METHOD AND APPARATUS FOR RETAINING WEIGHTED FLUID IN A TUBULAR SECTION
First Claim
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1. A HOP assembly for a fluid filled casing string comprising:
- a housing configured to attach to said casing string wherein said housing contains an adjustable one-way check valve, wherein hydrostatic forces resulting from fluid inside said casing string creates a pressure differential across said adjustable one-way check valve and said one-way check valve supports said hydrostatic forces such that it prevents fluid flow up to a first predetermined pressure differential so as to retain said casing string in a fluid filled state and wherein said one-way check valve is adjustable such that said first predetermined pressure differential can be increased or decreased.
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Abstract
A floating apparatus for use in a casing string and especially for use in offshore casing operations. The apparatus includes a valve configured such that, when there is a pressure differential across the valve below a predetermined mid-pressure threshold, the valve prevents fluid flow and, when the pressure differential exceeds a predetermined high-pressure threshold, said valve non-resiliently allows fluid flow across the valve.
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Citations
21 Claims
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1. A HOP assembly for a fluid filled casing string comprising:
a housing configured to attach to said casing string wherein said housing contains an adjustable one-way check valve, wherein hydrostatic forces resulting from fluid inside said casing string creates a pressure differential across said adjustable one-way check valve and said one-way check valve supports said hydrostatic forces such that it prevents fluid flow up to a first predetermined pressure differential so as to retain said casing string in a fluid filled state and wherein said one-way check valve is adjustable such that said first predetermined pressure differential can be increased or decreased. - View Dependent Claims (2, 3)
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4. A HOP nose for a casing string, comprising:
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a housing having a first housing end configured for attachment to said casing string;
a second housing end;
an exterior face extending from said first housing end to said second housing end;
an interior face extending from said first housing end to said second housing end and defining a central bore; and
an aperture extending from said exterior face to said interior face; anda valve positioned in said bore, said valve configured such that, when there is a pressure differential between said first housing end and said aperture below a predetermined mid-pressure threshold, said valve prevents fluid flow between said first housing end and said aperture, and when said pressure differential exceeds a predetermined high-pressure threshold, said valve non-resiliently allows fluid flow from said first housing end to said aperture. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of placing a casing string having an interior into a wellbore at the bottom of a body of water, the method comprising:
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(a) attaching a HOP nose to said casing string, said HOP nose having an interior and an aperture, which allows fluid flow communication between said interior of said HOP nose and the outside of said HOP nose; (b) lowering said casing through said water and into said wellbore; (c) introducing a fluid into said interior of said casing, said fluid having a fluid pressure; (d) during said lower lowering step (b), preventing fluid flow communication between said interior of said casing and said aperture of said HOP nose when said fluid pressure is below a predetermined mid-pressure threshold; (e) after said lowering of step (b), preventing fluid flow communication between said interior of said casing and said aperture of said HOP nose only when said fluid pressure is below a predetermined low-pressure threshold, wherein said predetermined low-pressure threshold is less than said predetermined mid-pressure threshold. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification