Snubbing units were primarily designed to work in well control situations to “snub” drill pipe and or casing into, or out of, a well bore when conventional well killing methods could not be used. Unlike conventional drilling and completions operations, snubbing can be performed with the well still under pressure (not killed). When done so, it is called hydraulic workover which can also be performed without having to remove the Christmas tree from the wellhead.
Typically, a minimum of four slip bowls are used in snubbing operations. Two slip bowls are designated for “pipe light” operations, ones where the well bore forces are greater than the tubular weight in the well bore. The other two slip bowls are designated for “pipe heavy” operation, one which occur when, e.g., enough pipe has been snubbed into the well bore and fluid weight inside of the pipe is greater than the snub forces acting against the pipe in the well bore. Traditional slip bowls can only hold pipe load in one direction, require jack force or pipe weight to generate clamping force, require reversed pipe motion to unseat the clamp on the pipe, have no method of measuring the pipe weight being held by the slip bowl, rely on serrated toothed inserts that mechanically bite and mark the pipe, and are not used subsea.
In addition, traditional snubbing jacks are not used subsea, use hydraulic power to drive hydraulic jacking cylinders, use mechanical and/or hydraulic interlocks, and do not have leg motion misalignment measurement and control, relying instead on equalizing pressure across cylinders. Further, traditional snubbing jacks use hydraulic circuits to control jack leg and slip bowl, use hydraulic power to drive hydraulic jacking cylinders, use mechanical and/or hydraulic interlocks, and do not have leg motion misalignment measurement and control, relying instead on equalizing pressure across cylinders.
However, using direct hydraulic drive is not practical in deeper water; very high pressure is required or heavy walled cylinders, high hysteresis circuit losses leading to poor system response
Various figures are included herein which illustrate aspects of embodiments of the disclosed inventions.
Generally, referring generally to
In a first embodiment, still referring generally to
In embodiments, two jack legs 20a, 20b of the plurality of jack legs 20 are disposed diagonally with respect to each other and the diagonally disposed pair of jack legs 20 are configured to perform redundantly in that either diagonal pair 20a, 20b can perform a desired snubbing operation and either can be disengaged while still in operation on the well should there be a jack leg failure. In certain of these embodiments, the diagonally disposed pair of jack legs 20 is configured to be disengaged while still in operation on the well should there be a jack leg failure of one of the diagonally disposed pair of jack legs.
In most configurations, first slip bowl 34 and second slip bowl 32 can hold light or heavy pipe loads and are adapted to create a clamping load internally, do not rely on pipe weight or the force of the subsea jack to develop clamping force, and do not require pipe motion to unseat the clamp on the pipe. Typically, at least one of first slip bowl 34 and second slip bowl 32 can traverse bi-directionally within the plurality of jack legs 20. Typically, first slip bowl 34 is fixed within the plurality of jack legs 20 and second slip bowl 32 travels within the plurality of jack legs 20 such as by having second slip bowl 32 slidingly connected to the plurality of jack legs 20. Where second slip bowl 32 is slidingly connected, traveling bracket 52 may be present and connected to first end 21 of the plurality of jack legs 20 and to second slip bowl 32 and fixed bracket 14 connected to second end 23 of the plurality of jack legs 20 distally from traveling bracket 52 and to first slip bowl 34.
Referring additionally to
Referring back to
Referring now to
Although illustrated as being deployed proximate well 200 and operatively connected to subsea assist snubbing jack via comm link 83, electronic controller 84 can be located proximate to, collocated with, or as part of control system 80 at a location that is not subsea.
Referring back to
In certain embodiments, subsea assist snubbing jack 1 further comprises one or more control interfaces 40 and control system 80 (
Subsea assist snubbing jack 1 may further comprising a predetermined set of smooth faced inserts 70 that do not mark a pipe.
As one of ordinary skill in snubbing jack art can discern, using direct hydraulic drive is not practical in deeper water; the very high pressure required or heavy walled cylinders, high hysteresis circuit losses lead to poor system response. As can be discerned, subsea assist snubbing jack 1 can be used and is therefore practical for use in deeper water. In embodiments, subsea assist snubbing jack 1 uses power screw and “nut” system as a jack leg and use one or more subsea electric motors to power the screws.
The foregoing disclosure and description of the inventions are illustrative and explanatory. Various changes in the size, shape, and materials, as well as in the details of the illustrative construction and/or an illustrative method may be made without departing from the spirit of the invention.
This application claims priority through U.S. Provisional Application 62/924,048 filed on Oct. 21, 2019.
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Number | Date | Country | |
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20210140261 A1 | May 2021 | US |
Number | Date | Country | |
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62924048 | Oct 2019 | US |