초록 ▼

An offshore marine structure for drilling wells into the ocean floor including a floating vessel which carries the necessary drilling equipment. A riser which extends from the vessel to a well head at the ocean floor, encloses a drill string and permits circulation of the drilling mud and fluids. Th

An offshore marine structure for drilling wells into the ocean floor including a floating vessel which carries the necessary drilling equipment. A riser which extends from the vessel to a well head at the ocean floor, encloses a drill string and permits circulation of the drilling mud and fluids. The riser is comprised of at least two detachably connectable segments, one of which can be moved with the floating vessel, while the other remains buoyantly in place until such time as the two segments are reconnected. A riser system used for production activities where the riser comprises at least two detachable segments is also provided.

대표청구항 ▼

An offshore system for drilling well bores through a well head on an ocean floor which includes: a drilling vessel floatably positioned at the water\s surface; an elongated riser adapted to extend from the wellhead to the drilling vessel comprising: a lower tubular segment comprising standard riser

An offshore system for drilling well bores through a well head on an ocean floor which includes: a drilling vessel floatably positioned at the water\s surface; an elongated riser adapted to extend from the wellhead to the drilling vessel comprising: a lower tubular segment comprising standard riser joints and having an upper end and a lower end, said lower segment having means for connecting to the subsea wellhead and a means for disconnectably engaging an upper tubular segment, wherein said means for disconnectably engaging the upper segment further comprises a buoyancy system for suspending the lower segment above the ocean floor; said upper tubular segment comprising standard riser joints and means for disconnectably engaging to the lower segment and to the drilling vessel; a stress joint positioned at said lower end of the lower segment, said stress joint being secured to a flex joint having greater flexibility than the stress joint; said stress joint having a main body part which is tubular, having a first section and a second section, said second section having a smaller cross sectional area whereby the main body has an increased flexibility at the second section as compared with the first section; said flex joint having a tubular main body and further comprising a flexible internal elastomeric lining which fits intimately and securely around the elongated riser; a means for passing a drilling string through said elongated riser to form said well bore in the ocean floor; a first blow-out prevention means connected to the wellhead; said buoyancy system positioned on said lower tubular segment to externally support said lower segment whereby to maintain the latter in a substantially upright position when said lower segment has been disengaged from the riser upper segment; and a second blow-out prevention means connected to said lower tubular segment of the riser.