Drilling riser elastic swivel for boundary layer control

Abstract

The present invention relates to the marine drilling risers and other submerged hulls, and methods and apparatuses for reducing vibration and drag in the drilling risers when they are beset by ocean currents, for instance elastic swivel devices for use in orienting a riser in a desired direction for boundary layer control applications.

1 . A compliant swivel coupling for accommodating torsional forces induced by axial rotation of a marine drilling riser, comprising:
 a torsionally compliant member disposed about an external surface of a first portion of a drilling riser, the torsionally compliant member helping to connect the first drilling riser portion to a second drilling riser portion and thereby forming a coupling there between;   wherein the torsionally compliant member is adapted to allow the first riser portion to rotate axially relative to the second riser portion; and   wherein the torsionally compliant member is adapted to prevent water ingress or drilling mud egress through the coupling.   
     
     
         2 . The swivel of  claim 1 , wherein the torsionally compliant member comprises a vertical composite elastomeric tube. 
     
     
         3 . The swivel of  claim 2 , wherein the vertical composite elastomeric tube comprises alternating horizontal layers of metal and elastomer. 
     
     
         4 . The swivel of  claim 3 , wherein the alternating horizontal layers of metal and elastomer are bonded to one another. 
     
     
         5 . The swivel of  claim 4 , wherein the layers are substantially conical in shape. 
     
     
         6 . The swivel of  claim 1 , wherein the torsionally compliant member is configured to resist vertical tension on the riser by resisting axial compression. 
     
     
         7 . The swivel of  claim 1 , wherein the riser further comprises an auxiliary pipeline, wherein the auxiliary pipeline comprises an upper pipeline portion coupled to the axially rotatable upper drilling riser portion and a lower pipeline portion coupled to the fixed lower drilling riser portion, and wherein the upper pipeline portion is coupled to the lower pipeline portion by a flexible hose-pipe. 
     
     
         8 . The swivel of  claim 7 , wherein the RES comprises two or more auxiliary pipelines. 
     
     
         9 . The swivel of  claim 1 , wherein the axially rotatable upper drilling riser portion is configured to rotate axially when a vertical axis moment is applied to a top portion of the axially rotatable upper drilling riser portion. 
     
     
         10 . The swivel ES of  claim 9 , wherein the axially rotatable upper drilling riser portion is configured to receive the vertical axis moment at an elevation location below that of a heave compensator of a drilling vessel. 
     
     
         11 . The swivel of  claim 1 , wherein the torsionally compliant member is configured to allow the axially rotatable upper drilling riser portion to rotate approximately 180 degrees in either direction with respect to the fixed lower drilling riser portion. 
     
     
         12 . The swivel of  claim 1 , wherein the RES is positioned on the drilling riser at a position immediately above a Lower Marine Riser Package (LMRP). 
     
     
         13 . The swivel of  claim 12 , wherein the RES is positioned on the drilling riser at a position immediately above a lower ball joint associated with the LMRP. 
     
     
         14 . A method of providing axial rotation in a marine drilling riser, comprising:
 coupling an axially rotatable upper drilling riser portion to a fixed lower drilling riser portion with a torsionally compliant member and forming a coupling there between, wherein the torsionally compliant member allows the upper riser portion to rotate axially relative to the lower riser portion, and wherein the torsionally compliant member is adapted to prevent water ingress or drilling mud egress through the coupling.   
     
     
         15 . The method of  claim 14 , wherein coupling the axially rotatable upper drilling riser portion to the fixed lower drilling riser portion with a torsionally compliant member comprises coupling the axially rotatable upper drilling riser portion to the fixed lower drilling riser portion with a vertical-axis cylindrical composite elastomeric tube. 
     
     
         16 . The method of  claim 15 , wherein coupling the axially rotatable upper drilling riser portion to the fixed lower drilling riser portion with a torsionally compliant member comprises coupling the axially rotatable upper drilling riser portion to the fixed lower drilling riser portion with a vertical composite elastomeric tube comprising alternating horizontal layers of metal and elastomeric material. 
     
     
         17 . A marine drilling riser, comprising:
 an axially rotatable upper drilling riser portion;   a fixed lower drilling riser portion, the upper and lower riser portions having a common internal bore and an external surface;   a torsionally compliant member disposed about the external surface of the drilling riser and connecting the upper drilling riser portion to the lower drilling riser portion thereby forming a coupling there between, wherein the torsionally compliant member is adapted to allow the upper riser portion to rotate axially relative to the lower riser portion; and wherein the torsionally compliant member is adapted to prevent water ingress or drilling mud egress through the coupling.   
     
     
         18 . The swivel of  claim 17 , wherein the torsionally compliant member comprises a vertical composite elastomeric tube. 
     
     
         19 . The swivel of  claim 18 , wherein the vertical composite elastomeric tube comprises alternating horizontal layers of metal and elastomer. 
     
     
         20 . The swivel of  claim 19 , wherein the alternating horizontal layers of metal and elastomer are bonded to one another. 
     
     
         21 . The swivel of  claim 17 , wherein the torsionally compliant member is configured to resist vertical tension on the riser by resisting axial compression.