Power connection to and/or control of wellhead trees

Abstract

A hydrocarbon extraction system ( 1 ) comprises a host facility ( 2 ), a wellhead tree ( 3 ) and a retrievable electrical power connection/control module ( 4 ). The module has a load ( 12 ) and is connected to the host facility and the tree via first and second wet mateable connectors ( 6, 8 ) respectively. The module also has qwitchgears ( 14, 15 ) controlled by the load for isolating the load from the host facility or the tree. The host facility is arranged to provide power to the module, and to the tree via the module when the switchgears ( 14, 15 ) are closed, and the load ( 12 ) of the module is arranged to control the via one ( 15 ) of the closed switchgears.

1 . A retrievable electrical power connection/control module ( 4 ) for a hydrocarbon extraction system ( 1 ), comprising: 
 first disconnectable connection means ( 8 ) arranged to connect the module to at least one wellhead tree ( 3 ) and second disconnectable connection means ( 6 ) arranged to connect the module to a host facility ( 2 );    power/control means ( 12 ) arranged to provide power and/or control operation of at least one said wellhead tree via the first connection means; and.    isolating means ( 14 , 15 ) for isolating the power/control means from at least one said wellhead tree.    
     
     
         2 . A module as claimed in  claim 1 , wherein the power/control means ( 12 ) is arranged to receive power and/or control signals from the host facility ( 2 ) and to supply it to at least one said wellhead tree.  
     
     
         3 . A module as claimed in  claim 1  or  2 , wherein the isolating means ( 14 , 15 ) is arranged to isolate the power control means ( 12 ) from the host facility ( 2 ).  
     
     
         4 . A module as claimed in  claim 1 ,  2  or  3 , including voltage reduction means ( 16 ) for receiving electrical power at a first voltage level from the host facility ( 2 ) and supplying electrical power at a second lower voltage level to at least one said wellhead tree ( 3 ).  
     
     
         5 . A module as claimed in any preceding claim, wherein the isolating means comprises at least one switchgear ( 14 , 15 ), the or each switchgear arranged to be controlled from the power control means ( 12 ) of the module ( 4 ).  
     
     
         6 . A hydrocarbon extraction system ( 1 ) comprising a host facility ( 2 ), at least one wellhead tree ( 3 ), at least one retrievable electrical power connection/control module ( 4 ) as claimed in any preceding claim, the or each module being electrically disconnectably connected to the host facility by its second connection means ( 6 ) and to the at least one tree by its first connection means ( 8 ), the host facility being arranged to provide power to the or each module and the power/control means ( 12 ) of any said module being arranged to provide power and/or control to at least one said tree via said first connection means ( 8 ).  
     
     
         7 . A system as claimed in  claim 6 , including power isolating means for enabling the power/control means ( 12 ) to supply power or negligible or no power to said at least one tree.  
     
     
         8 . A system as claimed in  claim 7 , wherein each module ( 4 ) has a module based part ( 83 ) of the power isolating means, and each wellhead tree ( 3 ) has a tree based part ( 84   a - e ) of the power isolating means.  
     
     
         9 . A system as claimed in  claim 6 ,  7  or  8 , wherein the power/control means ( 12 ) includes power means ( 82 ) for supplying power from the module ( 4 ) to said at least one tree ( 3 ).  
     
     
         10 . A system as claimed in claims  7  or  9 , wherein the power/control means includes control means ( 85 ) for controlling the power means ( 82 ) and/or the power isolating means ( 83 , 84   a - e ).  
     
     
         11 . A system as claimed in any one of  claims 6  to  10 , wherein the power/control means ( 12 ) is arranged to send control signals to at least one said tree ( 3 ) in parallel to the power.  
     
     
         12 . A system as claimed in any one of  claims 6  to  11 , including a system module including said retrievable module ( 4 ) and being remote from the at least one tree ( 3 ).  
     
     
         13 . A system as claimed in any one of  claims 6  to  12 , wherein at least one said module ( 21 , 41 , 51 , 61 ) is connected by said first disconnectable connection means ( 8 ) to a plurality of said trees ( 28 , 29 ; 43 - 46 ; 54 , 55 ; 65 - 67 ) in parallel.  
     
     
         14 . A system as claimed in any one of  claims 6  to  13 , wherein at least one said tree ( 28 , 43 , 54 , 65 ) is connected to a plurality of said modules ( 21 , 22 ; 41 , 42 ; 51 - 53 ; 61 , 62 ) in parallel.  
     
     
         15 . A system as claimed in anyone of  claims 6  to  14 , wherein a plurality of said modules ( 41 , 42 , 51 - 53 , 61 - 64 , 71   a - d ) are connected in series with the host facility ( 27 ) to form a circuit.  
     
     
         16 . A system as claimed in any one of  claims 6  to  15 , wherein at least one said tree ( 28 , 43 , 54 , 65 , 72 ) is connected in series between two said modules ( 21 , 22 ; 41 , 42 ; 51 , 53 ; 61 , 62 ; 71 ).  
     
     
         17 . A system as claimed in  claim 15 , wherein at least one said tree ( 43 , 54 , 65 , 72 ) is connected in parallel to a plurality of said modules ( 41 , 42 ; 51 - 53 ; 61 , 62 ; 71 ).  
     
     
         18 . A system as claimed in any one of  claims 6  to  17 , including a plurality of modules and module isolating means for isolating at least one module so that the isolated module ( 22 , 42 ) or modules can be removed without cutting off the supply of electrical power to any of the trees ( 28 , 29 , 43 - 46 ) or any of the remaining modules ( 21 , 41 ) of the system.  
     
     
         19 . A system as claimed in  claim 18 , wherein the host facility ( 27 ) has a host facility based part ( 25 , 26 ) of the module isolating means.  
     
     
         20 . A system as claimed in  claim 18  or  19 , wherein each wellhead tree ( 28 , 29 , 43 - 46 ) has a tree based part ( 34   a,   34   b;   35   a,   35   b;   49 ) of the module isolating means.  
     
     
         21 . A system as claimed in  claim 18 ,  19  or  20 , wherein each module ( 41 , 42 ) has a module based part ( 48 ) of the module isolating means.  
     
     
         22 . A system as claimed in any one of  claims 18  to  21 , wherein parts ( 25 , 48 , 49 ) of the module isolating means electrically adjacent to the module ( 41 ) to be removed are arranged to isolate the module.  
     
     
         23 . A system as claimed in any one of  claims 18  to  22 , wherein the module isolating means is arranged to isolate a plurality of serially adjacent modules.  
     
     
         24 . A system as claimed in any one of  claims 18  to  23 , wherein the module isolating means and/or the power isolating means comprises switchgears.  
     
     
         25 . A system as claimed in any one of  claims 6  to  24 , wherein at least one said tree ( 3 ) has a parallel supply of power from a said: module ( 4 ) and an emergency shut down facility ( 90   a - d ) for closing at least one valve ( 80   a - d ) in the tree ( 3 ) when there is an absence of the parallel supply of power.  
     
     
         26 . A hydrocarbon extraction system ( 1 ) comprising: 
 a host facility ( 2 ) for supplying electrical power;    at least one retrievable electrical power connection/control module ( 4 );    at least one wellhead tree ( 3 ) remote from the or each module; and    means ( 12 ) for powering/controlling at least one said tree including means for transmitting the electrical power from the host facility to the tree and/or transmitting electrical control signals from the module to at least one said tree.    
     
     
         27 . A method of powering/controlling a wellhead tree ( 3 ) in a hydrocarbon extraction system ( 1 ) including the step of supplying at least one said tree ( 3 ) with electrical power and/or electrical control signals from a remote retrievable power/control module ( 4 ).  
     
     
         28 . A method as claimed in  claim 27 , including the step of supplying the module ( 4 ) with power and/or control signals from a host facility ( 2 ).  
     
     
         29 . A method as claimed in  claim 27  or  28 , wherein at least one said tree ( 3 ) is supplied with control signals in parallel to the electrical power.  
     
     
         30 . A method as claimed in  claim 29 , including the steps of: 
 (a) activating the module ( 4 ) to supply negligible or no power to at least one said tree ( 3 );    (b) activating power isolating means to enable the module ( 4 ) to be able to supply power to at least one said tree ( 3 ); and    (c) activating the module to supply power from the module ( 4 ) to at least one said tree ( 3 ).    
     
     
         31 . A method as claimed in  claim 30 , including before step (a) the step of activating the power isolating means to isolate the module ( 4 ) from at least one said tree ( 3 ).  
     
     
         32 . A method as claimed in  claim 30  or  31 , including after step (c), the steps of: (d) activating the module ( 4 ) to supply negligible or no power to at least one said tree ( 3 ); and (e) activating the power isolating means to isolate the module ( 4 ) from at least one said tree ( 3 ).  
     
     
         33 . A method as claimed in  claim 32 , wherein step (e) includes activating a module based part ( 83 ) of the power isolating means before a tree based part ( 84   a - e ) of the power isolating means.  
     
     
         34 . A method as claimed in any one of  claims 30  to  33 , wherein step (b) includes activating a tree based part ( 84   a - e ) of the power isolating means before a module based part ( 83 ) of the power isolating means.  
     
     
         35 . A method as claimed in any one of preceding  claims 30  to  34 , including controlling the activating steps by control means ( 85 ) in the retrievable module ( 4 ).  
     
     
         36 . A method as claimed in any one of  claims 28  to  35 , including transmitting electrical power at a first voltage from the host facility ( 2 ) to voltage reduction means ( 16 ) and transmitting electrical power at a second lower voltage from the voltage reduction means to at least one said tree ( 3 ), and transmitting said electrical control signals from control means ( 12 ) in the retrievable module ( 4 ) to at least one said tree ( 3 ).  
     
     
         37 . A method as claimed in any one of  claims 28  to  35 , including transmitting electrical power and control signals from the host facility ( 2 ) to said at least one tree ( 3 ), and reducing the voltage between the host facility ( 2 ) and said at least one tree ( 3 ).