Boring or penetrating the earth – Processes – Boring curved or redirected bores
Patent
1991-05-01
1992-05-19
Neuder, William P.
Boring or penetrating the earth
Processes
Boring curved or redirected bores
175 73, 175 76, E21B 708
Patent
active
051139537
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a directional drilling apparatus and method.
When drilling oil and gas wells for the exploration and production of hydrocarbons, it is very often necessary to deviate the well off vertical and in a particular direction. Such deviation may be required, for example, when drilling from land to explore formations beneath the sea or below a lake, or in the case of oil and gas production offshore, when drilling 20 or 30 wells from the same platform, each going in a different direction to gain the widest coverage of the hydrocarbon bearing structure. The latter can result in wells being as much as 3 to 4 miles apart at the point where they pass through the production zone.
Procedures for deviating wells have improved greatly over recent years with the introduction of powerful and reliable downhole motors and downhole turbines, and the introduction of Measurement While Drilling (MWD) techniques.
Use of a downhole motor or turbine allows the hole to deviated by the introduction of a fixed offset or bend just above the drill bit and this offset or bend can be oriented by means of the MWD system which is capable of giving toolface (direction of fixed offset or bend) hole angle and azimuth, all in real time
Consequently, it is possible to rotate the drill string slowly until the toolface is in the desired direction of deviation, stop rotating the drill string with the toolface pointing in the desired direction, then start the motor or turbine to extend the hole in the desired deviated direction.
There are however a number of inherent problems in this approach to directional drilling, namely: place, giving rise to the disadvantages of greater likelihood of getting stuck due to differential sticking, and difficulty in transferring weight to the bit due to drag on the static drill string; normally every 30 feet at the singles change (the addition of a new length of drill pipe), giving rise to the disadvantages that shift of tool face due to reactive torque of motor or turbine can only be identified after the shift has occurred, and correction of undesired hole angle change can only take place every 30 feet at the least.
In order to obviate or mitigate these problems which currently cost oil companies millions of dollars per year, it is an object of the invention to provide directional drilling apparatus and method whereby the offset or bend (toolface) can be created dynamically such that the drill string may be rotated whilst maintaining the toolface in a set direction. There is preferably also an ability to change the toolface direction whilst the drill string is rotating, in order to correct any deviation of hole caused by external influences e.g. formation change, or dip angle etc.
According to a first aspect of the present invention there is provided directional drilling apparatus for deviating a drill bit on the lower end of a drill string substantially in a selected direction, said apparatus comprising upper end coupling means for coupling the upper end of said apparatus to the lower end of the drill string, lower end coupling means for coupling of the drill bit to the lower end of said apparatus, force coupling means linking said upper and lower end coupling means for transmission of torsional and axial forces therebetween such that torque applied to said drill string in use of said apparatus is transmitted to the drill bit coupled to said lower end coupling means in use of said apparatus while axial downthrust or uplift applied to said drill string is transmitted to the coupled drill bit, said force coupling means further allowing the rotational axis of said lower end coupling means to be omni-directionally deviated with respect to the rotational axis of said upper end coupling means and the rotational axis of said drill string in use of said apparatus, characterised in that said apparatus comprises rotatable deviation direction control means for deviating the rotational axis of said lower end coupling means with respect to the rotational axis of said upper end coupling means in a direct
REFERENCES:
patent: 3743034 (1973-07-01), Bradley
patent: 4577701 (1986-03-01), Dellinger et al.
patent: 4667751 (1987-05-01), Geczy et al.
patent: 4697651 (1987-10-01), Dellinger
patent: 4811798 (1989-03-01), Falgout, Sr. et al.
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