part, and the pin may be in a second position when the pin is arranged in the first part of the second longitudinal slot part.

In addition, the first longitudinal slot part may be displaced from the second longitudinal slot part along a circumference of a tool housing.

Furthermore, the slot may comprise a second guiding slot part connecting the second longitudinal slot part with another first longitudinal slot part.

Also, the guiding slot part may further comprise a first inclined slot part, a second inclined slot part and an intermediate slot part connecting the first inclined slot part and the second inclined slot part.

Moreover, the first inclined slot part may be connected to the first longitudinal slot part, and the second inclined slot part may be connected to the second longitudinal slot part.

Further, the bit may be moved radially in relation to the axial extension by means of an electric motor and/or hydraulics.

In addition, the bit may be moved radially by means of a hydraulic cylinder.

Furthermore, the bit may form a piston of the hydraulic cylinder.

The hydraulic cylinder may comprise a spring arranged between a bottom of the cylinder and the piston so that the piston is retracted when pressurised fluid is not pressing the piston outwards, the spring being squeezed between the piston and a flange of the cylinder housing when the piston and the bit are pressed outwards in the projected position of the bit.

Also, the piston may form part of a gear that engages another gear of the shaft.

Moreover, the first tool part may be arranged closer to the top of the well than the second tool part.

Further, the system may comprise a second anchoring section, and the anchoring sections may be arranged with a mutual axial distance between them, both anchoring sections being arranged closer to the top of the well than the second tool part and the bit.

In addition, one anchoring section may be axially movable in relation to the other.

Furthermore, the first actuator may comprise a gear for changing a rotational speed of the electric motor.

Moreover, the gear may be a planetary gear.

Further, the perforation tool system may moreover comprise a control unit for controlling the movement of the pin in the slot.

In addition, the control unit may be connected to the sleeve of the rotation unit for forcing the pin towards one side of the slot or forcing the pin towards the opposing side of the slot.

Furthermore, the axial actuator may comprise a hydraulic cylinder and a reciprocating piston connected to the shaft.

Also, the system may further comprise a pinching or cutting tool projectable through an opening in the casing provided by the machining bit.

Moreover, the bit may be moved radially in a bit housing, the bit having a sharp end facing the casing and a piston end, and the bit being moved radially in relation to the axial extension by means of an electric motor driving a hydraulic cylinder which is in fluid communication with the bit housing, pressing onto the piston end.

Further, the system may also comprise a fluid cleaner for cleaning up cuttings from the machining process.

In addition, the system may further comprise a driving unit, such as a downhole tractor.

Furthermore, the invention relates to a perforation method comprising:.

Also, the perforation method may further comprise:.

Moreover, the perforation method may further comprise moving the perforation tool system to a new position along the axial extension.

Finally, the perforation method may further comprise anchoring the system in the casing.

The invention and its many advantages will be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which:.

<FIG> shows a perforation tool system <NUM> for perforating a screen, a sliding sleeve or a casing wall of a casing <NUM> or another well tubular metal structure in a borehole <NUM>. The perforation tool system <NUM> comprises a first tool part <NUM> having an axial extension <NUM>, which is also the axial extension of the perforation tool system <NUM>, and at least one anchoring section <NUM>, 6A, 6B, 6C (shown in <FIG>) for anchoring the tool system <NUM> in the well when perforating, i.e., making openings in the screen, the sliding sleeve or the casing wall of a casing <NUM>. The perforation tool system <NUM> further comprises a second tool part <NUM> adapted to rotate around the axial extension <NUM> and move axially in relation to the first tool part <NUM>, the second tool part <NUM> comprising a machining bit <NUM> which is movable in a direction <NUM> radial to the axial extension in order to make the opening/perforation. The first tool part <NUM> is arranged closer to the top of the well than the second tool part <NUM>. The perforation tool system <NUM> further comprises an axial actuator <NUM> comprised in the first tool part <NUM> and comprising a shaft <NUM> for axially moving the second tool part <NUM> in relation to the first tool part <NUM>, a rotation unit <NUM> for rotating the second tool part <NUM> in relation to the first tool part <NUM>, and a first actuator <NUM> comprising an electric motor 11A for rotating the bit <NUM>. The rotation unit <NUM> comprises a tubular sleeve <NUM> having a slot <NUM> engaging a pin <NUM> of the shaft <NUM>, and the slot <NUM> comprises a first longitudinal slot part 18A, a second longitudinal slot part 18B (shown in <FIG>) and a first guiding slot part <NUM> connecting the first and second longitudinal slot parts. The pin is fixedly fastened to the shaft. In the non-activated position of the axial actuator <NUM>, the bit <NUM> can drill a first opening, e.g. in the casing wall, in a first position P1. As the axial actuator <NUM> moves the shaft <NUM> along the axial extension <NUM> away from the first tool part <NUM> in a first direction D1, the second tool part <NUM> is rotated along a rotation direction R as the pin <NUM> on the shaft <NUM> moves in the slot <NUM> and as the sleeve <NUM> is fixedly fastened to the first tool part <NUM>, and then the shaft <NUM> is forced to rotate, rotating the second tool part <NUM> and thus the bit <NUM>. In this second position P2, the bit <NUM> drills a second opening in the casing wall. When the axial actuator <NUM> retracts the shaft <NUM> along the axial extension <NUM> towards the first tool part <NUM> in a second direction D2 opposite the first direction, the pin <NUM> moves along the slot <NUM>, and the shaft <NUM> is forced to rotate to a third position P3.

In another embodiment, the sleeve <NUM> rotates with the second tool part <NUM> and is fixedly fastened to the second tool part <NUM>, and not to the first tool part. In this embodiment, the shaft <NUM> does not rotate but merely moves back and forth along the axial extension <NUM>.

The bit <NUM> is a drill bit moving along the direction <NUM> radially and perpendicularly to the axial extension <NUM> in order to make the openings/perforations. The openings/perforations are drilled in, e.g., the casing wall with a mutual distance in the requested perforation pattern in order to provide a perforated zone without the use of explosives. Thus, the slot is made in a pattern matching the requested perforation pattern. The perforation tool system <NUM> is thus a mechanical perforation tool system, i.e., a system not using explosives.

As can be seen in <FIG>, the perforation tool system <NUM> is powered through a wireline <NUM>, i.e., the perforation tool system <NUM> is a perforation wireline tool system <NUM>. Thus, the first tool part is arranged closer to the wireline than the second tool part. The perforation tool system <NUM> comprises an electric motor <NUM> powered through the wireline <NUM> for driving a pump 25B. The perforation tool system <NUM> further comprises an electronic section <NUM> for controlling the operation of the perforation tool system. Also, the perforation tool system <NUM> comprises a compensator <NUM> for providing overpressure inside the perforation tool system. The pump 25B drives the axial actuator <NUM> to move the shaft <NUM> back and forth along the axial extension <NUM>. In <FIG>, the shaft <NUM> of the axial actuator <NUM> is retracted, and in <FIG> the shaft <NUM> is in its projected position in which the bit <NUM> has been rotated to a new position to drill a new opening.

In <FIG>, the first longitudinal slot part 18A has a first part <NUM> and a second part <NUM>, and a first guiding slot part <NUM>, <NUM>' is connected to the first longitudinal slot part 18A between the first part and the second part so that the pin <NUM> moving in the second longitudinal slot part 18B moves past another second guiding slot part <NUM>, <NUM>" into the intended first guiding slot part <NUM>, <NUM>' and further into the first longitudinal slot part 18A. The slot <NUM> comprises the second guiding slot part <NUM>, <NUM>" connecting the second longitudinal slot part 18B with another first longitudinal slot part 18A. The second longitudinal slot part 18B has a first part <NUM> and a second part <NUM>, and the second guiding slot part <NUM>, <NUM>" is connected to the second longitudinal slot part 18B between the first part <NUM> and the second part <NUM>. A corner <NUM> provided in the transition between the second part <NUM>, <NUM> and the guiding slot part <NUM> forces and guides the pin <NUM> into the intended guiding slot part <NUM>. When moving from the guiding slot part <NUM> into the longitudinal slot part <NUM>, the pin <NUM> enters the longitudinal slot part <NUM> from one side <NUM> and bumps against the opposing side <NUM> of the longitudinal slot part <NUM> and is guided further along the longitudinal slot part to the first part <NUM>, <NUM>. The pin <NUM> is in a first position P1 when the pin <NUM> is arranged in the first part <NUM> of the first longitudinal slot part 18A, and the pin <NUM> is in a second position P2 when the pin <NUM> is arranged in the first part <NUM> of the second longitudinal slot part 18B. The first longitudinal slot part 18A is displaced from the second longitudinal slot part 18B along a circumference of a tool housing <NUM> (shown in <FIG>) and slightly overlapping the second longitudinal slot part along the axial extension <NUM>.

In <FIG>, the guiding slot part <NUM> of the slot <NUM> further comprises a first inclined slot part 20A, a second inclined slot part 20B and an intermediate slot part 20C connecting the first inclined slot part 20A and the second inclined slot part 20B. The first inclined slot part 20A is connected to the first longitudinal slot part 18A, and the second inclined slot part 20B is connected to the second longitudinal slot part 18B. The sleeve <NUM> of <FIG> has more positions than the sleeve <NUM> of <FIG>, as the sleeve <NUM> of <FIG> has reverse positions RP1, RP2 as well as the positions of the sleeve <NUM> of <FIG>. A control unit <NUM> for controlling the movement of the pin <NUM> in the slot <NUM> is arranged in connection with the sleeve <NUM> so as to force the sleeve <NUM> in one rotational direction to move the pin <NUM> between the "forward" positions and to force the sleeve <NUM> in the opposing rotational direction to move the pin <NUM> between the "reverse" positions. The control unit <NUM> is connected to the sleeve <NUM> of the rotation unit <NUM> for forcing the pin <NUM> towards one side of the slot <NUM> or forcing the pin <NUM> towards the opposing side of the slot <NUM>. In this way, the perforation tool system <NUM> is able to drill more holes before the perforation tool system has to move position along the axial extension <NUM>.

In <FIG>, the rotation unit <NUM> is disclosed without any cover but may have a cover for covering and protecting the slot <NUM> from the well fluid. In <FIG>, the rotation unit <NUM> is comprised inside the tool housing <NUM>, and the sleeve <NUM> surrounds the shaft <NUM> of the axial actuator <NUM>. The axial actuator <NUM> comprises a hydraulic cylinder <NUM> and a reciprocating piston <NUM> connected to the shaft <NUM> for moving the shaft <NUM> and the pin <NUM> back and forth in the slot <NUM>. The bit <NUM> is moved radially in relation to the axial extension <NUM> by means of an electric motor and/or hydraulics along the direction <NUM>. The bit <NUM> is rotated by an electric motor 11A of the first actuator <NUM> so that the first actuator <NUM> comprises a gear <NUM> for changing a rotational speed of the electric motor 11A.

In <FIG>, the bit <NUM> is moved radially in a bit housing/cylinder <NUM>, the bit <NUM> having a sharp end <NUM> facing the casing <NUM> and a piston end of the piston <NUM>, and the bit <NUM> being moved radially in relation to the axial extension by means of an electric motor driving a hydraulic cylinder which is in fluid communication with the bit housing <NUM> pressing onto the piston end.

In <FIG>, the bit <NUM> is moved radially by means of a hydraulic cylinder <NUM>, and thereby the weight on bit (WOB) can be held more constant than when using a motor. The bit <NUM> forms a piston <NUM> of the hydraulic cylinder <NUM>. The hydraulic cylinder <NUM> comprises a spring <NUM> arranged between a bottom of the cylinder <NUM> and the piston <NUM> so that the piston is retracted when pressurised fluid is not pressing the piston <NUM> outwards. The spring <NUM> is squeezed between the piston <NUM> and a flange <NUM> of the cylinder housing <NUM> when the piston and the bit <NUM> are pressed outwards in the projected position of the bit. In that way, the spring <NUM> acts as a failsafe mechanism as the spring <NUM> retracts the bit <NUM> when the power to the tool is switched off, and the system can be retracted from the well. The piston <NUM> forms part of a gear <NUM> that engages another gear <NUM> of the shaft <NUM>. The bit <NUM> is rotated by an electric motor 11A of the first actuator <NUM> so that the first actuator <NUM> comprises the gear <NUM> for changing a rotational speed of the electric motor 11A, which gear engages with the piston housing <NUM> engaging the bit <NUM> via a key in a keyway connection. The gear <NUM> is a bevel gear, but it may also be a planetary gear.

In <FIG>, the system comprises a first anchoring section <NUM>, 6A and a second anchoring section <NUM>, 6B, and the anchoring sections are arranged with a mutual axial distance between them, both anchoring sections being arranged closer to the top of the well than the second tool part <NUM> and the bit <NUM>. The system comprises a third anchoring section <NUM>, 6C which is axially movable in relation to the other anchoring sections. By having several anchoring sections, the machining operation when the bit <NUM> is drilling can be better controlled than when having only one anchoring section. In <FIG>, the anchoring sections furthermore have the function of displacing the whole tool string/tool system <NUM> in relation to the casing wall so that the bit <NUM> is brought into contact with the inner face of the casing <NUM> before the bit <NUM> starts drilling and moving radially along the direction <NUM>.

The system may further comprise a pinching or cutting tool <NUM> projectable through an opening in the casing <NUM> provided by the machining bit <NUM> for cutting a control line outside the casing <NUM>. The perforation tool system <NUM> may also comprise a fluid cleaner for cleaning up cuttings from the machining process and a driving unit, such as a downhole tractor.

Perforations are normally made in a predetermined pattern in order to optimise the inflow of well fluid. In order to make such openings/perforations with a predetermined distance without the use of explosives, the perforation tool system <NUM> is arranged in the casing <NUM> opposite a section to be perforated, and then a first opening is drilled in the casing <NUM> by rotating the machining bit <NUM> and moving the machining bit <NUM> in the direction <NUM> radial to the axial extension for contacting an inner face of the casing <NUM>. Subsequently, the bit <NUM> is retracted, and the axial actuator <NUM> is activated to move the shaft <NUM> and the pin <NUM> in a first direction along the slot <NUM> from the first position P1 to the second position P2, where a second opening is drilled in the casing <NUM> by rotating the machining bit <NUM> and moving the machining bit <NUM> in the direction <NUM> radial to the axial extension for contacting an inner face of the casing <NUM>, and then the bit <NUM> is retracted again. In order to make more than two openings, the axial actuator <NUM> is activated to move the shaft <NUM> and the pin <NUM> in a second direction opposite the first direction along the slot <NUM> from the second position P2 to the third position P3, a third opening is drilled in the casing <NUM> by rotating the machining bit <NUM> and moving the machining bit <NUM> in the direction <NUM> radial to the axial extension <NUM> for contacting an inner face of the casing <NUM>, the bit <NUM> is retracted, and this process is repeated until the openings are made. In order to make further openings at a distance from the openings that were made first, the perforation tool system <NUM> is moved to a new position along the axial extension <NUM>, and the process is repeated. In this way, several metres of perforated zone/section can be made in a predetermined pattern without the use of explosives as in the known perforation guns.

An axial actuator may be called a stroking tool, being a tool providing an axial force. The axial actuator/stroking tool comprises an electric motor for driving a pump. The pump pumps fluid into a piston housing/cylinder <NUM> to move a reciprocating piston <NUM> acting therein. The piston <NUM> is arranged on the stroker shaft <NUM>. The pump may pump fluid out of the piston housing/cylinder <NUM> on one side and simultaneously suck fluid in on the other side of the piston <NUM>.

By "fluid" or "well fluid" is meant any kind of fluid that may be present in oil or gas wells downhole, such as natural gas, oil, oil mud, crude oil, water, etc. By "gas" is meant any kind of gas composition present in a well, completion or open hole, and by "oil" is meant any kind of oil composition, such as crude oil, an oil-containing fluid, etc. Gas, oil and water fluids may thus all comprise other elements or substances than gas, oil and/or water, respectively.

By "casing" or "well tubular metal structure" is meant any kind of pipe, tubing, tubular, liner, string, etc., used downhole in relation to oil or natural gas production.

In the event that the tool is not submergible all the way into the casing, a downhole tractor can be used to push the tool all the way into position in the well. The downhole tractor may have projectable arms having wheels, wherein the wheels contact the inner surface of the casing for propelling the tractor and the tool forward in the casing. A downhole tractor is any kind of driving tool capable of pushing or pulling tools in a well downhole, such as a Well Tractor®.

Claim 1:
A perforation tool system (<NUM>) for perforating a screen, a sliding sleeve or a casing wall of a casing (<NUM>) in a borehole (<NUM>) having a top, comprising:
- a first tool part (<NUM>) having an axial extension (<NUM>) and an anchoring section (<NUM>, 6A, 6B, 6C),
- a second tool part (<NUM>) adapted to rotate and move axially in relation to the first tool part, the second tool part comprising a machining bit (<NUM>) which is movable in a direction (<NUM>) radial to the axial extension,
- an axial actuator (<NUM>) comprised in the first tool part and comprising a shaft (<NUM>) for axially moving the second tool part in relation to the first tool part,
- a rotation unit (<NUM>) for rotating the second tool part in relation to the first tool part, and
- a first actuator (<NUM>) comprising an electric motor (11A) for rotating the bit,
characterised in that
the rotation unit comprises a sleeve (<NUM>) having a slot (<NUM>) engaging a pin (<NUM>) of the shaft, the slot comprising a first longitudinal slot part (18A), a second longitudinal slot part (18B) and a first guiding slot part (<NUM>, <NUM>') connecting the first and second longitudinal slot parts.