Desiccant Box and Downhole Assembly Comprising A Desiccant Box

Abstract

The disclosure is about a desiccant box comprising at least one wall defining an inside compartment containing a desiccant material. The box is designed so that: at a first temperature value, the inside compartment is a substantially vapor tight closed compartment, at a second temperature value superior to the first temperature value, at least a portion of the box is permeable to vapor so that vapor can penetrate into the inside compartment.

1 . A desiccant box comprising at least one wall defining an inside compartment containing a desiccant material, wherein the box is designed so that:
 at a first temperature value, the inside compartment is a substantially vapor tight closed compartment,   at a second temperature value superior to the first temperature value, at least a portion of the box is permeable to vapor so that vapor can penetrate into the inside compartment.   
     
     
         2 . The desiccant box according to  claim 1 , in which the at least one of the portions of the box is movable, this portion being designed so that its movement is activated in function of the temperature. 
     
     
         3 . The desiccant box according to  claim 1 , in which the at least one portion of the box is made of a shape memory material. 
     
     
         4 . The desiccant box according to  claim 2 , in which the at least one portion of the box is made of a bimetallic element. 
     
     
         5 . The desiccant box according to  claim 1 , in which the at least one portion of the box is made of a material whose melting point is comprised between the first and second temperature value. 
     
     
         6 . The desiccant box according to the  claim 1 , in which at least one portion of the box is made of a material which is substantially vapor tight at the first temperature value and permeable to water vapor at the second temperature value. 
     
     
         7 . The desiccant box according to  claim 1 , in which the at least one portion of the box is made of a non-porous thermoplastic film whose glass-transition temperature is set between the first and second temperature value. 
     
     
         8 . The desiccant box according to  claim 1 , in which the thermoplastic film is chosen among PEK (polyetherketone), PEEK (polyetheretherketone), PES (polyethersulfone), PSU (polysulfone), PPSU (polyphenylsulfone), PPF (polypropylene fumarate), PFA (polyfluoroalkoxy). 
     
     
         9 . The dessicant box according to  claim 1 , in which the box is an assembly of at least two carriers defining the compartment, at least a sealing element being interposed at the interface of the carriers. 
     
     
         10 . The desiccant box according to  claim 1 , in which the first temperature value is inferior to 50° C. 
     
     
         11 . The desiccant box according to  claim 1 , in which the second temperature value is superior to 80° C. 
     
     
         12 . A downhole assembly intended to be inserted into a borehole comprising a sealed housing, wherein at least an electrical component and a desiccant box comprising at least one wall defining an inside compartment containing a desiccant material, wherein the box is designed so that:
 at a first temperature value, the inside compartment is a substantially vapor tight closed compartment,   at a second temperature value superior to the first temperature value, at least a portion of the box is permeable to vapor so that vapor can penetrate into the inside compartment.   
     
     
         13 . A method of operating a downhole assembly intended to be lowered in the well, comprising at least an electrical component and a desiccant box, wherein the method comprises:
 setting the box in the housing of the downhole assembly and sealing the housing at a first temperature value so that the compartment of the box is a substantially vapor-tight closed compartment,   deploying the tool into a borehole of a well, the borehole temperature being a second temperature value,   absorbing the vapor in the housing of the downhole assembly thanks to the desiccant material contained in the compartment of the desiccant box.