Collecting device and method for loosen and collect debris in a well

Abstract

A collecting device for loosening and collecting debris in a well comprises a first and second end portions, a collecting receptacle between the first and second end portions having at least one receptacle section and at least one screen receptacle, and a motor. The device at its first end includes a feed pipe, a conveying screw in feed pipe driven by the motor and arranged to move the debris in towards the collecting receptacle, and a tool at the leading end portion of the conveying screw. A method described of loosening and collecting debris in a well by the collecting device.

Claims

1. A collecting device for loosening and collecting debris in a well, the collecting device comprising: a first end portion and a second end portion; a collecting receptacle between the first end portion and the second end portion including at least one receptacle section and at least one screen receptacle with a wall screen; a motor; at the first end portion, the collecting device further includes: a feed pipe; a conveying screw in the feed pipe driven by the motor, the conveying screw being arranged to move the debris in towards the collecting receptacle; a tool at a leading end portion of the conveying screw; a Mono pump at a trailing end portion of the conveying screw and connected to the motor, the Mono pump forming a suction side and a pressure side; the at least one screen receptacle being in a flow path on a delivery side of the Mono pump between the Mono pump and the second end portion; the conveying screw being arranged to move the debris to the Mono pump: wherein the conveying screw is supported in an outer bearing housing in the feed pipe, the outer bearing housing is provided with a through open directed axially, the outer bearing housing is provided with a closing device on a side facing the conveying screw.

2. The collecting device according to claim 1, wherein the collecting device further includes at least one receptacle section in the flow path on a suction side of the Mono pump.

3. The collecting device according to claim 1, wherein the conveying screw is connected to the motor in a motor housing positioned in the second end portion of the collecting device, and the motor drives the conveying screw via a driveshaft.

4. The collecting device according to claim 1, wherein a motor housing with the motor is positioned in the second end portion of the collecting device, and the motor drives the Mono pump via a driveshaft provided with articulations.

5. The collecting device according to claim 1, wherein the motor positioned in a lower portion of a receptacle section on a delivery side of the Mono pump, and the motor drives the Mono pump via a driveshaft provided with articulations.

6. The collecting device according to claim 1, wherein the conveying screw is connected to the Mono pump with an articulated intermediate shaft.

7. The collecting device according to claim 1, wherein the feed pipe includes at least one through main inlet opening in a wall and is further provided with a plurality of through inlet relief openings directed radially, distributed around the circumference of the feed pipe.

8. The collecting device according to claim 7 wherein the at least one through main inlet opening is distributed around the circumference of the feed pipe.

9. The collecting device according to claim 7, wherein at least one through main inlet opening is elongated in a longitudinal direction of the collecting device.

10. The collecting device according to 7, wherein at least one of the at least one through main inlet opening and the plurality of through inlet relief openings is closable.

11. The collecting device according to claim 1, wherein, in a portion, a driveshaft is provided with a screw blade.

12. The collecting, device according to claim 1, wherein an upper portion of a driveshaft is smooth.

13. The collecting device according to claim 1, wherein, at a standstill, the Mono pump functions as a check valve between the at least one receptacle section on the delivery side of the Mono pump and the feed pipe.

14. The collecting device according to claim 1, wherein, the conveying screw is supported in an inner bearing housing in the feed pipe and the inner bearing housing is provided with through openings directed axially, the through opening is a screen opening.

15. The collecting device according to claim 14, wherein the feed pipe is a container for particles retained by the screen opening.

16. The collecting device according to claim 1, wherein the collecting receptacle is modular.

17. The collecting device according to claim 16, wherein the wall screens are intentionally positioned along a length of the collecting receptacle.

18. The collecting device according to claim 1, wherein the closing device is a flap valve.

19. A method of loosening and collecting debris in a well by means of a collecting device the method includes: providing the collecting device with a Mono pump; providing the collecting device with a closing device in an outer bearing housing in a feed pipe, the outer bearing housing being provided with a through opening directed axially, and the closing device is facing a conveying screw; displacing the collecting device inside a well pipe up to debris in the well pipe; activating the collecting device by starting the Mono pump, a conveying screw and a tool; moving the tool into the debris to loosen the debris; mixing the debris with an ambient fluid and carrying the debris up to a suction side of the Mono pump; passing the diluted debris through the Mono pump and into a collecting receptacle on a delivery side of the Mono pump; separating debris and fluid in the collecting receptacle by letting fluid flow out through the wall screen; stopping the Mono pump so that separated debris in the collecting receptacle is prevented from flowing out of the collecting device through the feed pipe; retaining particles within the feed pipe; displacing the collecting device back and out of the well pipe, and emptying the collecting receptacle of the collecting device of collected debris and the feed pipe of collected particles.

20. The method according to claim 19, wherein the method further includes: providing the collecting device with a main inlet opening and an inlet relief opening; and mixing debris in the feed pipe with ambient fluid which is flowed into the feed pipe through at least one of the main inlet opening, and the inlet relief opening.

21. The method according to claim 19 wherein the method further includes flowing ambient fluid into the feed pipe selectably through at least one of the inlet openings by closing at least one of the main inlet opening, and the inlet relief opening.

Description

(1) In what follows, examples of preferred embodiments are described, which are visualized in the accompanying drawings in which:

(2) FIG. 1 shows a principle drawing of a wall screen;

(3) FIG. 2 shows, in perspective, a collecting device according to the invention during work in a well pipe;

(4) FIG. 2 shows a longitudinal section of the collecting device of FIG. 2;

(5) FIG. 3 shows a longitudinal section, on the same scale as FIG. 3, of the collecting device in an alternative embodiment;

(6) FIG. 4 shows a longitudinal section, on the same scale as FIG. 3, of the collecting device in a further alternative embodiment;

(7) FIG. 5 shows a longitudinal section, on the same scale as FIG. 3, of the collecting device in a further alternative embodiment;

(8) FIG. 6 shows a longitudinal section, on the same scale as FIG. 3, of the collecting device in a further alternative embodiment; and

(9) FIG. 7 shows a longitudinal section, on the same scale as FIG. 3, of the collecting device in a further alternative embodiment.

(10) In the drawings, the reference numeral 1 indicates a collecting device which is shown in a well pipe 2 in FIG. 2. In its first end portion, the collecting device 1 includes a feed pipe 6 with an inlet 7, the feed pipe 6 being in fluid communication with a collecting receptacle 8. The collecting receptacle 8, which is typically of a modular structure, may include one or more receptacle sections 10. In its second end portion, the collecting device 1 further includes a top section 16, a motor housing 14 and a coupling piece (not shown) which may be attachable to a wireline (not shown) or to a wireline tractor (not shown). The wireline tractor can move the collecting device 1 in the well pipe 2.

(11) A conveying device 18 is arranged in the feed pipe 6. The conveying device 18 may be rotatable and is shown here in the form of a conveying screw 18′. The conveying device 18 is provided with a tool 20 at its leading end portion, for loosening debris inside the well pipe 2. The tool 20 is shown here as a scraper 20′. The tool 20 may be of other types such as a brush, a so-called rock bit or a so-called PDC bit. The type of tool 20 is chosen according to the type of debris to be removed from the well pipe 2.

(12) The conveying device 18 is supported in an outer bearing housing 30 which is provided with through openings 33 directed axially for conveying debris through the outer bearing housing 30. The conveying device 18 is further supported in an inner bearing housing 32, see FIG. 3. The inner bearing housing 32 is provided with through openings 34 directed axially for conveying debris through the inner bearing housing 32. The openings 34 also work as screen openings for preventing larger particles from being conveyed into the collecting receptacle 8. The outer bearing housing 30 is further, on its side facing the conveying device 18, provided with a closing device 36 which is arranged to prevent a fluid flow in the direction from the feed pipe 6 to the tool 20. The closing device 36 may comprise a flap valve. In some cases in which the debris has a high viscosity, the closing device 36 may be omitted to facilitate the subii) sequent emptying of the collecting device 1. Particles passing the through openings 33 directed axially, but being too large to pass the through openings 34 directed axially, are retained by the closing device 36. These particles will be in the feed pipe 6 when the collecting device 1 is transported out of the well pipe 2.

(13) A Mono pump 12 is positioned between the inner bearing housing 32 and the collecting receptacle 8. The conveying device 18 is thus positioned on the suction side of the Mono pump 12, and the collecting receptacle 8 is positioned on the delivery side of the Mono pump 12, as is shown in the embodiments according to FIGS. 3-5. The through openings 34 directed axially prevent large particles that can ruin the Mono pump 12 from being carried all the way up to the inlet (not shown) of the Mono pump 12.

(14) The motor 22 in the motor housing 14 drives the Mono pump 12 via a driveshaft 28.

(15) Because of the way the Mono pump 12 operates, the driveshaft 28 is provided with articulations 26. An intermediate shaft 24, which is also articulated, extends from the Mono pump 12 to the conveying device 18. The driveshaft 28 may be provided with a number of screw blades 29 as shown in FIG. 3. The motor 22 thus drives the conveying device 18 and the tool 20 via the driveshaft 28, the Mono pump 12, the intermediate shaft 24 and associated articulations 26.

(16) The collecting receptacle 8 may comprise several receptacle sections 10. At least one of the receptacle sections 10 is provided with a wall screen 9 and forms a screen receptacle 10′. FIG. 1 shows a principle drawing in section of the wall screen 9 in the form of a wire-wrapped screen. Keystone-shaped wires 91 form openings 93 between them, with a spacing chosen according to the particle size that should be able to pass the wall screen 9. The wall screen 9 may extend axially over the entire length of the screen receptacle 10′. In another embodiment, the wall screen 9 may constitute a portion of the length of the screen receptacle 10′. In an alternative embodiment, the wall screen 9 may consist of a premium screen.

(17) Each receptacle section 10, 10′ may include a portion of the driveshaft 28 and the screw blade 29. Each receptacle section 10, 10′ is provided with an upper shaft support (not shown) and a lower shaft support (not shown). In one embodiment, the receptacle section 10, 10′ that is positioned the nearest to the motor 22 may be provided with a driveshaft 28 with an upper smooth portion 28′ nearest to the motor 22, see FIG. 3.

(18) The modular structure makes it possible to combine receptacle sections 10 with screen receptacles 10′ of different designs. This is advantageous as the overall screen area may be varied and the positioning of wall screens 9 may be varied along the length of the collecting receptacle 8. The collecting device 1 may therefore easily be adapted for the conditions in the well in question.

(19) In a lower portion of a wall 62, the feed pipe 6 is shown provided with a plurality of through main openings 64 directed radially. In its upper portion, the wall 62 is shown provided with a plurality of through relief openings 66 directed radially. The main openings 64 are shown as elongated openings in the longitudinal direction of the collecting device 1. The openings 64, 66 are distributed around the circumference of the feed pipe 6.

(20) The collecting device 1 is further shown provided with through auxiliary openings 68 directed radially in a wall right below the stator (not shown) of the Mono pump 12.

(21) The openings 64, 66 and 68 may selectably and independently of each other be closed and opened with closing devices (not shown).

(22) The feed pipe 6, the Mono pump 12, the collecting receptacle 8 with the screen receptacle 10′, which includes the wall screen 9, form a flow path 40 through the collecting device 1.

(23) The fluid following the flow path 40 will choose the flow path 40 offering the least flow resistance. This will usually be with an outlet at the bottom of the collecting receptacle 8. The fine matter like clay, silt and fine sand will gradually clog up a portion of the wall screen 9, so that the flow path 40 changes and reaches the top section 16. Gradually, a more or less fluid-tight channel will form within the collecting receptacle 8. The Mono pump 12 may push or press the mixture of fluid and debris all the way up to the top section 16.

(24) The collecting device 1 is shown in an alternative embodiment in FIG. 4. In this embodiment, the smooth portion 28′ of the driveshaft 28 has been carried through the entire collecting receptacle 8. This may be advantageous when the mixture of debris and fluid contains much fluid and the Mono pump 12 exerts so great a pressure that the mixture may flow all the way to the top section 16. Screw blades 29, if any, may slow down the mixture along the flow path 40.

(25) The collecting device 1 is shown in a further alternative embodiment in FIG. 5. In this embodiment, the motor 22 is positioned at the bottom of the collecting receptacle 8 in a lower portion of a receptacle section 10, 10′. Mounting brackets for the motor 22 and wiring for the energy supply to the motor 22 are not shown. This embodiment has the advantage of allowing the collecting receptacle 8 to be without any internal obstructions from the motor 22 to the top section 16 without supports for a driveshaft 28. This simplifies the assembly of several receptacle sections 10, 10′ into one collecting receptacle 8. It also makes there be fewer restrictions and obstructions along the flow path 40.

(26) The collecting device 1 is shown in a further alternative embodiment in FIG. 6. In this embodiment, the collecting device 1 is provided with at least one receptacle section 10 on the suction side of the Mono pump 12 and at least one screen receptacle 10′ on the delivery side of the Mono pump 12. Collected debris in the collecting receptacle 8 on the suction side of the Mono pump 12 is retained by the closing device 36 so that it cannot flow out of the collecting receptacle 1. FIG. 5 shows an embodiment in which the smooth portion 28′ of the driveshaft 28 has been carried through the entire part of the collecting receptacle 8 that is on the delivery side of the Mono pump 12. The intermediate shaft 24 is also shown as a smooth shaft.

(27) In an embodiment not shown, the collecting device 1 shown in FIG. 6 may be provided with a driveshaft 28 with screw blades 29 as shown in FIG. 3. The driveshaft 28 may have a smooth portion 28′ extending through the top section 16. In a further (not shown) embodiment, the shaft 24 may be provided with a number of screw blades (not shown). In further embodiments not shown, an intermediate shaft 24 with or without screw blades may be combined with a driveshaft 28 with or without screw blades 29.

(28) In an embodiment not shown, the collecting device 1 shown in FIG. 6 may be provided with a motor 22 in a lower portion of a receptacle section 10, 10′ as shown in FIG. 5. The shaft 24 may be without screw blades as shown in FIG. 6 or with screw blades (not shown).

(29) The collecting device 1 is shown in a further alternative embodiment in FIG. 7. In this embodiment, the conveyor 18 is connected directly to the motor 22 via the driveshaft 28. The driveshaft 28 may be smooth like the driveshaft 28 shown in FIG. 4. The driveshaft 28 may be provided with a number of screw blades 29 like the driveshaft 28 shown in FIG. 3. In one embodiment, the driveshaft 28 may be provided with an upper smooth portion 28′ nearest to the motor 22, like the driveshaft shown in FIG. 3.

(30) When the collecting device 1 is being displaced into the well pipe 2 by means of a wireline tractor (not shown), for example, the propulsion resistance of the wireline tractor increases when the collecting device 1 is being moved into debris. It may be beneficial to pull the collecting device 1 back somewhat when the debris has been localized. Then the collecting device 1 is activated and the collecting device 1 is eased into the debris with the conveying device 18 activated, tool 20 activated and pump 12 activated. Thereby the debris is loosened while, at the same time, the tool 20 is feeding the debris into the conveying device 18. The debris is then displaced internally through the feed pipe 6 by means of the rotating conveying device 18 while, at the same time, the debris is mixed with ambient fluid entering through at least one of the openings 64, 66, 68 directed radially. The mixture is carried up to the suction side of the Mono pump 12 through the openings 34 directed axially in the inner bearing housing 32. The Mono pump 12 pumps the mixture of debris and ambient fluid into the collecting receptacle 8.

(31) In well pipes 2 oriented vertically, the debris may form a relatively solid bridge or plug. The tool 20 will dig loose debris in the surface of the bridge. Fluid present on the surface of the bridge will mix with the debris and a mixture of fluid and debris is carried into the feed pipe 6. Ambient fluid may also enter the feed pipe 6 through the main openings 64. The conveying device 18 will further mix debris and fluid together and carry this mixture to the suction side of the Mono pump 12. The mixture is carried through the Mono pump 12 and out on the delivery side of the Mono pump 12. The mixture is carried at a pressure higher than the ambient pressure upwards in the collecting receptacle 8. In one embodiment as shown, in which the driveshaft 28 is provided with screw blades 29 in a portion, the screw blades 29 will further contribute to carrying the mixture of fluid and debris upwards in the collecting receptacle 8. The fact that the debris is on the delivery side of the Mono pump 12 will alone enable the use of an extended collecting receptacle 8. The fact that the driveshaft 28 is provided with screw blades 29 will, in combination with the fact that they are on the delivery side of the Mono pump, further contribute to enabling the use of an extended collecting receptacle 8.

(32) The openings 34 in the inner bearing housing 32 are chosen in a size that prevents particles that might damage the Mono pump 12 from being carried up to the Mono pump 12.

(33) If the debris forms a bridge which is so loose that the collecting device 1 sinks into the debris until this covers the main openings 64, the loosened matter could be too dry for the Mono pump 12 to work efficiently. The relief openings 66 are therefore opened so that ambient fluid may enter the feed pipe 6 through the relief openings 66 from the annulus between the collecting device 1 and the well pipe 2. If the debris is so loose that the relief openings 66, too, are covered up, the auxiliary openings 68 are opened. Ambient fluid may then enter the collecting device 1 between the inner bearing housing 32 and the Mono pump 12 through the auxiliary openings 68 from the annulus between the collecting device 1 and the well pipe 2. The third openings 68 are chosen in a size that prevents particles that could damage the Mono pump 12 from flowing through the third openings 68. Thereby it is ensured that the Mono pump 12 is supplied with a mixture of debris and ambient fluid.

(34) The mixture of debris and fluid is carried upwards in the collecting receptacle 8 to the top section 16 along the flow path 40. Fluid exits through the wall screen 9 as the pressure inside the collecting receptacle 8 is greater than the ambient pressure. The particulate debris which has a size that is larger than the light opening of the wall screen 9 is retained by the wall screen 9 and separated from the fluid. The particles separated are collected in the collecting receptacle 8.

(35) When the collecting receptacle 8 has been filled up with debris, the Mono pump 12 is stopped. Fluid and particles cannot flow through the Mono pump 12 when the rotor (not shown) is stationary relative to the stator. Therefore, at a standstill, the Mono pump 12 will function as a check valve which prevents the mixture of fluid and particles from flowing out of the collecting receptacle 8 and out through the feed pipe 6 when the collecting device 1 is being returned to the surface where the collecting receptacle 8 is emptied.

(36) The cleaning operation is repeated until the debris has been removed.

(37) In deviated wells, whether ERD wells or horizontal wells, the method is the same. In such wells, debris does not form bridges. In most cases, one or more of the main openings 64 will face upwards and not be buried in debris. This ensures that ambient fluid will enter the feed pipe 6 and become mixed with loosened debris there.

(38) When the collecting device 1 in an embodiment as shown in FIG. 7 is displaced into the well pipe 2 by means of a wireline tractor (not shown), for example, the propulsion resistance of the wireline tractor increases when the collecting device 1 is being moved into debris. It may be beneficial to pull the collecting device 1 back somewhat when the debris has been localized. Then the collecting device 1 is activated and the collecting device 1 eased into the debris with the transport device 18 activated and tool 20 activated. Thereby the debris is loosened at the same time as the tool 20 is feeding the debris into the conveying device 18. The debris is then moved internally through the feed pipe 6 by means of the rotating conveying device 18 into the collecting receptacle 8. The debris and entrained ambient fluid are carried at a pressure to higher than the ambient pressure upwards in the collecting receptacle 8.

(39) In one embodiment as shown, in which the driveshaft 28 is provided with screw blades 29 in a portion, the screw blades 29 will further contribute to the mixture of fluid and debris being carried upwards in the collecting receptacle 8. Fluid flows out of the wall screen 9 in the screen receptacle 10′. The large screen area enables the use of an extended collecting receptacle 8.

(40) It should be noted that all the above-mentioned embodiments illustrate the invention, but do not limit it, and persons skilled in the art may construct many alternative embodiments without departing from the scope of the attached claims. In the claims, reference numbers in parentheses are not to be regarded as restrictive. The use of the verb “to comprise” and its different forms does not exclude the presence of elements or steps that are not mentioned in the claims. The indefinite article “a” or “an” before an element does not exclude the presence of several such elements.

(41) The fact that some features are indicated in mutually different dependent claims does not indicate that a combination of these features cannot be used with advantage.