A retrievable subsea apparatus with a pressure and volume compensating system

Abstract

A retrievable subsea apparatus ( 1 ) with a pressure and volume compensating system, the apparatus comprising: a housing ( 1′ ) having in its interior a control system ( 9 ) located in a first section ( 3 ) thereof and an operating unit ( 6 ) located in a second section ( 4 ) thereof. The apparatus further comprises a penetrator ( 2 ) which constitutes an interface between the first section ( 3 ) and the second section ( 4 ), wherein the first section ( 3 ) has a substantially constant first pressure. An external pressure compensator ( 5, 5′ ) is associated with the second section ( 4 ) having a second pressure. The operating unit ( 6 ) comprises at least a first sub-unit ( 6′ ) and at least a second sub-unit ( 6″ ). The second section ( 4 ) is subdivided into at least a first sub-section ( 4′ ) and at least a second sub-section ( 4″ ) which is sealed off from the first 1,1 section ( 4′ ) and being associated with respective sub-unit ( 6′, 6″ ).

1 . A retrievable subsea apparatus with a pressure and volume compensating system, the apparatus comprising:
 a housing having in its interior a control system located in a first section thereof and an operating unit located in a second section thereof, wherein   a penetrator constitutes an interface between the first section and the second section, wherein the first section has a substantially constant first pressure,   that an external pressure compensator is associated with the second section having a second pressure,   that at least a first sub-unit and at least a second sub-unit constitute the operating unit,   that at least a first sub-section and at least a second sub-section constitute the second section,   that a first liquid is located in the first sub-section, and a second liquid is located in the second sub-section,   that the second sub-section is sealed off from the first sub-.section,   that the external compensator is in communication with the first sub-section,   that the first sub-unit is at least partly associated with the first sub-section and the second sub-unit is associated with the second sub-section, and   that an internal pressure compensator is configured to adjust for any pressure differences between the first and second sub-sections and is in contact with the first liquid in the first sub-section and with the second liquid in the second sub-section.   
     
     
         2 . The apparatus of  claim 1 , wherein the first liquid has a first set of properties, and wherein the second liquid has a second set of properties. 
     
     
         3 . The apparatus of  claim 2 , wherein the first and second properties are at least one of viscosity, dielectric property, lubrication and materials compatibility. 
     
     
         4 . The apparatus of  claim 1 , wherein the first sub-unit comprises an electric motor, and wherein the second sub-unit comprises a gear assembly. 
     
     
         5 . The apparatus of  claim 1 , wherein the first pressure in the first section is substantially at sea surface level atmospheric pressure. 
     
     
         6 . The apparatus of  claim 1 , wherein the second pressure is equal to or above subsea pressure surrounding the apparatus housing. 
     
     
         7 . The apparatus of  claim 1 , wherein the external pressure compensator is pre-tensioned to one side to yield a pressure in the second section above an external pressure, e.g. a subsea pressure. 
     
     
         8 . The apparatus of  claim 1 , wherein the external compensator is linked to or communicates with a compensator movement sensor. 
     
     
         9 . The apparatus of  claim 8 , wherein the external pressure compensator is configured to effect a volumetric displacement of the first liquid in the first sub-section to cause the internal pressure compensator to yield a corresponding volumetric change in the second sub-section. 
     
     
         10 . The apparatus of  claim 1 , wherein the external pressure compensator is a first bellow open at one end and closed at the other end, the inside of the first bellow to be in communication with sea water, and wherein the outside and closed end of the first bellow being surrounded by the first liquid. 
     
     
         11 . The apparatus of  claim 1 , wherein the external pressure compensator is made from at least one of or a composition of at least two of: a metal, a metal alloy, a rubber-type material and a plastics material. 
     
     
         12 . The apparatus of  claim 1 , wherein the external pressure compensator is linked to or communicates with a movement sensor. 
     
     
         13 . The apparatus of  claim 10 , wherein the closed end of the first bellow is linked to or communicates with a bellow movement sensor. 
     
     
         14 . The apparatus of  claim 12 , wherein the sensor is a linear movement sensor of inductive, capacitive or resistive type. 
     
     
         15 . The apparatus of  claim 1 , wherein the control system communicates with external power and communication equipment via the penetrator and the first sub-section. 
     
     
         16 . The apparatus of  claim 1 , wherein the control system communicates with the first sub-unit, e.g. a motor, and a movement sensor of the external pressure compensator. 
     
     
         17 . The apparatus of  claim 1 , wherein the internal pressure compensator is located in or associated with a wall or component which divides the first sub-section and the second sub-section. 
     
     
         18 . The apparatus of  claim 17 , wherein the wall between the first and second sub-sections is integral with or is in a sealed engagement with a housing of the first sub-unit. 
     
     
         19 . The apparatus of  claim 1 , wherein the internal pressure compensator is a piston movable in a cylindrical hole in the wall, and wherein a first end face of the piston contacts the first liquid, and a second end face of the piston contacts the second fluid. 
     
     
         20 . The apparatus of  claim 1 , wherein the internal pressure compensator is a diaphragm membrane located transversely of a hole in the wall, and wherein a first face of the membrane contacts the first liquid, and a second end face of the membrane contacts the second fluid. 
     
     
         21 . The apparatus of  claim 20 , wherein the membrane is located at one axial end of the hole. 
     
     
         22 . The apparatus of  claim 20 , wherein a perforated member is located at the other axial end of the hole and being integral with the wall. 
     
     
         23 . The apparatus of  claim 1 , wherein the wall has a circle shaped opening radially inwards of its circumference and extending axially through the wall, wherein the internal pressure compensator is a diaphragm membrane which is located transversely of the opening at one axial end thereof, wherein a first face of the membrane contacts the first liquid, and wherein a second face of the membrane contacts the second fluid. 
     
     
         24 . The apparatus of  claim 23 , wherein a perforated member is located at the other axial end of the opening integrally with the wall. 
     
     
         25 . The apparatus of any one of claims  claim 1 , wherein the internal pressure compensator is a bladder or a second bellow of rubber material being substantially located in the first sub-section and having an outlet which communicates with an axially extending hole through the wall, an interior of said the bladder or second bellow being in communication with the second liquid present in the second sub-section. 
     
     
         26 . The apparatus of  claim 1 , wherein the internal pressure compensator is a circular continuous hose of rubber material being substantially located in the first sub-section, wherein the hose has at least one branched-off outlet which engages a hole through the wall, an interior of the outlet and hose being in communication with the second liquid present in the second sub-section. 
     
     
         27 . The apparatus of  claim 26 , wherein the hose resides with a part of its body in a recess of a face of the wall in the first sub-section. 
     
     
         28 . The apparatus of  claim 1 , wherein at least one of the first and second liquids is a mineral oil, a synthetic or semi-synthetic oil or a silicone oil. 
     
     
         29 . The apparatus of  claim 1 , wherein the first section is a dry chamber filled with air or gas. 
     
     
         30 . The apparatus of  claim 1 , wherein a first dynamic seal is present between the first sub-unit and the second sub-unit, and wherein a second dynamic seal is present at a downstream region of the second sub-unit. 
     
     
         31 . (canceled)