Boring or penetrating the earth – With below-ground tool drive prime mover
Reexamination Certificate
2000-09-01
2001-11-06
Pezzuto, Robert E. (Department: 3671)
Boring or penetrating the earth
With below-ground tool drive prime mover
C175S215000
Reexamination Certificate
active
06311791
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a hydraulic underreamer and improved sections for use therein.
A hydraulic underreamer is used to hydraulically wash out or more typically enlarge a wellbore extending through a subterranean formation to thereby create a cavity in the formation. Hydraulic underreaming can be applied to a coal formation (“coal seam”) to enhance the production of methane flowing from fractures (“cleats”) in such a formation, or to other formations in which enlargement of a wellbore is desired.
One type of hydraulic underreamer includes: a packer section for sealing against a well casing so as to isolate an annulus above the packer section as defined between the casing and a work pipe; a cutting section for hydraulically enlarging a wellbore below the casing to thereby produce a mixture of liquid and formation fragments in the resulting cavity; and a jet pump section for pumping mixture from the cavity for passage through the above-mentioned annulus to the surface.
SUMMARY OF THE INVENTION
It is an object of the invention to provide improved packer, cutting, and jet pump sections, as well as a novel mill section, for use in a hydraulic underreamer.
A packer section is provided which comprises: a tubular drive bushing having an upper end and a lower end; a tubular packer mandrel having an upper end and a lower end, the packer mandrel being mounted on the drive bushing with the packer mandrel lower end being closely adjacent to but not connected to the drive bushing upper end so that the drive bushing may rotate while the packer mandrel remains stationary; at least one tubular sealing element received on and around the packer mandrel; a tubular drive mandrel defining a packer section central bore therethrough and substantially coaxially extending through the drive bushing and packer mandrel so as to define a packer section annulus, the tubular drive mandrel being fixedly connected to the drive bushing so that rotation of the drive mandrel rotates the drive bushing.
A cutting section is provided which comprises: an outer pipe; an inner pipe defining a cutting section central bore therethrough and extending substantially coaxially through the outer pipe to define a cutting section annulus between the inner and outer pipes; a cutting nozzle housing extending through the cutting section annulus between the inner and outer pipes so as to be fixedly connected thereto, the cutting nozzle housing having an inlet portion in communication with the cutting section central bore and also having an outlet portion; a baffle mounted in the housing inlet portion; and a cutting nozzle mounted in the housing outlet portion.
A jet pump section is provided which comprises: a body having a longitudinal axis, a longitudinally extending pump section central bore with an upper end defining an inlet and a lower end defining an outlet, and a plurality of turn chambers circumferentially spaced around the pump section central bore, each turn chamber having at least one inlet passageway, in communication with the pump section central bore, and also having an outlet; a plurality of ejector nozzles corresponding to the plurality of turn chambers such that each ejector nozzle has an inlet in communication with a corresponding turn chamber outlet, each ejector nozzle also having an outlet; a plurality of venturis corresponding to the plurality of ejector nozzles such that each venturi has an inlet aligned with but spaced above a corresponding ejector nozzle outlet, each venturi also having an outlet; wherein the body further has defined therein a diffusion chamber surrounding the pump section central bore, the diffusion chamber having a plurality of inlets in respective communication with the venturi outlets and also having a substantially annular outlet adjacent to the inlet of the pump section central bore.
A mill section is provided which comprises: a tubular bit sub having an upper end and a lower end; a tubular primary mill having an upper end, removably connected to the bit sub lower end, and also an abrasive lower end; and a center assembly having a passageway therethrough and adapted to be received in a mill section central bore defined in the bit sub and primary mill, wherein the center assembly includes (i) a locking mandrel having an upper end and a lower end and being selectively lockable in the mill section central bore, (ii) a center mill having an upper end removably connected to the locking mandrel lower end and also having an abrasive lower end adjacent to the primary mill lower end when the locking mandrel is locked in the mill section central bore, and (iii) a mill nozzle connected to the center mill lower end so as to be in communication with the center assembly passageway.
There is also provided a hydraulic underreamer comprising the above-described sections, as well as an intermediate section, connected together in a string in a manner further described below.
Operational advantages of this invention are discussed in the context of preferred embodiments in the Detailed Description of the Invention.
REFERENCES:
patent: 4296970 (1981-10-01), Hodges
patent: 4934466 (1990-06-01), Paveliev et al.
patent: 5366030 (1994-11-01), Pool, II et al.
patent: 5494108 (1996-02-01), Palmer et al.
patent: 5505262 (1996-04-01), Cobb
Fraim Michael L.
McCoy Stephen D.
Cross Ryan N.
Pezzuto Robert E.
Phillips Petroleum Company
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