Wells – Receptacles – Lateral ports used in well
Reexamination Certificate
2000-03-03
2001-09-18
Schoeppel, Roger (Department: 3672)
Wells
Receptacles
Lateral ports used in well
C166S175000, C166S223000, C166S334400
Reexamination Certificate
active
06289987
ABSTRACT:
BACKGROUND—FIELD OF THE INVENTION
This invention relates generally to downhole tools used in the oil and gas industry. With further specificity, this invention relates to an improved design of tool adapted to be run downhole in a wellbore being drilled, especially a wellbore drilled from a floating vessel, to permit the pumping of fluids (typically drilling muds) through the tool directed toward the sides of the wellbore and downhole equipment such as a wellhead or blowout preventer assembly, to effect cleaning of the equipment surfaces.
BACKGROUND—RELATED ART
Although earthen boreholes may be drilled for a variety of reasons, in particular many are drilled for oil and gas exploration and production. Typically, drilling fluid or “mud” is pumped downhole through the drillstring, through the drill bit and back to surface, to remove “cuttings” (which are the pieces of earth removed in the drilling process) and perform other functions such as downhole pressure control, cooling of the drill bit, etc. Depending upon the formations being drilled, the cuttings may be very sticky, as in the gumbo mud regions of the Gulf Coast, and often tend to stick onto and accumulate on the inner surfaces of downhole equipment, including the casing strings, wellheads, blowout preventers, and the like.
Increasingly, wells are being drilled offshore in water depths requiring floating drilling rigs, either semi-submersibles or drill ships. With a floating drilling vessel, a large diameter “riser” connects the drilling rig to a subsea blowout preventer stack, and thereby to a subsea wellhead, which rests on the ocean floor. The subsea wellhead has an inner profile to accommodate casing “hangers” or spools attached to the upper ends of casing strings, and which seat in the subsea wellhead or in the profiles of previously-run hangers of the larger casing strings. It will be readily understood that it is necessary to have a clean seating profile, that is, free of adhered drill cuttings, gumbo mud and the like, in order to present a seating profile which will accept a later-run casing hanger, and ensure proper seating, pressure sealing, etc. In addition, blowout preventers must be periodically pressure tested to satisfy safety tests and regulatory requirements. To pressure test blowout preventers, a test plug must be seated in the subsea wellhead to provide a seal against which to pressure up and verify that blowout preventer rams and annular preventers are properly functioning.
It is therefore desirable to have a means by which downhole equipment, including but not limited to subsea blowout preventer stacks and subsea wellheads, may be cleaned of adhering drill cuttings and the like.
Prior art apparatus and methods have included the use of downhole brushes, manipulated across from the area to be cleaned, to mechanically dislodge any adhering cuttings, etc. Other prior art methods have employed the use of tools generating a stream of drilling fluid pumped under high rates and/or pressures, and directed toward the sides of the wellbore or downhole equipment. The fluid impinges upon the surface, dislodges any accumulated material, and thereby cleans the downhole surface. It will be appreciated, then, that delivering the fluid with maximum velocity, and consequently force, against the surface to be cleaned, is of key importance. Further, as wash tools are employed downhole at times and are at times subject to rough treatment, it is further desired that the tool be of rugged construction. Further still, wash tools should be adapted to closely match the profile of the wellbore surfaces being cleaned, once again to permit at least some mechanical cleaning of the surface, centralize the tool in the wellbore, and the like.
Such prior art downhole wash tools have been of various simple designs, such as merely a partial joint of tubing or drill pipe blanked or closed off at its lower end and having a number of holes drilled in the wall of the pipe, so that drilling fluids pumped therethrough must exit the tubing or drill pipe, and be directed toward inner surfaces of downhole equipment. Such tools lack effectiveness for a number of reasons: the tool is poorly centered in the wellbore; the wash stream of fluid is not properly focused; and the outlet of the wash port is (relatively speaking) a significant distance from the surface to be cleaned, so that much velocity and consequently energy is lost. Another design of wash tool is shown in U.S. Pat. No. 5,839,511 to Williams, which has outwardly extending (apparently non-integral) blades and offset (not concentric with the blades) wash jets, and further combined (in at least one embodiment) with brushes.
However, the known prior art does not disclose a downhole wash tool of unitary construction, having integral outwardly extending blades, with wash ports extending from a central, longitudinal bore of the tool through the blades to their outermost faces, thereby placing the port outlets close to the surface of the equipment being cleaned, and delivering the fluid with great force. Further, the known prior art does not disclose such a downhole wash tool having an outer profile closely matching the inner profile of the equipment into which it will be run.
REFERENCES:
patent: 3720264 (1973-03-01), Hutchison
patent: 3811499 (1974-05-01), Hutchison
patent: 3850241 (1974-11-01), Hutchison
patent: 4088191 (1978-05-01), Hutchison
patent: 5033545 (1991-07-01), Sudol
patent: 5327974 (1994-07-01), Donovan et al.
patent: 5735359 (1998-04-01), Lee et al.
patent: 5839511 (1998-11-01), Williams
Lambert Jesse D.
Schoeppel Roger
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