NO340765B1 - Drilling module for radial drilling in a well, as well as drilling tools comprising the drilling module - Google Patents

Description

DRILLING MODULE FOR RADIAL DRILLING IN A WELL, AS WELL AS WELL TOOLS INCLUDING THE DRILLING MODULE

The invention relates to a drilling module for radial drilling in a well, as well as a well tool comprising said drilling module.

When a petroleum well has been drilled, it must be made ready for production. In this so-called completion phase, the well will be supplied with casing, which in turn will be perforated in the areas believed to give the best production. Perforation is also applicable in other phases of production, in injection wells and during well intervention. Furthermore, perforation can be carried out in open wells, that is without casing, to increase recovery from a zone.

According to known technology, a perforating tool is lowered to the desired area in the well and the perforating tool is used to create the required number of holes in the casing. Typically, the perforating tool comprises a series of small explosive charges that are detonated at the desired location. Using explosives can produce uneven hole quality and sometimes no holes at all. The handling and transport of explosives is becoming increasingly difficult due to stricter legislation. An alternative to the use of explosives, which is also a known technique, is to punch holes using hydraulic pressure. However, this is only an option in pipes with thin walls. Doring requires a lot of heavy and space-consuming equipment. It is always a challenge to get enough space for equipment in well tools, which generally have a small diameter.

Radial drilling can also be used for perforating pipes. A known well tool that is used for this is the applicant's own tool called "MaxPERF" which has been developed by the Canadian company Penetrators Canada Inc. Known tools from Penetrators Canada Inc. are described in the patent publications US 6167968 Bl and US 5392858 A. Said tools drill 1" («25.4mm) diameter holes in casing and longer 0.7" («17.8mm) diameter tunnels or boreholes in the outside formation. These two drillings, respectively through the casing and out into the formation, are carried out with two different applications in the same tool. Drilling through casing requires a steady and stable drilling rig, while the longer tunnels can be drilled with a flexible string-shaped drill bit.

When perforating by means of drilling, accidental damage to casing and/or external formation is avoided. When drilling, the diameter of the hole is known and, in addition, drilling gives significantly greater control over the depth of the hole and that penetration can be verified. In connection with injection wells, injection calculations will thus also become more accurate. One of the challenges associated with drilling as a perforation method is, with the limited diameter of a well tool, getting a sufficient stroke length for the drill, so that even thick casings can be perforated.

The purpose of the invention is to remedy or to reduce at least one of the disadvantages of known technology, or at least to provide a useful alternative to known technology.

The purpose is achieved by the features indicated in the description below and in the subsequent patent claims.

The invention is defined by the independent patent claims. The independent claims define advantageous embodiments of the invention.

In a first aspect, the invention relates more specifically to a drilling module for radial drilling in a well, where the well is defined by a wall and where the well has an extension in an axial direction, and where the drilling module comprises: - a piston to receive a drill for the radial the bore, and to displace the drill in a radial direction against the wall of the well; and

- a cylinder to receive and guide the piston,

where the drilling module is characterized by the fact that both the piston and the cylinder, at least in part, are guide-free, non-circularly designed to prevent rotation between them.

By "circularly designed" here is meant a shape that has a circular base shape, i.e. a circular periphery, for example a circularly designed piston with grooves or guides. Similarly, "non-circularly designed" means that the basic shape is different from the circular one, for example an oval.

In a downhole tool, as is known, the space conditions are limited as a result of the size of the wellbore, and in particular for tools that have their operating zone in the radial direction from the downhole tool. For such tools, for example a drilling module for radial drilling, the range will be limited by the diameter of the downhole tool.

A piston usually has circular end surfaces and a curved side surface, and the piston in a drilling machine of a known type will typically be circular. When using a circular piston and cylinder complementary to the piston, the piston will be able to move the drill bit towards the well wall. The cylinder housing is set in rotation via, for example, an angle drive connected to a motor. Relative rotation between the cylinder and the piston will be unfavorable both in terms of wear and in terms of optimal transmission of torque to the drill. In order to prevent, or at least minimize, the rotation of the cylinder and the piston in relation to each other, it is known to provide a rotation-preventing mechanism, such as guides. These guides will be placed between the piston and the cylinder housing, as longitudinal grooves in which the piston is guided. In a drilling apparatus of a known type, there will be guides, or grooves, in an upper part of the piston, which fit into corresponding guides/grooves in the cylinder housing. Furthermore, such a piston in a drilling apparatus of a known type will be hydraulically driven, and the seals which are necessary to avoid leakage in the hydraulics are placed below the part of the piston where the guides are. The seals are fixed, and thus constitute the limit for how far out the piston can be displaced. The guide rings are thus limiting for the drill's stroke length.

The drilling module according to the invention indicates that a drilling module's piston and cylinder can have a shape other than circular, at least in part. With the non-circular design of the drilling module's piston and cylinder, rotation between the piston and the cylinder will be prevented without the need for space-consuming guides. The piston's, and thus the drill's, stroke thus becomes correspondingly longer.

By "guide-free" it is meant here that the piston and cylinder are designed without the above-mentioned longitudinal grooves which are known from the state of the art.

The drilling module according to the invention thus contributes to the state of the art by specifying a design of the piston and cylinder, which can be said to be the opposite of normal intuitive thinking within this field, namely to start from a different shape of the piston instead of modifying the circular shape and use guides for stabilization. In addition to preventing rotation between the piston and the cylinder, the additional effect is thus achieved that space-consuming guides become redundant and thereby the stroke length of the piston - and the reach of the drill - become longer.

A further effect of the non-circular piston will be better power transmission, because none of the piston's end face area is lost due to guides.

The piston and the cylinder can at least in part be oval shaped. The oval design of the piston and cylinder constitutes one embodiment of the drilling module according to the invention. Oval design is particularly appropriate in terms of wear, as the frictional forces acting on the piston and cylinder housing are relatively more evenly distributed than, for example, with a more irregular non-circular design. The oval design therefore provides both great stability and little wear in addition to the extended range as mentioned above.

The piston and the cylinder can at least in part be triangular in shape. Triangular design constitutes one embodiment of the drilling module according to the invention. It can be advantageous to have rounded corners in a triangular design, as this will reduce the surface tension in the relevant area.

The piston can be telescopic. Telescopic ram will be able to further increase the reach of the radial drill, where appropriate.

The piston can be fluid operated, which is a suitable way to drive a piston in a cylinder. The fluid inlet and fluid outlet will typically be located at the bottom of the cylinder, so that when the piston is pushed out, the fluid acts against the entire end surface of the piston. It would also be an advantage to provide a safety device, for example in the form of an accumulator. The hydraulic line from the accumulator can have inlets and outlets so far up in the cylinder that even when the piston is fully extended, fluid from the accumulator will be able to push the piston down again. The accumulator will then be able to be connected, for example, in the event of a power cut, to ensure that the piston and drill re-enter the tool before it is pulled out of the well.

The drilling module can comprise a motor arranged to rotate the cylinder housing which, via the piston, rotates the drill.

In a second aspect, the invention relates to a well tool comprising the drilling module according to a first aspect of the invention. The drilling module is thus one of two or more modules that make up the well tool. The drilling module can be placed in the well tool where it is most appropriate in relation to other modules. It must be understood that the well tool can also include more than one drilling module. This will make it possible to drill more holes in a shorter time and increase the number of holes that can be drilled per trip, i.e. before the well tool has to be pulled out again to change drills.

The well tool can further comprise an anchoring module connected to the drilling module, the anchoring module comprising a displacement device arranged to push against a part of the well's wall in the use position in order to press the anchoring module against an opposite part of the well's wall, where the anchoring module's displacement device is positioned opposite the drilling module's bit in the use position .

The well tool can comprise several modules in addition to the drilling module, where it must be understood that the drilling module is not necessarily placed separately, but can be part of a larger tool module. The well tool can comprise an anchoring module which functions so that when the anchoring module's displacement device in the use position pushes against the well wall, the well tool will be displaced radially in the well. The anchoring module can press the well tool against the well wall and in that way clamp the tool between the displacement device and the wall. In the case of radial well operations such as radial drilling for perforation of casing, the aforementioned anchoring module will provide the advantage that the drilling module comes closer to the pipe wall and is kept clamped, which results in increased stroke length for the radial drilling, i.e. increased radial range for the well operation device seen in relation to the use of anchoring devices that anchor the tool centered in the well.

An anchoring module is also described for use in a well tool in a well, where the well is defined by a wall and where the well extends in an axial direction, and where the anchoring module in the position of use extends in the axial direction of the well, characterized in that the anchoring module comprises a displacement device arranged in the position of use to push against a part of the well's wall in order to press the anchoring module against an opposite part of the well's wall.

When the anchoring module's displacement device in use position pushes against the wall of the well, the well tool will be displaced radially in the well. The anchoring module presses the well tool against the wall of the well and in that way clamps the tool firmly between the displacement device and the wall. In radial well operations such as, for example, operations that take place through the wall of production tubing (so-called "through-tubing"/"thru-tubing") and radial drilling for perforating casing, the anchoring module will provide the advantage that the tool for radial operations, for example a drill , comes closer to the pipe wall, which results in an increased radial range.

The anchoring module thus contributes to eliminating the space between the well tool and the well, in addition to the tool being stabilized by the tension to the wall of the well.

The anchoring module contributes to the state of the art by specifying a way to stabilize a tool in a well, where the tool is pressed against the well wall. This can be said to work the opposite of what is common in this field, namely to stabilize the well tool centered or nearly centered in the well. In addition to providing an off-center stabilization of the well tool, the additional effect is also achieved that the reach of the tool increases in the radial direction.

The displacement device may comprise at least one displacement element. The use of a displacement element constitutes one way of forming the displacement device. Where the displacement device comprises only one displacement element, in a preferred embodiment, the displacement device and the displacement element can be the same. Where the displacement device comprises two or more displacement elements, the displacement device can be seen as a housing or a container from which the displacement elements protrude in a position of use. Each displacement element is thus smaller in cross-section than the displacement device. The overall contact surface between the displacement elements and the wall of the well is thus limited by the dimensions of the displacement device. By using two or more displacement elements, it is also possible to imagine an embodiment where the displacement elements can be displaced independently of each other and thus provide a more flexible anchoring module. This could, for example, be an advantage where the anchoring module is used in an open well or other places where the well wall may be uneven. The displacement elements can be the same, or they can be different and adapted to the design of the displacement device.

The displacement elements can be placed along a common axis which is parallel to the axial direction of the well tool. In cases where the displacement device comprises more than one displacement element, the best effect will be achieved in terms of pressing the well tool against the wall of the well, if the displacement elements are placed one after the other along an axis that is parallel to the axial direction of the well tool.

The displacement device can have an axial extent that is orthogonal to the axial direction of the well tool, which will be an advantage purely in terms of space inside the well tool. In addition, such an orientation of the displacement device in relation to the well tool will be most appropriate in terms of stability and transmission of power.

The at least one displacement element may be telescopic. Telescopic displacement elements make it possible to use the anchoring module in well tools in pipes and wells with a larger range of dimensions. An example could be that the tool is led through a 7" pipe and out into a 9 5/8" pipe to be anchored in this.

The displacement device may be oblong in the axial direction of the tool. The fact that the displacement device is elongated in the axial direction of the tool means that the displacement device can be designed so that it is relatively smaller in extent in the radial direction of the well tool, while the same, or greater, contact surface with the wall of the well is achieved. In the case of, for example, a circular cross-section of the displacement device, the displacement device's diameter will be the same as the diameter of the anchoring module, and thus of the well tool, at most. The diameter of the borehole eye is thus the absolute limitation on the displacement device's cross-section, because the displacement device is accommodated inside the anchoring module in its passive, retracted position. In the case of an elongated design of the displacement device, the cross-section can be made as large or larger than the cross-section in the case of a circular design of the displacement device. An advantage of an increased cross-section of the displacement device is increased stability in the anchoring of the well tool. A particular advantage of an elongated design of the displacement device is that space is provided inside the well tool for cables and other components to pass past the displacement device. Since the anchoring module's cross-section can be very small, an elongated displacement device will provide greater force than, for example, a circular displacement device which is necessarily limited by the anchoring module's cross-section.

The displacement device can be oval. An oval design of the displacement device is a particularly suitable variant of the above-mentioned oblong design. The oval shape allows the use of simple and previously known seals, and thus makes the production and operation of the displacement device easier and less expensive than if components have to be specially adapted. With hydraulic operation of the displacement device, the oval shape will make it easy to avoid leaks. The most preferred oval shape is ellipse.

The displacement device can be fluid operated. In the case of fluid operation, usually hydraulic operation, the displacement device and its displacement elements function as cylinders and pistons. It is particularly suitable with an oval design of the displacement device and displacement elements in the case of a hydraulically driven displacement device, as it is easier to avoid leaks than if the displacement device has a design that, for example, includes corners or protrusions.

The anchoring module can further comprise a safety device for releasing the anchoring module's pressure against the well wall. If the well tool loses its power supply or becomes stuck, or other problems arise, so that the displacement element cannot be retracted in the normal way, the safety device will be able to constitute a backup solution to free the anchoring module from its tensioned position against the well wall. Such a safety device may comprise a device for cutting off the displacement element or a device for pulling or pressing the displacement element back in. One way to do this is to machine a groove on the inside of the displacement element, so that this will be cut at a given force. Another possible safety device can be constituted by springs which are arranged inside or outside the displacement element and which are arranged to pull the displacement element back.

The safety device may comprise an accumulator. The accumulator can be charged, for example by tensioning a spring when the piston is first retracted. This charging can be done before the well tool with the anchoring module is led into the well or as a test of the accumulator after the tool has been brought into the desired position in the well, and before the start of the well operation. The hydraulic line to the accumulator is fitted with a non-return valve so that the accumulator is not discharged. The displacement element or piston is driven out to the well wall and anchored by a given hydraulic pressure that works against the accumulator pressure, where the accumulator pressure in an emergency situation will be enough to pull the displacement element back into the anchoring module. If the power supply to the anchoring module fails, the stored energy in the accumulator will therefore function as a reserve.

The safety device can be arranged to be able to pull the displacement device back from the wall of the well. This will have the effect that if, for example, the power supply to the anchoring module is lost while it is activated, i.e. while the displacement device or at least one displacement element protrudes from the anchoring module, the safety device will be able to pull the displacement device or the displacement element back from the wall of the well. This is done by releasing the tensioned spring in the accumulator so that hydraulic oil is forced out of the safety device and via a hydraulic line onto a surface on the upper side of the displacement element's lower part, and pushes the displacement element back into the anchoring module.

Both the drilling module and the anchoring module use the principle of a non-circular, preferably oval, design of piston and cylinder. For the drilling module, this results in, among other things, an increased stroke length for the drill and for the anchoring module, this results in, among other things, better space inside the tool for guiding hydraulic lines and other cables. The anchoring module according to the invention will, in a tool where it is combined with the drilling module, bring the drilling module into contact with the well wall and thus further increase the reach of the drill, as the distance between the tool and the well wall is eliminated. The safety device, for example in the form of an accumulator described here, in tools where several modules are connected together, will be able to function as a safety device for several of the modules at the same time. This means that, for example, in a well tool with both an anchoring module and a drilling module as described above, the accumulator will be able to draw in both the anchoring module's displacement elements and the drilling module's piston and drill.

In what follows, an example of a preferred embodiment is described which is visualized in the accompanying drawings, where: Fig. 1 shows a side section of a drilling module for radial drilling, with a retracted drill bit; Fig. 2 shows a side section of the drill module with retracted drill, where the piston and cylinder are rotated 90 degrees in relation to figure 1; Fig. 3 shows a side section of the drill module in Fig. 2, but with the drill extended;

Fig. 4 shows an embodiment of a piston according to the invention; and

Fig. 5 shows a well tool which comprises an anchoring module and a drilling module.

Similar or equivalent elements are indicated with the same reference number in the figures.

Position and orientation indications such as upper, lower, above, below, vertical and horizontal allude to the position shown in the figures.

Figure 1 shows a longitudinal section of a drilling module 1 in a passive position. In the drilling module 1, a recess 13 or opening 13 is shown here, in which a cylinder housing 10 and a cylinder 12 are accommodated. The cylinder housing 10 can also be referred to as a rotary body 10 as it is set in rotation by means of a motor 15 via a system for power and rotation transmission which includes, for example, a shaft 16, necessary ball bearings 17 and two gears 14 which make up an angle drive, of which one gear wheel 14 is attached to the cylinder housing 10, for example with screws. The motor 15 can, for example, be an electric motor or a fluid-driven motor. The motor 15 and the system for power and rotation transmission to the cylinder 12 of the drilling module 1 will not be described in more detail herein as it is known technology in and of itself and is considered to be obvious to a person skilled in the art.

The cylinder 12 is arranged to receive and guide a piston 11, alternatively called a feed piston 11. The piston 11 and the cylinder 12 are at least in part designed non-circular. In Figure 1, the section through the piston 11 and the cylinder 12 is taken over the smallest diameter, while the piston 11 and the cylinder 12 in Figure 2 are turned 90 degrees in relation to Figure 1. Thus the non-circular, in this case oval, design appears of the piston 11 and the cylinder 12. The design of the piston 11 is best shown in Figure 4. The piston 11 is also arranged to receive a drill 3. In both Figure 1 and Figure 2, the piston 11 is shown completely retracted into the cylinder 12. During drilling, the piston 11, which is here shown hydraulically driven, is guided upwards in the cylinder 12, i.e. in a radial direction towards a well wall 21 (shown in Figure 5). Input and output for hydraulic oil are at the bottom of the cylinder housing 10, but are not shown in the figures as hydraulic operation of a piston in a cylinder is considered to be professional. The piston 11 and the cylinder 12 are designed so that the piston 11 cannot rotate in the cylinder 12, for example in that a first part 111 of the piston 11 is oval in circumference and is tightly enclosed by a corresponding oval design of the cylinder 12. The rotation of the cylinder housing 10 will thus is transferred to the piston 11 and through it to the drill 3. The drill 3 is attached to a second part 112 of the piston 11.

Figure 3 shows the drill module 1 from figure 2, but with the piston 11 and thus the drill 3, at maximum displacement in relation to the cylinder 12.

Figure 4 shows, as mentioned above, a piston 11 with a first part 111 which is oval. In this embodiment, the piston 11 has a second part 112 which is circular. The drill 3 (shown in figures 1-3) is received and fixed in a recess 113 in the second part 112 of the piston 11.

Figure 5 shows how the drilling module 1 forms part of a well tool 5, where the well tool 5 also comprises an anchoring module 6, here shown provided with a displacement device 61 arranged to push against a part of the wall 21 of the well 2 in order to press the anchoring module 6 against a opposite part of the well's 2 wall. The drilling module 1 and the anchoring module 6 are preferably located close to each other, preferably next to each other, in the well tool 5. The drilling module 1 and the anchoring module 6 are also preferably placed in the well tool 5 in such a way that the displacement device 61 and the piston 11 protrude opposite each other in the position of use. As the anchoring module 6 pushes the well tool 5 against the wall 21 of the well 2, the drilling module 1 will come into contact with the wall 21 and thus achieve further radial reach.

It should be noted that all of the above embodiments illustrate the invention, but do not limit it, and those skilled in the art will be able to devise many alternative embodiments without departing from the scope of the dependent claims. In the requirements, reference numbers in parentheses should not be seen as limiting. The use of the verb "to comprise" and its various forms does not exclude the presence of elements or steps not mentioned in the claims. The indefinite articles "an", "ei" or "et" before an element do not exclude the presence of several such elements. The invention can be implemented by means of hardware comprising several separate elements, and by means of a suitably programmed computer. In device claims that mention several means, several of these means may be included in one and the same element of the hardware. The fact that certain features are listed in mutually different dependent claims does not indicate that a combination of these features cannot be used with advantage. In the figures, similar or corresponding features are indicated by the same reference number or inscription.

Claims (8)

1. Drilling module (1) for radial drilling in a well (2), where the well (2) is defined by a wall (21) and where the well has an extension in an axial direction (A), and where the drilling module (1) comprises: - a piston (11) to receive a drill (3) for the radial drilling, and to displace the drill (3) in a radial direction against the wall (21) of the well (2); and - a cylinder (12) to receive and guide the piston (11), where the drilling module (1) is characterized in that both the piston (11) and the cylinder (12) are, at least in part, guide-free, non-circular designed to prevent rotation between them. 2. Drilling module (1) according to claim 1, where the piston (11) and the cylinder (12) are at least partially oval-shaped. 3. Drilling module (1) according to claim 1, where the piston (11) and the cylinder (12) are at least in part triangularly designed. 4. Drilling module (1) according to any one of the preceding claims, where the piston (11) is telescopic. 5. Drilling module (1) according to any of the preceding claims, where the piston (11) is fluid operated. 6. Drilling module (1) according to any one of the preceding claims, where the drilling module comprises a motor (15) arranged to rotate the cylinder (12) which via the piston (11) rotates the drill (3). 7. Well tool (5) comprising the drilling module (1) according to any one of the preceding claims. 8. Well tool (5) according to claim 7, where the well tool (5) comprises: - an anchoring module (6) connected to the drilling module (1), the anchoring module (6) comprising the displacement device (61) arranged to push against a part of the wall (21) of the well (2) to press the anchoring module (6) against an opposite part of the wall (21) of the well (2), where the displacement device (61) of the anchoring module (6) is placed opposite the drill (3) of the drilling module (1) in use position.