Marine structure with detachable anchor

Claim 2

Method for commencing directional drilling of an underwater well from a buoyant tension leg marine structure which includes; a buoyant base having a deck holding well drilling equipment thereon, a first anchor at the ocean floor having a registration passage therein, cable means under tension, connecting said marine structure to said first anchor whereby to partially overcome the buoyancy of said structure and to establish a vertical position defined by a substantially vertical relationship between said anchor and said marine structure and second anchor means depending from said deck connected to discrete anchors disposed at the ocean floor and positioned radially outward from said first anchor, which includes the steps of; laterally displacing said buoyant structure from its neutral position to establish a predetermined angle of inclination thereof with said first anchor, fixing said marine structure in said laterally displaced position, fixing the lower end of an elongated drill string conductor to said first anchor and the upper end thereof to said working deck in a position to receive a drill string from said drilling equipment.

Claim 3

In a floatable marine structure (10) capable of operating in offshore waters and including; a base (11), a working deck (18) spaced upwardly from the base to be floatably positioned at the water's surface, first anchor means (13) engaging the lower end of said marine structure and adapted to be positioned at the ocean floor, and tension cables (27) extending between said anchor means and said base for floatably positioning the latter at a desired water depth, said first anchor means (13) including; a body having a peripheral edge, means disposed on said body forming guide passages (36) having a sufficiently large opening to register the lower end of a drill guide conductor (31) therein, whereby to support the lower end of said drill guide conductor at a desired angle to the ocean floor during a drilling operation, and secondary anchor means connected to said marine structure including; a plurality of discrete anchors (39) spaced radially outward from said first anchor means (13), and cable means (42) depending from said deck (18) having one end connected to said discrete anchors (39) and the other end thereof operably connected to a cable adjusting means being operable to regulate the tension in selected of said cables, whereby to laterally displace said floating base (11) to a desired vertical orientation with respect to said anchor means (13).

Claim 4

In a floatable marine structure (10) capable of operating in offshore waters and including; a base (11), a working deck (18) spaced upwardly from the base to be floatably positioned at the water's surface, first anchor means (13) engaging the lower end of said marine structure and adapted to be positioned at the ocean floor, and tension cables (27) extending between said anchor means and said base for floatably positioning the latter at a desired water depth, said first anchor means (13) including; a body having a peripheral edge, means disposed on said body forming guide passages (36) having a sufficiently large opening to register the lower end of a drill guide conductor (31) therein, whereby to support the lower end of said drill guide conductor at a desired angle to the ocean floor during a drilling operation, and secondary anchor means connected to said marine structure including; a plurality of discrete anchors (39) spaced radially outward from said first anchor means (13), and cable means (42) depending from said deck (18) having one end connected to said discrete anchors (39) and the other end thereof operably connected to a cable adjusting means being operable to regulate the tension in selected of said cables, whereby to laterally displace said floating base (11) to a desired vertical orientation with respect to said anchor means (13).

Claim 5

In the apparatus as defined in claim 2, including a drill guide conductor (31) supported at said deck, extending downwardly therefrom and being registered in a guide passage (36).

Claim 6

In the apparatus as defined in claim 2, wherein said guide passage (36) includes an enlarged upper end to receive a drill guide conductor.

Claim 7

In the apparatus as defined in claim 2, including a plurality of guide passages disposed about the peripheral edge of said body.

Claim 8

In the apparatus as defined in claim 2, wherein said guide passages include an enlarged opening at the upper end thereof which is progressively constricted along at least a portion of the length thereof.

Claim 9

In the apparatus as defined in claim 2, wherein said means forming said guide passage includes; a conically shaped passage which terminates at a restricted opening at the lower end thereof.