WO2009153560A2

WO2009153560A2 - Improved downhole apparatus

Info

Publication number: WO2009153560A2
Application number: PCT/GB2009/001523
Authority: WO
Inventors: Kenny Armstrong; Jim Hardie
Original assignee: Viking Intervention (Uk) Ltd
Priority date: 2008-06-19
Filing date: 2009-06-18
Publication date: 2009-12-23
Also published as: GB0811259D0; NO20110083A1; GB201100814D0; WO2009153560A3; GB2474603A; GB2474603B

Abstract

An apparatus for creating a force downhole is described. The apparatus comprises a tubular body defining a chamber, a plug, the plug being moveable between a first position at a first chamber location to a second position at a second chamber location, a latch adapted to releasably fix the plug in the first position and a latch release mechanism adapted to release the latch.

Description

Improved Downhole Apparatus

FIELD OF THE INVENTION

The present invention relates to an improved apparatus for creating a force downhole. Particularly but not exclusively the invention relates to a hydrostatic bailer for use in removing debris from downhole tools.

BACKGROUND TO THE INVENTION

There are many circumstances in which it is necessary to create a force downhole. This might be a push force such as an impact to trigger a tool or it might be a pull force such as a suction to, for example remove something from a tool.

Hydrostatic bailers are used to remove debris from downhole tools using a suction action. A conventional hydrostatic bailer comprises a chamber which is sealed by a movable plug. Once sealed, the bailer chamber is at a fixed pressure, normally atmospheric. The movable plug is retained in position by one or more shear pins. In use, the conventional bailer is lowered downhole to the tool from which debris needs to be removed. At the tool location, the environmental pressure is significantly higher than the pressure within the bailer chamber. To remove the debris from the downhole tool, a jar is applied to the bailer to shear the pins and release the plug. Once released, the plug travels up the chamber at high velocity under the influence of the environmental pressure. The action of the plug causes a suction behind the plug which sucks the debris from the downhole tool into the chamber. A conventional bailer is provided with a sealing device in the form of a ball and a seat, the ball and seat permitting debris to flow into the chamber but resisting debris from exiting the chamber once the pressure is equalised and under the influence of gravity.

Conventional bailers have a number of drawbacks. Firstly, it is difficult to accurately rate the shear pins as they have to be able to withstand well pressure. If well pressure is low then a significant jarring force has to be applied from surface to shear the pins. Additionally conventional bailers are of relatively small diameters, and hence relatively small volumes, as a larger diameter bailer requires significantly stronger shear pins to withstand the well pressure and at low pressure it may not be possible to apply a sufficient jar to such a bailer to shear the pins. Finally, as the plug is fired up the chamber, the chamber can be damaged by the movement of the plug.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided an apparatus for creating a force downhole comprising: a tubular body defining a chamber; a plug, the plug being moveable between a first position at a first chamber location to a second position at a second chamber location; a latch adapted to releasably fix the plug in the first position; and a latch release mechanism adapted to release the latch.

In an embodiment of the invention, providing a latch and latch release mechanism allows for the differential pressure across the plug to be borne by the latch. The latch release mechanism can then be activated using a force or signal which is unaffected by downhole environmental conditions, subsequent movement of the plug creating a force.

The latch and latch release mechanism may be separate.

The chamber may be sealed by a seal between the plug and the first chamber portion.

The first chamber location may be adjacent a first end of the tubular body.

The second chamber location may be adjacent the second end of the tubular body.

For the avoidance of doubt, the term "tubular" is used to define a body with a bore extending at least partially through its length and is not intended to be restricted to a bore of circular cross-section. The cross-section could be, for example, oval, square, hexagonal, elliptical or any suitable shape.

In one embodiment the chamber is sealed by the plug in the first position at atmospheric pressure.

The plug may be sealed to the chamber wall by at least one seal.

The/each seal may comprise a chevron seal, O-ring seal or any suitable seal.

In one embodiment the latch comprises at least one element adapted to be retained in an engaged relationship with a chamber wall portion.

The at least one element may be retained in an engaged relationship with the chamber wall portion by a retaining member.

Preferably, the latch release mechanism releasably attaches the retaining member to the tubular body. In an alternative embodiment, the latch release mechanism releasably attaches the retaining member to the plug.

Preferably, the latch release mechanism is actuated by a mechanical force.

The latch release mechanism may comprise a shear pin, shear stock, breakable stud or the like.

Alternatively, the latch release mechanism is actuated by an electrical signal.

The latch release mechanism may comprise a solenoid operated mechanism.

In an further alternative, the latch release mechanism is actuated hydraulically.

In one embodiment, the mechanical force, hydraulic pressure/signal or electrical signal is applied from surface.

Preferably, the retaining member is a sleeve adapted to slide within a bore defined by the plug.

Preferably, the retaining member is movable between a retaining position in which the/each element is retained in the chamber wall recess and a release position in which the/each element is released from the chamber wall recess.

Preferably, in the release position, the/each element is in contact with the chamber wall. If the elements are retained in contact with chamber wall the elements can be used to stabilise the plug as it travels.

In one embodiment the/each latch element is a ball. Preferably, there are a plurality of balls. Balls are of particular utility as when the plug travels from the first position to the second position, the balls can be utilised to at least partially control the movement of the plug and reduce potential damage to the internal wall of the chamber.

Preferably, in the first position, the/each element is retained by the retaining member in a recess defined by the chamber wall portion.

In one embodiment the chamber wall portion is a sacrificial member in the chamber wall.

Alternatively, the at least one recess is defined by the chamber wall.

In one embodiment there are a plurality of recesses.

Preferably, the/each element is located within an aperture defined by the plug wall.

Preferably, the apparatus further comprises a sealing device to seal the chamber when the plug is in the second position.

In one embodiment the sealing device is unidirectional.

Preferably, the unidirectional sealing device permits material to flow into the chamber but prevent material exiting the chamber.

Preferably, the sealing device is biased to a sealed position.

Preferably, the sealing device is a flapper valve.

Alternatively, the sealing device may be a ball element. Preferably, the chamber includes a vent mechanism. A vent mechanism is provided to release pressure in the chamber as the plug moves from the first position to the second position.

Preferably, the vent mechanism is biased to a chamber sealed position.

In one embodiment the apparatus is a hydrostatic bailer.

According to a second aspect of the present invention there is provided a method of creating a force downhole, the method comprising: positioning an apparatus in a downhole location, the downhole tool being at an environmental pressure; applying a force or signal to an apparatus latch release mechanism to release an apparatus latch which in turn releases an apparatus plug, the plug being movable in an apparatus tubular body defining an apparatus chamber from a first chamber position to a second chamber position, movement of the plug creating a downhole force.

Preferably, the method further comprises the step of sealing the apparatus chamber when the plug is in the first position.

Accordingly a third aspect of the present invention there is provided a hydrostatic bailer comprising: a tubular body defining a chamber; a plug, the plug being movable between a first position at a first chamber location to a second position at a second chamber location; and a sealing device to seal a chamber inlet when the plug is in the second position, wherein the sealing device is a flapper. In one embodiment, a flapper is used to maximise the flow area into chamber when the flapper is open.

It will be understood that non-essential features listed in respect of any of the above described aspects may be equally applicable to the other aspects and have not been repeated for brevity.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a section view of a hydrostatic bailer according to a first embodiment of the present invention;

Figure 2 is an enlarged close up view of section X of the bailer of Figure 1 ;

Figure 3 is an enlarged close up view of section Y of the bailer of Figure 1 ;

Figure 4 is a further enlarged view of region A of Figure 3;

Figures 5, 6, 7, 8 and 10 are a series of section views of part of the bailer of Figure 1 showing the operation of the bailer of Figure 1 ; and

Figure 9 is a view through section B-B of Figure 8 showing the flapper in an open position.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring firstly to Figure 1 , there is shown a section view of a hydrostatic bailer, generally indicated by reference numeral 10, according to an embodiment of the present invention. Reference will also be made to Figure 2, an enlarged view of section X of Figure 1 , and Figure 3, an enlarged view of section Y of Figure 1.

The hydrostatic bailer 10 comprises a tubular body 12 defining a chamber 14. The bailer 10 further comprises a plug 16, the plug 16 being movable between a first position at a first chamber location 18 located adjacent the first end 20 of the bailer 10 and a second position at a second chamber location 22 adjacent a second end 24 of the bailer 10. The plug 16 is releasably fixed in the first position by a latch 26, and the latch 26 is held in this position by a latch release mechanism 28.

Referring to Figure 3 and to Figure 4 (an enlarged close up of section A of Figure 3), the latch 26 comprises seven ball elements 30 and a retaining member 32 in the form of a sleeve. The retaining sleeve 32 is movable within a plug bore 34 from a position, shown in Figure 3, in which a retaining sleeve external surface first portion 36 retains the ball elements 30 in engagement with seven recesses 38 defined by a sacrificial ring 40 mounted in the chamber wall surface 42.

As will be discussed, the retaining sleeve 32 further comprises a second external surface portion 44, of lesser diameter than the sleeve first external surface portion 36, into which the ball element 30 can move to disengage from the recesses 38 in the sacrificial ring 40. This will be discussed in due course.

The latch release mechanism 28 comprises a pin 46 which is adapted to shear when a jarring force is applied to the bailer first end 20.

The bailer first end defines lower housing 51 having an inlet 48 which is closed by a flapper 50. The lower housing inlet 48 is in fluid communication with the chamber 14. The flapper 50 is biased to the closed position by a flapper spring 52 around a flapper pivot 54.

Referring to Figure 2, the chamber 40 is sealed by a vent mechanism 58. The vent mechanism is a stopper adapted to seal a chamber outlet 60 and includes an O-ring 62 for this purpose. The stopper 58 is biased to the outlet seal position shown in Figure 2 by a spring 64. The purpose of the vent mechanism 58 will be described in due course.

The plug 16 is sealed in the first position by an O-ring seal 56. This arrangement means the pressure inside chamber 14 is fixed. When the bailer 10 is lowered into a well of higher pressure, the differential pressure acts across the plug 16 and an axial force is applied to the ball elements 30 in the direction of arrows "F". However, the latch release mechanism 28 does not experience this differential pressure as the pressure is balanced across the latch release mechanism 28. As the retaining sleeve 32 is only in releasable contact with the ball elements 30 and the tangent from the contact point is parallel to the direction of arrow F, the retaining sleeve 32 does not experience the full effect of the differential pressure. As a result, the force required to shear the latch release mechanism shear pin 46 is unaffected by downhole environmental conditions.

Referring now to Figure 5, 6, 7, 8 and 10, there is shown a series of enlarged section views of portion Y of Figure 1 showing the operation of the bailer 10. The bailer 10 is lowered into a wellbore (not shown) and into engagement with a downhole tool 70 which is covered in debris 72. For clarity only a small amount of debris 72 is shown. In this position the latch ball elements 30 are locked into the sacrificial ring recesses 38 by the retaining sleeve external surface first portion 36. The retaining sleeve 32 is secured in position by the latch release mechanism shear pin 46.

If it is desired to remove the debris 72 from the tool 70, a jarring force J (Figure 6) is applied to the bailer 10. The jarring force J acts against the lower housing 51 which is engaged with, and fixed relative to, the tool 70. As the jarring force J is applied, the tubular body 12 moves towards the lower housing 51 until a bailer mandrel 74, which is fixed to the lower housing 51 , engages the shear pin 46. Continual application of the jarring force J forces the pin 46 to shear. As can be seen from Figure 6, the retaining sleeve 36 has been released and moved upwardly with respect to the ball elements 30.

Referring now to Figure 7, continued application of the jarring force J leads to further pressure being applied to the retaining sleeve 36 by the mandrel 74 until the retaining sleeve external surface second portion 44 is behind the ball elements 30. In this position the ball elements 36 release from the sacrificial ring recesses 38 permitting the plug 16 to move with respect to the tubular body 12.

Referring now to Figure 8, the plug's 16 movement from the first position creates a suction force which opens the flapper 50 against the bias of the flapper spring 52. As the plug 16 continues to travel up the chamber 14 defined by the tubular body 12, the suction force will suck the debris 72 into the chamber 14.

As can be seen from Figure 8, whilst the retaining sleeve second surface portion 44 permits the ball elements to disengage from the recesses 38, the outside diameter of the second portion 44 is sized such that the ball elements 30 remain in contact with the chamber wall 42. This stabilises the plug 16 as it travels up the chamber 14 and minimises damage to the chamber wall 42.

The use of a flapper valve 50 to seal the chamber inlet 48 is particularly advantageous because, as can be seen from Figure 9, in the open position the chamber inlet 48 is largely unobscured by the flapper 50. This contrasts with the conventional bailer which utilises a ball element, which the debris 72 has to pass around to enter the chamber 14.

Referring now to Figure 10, the plug 16 (not shown) has travelled to the second position (not shown) in the second chamber location 22 and the debris 72 is inside the chamber 14 and retained in the bailer 10 by the flapper 50, which has returned to the closed position under the action of the flapper spring 52. Once the plug 16 reaches the second chamber location 22, the pressure is equalised within the chamber 14 permitting the flapper 50 to return to the position shown in Figure 10.

Referring back to Figure 2, as the plug 16 travels up the bailer 10, pressure will build up ahead of the plug 16. To ensure the suction behind the plug 16 is maximised, this pressure needs to be vented. The pressure builds up on the stopper 58, and once the pressure is sufficient to overcome the biasing spring 64, the stopper 58 will open the outlet 60 allowing the portion of the chamber 14 ahead of the plug 16 to vent.

Various modifications and improvements may be made to the above described embodiments without departing from the scope of the invention. For example, although a jarring force is applied to sever a shear pin in the embodiment described, any suitable method of releasing the retaining sleeve could be employed such as a hydraulic piston or solenoid switch. Although seven ball elements and recesses are described, in a further example more or less than seven could be used.

Claims

1 An apparatus for creating a force downhole comprising: a tubular body defining a chamber; a plug, the plug being moveable between a first position at a first chamber location to a second position at a second chamber location; a latch adapted to releasably fix the plug in the first position; and a latch release mechanism adapted to release the latch.

2 The apparatus of claim 1 , wherein the latch and latch release mechanism are separate.

3 The apparatus of either of claims 1 or 2, wherein the chamber is sealed by a seal between the plug and the first chamber portion.

4 The apparatus of any preceding claim, wherein the first chamber location is adjacent a first end of the tubular body.

5 The apparatus of any preceding claim, wherein the second chamber location is adjacent the second end of the tubular body.

6 The apparatus of any preceding claim, wherein the chamber is sealed by the plug in the first position at atmospheric pressure. 7 The apparatus of any preceding claim, wherein the plug is sealed to the chamber wall by at least one seal.

8 The apparatus of claim 7, wherein the/each seal comprises a chevron seal, O-ring seal or any suitable seal.

9 The apparatus of any preceding claim, wherein the latch comprises at least one element adapted to be retained in an engaged relationship with a chamber wall portion.

10 The apparatus of claim 9, wherein the at least one element is retained in an engaged relationship with the chamber wall portion by a retaining member.

11 The apparatus of claim 10, wherein the latch release mechanism releasably attaches the retaining member to the tubular body.

12 The apparatus of any of claims 1 to 10, wherein the latch release mechanism releasably attaches the retaining member to the plug.

13 The apparatus of any preceding claim, wherein the latch release mechanism is actuated by a mechanical force.

14 The apparatus of claim 13, wherein the latch release mechanism comprises a shear pin, shear stock, breakable stud or the like. 15 The apparatus of any of claims 1 to 12, wherein the latch release mechanism is actuated by an electrical signal.

16 The apparatus of claim 15, wherein the latch release mechanism comprises a solenoid operated mechanism.

17 The apparatus of any of claims 1 to 12, wherein the latch release mechanism is actuated hyd radically.

18 The apparatus of any of claims 13 to 17, wherein the mechanical force, hydraulic pressure/signal or electrical signal is applied from surface.

19 The apparatus of claim 10 or any of claims 11 to 18 when dependent on claim 10, wherein the retaining member is a sleeve adapted to slide within a bore defined by the plug.

20 The apparatus of claim 10 or any of claims 11 to 19 when dependent on claim 10, wherein the retaining member is movable between a retaining position in which the/each element is retained in the chamber wall recess and a release position in which the/each element is released from the chamber wall recess.

21 The apparatus of claim 20, wherein in the release position, the/each element is in contact with the chamber wall. 22 The apparatus of 9 or any of claims 10 to 21 when dependent on claim 9, wherein the/each latch element is a ball.

23 The apparatus of claim 22, wherein there are a plurality of balls.

24 The apparatus of claim 9 or any of claims 10 to 23 when dependent on claim 9, wherein, in the first position, the/each element is retained by the retaining member in a recess defined by the chamber wall portion.

25 The apparatus of claim 24, wherein the chamber wall portion is a sacrificial member in the chamber wall.

26 The apparatus of claim 9 or any of claims 10 to 23 when dependent on claim 9, wherein the at least one recess is defined by the chamber wall.

27 The apparatus of claim 26, wherein there are a plurality of recesses.

28 The apparatus of claim 10 when dependent on claim 9 or any of claims 11 to 27 when dependent on claims 9 and 10, wherein the retaining member is movable between a retaining position in which the/each element is retained in the chamber wall recess and a release position in which the/each element is released from the chamber wall recess. 29 The apparatus of claim 9 or any of claims 10 to 28 when dependent on claim 9, wherein the/each element is located within an aperture defined by the plug wall.

30 The apparatus of any preceding claim, wherein the apparatus further comprises a sealing device to seal the chamber when the plug is in the second position.

31 The apparatus of claim 30, wherein the sealing device is unidirectional.

32 The apparatus of claim 31 , wherein the unidirectional sealing device permits material to flow into the chamber but prevent material exiting the chamber.

33 The apparatus of any of claims 30 to 32, wherein the sealing device is biased to a sealed position.

34 The apparatus of any of claims 30 to 33, wherein the sealing device is a flapper valve.

35 The apparatus of any of claims 30 to 33, wherein the sealing device is a ball element.

36 The apparatus of any preceding claim, wherein the chamber includes a vent mechanism. 37 The apparatus of claim 36, wherein the vent mechanism is biased to a chamber sealed position.

38 The apparatus of any preceding claim, wherein the apparatus is a hydrostatic bailer.

39 A method of creating a force downhole, the method comprising: positioning an apparatus in a downhole location, the downhole tool being at an environmental pressure; applying a force or signal to an apparatus latch release mechanism to release an apparatus latch which in turn releases an apparatus plug, the plug being movable in an apparatus tubular body defining an apparatus chamber from a first chamber position to a second chamber position, movement of the plug creating a downhole force.

40 The method of claim 39, wherein the method further comprises the step of sealing the apparatus chamber when the plug is in the first position.

41 A hydrostatic bailer comprising: a tubular body defining a chamber; a plug, the plug being movable between a first position at a first chamber location to a second position at a second chamber location; and a sealing device to seal a chamber inlet when the plug is in the second position, wherein the sealing device is a flapper.

42 The bailer of claim 41 , wherein a flapper is used to maximise the flow area into chamber when the flapper is open.