Patent Application
20170191323
Field of the Invention
The invention relates to drilling apparatus, especially for drilling for hydrocarbons.
Prior Art Discussion
My prior published PCT patent specification WO2012/0176182 describes an apparatus in which joints are made or broken within a pressure chamber. Snubbers below and above the chamber take over the drive from a top drive, and apply a differential torque so that a connection may be made. The apparatus therefore achieves both continuous mud circulation and continuous rotation while making or breaking connections.
The pressure chamber is at the mud operating pressure so that circulation is continuous during disconnections and the pressure chamber can be segregated into two parts so that the upper part can be depressurised to release and accept tubulars.
It is known that snubbers can comprise chucks which move axially to grip onto the drill string, akin to the chuck of a lathe for example. However a problem with such a mechanism is that considerable volume is required in the axial direction and/or radial direction. This leads to the problems of designing a drilling apparatus that is: a) short enough in height to fit or retro-fit on many existing drilling rigs and/or b) compact enough to limit the size of the pressure chamber around the tool joint connection.
The invention addresses these problems.
According to the invention, there is provided a drilling apparatus for use on a rotary drilling rig with a top drive which enables circulation and rotation of a drill string to continue uninterrupted during the making of drill string connections, wherein the apparatus comprises a tool joint gripping mechanism arranged to rotate at the same speed as a drill string and comprising gripping pads arranged to move radially relative to a drill string tubular or upset, and a drive to drive the pads radially relative to a drill string tubular or upset.
In one embodiment, the gripping pads are wedge-shaped, with a tapered surface upon which a gripping force is exerted and a contact surface for contacting a drill string or tubular.
In one embodiment, the gripping mechanism comprises one or more drive cylinders each having an internal wedge profile which, on relative rotation, moves the pads radially to contact and grip a tool.
In one embodiment, the gripping mechanism comprises a guide to restrain the pads to move radially. In one embodiment, the drive is arranged to rotate the drive cylinder and the guide at the same speed, and to introduce a temporary relative movement to cause radial movement of the pad. Preferably, each of the drive cylinder and the guide comprises a flange which is engaged by a drive member to rotate.
In one embodiment, the drive member comprises a gear. In one embodiment, the guide and the drive cylinder overlap in the radial direction.
In one embodiment, the guide and the drive cylinder are at least partially offset in the axial direction so that they do not overlap in the radial direction for at least some of the axial dimension of the pad. In one embodiment, the guide comprises guide rings engaging upper and lower parts of the pad and the drive cylinder is arranged to engage the pad between said guide rings.
In one embodiment, the guide comprises at least one drive shaft interconnecting said guide rings.
In one embodiment, the gripping mechanism comprises collets arranged to engage an upset at a shoulder with a tubular, and a collet drive arranged to move the collet radially with respect to the tubular or upset.
In one embodiment, the collet is adjacent to the pad in the axial direction.
In one embodiment, the gripping mechanism comprises one or more drive cylinders each having an internal wedge profile which, on relative rotation, moves the pads radially to contact and grip a tool, and wherein said guide cylinder includes a port for the pad and a port for the collet.
In one embodiment, the collet drive and the pad drive are interconnected.
In one embodiment, the apparatus comprises a pressure chamber and two gripping mechanisms including an upper gripping mechanism arranged to engage a tubular or upset above the pressure chamber and a lower mechanism arranged to engage a tubular or upset below the pressure chamber.
In one embodiment, said gripping mechanisms are snubbers.
In one embodiment, the gripping mechanism comprises seals arranged to act on a tool joint upset immediately adjacent to and above and below a blind ram or valve that segregates a pressure chamber into two parts.
In one embodiment, the pads and seals are arranged to contact an upper upset and the apparatus comprises a lower gripping mechanism having grips and seals arranged to contact a lower upset while leaving space for an open blind ram or valve between them when a tool joint is connected.
In one embodiment, the collets and the pads are held in place by a keyway or ridge in the drive cylinder and are releasable by an additional rotation of the drive cylinder to facilitate inspection and replacement, being as they.
In one embodiment, the apparatus further comprises a jack arranged to lift the gripping mechanism relative to a blind ram or valve or of the blind ram or valve relative to a lower gripping mechanism to provide separation to inspect the gripping mechanisms.
In one embodiment, the lower gripping mechanism collets are configured to support a tool joint box upset shoulder (20) before the collets of the upper mechanism are closed and lowered to interfere with a tool joint pin upset shoulder.
In one embodiment, the collets provide a fail-safe support for the tool joint upset, such that the collets of the lower mechanism cannot retract until the drill string weight is taken off the collets and the collets of the upper mechanism cannot be retracted until the snubbing force is removed.
In one embodiment, the pad drive and the collet drive are related by differential gearing.
In one embodiment, the differential gearing comprises planet gears arranged such that movements of planet gears can alter the rotary relationship between the drives.
In another aspect, the invention provides a method of operation of a drilling apparatus as defined above in any embodiment, wherein the method comprises the steps of driving the gripping mechanisms so that the pads and the collets rotate at the same speed as a drill string, and retarding or advancing the pad drive to radially move the pad relative to the drill string.
In one embodiment, the apparatus is fixed to a rig floor and an extension sub in the drill string enables a bit to drill on during connections with a predetermined weight on bit.
In one embodiment, the apparatus is mounted on a hoist to allow vertical motion during connections and therefore enable continuous drilling and continuous tripping if required on new rigs.
In one embodiment, a pin upset is moved away from a box upset by the depth of the pin plus a distance to allow blind ram or valve to close and to allow mud to flow into the drill string below and out of a tubular above.
Detailed Description of the Invention
The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings in which:
Referring to
The overall height is about 1092 mm,
In the apparatus 1 gripping by a snubber is achieved by a circumferential taper which, as it rotates, presses the grips 14 radially to grip the tool joint upset 11. This saves considerable space in the axial direction enabling the sliding seals in the pressure chamber wall to be reduced from a diameter of approximately 584 mm down to approximately 432 mm in the case of concentric cylinders (apparatus 1, a described below), or 381 mm in the case of the apparatus 70. This, in turn, reduces the snubbing force, from a possible 900 tonnes (at a chamber pressure of 345 bar), down to a more manageable 500 tonnes or 400 tonnes respectively. This is also necessary because high snubbing forces directly relate to increased size and weight of the jacks and longer actuation times.
The radial wedges or ‘grips’ 14 have teeth on the inside curved surface to grip the tool joint upset 11 and transmit torque; and a smooth outside curved surface to slide within the smooth internal curved profile 36 of the drive cylinder 34. Thus, when the drive cylinder 34 rotates faster than the grips 14, the grips 14 are forced inwards and into contact with the tool joint upset 11. When the drive cylinder 34 rotates slower than the grips, the grips 14 are retracted outwards and away from contact with the tool joint upset 11. When the drive cylinder 34 is rotating at the same speed as the grips 14, the grips 14 do not move radially inwards or outwards. The gradient of the radial wedges is similar to the gradient used typically in axial slips of approximately 1 in 6, or 9.5°.
The invention avoids problems associated with the known methods for gripping drilling tubulars (including wrenches, rotating rollers, Kelly bushing, or vice jaws). The prior approaches require mechanical, electric or hydraulic actuation, which requires significant space. Additionally, transmission of such mechanical, electric or hydraulic power to the rotating collets, wedges or seals is complex.
The curved wedge-shaped grips 14 occupy approximately half of the radial space of conventional gripping mechanisms, without requiring additional vertical space. This enables the diameter of the upper and lower snubbers to be reduced by about 152 mm and approximately halves the snubbing force to about 400 to 500 tonnes, as above. This allows space to ‘park’ the blind ram 7 or valve between the upper and lower snubbers when the tool joint is connected, enabling the bore of the blind ram or valve to be minimised to the bore of the apparatus.
In more detail, the drilling apparatus 1 assumes concentric cylinders; an outer drive cylinder 34 with internal wedging profile 41 and an inner concentric guide cylinder 30 to guide the collets 13, wedges 14 or seals 15.
The grips drive cylinder 34 is rotated by the drive gear 35 and, when rotated faster or slower than the guide cylinder 30 it causes the grips 14 to move in or out of contact with the tool joint upset.
The collet cylinder 32 is rotated by the collet cylinder drive gear 33, and it can have the same internal profile as the grips drive cylinder 34. It is required to act separately from the drive cylinder, since the collets 13 are actuated before the tool joint lands and after it departs. The purpose of the collets 13 is to retain the drill string 3 in place by acting on the taper 19 at the upper end of the riser 11. In general it is not applying pressure, only when there is an upward force applied to the tubulars 2 on the top side of the pressure chamber. Of course, the lower collets 18 act likewise for downward force of the tubulars 2 below the pressure chamber 5.
Regarding the sequence of operation, the collets 13 of the drill string drive are moved into place and locked in place in the ports 44, before the tool joint upset 11 is landed on the collets 13 to interfere with the upset shoulder of the tool joint. The drive cylinder 32 for the collets is independent of the grips drive cylinder 34, thereby making the motion of the collets 13 independent of the motion of the wedges or grips 14. Because the shoulder of the box upset 11 is only 20°±2° to the vertical, the mounting of collets 13 in the drill string drive is allowed to move laterally, just sufficiently to allow the drill string to be subsequently centralized by the grips 14, thus allowing the gripping force between the grips to balance out.
In the case of the collets 13 of the snubber, these are moved into place after the drill string 3 has landed on the collets of the drill string drive 9 before disconnections, or after a new tubular 2 is inserted into the snubber 10. In either case, the snubber 10 may move downwards to allow the collets 13 to engage the shoulder of the pin tool joint upset, before all of the grips 14 and seals are actuated to engage the tool joint upset 11.
Since the seals, grips and collets need to be replaced when worn, and because of the limited travel required, they are devised as replaceable inserts, which are sized to suit each particular drill pipe size 168 mm, 152 mm, 149 mm, 140 mm, 127 mm, 114 mm, 102 mm, (and even 89 mm, 73 mm, & 67 mm). This allows the apparatus 1 actuation to be a modest fixed travel for all the seals and grips of ˜19 mm (plus up to 6 mm for any tool joint upset wear); and 25 mm for the collets; regardless of the drill pipe size from 67 mm to 168 mm (being tool joint upset diameters of 89 mm to 102 mm).
It will be appreciated that in various embodiments there is a drive cylinder with a wedging internal profile which rotates relative to the grips, such that the grips are forced inwards or retracted outwards. This relative rotation may be provided as shown by drive gears 35 or by a concentric guide cylinder or concentric guide discs guiding the grips, or by chain. This provides a compact and simple mechanical actuation, which: minimises the volume and weight of the pressure chamber 5; minimises the diameter of the pressure vessel and therefore minimises the force necessary to snub the tubular and drill string into the pressure vessel.
It will also be appreciated that the collets, grips and seals can be easily removed for inspection and replacement by sliding out of the keyways shown 38 and 42 and may also be sized to perfectly suit each size of tool joint upset dimensions. The travel of these collets, grips and seals from their retracted positions to contact with the tool joint upsets is therefore minimised to less than 25 mm, including the additional travel when the tool joint upset is worn. These replaceable collets, grips and seals can therefore accommodate most tool joint sizes.
The apparatus minimises the travel of the seals, grips and collets, so that inserts can be used appropriate to each standard tool joint size plus moderate wear; minimises the bore 22 of the blind ram or valve 7; and minimises the travel 23 of the pin 11 from the box 12; and minimises the height, weight, complexity and cost of the drilling apparatus 1.
The sealing between the pressure chamber 5 wall, which contains the blind ram or valve 7, and the upper snubber 10 above and the lower snubber or drill string drive 9 below, can be effected using piston ring technology 49, as developed for marine diesel engines, not hitherto applied to drilling equipment.
When the guide and drive components in the upper snubber 10 rotate at the same speed, the collets, grips and seals in the upper snubber do not move radially. Likewise, when the guide and drive components in the drill string drive 9 rotate at the same speed the collets, grips and seals in the drill string drive do not move radially. However in both cases when there is a difference in rotation between the guide and drive components, the collets, grips or seals are actuated to move radially.
This travel of the pin out of and away from the box of approximately 203 mm is shared between the vertical movement of the pressure chamber wall relative to the drill string drive of approximately 102 mm and the movement of the snubber relative to the pressure chamber of approximately 102 mm.
Because the gripping mechanism of the invention is applied to the tool joint upset 11 instead of to the tubular shafts or bodies 2, the gripping force to achieve sufficient torque to rotate the drill string plus break a connection may be increased to 108 k Nm or even 136 k Nm, compared to conventional torque of some 88 k. This will be limited by the hoop strength of the drive cylinder and torsional strength of guide cylinder or discs, and the power limit of the gear train, for which special high strength materials may usefully be chosen.
The grips 17 of the drill string drive 9 are positioned to grip the box tool joint below the threaded parts. (of some 127 mm) to minimise distortion of the threads, which could otherwise overly affect the necessary breaking and intended making up torques.
The simple mechanical drive cylinder and guides concept significantly minimises the number of components and/or moving parts, which should also increase reliability and minimise cost.
To achieve continuous drilling, the drill bit will be able to drill ahead during connections at a known constant “WOB” (weight on bit) by either lowering the drilling apparatus during connections or, particularly when applied to existing drilling rigs, where the available height is limited, inserting an extending sub or tubular, (Xsub), in the drill string close to the neutral point, being approximately above, or close to the top of, the drill collars or the HWDP (Heavy Weight Drill Pipe) section, which is addressed in a separate patent.
Choosing high strength materials to apply sufficient gripping, with the grips (curved wedge) radial dimension from 19 mm to 44 mm and the drive cylinder varying in thickness from 19 mm to 57 mm, the internal diameter of the pressure chamber may be reduced to approximately 356 mm, which would reduce the snubbing forces to 344 tonnes (at 345 bar drilling fluid operating pressure) or 516 tonnes (at 517 bar).
The seals, grips and collets are preferably equally spaced around the tool joint, there being two or more of each (preferably three of each as shown in illustrations). Though some compliance in the mounting of the collets and their drive cylinders, will enable the grips to subsequently centralize the tubular and drill string prior to connection or disconnection and balance the gripping forces.
In one mode of use, first the lower collets 18 are closed so that the next box tool joint upset shoulder (17b) can ‘land’ on them, thus zeroing the distances of the grips, seals, valve and collets above to match the tool joint dimensions. Once landed the upper collets 13 close and move down to find the pin tool joint upset shoulder 19. Then all grips and seals move inwards to contact the joint upset 11. Then the pressure chamber 5 fills with drilling fluid up to the circulating pressure and the tool joint can be broken, separated and the valve closed, so that the upper chamber can be de-pressured, opened and a new tubular inserted.
An alternative drilling apparatus, 70, with a gripping mechanism of the upper snubber and the lower snubber is shown in more detail in
The overall height is about 1100 mm,
The guide cylinders of the apparatus 1 may be replaced by guide rings, above and below the grips drive cylinder wedge profile. The pressure chamber bore may be reduced to about 230 mm plus the drive cylinder width, which needs to be the depth of the wedge profile ˜38 mm, plus sufficient width to contain the hoop stress ˜32 mm, plus a sealing distance of some 6 mm; reducing the pressure chamber bore to 381 mm, which may, if extra strength materials are used, be reduced to 356 mm.
The collet 51 width of 51 mm to 76 mm is adequate to transfer the high snubbing force on to the apparatus body and, in the case of the drill string drive, the collets support the entire drill string weight. The guide rings 71 are adequately strong to force the grips into wedging contact between the tool joint upset and drive cylinder profile, or to break such wedging contact. The drive cylinder 72 is strong enough to withstand the high hoop stress of the wedging action. The guide rings 71 are connected structurally or, as shown, by gears 76 on a shaft 85 to ensure that the forces on the top and bottom of the grips 75 are balanced.
Referring back to
The further reduction in size provided by the apparatus 70 is illustrated in
It should be emphasised that the geometry is such that the locii of the centres of curvature of the drive cylinder profile and the grips profile are not the same but close enough to be accommodated in the design of the guides of the guide cylinder. Using 120° (⅓ of the rotary plane) per grip (if three grips are used) and using the 1 in 6 gradient, the radial travel of each grip of ˜25 mm is more than adequate to allows for the reduced diameter of a worn tool joint.
It also allows for rotating the cylinders relative to each other by an extra 10° or so to allow the collets, grips and seals to be released from the keyways in the drive cylinders, for inspection or replacement.
It will be appreciated that the invention provides a drilling apparatus for allowing continuous circulation and rotation while adding or removing tubulars from a drill string during the drilling of a well. The collets act on the shoulders of the tool joint upset and positively snub the tubular and drill string into a pressure chamber, grips to grip the tool joint upsets and transmit torque to make or break tool joint connections, seals to seal the tool joint upsets into the pressure chamber, blind ram or valve to separate the upper and lower parts of the pressure chamber.
The collets, or grips or seals are actuated by a mechanical system which is simple and compact, to minimise the pressure chamber size and weight, the snubbing forces, the number of components, moving parts, and cost. The drive cylinder with a wedging internal profile, when rotated relative to the rotating collets, forces them inwards to support, contact or grip the tool joint upset. Such relative rotation is effected by the drive cylinder rotating relative to a concentric guide cylinder, which is restraining the collets, grips or seals.
There may alternatively be guide discs or rings replacing the guide cylinder to guide the collets, grips or seal and achieve the relative motion with the drive cylinder that achieves or relieves the wedging actuation and thus further reducing the internal diameter of the pressure chamber and the drilling apparatus The collets, may be held in place with keys sliding in keyways in the sloping or wedging face of the drive cylinder. The collets may be released if, by rotation, the keys are released from the said keyways and thereby enabling collets, grips or seals to be easily removed for inspection or replacement. The collets may be sized to suit the range of tool joint upset dimensions of the typical range of drilling tubular sizes. The required tool joint separation of the pin from the box may be shared between an axial motion of the snubber, which is an upper snubber, relative to the pressure chamber and an axial motion of the pressure chamber relative to the drill string drive, which is a lower snubber.
The seals may be connected to the grips and moved into or out of place by the movement of the grips and in which the seals can be further actuated by the drilling fluid pressure. The sealing between the upper and lower snubbers and the pressure chamber may be effected by piston ring technology. Also, there may be an extended jacking motion of either of the two snubbers relative to the pressure chamber, sufficiently to separate them by some 152 mm to enable the collets, grips or seals to be easily replaced.
It will be appreciated that the invention achieves the benefits of:
It will also be appreciated that drilling apparatus of various embodiments of the invention that have a gripping mechanism with a radially-moving wedge-shaped gripper (a “radial wedge”) enables some or all of the following:
The invention is not limited to the embodiments described but may be varied in construction and detail.
| Number | Date | Country | Kind |
|---|---|---|---|
| 14171029.3 | Jun 2014 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/061237 | 5/21/2015 | WO | 00 |
