Abstract: A tensioner system for a riser of a subsea production well. A plurality of at least three tensioners are each pivotally secured to both a lower surface of the production platform and to a tensioner ring that is itself secured to the riser. The tensioner ring may be generally octagonal with arms protruding from alternate faces of the octagon. These arms define the connecting points for the tensioners. The tensioners are angulated with respect to the axis of the riser, converging toward a single point lying on that axis and defining a first angle. The arms preferably form a second angle with respect to the body of the tensioner ring that is equal to said first angle so that the reaction surface defined by the bottom of the arms is perpendicular to the force lines along which the tensioners act. The failure of one of the tensioners will not result in unbalanced forces that could produce bending torsion, as occurred with previous designs.

Abstract: Method and apparatus for retrieving a running tool/guideframe assembly without the use of winch wires. A portion or each guidepost assembly can be unlatched from the seafloor-mounted template to permit that portion to be retrieved using the guidewires. The unlatchable portion of the guidepost system is formed with a load support that engages and supports the running tool/guideframe assembly so that the assembly is retrieved concurrently with the unlatchable portions of the guidepost assemblies.

Abstract: A tensioner system for a riser of a subsea production well. A plurality of at least three tensioners are each pivotally secured to both a lower surface of the production platform and to a tensioner ring that is itself secured to the riser. The tensioner ring may be generally octagonal with arms protruding from alternate faces of the octagon. These arms define the connecting points for the tensioners. The tensioners are angulated with respect to the axis of the riser, converging toward a single point lying on that axis and defining a first angle. The arms preferably form a second angle with respect to the body of the tensioner ring that is equal to said first angle so that the reaction surface defined by the bottom of the arms is perpendicular to the force lines along which the tensioners act. The failure of one of the tensioners will not result in unbalanced forces that could produce bending torsion, as occurred with previous designs.

Abstract: An adjustable riser top joint for connecting an offshore subsurface well to a deck mounted welltree. A first plurality of generally annular protrusions on the riser top joint section affords a plurality of connecting points for the wellhead tree using either a unitary or a split collar type attachment. A second plurality of protrusions positioned below deck afford a second plurality of connecting points for riser tensioning means that may also, preferably, be attached using either a unitary or a split collar. The generally annular protrusions are formed as a continuous spiral groove on an external surface of the riser section in a first preferred embodiment and as a series of generally cylindrical protrusions of equal length and spacing in a second preferred embodiment.

Abstract: A flame sprayed aluminum coating of high strength steel components offers excellent seawater corrosion protection, increased fatigue life and uniform low level cathodic protection that avoids hydrogen embrittlement. Marine mooring and riser elements fabricated from such components are superior in the above respects to steel components protected from corrosion by common sacrificial anode cathodic protection systems. In addition, the need of welding a stud to the steel to insure electrical continuity between the steel and the sacrificial anodes is eliminated.