Boring or penetrating the earth – With tool shaft detail
Reexamination Certificate
1999-07-26
2001-02-13
Puzzuto, Robert E. (Department: 3671)
Boring or penetrating the earth
With tool shaft detail
C166S242600
Reexamination Certificate
active
06186249
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a release equipment or accessory for a rotating drill string, said drill string release accessory being adapted for activation in order to release and disengage the drill string, e.g. upon a wedged bit situation or other situations where an accessory is stuck in a bottom hole position.
At high drilling speeds, e.g. 100 meters per hour, there exists a particularly great risk for the bit to get wedged and stuck in the formation in which drilling is carried out. There are examples where several thousand metres of drilled hole have been lost in connection with such wedged and unsuccessful drill string release situations. When such situations arise, it is important to have the drill string released as rapidly as possible and, thereafter, to return to ordinary drilling without having lost too much old bore hole.
If the bit wedges itself or get stuck in some other way in the formation in which drilling is carried out, one will, at first, try to pull the bit free in an upward direction, by means of the drill string. Often, this cannot be done and, therefore, in order to get the drill string released, explosives in the form of an explosive charge suspended from a wire are pumped down to the place where the bit is wedged, in order to free the stuck bit through blasting to pieces a drill string portion above the stuck bit.
Thus, conventional and other known technology comprises, first of all, the use of explosives and the utilization of blasting technique. Primarily, this is time-consuming because it takes time to mobilize accessories and personnel. Additionally, the blasting in itself represents a risk moment, namely upon unintentional blasting to pieces the surrounding formation and destructing old bore hole.
SUMMARY OF THE INVENTION
According to the present invention, one has aimed at providing a release device adapted to be coupled into a drill string in order to, using simple and cheap means as well as non-complex operational steps, enabling the release of the bit or other bottom hole equipment, respectively, avoiding the large time delays associated with the prior art.
In accordance with the invention, this is realized by means of a drill string release piece such shaped and designed that it exhibits the following features of a splined locking piece to be joined into a drill string to couple and uncouple a pair of locking sleeves by engaging mating splines in the locking sleeves. The splines of the locking piece are locking members comprising straight, axially extending grooves and intermediate, straight, axially extending, list-shaped projections that exert no wedging effect. The locking members of one sleeve part in the end portion thereof, extend from a radial contact face common for the two sleeve parts, axially away therefrom. The other sleeve part's locking members extend in the opposite direction, axially away therefrom. The locking members of the locking device are gathered in a toothed rim-like portion on the locking device. One sleeve part's straight, axially extending grooves are axially aligned with the other sleeve part's straight, axially extending grooves and also aligned with the locking device's straight, list-like projections, while said one sleeve part's straight, list-like locking members are axially aligned with the other sleeve part's straight axially extending projections, and the locking device's straight, axially extending grooves. One axial end of the tubular, locking device has a seat for a ball-shaped sealing body for closing the through-going bore, in order to establish sealing conditions to enable hydraulic exertion of force against ball and seat in order to cause an axially directed displacement of the locking device for the purpose of releasing the two sleeves.
Such a release piece is elongated and has a longitudinal symmetry axis. It comprises two at adjacent end portions interscrewable sleeve parts having coaxial, axially through-going bores and each, at the opposite end thereof, is shaped in order to be connected to an opposing end portion of an upstream drill string section and an end portion of a downstream drill string section extending down to the bit, respectively.
The elongate release piece may be positioned in the neighbourhood of the bit or other bottom hole equipment.
If right-hand threads have been chosen for adjacent, interscrewable drill pipe sections incorporated in a drill string, preferably left-hand threads are chosen for the threaded connection between the release piece's two screwable/unscrewable sleeve parts.
In the release piece is, as an essential component, included a locking device comprising locking means cooperating partly with locking means associated with one sleeve part, partly with locking means associated with the other sleeve part, a force-exerting means, preferably a spring, e.g. a pressure spring in the form of a screw spring, maintaining the locking device in the locking position and, thus, the cooperating locking means in mutual engagement until it intentionally is created a counter force which is larger than the holding force yielded by said pressure spring.
The locking device of the release piece may have the form of a separate, elongate, tubular element having an axially through-going bore. The locking means thereof may consist of an axially directed roller having a gear wheel-like cross-sectional shape, exhibiting parallel, longitudinally extending grooves equidistantly distributed circumferentially and intermediate, list-shaped projections (teeth). In principle, the locking device of the release piece comprises at least one longitudinal projection and/or at least one longitudinal groove.
Then, the locking device's at least one longitudinal projection/groove will cooperate with one locking means in the form of a longitudinal groove/projection assigned each of the sleeve parts, but it is preferred that the locking device as well as each of the sleeve parts have several parallel locking means in the form of longitudinal grooves and therein engaging, substantially complementary projections, preferably equidistantly distributed around the circumference of the locking body of the locking device and with locking means disposed along the internal circumference of cavities in the screwing area, for said locking body.
One of these cavities has a radially directed stop face against which one end of said spring rests supportingly.
The tubular locking element/device is axially displaceably mounted in the aligned bores in the sleeve parts, the locking means of the locking body are being kept in engagement with corresponding locking means internally assigned the sleeve parts which are screwed together, said spring acting as a force-exerting safety means which secures the mutual engagement of the locking means and, thus, the the locking action.
In a drill string having a release device of the invention mounted therein, positioned just above the bit, and where the drill string is rotary, the upstream portion (above the bit) of the drill string may rapidly and simply be released from the stuck bit through the release device according to the invention, in the following way:
One end of the tubular locking device, i.e. the upper end in the position of use, is, preferably, formed with a circumferential, upwardly facing seat for a ball-shaped body having a somewhat larger circumference than that of the seat, or a similarly shaped and dimensioned closure means, e.g. a plug, which can be dropped from a surface position.
After said ball has landed in the upper seat of the tubular locking device, the pump pressure—representing a counter force acting against the spring—is increased to exceed the spring force. Thus, the spring is compressed, allowing displacement of the locking device. Upon this displacement of the tubular locking device in the downstream direction, the locking engagement between locking means assigned to the upstream sleeve part and locking means assigned to the locking device is neutralized. The axial length of e
Knobbe Martens Olson & Bear LLP
Puzzuto Robert E.
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