Rotating Control Device with Mechanical Seal

Abstract

A rotating control device for use in a drilling system, the rotating control device comprising a non-rotating tubular RCD housing enclosing an elongate passage, a mandrel which extends along the elongate passage, the mandrel having an axis and being configured in use to rotate about said axis, and a seal assembly which is configured to provide a substantially fluid tight seal between the RCD housing and the mandrel, wherein the seal assembly comprises a first seal ring which is fixed around an exterior face of the mandrel for rotation with the mandrel, and a second seal ring which is secured to the RCD housing, the first and second seal rings each having a sealing face, and a biasing assembly which acts on one of the seal rings to push the sealing faces together by means of a biasing force which is generally parallel to the axis of the mandrel.

What is claimed is: 
     
         1 . A rotating control device for use in a drilling system, the rotating control device comprising:
 a non-rotating tubular RCD housing enclosing an elongate passage;   a mandrel which extends along the elongate passage, the mandrel having an axis and being configured in use to rotate about said axis; and   a seal assembly which is configured to provide a substantially fluid tight seal between the RCD housing and the mandrel, wherein the seal assembly comprises:
 a first seal ring which is fixed around an exterior face of the mandrel for rotation with the mandrel, and a second seal ring which is secured to the RCD housing, the first and second seal rings each having a sealing face, and 
 a biasing assembly which acts on one of the seal rings to push the sealing faces together by means of a biasing force which is generally parallel to the axis of the mandrel. 
   
     
     
         2 . A rotating control device according to  claim 1 , wherein the sealing faces extend generally perpendicular to the axis of the mandrel. 
     
     
         3 . A rotating control device according to  claim 1 , wherein the biasing assembly is located between the RCD housing and the second seal ring. 
     
     
         4 . A rotating control device according to  claim 1 , wherein the second seal ring is mounted on a floating seal carrier which has a first seal to provide a substantially fluid tight seal between the RCD housing and the seal carrier. 
     
     
         5 . A rotating control device according to  claim 1 , wherein the floating seal carrier further comprises a second seal between the mandrel and the seal carrier, and a vent passage which extends through the seal carrier from a volume enclosed by the seal carrier, the seal assembly and the mandrel to a low pressure region, the second seal being configured such that the seal carrier does not rotate with rotation of the mandrel. 
     
     
         6 . A rotating control device according to  claim 4 , wherein the biasing assembly is mounted between the floating seal carrier and the second seal ring. 
     
     
         7 . A rotating control device according to  claim 1 , further comprising a separator which, with the seal assembly and RCD housing, contains a lubricant cavity around the mandrel. 
     
     
         8 . A rotating control device according to  claim 7 , wherein the separator comprises a further seal carrier having a first seal which provides a substantially fluid tight seal with the RCD housing, and a second seal which provides a substantially fluid tight seal with the mandrel, the further seal carrier having at least one inlet passage to allow for flow of fluid into the lubricant cavity from the side of the seal carrier opposite to the lubricant cavity. 
     
     
         9 . A rotating control device according to  claim 8 , wherein the second seal of the further seal carrier is configured such that the further seal carrier does not rotate with rotation of the mandrel. 
     
     
         10 . A rotating control device according to  claim 8 , further comprising at least one baffle which provides an extended flow path for fluid entering the lubricant cavity from the inlet passage to the seal rings. 
     
     
         11 . A rotating control device according to  claim 7 , further comprising a diaphragm which extends between the RCD housing and the separator so that the RCD housing, seal assembly, diaphragm and separator enclose the lubricant cavity. 
     
     
         12 . A rotating control device according to  claim 1 , wherein the first seal ring is mounted on a thermally conductive ring which is fixed to the mandrel. 
     
     
         13 . A rotating control device according to  claim 1 , wherein the mandrel is provided with at least one fin which moves fluid into which the fin extends during rotation of the mandrel. 
     
     
         14 . A rotating control device according to  claim 12 , wherein the thermally conductive ring is provided with at least one fin which moves fluid into which the fin extends during rotation of the mandrel. 
     
     
         15 . A rotating control device according  claim 1 , wherein baffles are mounted on the inside of the RCD housing. 
     
     
         16 . A rotating control device according to  claim 1 , wherein a resilient damper is installed between the first seal ring and the mandrel. 
     
     
         17 . A rotating control device according to  claim 1 , wherein a resilient damper is installed between the second seal ring and the RCD housing. 
     
     
         18 . A rotating control device according to  claim 6 , wherein a resilient damper is installed between the second seal ring and the biasing assembly and the floating seal carrier. 
     
     
         19 . A drilling system comprising a rotating control device in accordance with  claim 1  with a drill string located within the mandrel and extending along the axis thereof.