Boring or penetrating the earth – With below-ground tool drive prime mover – With positive connection between tool and support shaft for...
Reexamination Certificate
1998-12-04
2001-03-06
Tsay, Frank (Department: 3672)
Boring or penetrating the earth
With below-ground tool drive prime mover
With positive connection between tool and support shaft for...
C175S171000, C175S257000
Reexamination Certificate
active
06196336
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method of and an apparatus for drilling a borehole in underground formations with at least one formation that has a significantly different formation pressure than an adjacent formation or where time dependent unstable formations do not allow sufficient time to case off the hole in a subsequent run.
BACKGROUND OF THE INVENTION
A collapsed hole adds great expense to the drilling of a wellbore and can lead to the abandonment of the hole. Hole collapse can be caused by a number of drilling conditions including shale swelling, sloughing, and unconsolidated sands that cause a hole to wash out or collapse as soon as it is drilled. In these unstable formations, the bore hole can not be cased off and protected in time, when running a liner in a subsequent run after the hole was drilled.
Another cause of wellbore/hole collapse is an extreme pressure drop between adjoining formations. Drilling into a low pressure formation with a heavy mud that is designed to drill through an overlying high pressure zone will result in severe mud losses and simultaneous hole collapse. An opposite situation is encountered when a borehole is drilled through a first formation having a low formation pressure into a formation of substantially higher formation pressure, then there is the danger of fluids from the lower formation entering the borehole and damaging the upper formation. If the pressure difference is large enough, there is a risk of a blowout. If the mud weight is increased to prevent such a blowout, then the mud can damage the low pressure formation.
There is a need for an apparatus and method of drilling boreholes that avoids these problems. Such an invention should preferably reduce the operational time in its use. It should preferably be adaptable for use with directional drilling systems. It should reduce the exposure of the formations to the dynamic circulation pressure of the drilling mud and thereby reduce formation damage. A further desirable aspect is ro reduce the likelihood of getting stuck in the borehole. In addition, if the apparatus does get stuck, it should be possible to continue drilling ahead. The present invention satisfies this need.
SUMMARY OF THE INVENTION
The present invention is an apparatus and method for drilling through formations in which the pressure is significantly different from the pressure in the adjacent formations, and/or unstable formations make it difficult to protect the formation with a liner or casing in the hole. The drilling liner system consists of an inner string carrying an inner assembly having a pilot bit, and an outer assembly having a core bit. Both assemblies are temporarily connected via retractable splines that ensure that the inner and outer assemblies are properly aligned with each other. When running in the hole, the splines are retracted and, upon reaching the proper alignment, extend automatically. After the liner is set, the process of pulling the inner string from the liner forces the splines to retract once again. One embodiment of the invention is a system in which there is no inner string between the bottom hole assembly and the liner hanger. Besides eliminating the trip time for the inner string, this makes it possible to fish the bottom hole assembly out of the hole with a jointed pipe or a wireline. Another embodiment of the invention has a steerable drilling liner, the steering being accomplished by a tilted joint, or with steering pads. Another embodiment of the invention has a sealed annulus between the open hole and the liner. This isolates the open hole from the dynamic pressure of the circulating mud system. Yet another embodiment of the invention incorporates a reamer on the outer part of the liner to enlarge the hole and thereby reduce the risk of getting stuck. An expandable core bit or pilot bit may be used to provide a similar result. Another embodiment of the invention makes it possible to do some additional drilling even after getting stuck. In another embodiment of the invention, high pressure jetting nozzles are used with the pilot bit to enlarge the hole and reduce the risk of getting stuck. Instead of drilling pipe, the drilling liner can be used with coiled tubing.
REFERENCES:
patent: 3732143 (1973-05-01), Joosse
patent: 3901331 (1975-08-01), Djurovic
patent: 4281722 (1981-08-01), Tucker et al.
patent: 4842081 (1989-06-01), Parant
patent: 5074366 (1991-12-01), Karlsson et al.
patent: 5186265 (1993-02-01), Henson et al.
patent: 5197553 (1993-03-01), Leturno
patent: 5472057 (1995-12-01), Winfree
patent: 6024168 (2000-02-01), Kuck et al.
patent: 3839 760 (1990-01-01), None
patent: 3902 868 (1990-06-01), None
patent: 0 265 344 (1988-04-01), None
patent: 0 462 618 (1991-12-01), None
Fincher Roger
Hahn Detlef
Makohl Friedhelm
Watkins Larry
Baker Hughes Incorporated
Madan Mossman & Sriram P.C.
Tsay Frank
LandOfFree
Method and apparatus for drilling boreholes in earth... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for drilling boreholes in earth..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for drilling boreholes in earth... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2467212