Electrical transmission system

Abstract

A system for the transmission of electrical energy between different parts of an electrically conductive structure, and in particular for transmission of power and/or data signals to/from downhole equipment or instrumentation in oil and gas wells. A first layer of electrically insulative ceramic material is deposited on the structure, followed by a series of electrically conductive tracks and a second layer of electrically insulative ceramic material. The tracks which serve for the transmission of power and/or data signals are thus sandwiched between the two ceramic layers, insulated from the structure and the external environment and protected from damage. Each layer is deposited by a thermal spray process such as plasma spraying or high velocity oxy fuel spraying.

1 . A structure of electrically conductive material provided with means for the transmission of electrical energy between spaced locations along the structure, comprising a first layer of electrically insulative material deposited on the structure, one or more electrically conductive tracks deposited on said first layer, and a second layer of electrically insulative material deposited over said electrically conductive track(s), said first and second electrically insulative layers each comprising a ceramic material deposited by a thermal spray process.  
   
   
       2 . A structure according to  claim 1  wherein the electrically insulative material in said first and/or second layer is composed predominantly of aluminium oxide.  
   
   
       3 . A structure according to  claim 2  wherein the electrically insulative material in said first and/or second layer includes a proportion of titanium oxide.  
   
   
       4 . A structure according to  claim 3  wherein the electrically insulative material in said first and/or second layer includes titanium oxide in a proportion of 2-45% by weight.  
   
   
       5 . A structure according to  claim 4  wherein the electrically insulative material in said first and/or second layer includes titanium oxide in a proportion of 10-15 or 35-45%.  
   
   
       6 . A structure according to  claim 1  being a length of pipe.  
   
   
       7 . A structure according to  claim 1  being a pipeline for the conveyance of oil or gas.  
   
   
       8 . A structure according to  claim 7  being a pipeline in a well.  
   
   
       9 . A method of providing a structure of electrically conductive material with means for the transmission of electrical energy between spaced locations along the structure which comprises the steps of: (1) depositing a first layer of electrically insulative material on the structure; (2) depositing one or more electrically conductive tracks on said first layer; and (3) depositing a second layer of electrically insulative material over said electrically conductive track(s); said first and second electrically insulative layers each comprising a ceramic material and being deposited by a thermal spray process.  
   
   
       10 . A method according to  claim 9  wherein one or more of steps (1), (2) and (3) comprises heating particles of the material to be deposited in a plasma flame and directing a resultant stream of molten or softened such particles towards the structure.  
   
   
       11 . A method according to  claim 9  wherein one or more of steps (1), (2) and (3) comprises heating particles of the material to be deposited in a flame produced by combustion of fuel and oxygen and directing a resultant stream of molten or softened such particles towards the structure.  
   
   
       12 . A structure of electrically conductive material provided with means for the transmission of electrical energy between spaced locations along the structure by a method according to  claim 10 .  
   
   
       13 . A structure of electrically conductive material provided with means for the transmission of electrical energy between spaced locations along the structure by a method according to  claim 11.