Apparatus for forming tubular connections and method of use

Abstract

The invention in one aspect provides an apparatus and method for forming a connection between an inner tubular and a caisson of an offshore structure. The apparatus comprises a mandrel, and a seal arrangement disposed on the mandrel and configured to create a seal between the mandrel and an inner surface of an inner tubular in which the apparatus is located. The seal arrangement comprises first and second cup seals, axially separated on the mandrel, and configured to define a substantially annular volume between the mandrel and the inner tubular in use. A pressure transmission path delivers a pressurised fluid to the annular volume, and the apparatus is configured to pressurise the annular volume and thereby expand the inner tubular in a radial direction and into contact with the caisson to form a connection between the inner tubular and the caisson.

1 . An apparatus for forming a connection between an inner tubular and a caisson of an offshore structure, the apparatus comprising:
 a mandrel;   a seal arrangement disposed on the mandrel and configured to create a seal between the mandrel and an inner surface of the inner tubular in which the apparatus is located;   wherein the seal arrangement comprises first and second cup seals, axially separated on the mandrel, and configured to define a substantially annular volume between the mandrel and the inner tubular in use;   a pressure transmission path for delivering a pressurised fluid to the substantially annular volume;   wherein the apparatus is configured to pressurise the substantially annular volume and thereby expand the inner tubular in a radial direction and into contact with the caisson to form a connection between the inner tubular and the caisson.   
     
     
         2 . The apparatus according to  claim 1 , wherein the first and second cup seals each define an open end, and are axially separated on the mandrel such that the open ends of the cup seals face towards one another. 
     
     
         3 . The apparatus according to  claim 1 , wherein the first and/or second cup seals further comprise an anti-extrusion member which is substantially annular in form and which at least partially surrounds the outer surface of the first and/or the second cup seal. 
     
     
         4 . The apparatus according to  claim 3 , wherein the anti-extrusion member of the first and/or the second cup seal is formed from a material which is harder than that of the first and/or second cup seal. 
     
     
         5 . The apparatus according to  claim 1 , further comprising a support pin assembly comprising a plurality of support pins which are operable to extend radially outwards to bear the load of the inner tubular. 
     
     
         6 - 8 . (canceled) 
     
     
         9 . The apparatus according to  claim 5 , wherein the support pin assembly is hydraulically actuated, and wherein hydraulic extension lines and hydraulic retraction lines are provided between each support pin of the plurality of support pins and a hydraulic control system to provide hydraulic actuation to extend the support pins and hydraulic actuation to retract the support pins, respectively. 
     
     
         10 . The apparatus according to  claim 1 , further comprising at least one centralizer assembly comprising a plurality of centraliser members and having a retracted condition and an extended condition in which the plurality of centraliser members is configured to extend radially outwards and into contact with the inner surface of the inner tubular such that the mandrel of the apparatus is separated from the inner tubular by at least a minimum stand-off distance around its circumference 
     
     
         11 . (canceled) 
     
     
         12 . (canceled) 
     
     
         13 . The apparatus according to  claim 10 , wherein the centraliser assembly is connected to the pressure transmission path and is configured to be hydraulically actuated by the same pressurised fluid which pressurises the substantially annular volume. 
     
     
         14 . (canceled) 
     
     
         15 . The apparatus according to  claim 13  wherein the centraliser assembly is configured to be actuated into its extended condition at a first pressure upon delivery of the pressurised fluid, prior to expansion of the inner tubular, and wherein expansion of the inner tubular is configured to begins at a second pressure, and wherein the first pressure is lower pressure than the second pressure. 
     
     
         16 . (canceled) 
     
     
         17 . The apparatus according to  claim 13  wherein the apparatus is configured such that the centraliser assembly is caused to move into its retracted condition when pressurised fluid is removed or drained from the apparatus. 
     
     
         18 . (canceled) 
     
     
         19 . The apparatus according to  claim 1 , wherein the apparatus is configured to deform the inner and/or outer surfaces of the inner tubular such that the inner tubular is brought into contact with the caisson, and wherein a force from the expanded inner tubular on the caisson deforms the inner and/or outer surfaces of the caisson. 
     
     
         20 . The apparatus according to  claim 1 , wherein the apparatus is configured to expand the inner tubular in a radial direction to form a shoulder in the inner tubular and wherein a force from the expanded inner tubular on the caisson expands and forms a shoulder in the caisson. 
     
     
         21 . The apparatus according to  claim 1 , wherein the apparatus is configured to expand the inner tubular in a radial direction to form a shoulder in the inner and outer surfaces of the inner tubular and wherein a force from the expanded inner tubular on the caisson expands and forms a shoulder in the inner and outer surfaces of the caisson. 
     
     
         22 . A method of forming a connection between an inner tubular and a caisson of an offshore structure comprising:
 providing an apparatus comprising a mandrel, a seal arrangement disposed on the mandrel and configured to create a seal between the mandrel and an inner surface of the inner tubular in which the apparatus is located, wherein the seal arrangement comprises first and second cup seals, axially separated on the mandrel;   delivering a pressurised fluid to a substantially annular volume between the mandrel and the inner tubular in use;   pressurising the substantially annular volume and thereby expanding the inner tubular in a radial direction and into contact with the caisson to form a connection between the inner tubular and the caisson.   
     
     
         23 . The method according to  claim 22 , wherein the apparatus further comprises a support pin assembly comprising a plurality of support pins, and wherein the method comprises actuating the support pin assembly into an extended condition such that the plurality of support pins extend radially outwards into apertures in the inner tubular to engage with the inner tubular and bear the load of the inner tubular. 
     
     
         24 . (canceled) 
     
     
         25 . The method according to  claim 22 , wherein the apparatus further comprises a fluid delivery system configured to be coupled to a source of pressurised fluid and a pressure transmission path which enables the pressurised fluid to be delivered to the substantially annular volume, and wherein the method comprises filling the substantially annular volume with low pressure water. 
     
     
         26 . The method according to  claim 22 , wherein the apparatus further comprises a centraliser assembly which is hydraulically actuated by the same fluid which is used to pressurise the substantially annular volume, and wherein the method comprises actuating the centraliser assembly by delivering low pressure water to the substantially annular volume. 
     
     
         27 . (canceled) 
     
     
         28 . The method according to  claim 22 , comprising operating a high pressure pump to pump water into the substantially annular volume such that the first and second cup seals are energised by the water to form a seal between the apparatus and the inner surface of the inner tubular, and the substantially annular volume is pressurised. 
     
     
         29 . The method according to  claim 28 , wherein the inner tubular reacts to the pressure in the substantially annular volume and is deformed into an expanded position into contact with the caisson. 
     
     
         30 . The method according to  claim 29 , comprising continuing the application of pressure using the high pressure pump such that the caisson is expanded and deformed into an expanded diameter. 
     
     
         31 . The method according to  claim 22 , comprising forming a swaged connection between the inner tubular and the caisson. 
     
     
         32 . The method according to  claim 22 , wherein after the connection has been formed between the inner tubular and the caisson, the method comprises releasing residual pressure within the apparatus and/or the substantially annular volume and causing the centraliser assembly to retract. 
     
     
         33 . (canceled) 
     
     
         34 . The method according to  claim 22 , wherein after the connection has been formed between the inner tubular and the caisson, the method comprises retracting the support pins from the inner tubular to release the apparatus from the inner tubular. 
     
     
         35 . (canceled) 
     
     
         36 . The method according to  claim 22 , comprising using the apparatus to form more than one swaged connection between the inner tubular and the caisson. 
     
     
         37 . (canceled)