Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
  • E21B17/01—Risers
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
  • E21B17/01—Risers
  • E21B17/012—Risers with buoyancy elements
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B7/00—Special methods or apparatus for drilling
  • E21B7/12—Underwater drilling
  • E21B7/128—Underwater drilling from floating support with independent underwater anchored guide base

Definitions

• FIG. 6 is a simplified elevation view showing various stages of the construction and use of the tower structure
• tower 10 provides at least one, and preferably a plurality of riser ducts 22 (se Fig. 4, e.g.) which extend along the entire length of the tower, preferably principally externally of the tower struc ture per se.
• the riser ducts extend from connection points 20 (see Fig. 5) accessible from above at the upper end of the tower to lower ends at the lower end of the tower.
• the connection points are capable of receiving and mating with conventional subsea drilling equipment, such as a blowout preventer shown generally at 19 in FIG. 1 and in- more detai in FIG. 5.
• Each connection point 20 preferably has the structure and configuration of a landing stump such as is typically included in a landing base used in drilling off ⁇ shore oil and gas wells in water depths of 300 feet or so.
• Tower lower section 16 (see FIG. 2) is prefabricated as a unit having a length substantially greater than the fabricated length of any of the modular central sections 17 shown in FIG. 4; as shown in FIG. 2, the tower lower sectio may have a fabricated length on the order of 100 feet (30 meters) or so.
• the lower section has a lower end corre ⁇ sponding to tower lower end 15 which is defined by a base structure 21 which defines a hollow housing at the lower en
• the float body has sufficient positive buoyancy that it can support the assembled tower sections in the event that such unit should become negatively buoyant by a small amount. If, as may be the case, a tower central section has a length of 70 feet (21.2 meters) between flanged upper and lower ends, the float body may have a length of 80 feet (24.24 meters) or so to provide a base for vertical tracks 75 along which holding devices 76 may move.
• the holding devices (see FIGS. 12, 13 and 14) cooperate between the upper portion of the unit of assembled tower sections and the float body and serve to keep the unit centrally aligned in float passage 72 and to hold the unit vertically relative to the float as the buoyancy of the unit is periodically adjusted and as the unit is lowered relative to the float.
• the holding devices also enable the unit and the float to be locked together to float as an entity in the event of a storm requiring the unit and the float to be released from barge 45.
• the cart is mounted to the rails via rollers 79 and is driven up and down along the rails by a loop of chain or wire rope 80, to which the cart is connected as at 81, reeved over an idler pulley 82 adjacent the lower end of passage 72 and over a drive, wheel 83 located near the upper end of the float body and driven by a suitable motor 84.
• the cart drive system is positive and can be locked.
• the cart has a slide member 85 which is movable radially toward and away from the axis of passage 72 in response to operation of a double-acting linear actuator 8 coupled between the slide and the cart body.
• a pair of light-weight, nonstructural rails 101 are mounted to the exterior of the tower a.nd extend upwardly along the tower from adjacent the lowermost set of valves 97, 98, 100 to the top of the tower and also along the lowering spools, if used.
• the rails are nonstructural in that their presence is not relied upon to define any of the strength or structural integrity of the tower.
• the rails are located on either side of the line of valves 97, 98, 100, and provide a track for guiding vertical movement of manipulator 94.
• the manipulator is provided as a cart-like assembly 102 which is held captive between the rails by rollers 103.

Landscapes

• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Mining & Mineral Resources (AREA)
• Physics & Mathematics (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Mechanical Engineering (AREA)
• Earth Drilling (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=22517040

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (10)

Citations (15)

Family Cites Families (3)

• 1981
  • 1981-04-23 JP JP56501667A patent/JPS57500520A/ja active Pending
  • 1981-04-23 WO PCT/US1981/000531 patent/WO1981003157A1/en not_active Ceased
  • 1981-04-30 CA CA000376654A patent/CA1173358A/en not_active Expired
  • 1981-05-01 EP EP81301923A patent/EP0039589A3/en not_active Ceased
  • 1981-12-30 NO NO814490A patent/NO814490L/no unknown
• 1982
  • 1982-01-02 OA OA57582A patent/OA06985A/xx unknown

Patent Citations (15)

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