Offshore bipod
A bipod for use in ice prone offshore environments comprising a deck connected across a pair of members, each member having a neck, and angled portion disposed at the sea surface, and a base secured to the seafloor. The base is secured using a gravity-based system or pilings. An interior zone is defined between the pair of members which is maintained largely free of ice and provides ready access to the sea surface for resupply or emergency egress.
1. A bipod for use in ice prone offshore environments, comprising:
a first member and a second member disposed on a seafloor, each member comprising an angled portion, a neck, and a base, wherein each angled portion is disposed at the waterline, each base below the waterline, and each neck above the waterline and wherein each base is half conical in shape; wherein each angled portion comprises a first side and a second side, the first side of the first member facing the first side of the second member, the second side of the first member and the second side of the second member disposed opposite the respective first sides; the first side of the first member and the first side of the second member being parallel to one another and normal to the seafloor, wherein the second side of the first member and the second side of the second member are half conical in shape;
wherein each base has a cross-sectional area taken along a horizontal plane that is greater than a cross-sectional area taken along a horizontal plane of the respective neck and wherein the first and second members are separated by an interior zone between them; and
a deck connected across the necks of each of the first member and the second member.
2. The bipod of claim 1 wherein each base comprises a plurality of compartments for filling with ballast for securing each base to the seafloor.
3. The bipod of claim 1 wherein each base comprises a flange with a plurality of holes, each hole adapted to accommodate a piling driven into the seafloor in order to secure each base to the seafloor.
4. The bipod of claim 3 wherein each base has a width twice as large as a width of the respective neck.
5. The bipod of claim 3 further comprising at least one mechanical device connected to one of the first member and the second member, the mechanical device disposed in the interior zone and adapted to clear ice from the interior zone.
6. The bipod of claim 3 wherein the width of each angled portion where the respective angled portion meets the respective neck is one half the width of the respective angled portion where it meets the respective base.
7. The bipod of claim 1 , wherein the interior zone is defined by a flat side of the first member and an opposing flat side of the second member.
8. The bipod of claim 7 , wherein the interior zone is configured to extend below the waterline.
9. The bipod of claim 1 , wherein the interior zone is upwardly bounded by the deck.
10. A method of positioning a bipod in an ice prone offshore environment, wherein the bipod consists of a first leg and a second leg disposed on a seafloor, each leg having an angled portion, a neck, and a base, wherein each angled portion is disposed at the waterline and has a semi-conical shape, and wherein the first and second legs define an interior zone between them; and a deck connected across the neck of each of the first leg and the second leg, the method comprising:
determining the prevailing direction of ice floes in the offshore environment; and
aligning the first and second legs such that a line from the first leg to the second leg is parallel to the prevailing direction.
11. The method of claim 10 , further comprising affixing the base of the first and second legs to the sea floor.
12. The method of claim 11 , wherein the step of affixing the base further comprises driving pilings into the sea floor.
13. The method of claim 11 , wherein the step of affixing the base further comprises filling the base with ballast.
14. The method of claim 10 , further comprising clearing the interior zone of ice.
15. A method of building a bipod in an ice prone offshore environment, wherein the bipod consists of a first member and a second member disposed on a seafloor, each member having an angled portion, a neck, and a base, wherein each angled portion is disposed at the waterline and has a semi-conical shape, and wherein the first and second members define an interior zone between them; and a deck connected across the neck of each of the first member and the second member, the method comprising:
positioning the first member on the seafloor in the offshore environment;
positioning a jack up structure with a drilling rig proximate to the first member;
pre drilling a plurality of production wells with the drilling rig;
positioning the second member on the seafloor relative to the first member, subsequent to the step of pre drilling;
positioning the deck between the first and second member; and
connecting the plurality of production wells to the deck.
16. The method of claim 15 , further comprising the step of affixing the first member to the sea floor.
17. The method of claim 16 , further comprising the step of affixing the second member to the sea floor subsequent affixing the first member to the sea floor.
18. The method of claim 16 , wherein the steps of positioning the first member and the second member on the seafloor comprise floating the respective first and second member into position and submerging the base of the respective first member and the base of the respective second member.
19. A bipod for use in ice prone offshore environments, consisting of:
a first leg disposed on the seafloor:
the first leg having a first mid section, a first neck section and a first base section, wherein the first mid section is disposed at the waterline, the first base section below the waterline, and the first neck section above the waterline; wherein cross sections of each of the first mid section and the first base section have a perimeter including a first straight section connecting respective ends of a curved section, the curved section being symmetric about a line perpendicular to the straight section; the first leg being tapered from the first base section to the first neck section;
a second leg disposed on the seafloor:
the second leg having a second mid section, a second neck section and a second base section, wherein the second mid section is disposed at the waterline, the second base section below the waterline, and the second neck section above the waterline; wherein cross sections of each of the second mid section and the second base section have a perimeter including a second straight section connecting respective ends of a curved section, the curved section being symmetric about a line perpendicular to the second straight section; the second leg being tapered from the second base section to the second neck section;
wherein the curved sections of the first leg and the curved sections of the second leg are oriented away from one another and the straight sections of the first leg and the straight sections of the second leg define opposing faces of the first and second legs;
an interior channel defined between the opposing faces of the first and second legs; and,
a deck connected across from the first neck section of the first leg to the second neck section of the second leg, the deck defining a top of the interior channel,
wherein the bipod is oriented such that the interior channel is perpendicular to a prevailing direction of ice floes in the ice prone offshore environment.