Phase Change Fluid Spring and Method for Use of Same

Abstract

A phase change fluid spring ( 450 ) for actuating a downhole tool ( 50 ) in a wellbore. The phase change fluid spring ( 450 ) includes a housing ( 114 ) defining a fluid chamber ( 120 ) and a phase change fluid disposed within the fluid chamber ( 120 ). The phase change fluid is in a first phase and at a first pressure at the surface. The phase change fluid is in a second phase and at a second pressure in the wellbore, the second pressure being greater than the first pressure. The phase change fluid is operable to store and release energy downhole to actuate the downhole tool ( 50 ).

1 . A tool for use in a testing string disposed in a wellbore and forming an annulus therewith, the tool comprising:
 a housing defining a central flow conducting passage;   a circulating valve disposed within the housing operable to control fluid communication between the central flow conducting passage and the exterior of the housing;   a passageway valve disposed within the central flow conducting passage operable to control fluid flow through the central flow conducting passage; and   a phase change fluid spring operably associated with the circulating valve and the passageway valve, the phase change fluid spring operates in response to changes in pressure in the annulus, wherein the phase change fluid spring contains a fluid that is in a first phase at a first pressure at the surface and a second phase at a second pressure in the wellbore, the second pressure being greater than the first pressure.   
   
   
       2 . The tool as recited in  claim 1  wherein the phase change fluid spring stores and releases energy responsive to changes of annulus pressure. 
   
   
       3 . The tool as recited in  claim 1  wherein the first phase is a liquid phase. 
   
   
       4 . The tool as recited in  claim 1  wherein the second phase is one of a gas phase and a supercritical fluid phase. 
   
   
       5 . The tool as recited in  claim 1  wherein the first pressure is less than about 1,500 psi. 
   
   
       6 . The tool as recited in  claim 1  wherein the fluid is at least one of carbon dioxide, water, ammonia, diethyl ether, methane, ethane, propane, ethylene, propylene, methanol, ethanol, Freon, acetone and mixtures of thereof. 
   
   
       7 . A tool for use in a testing string disposed in a wellbore and forming an annulus therewith, the tool comprising:
 a housing defining a central flow conducting passage;   an operating element disposed within the central flow conducting passage operable between two positions, a first position wherein the flow conducting passage through the tool is blocked, and a second position wherein the flow conducting passage is not blocked;   a fluid circulating assembly disposed within the housing operable between two positions, a first position wherein fluid communication is allowed between the annulus and the central flow conducting passage and a second position wherein fluid communication between the annulus and the central flow conducting passage is blocked;   an operating mandrel assembly slidably disposed within the housing and operably associated with the operating element and the fluid circulating assembly, the operating mandrel assembly operable to move between a plurality of positions such that the operating element and the fluid circulating assembly are actuated to configure the tool into distinct operative modes; and   a phase change fluid spring operably associated with the operating mandrel assembly, the phase change fluid spring operates in response to changes in pressure in the annulus, wherein the phase change fluid spring contains a fluid that is in a first phase at a first pressure at the surface and a second phase at a second pressure in the wellbore, the second pressure being greater than the first pressure.   
   
   
       8 . The tool as recited in  claim 7  further comprising a pressure conducting channel within the exterior housing, the pressure conducting channel in fluid communication with the phase change fluid spring and the annulus for communicating changes in annulus pressure to the phase change fluid spring. 
   
   
       9 . The tool recited in  claim 7  wherein the phase change fluid spring stores and releases energy responsive to changes of annulus pressure. 
   
   
       10 . The tool as recited in  claim 7  wherein the first phase is a liquid phase. 
   
   
       11 . The tool as recited in  claim 7  wherein the second phase is one of a gas phase and a supercritical fluid phase. 
   
   
       12 . The tool as recited in  claim 7  wherein the first pressure is less than about 1,500 psi. 
   
   
       13 . The tool as recited in  claim 7  wherein the fluid is at least one of carbon dioxide, water, ammonia, diethyl ether, methane, ethane, propane, ethylene, propylene, methanol, ethanol, Freon, acetone and mixtures of thereof. 
   
   
       14 . A method for actuating a downhole tool disposed within a wellbore, the method comprising:
 filling a fluid spring with a phase change fluid at the surface, the phase change fluid being in a liquid phase during the filling and being maintained at a first pressure in the fluid spring at the surface;   operably associating the fluid spring with the downhole tool;   lowering the downhole tool and the fluid spring into the wellbore to a desired depth such that the phase change fluid transitions from the liquid phase to one of a gas phase and a supercritical phase and to a second pressure that is higher than the first pressure;   pressurizing the phase change fluid in the fluid spring downhole such that energy to stored in the fluid spring; and   releasing the energy stored in the fluid spring to actuate the downhole tool.   
   
   
       15 . The method as recited in  claim 14  wherein the step of filling a fluid spring with a phase change fluid at the surface further comprises filling the fluid spring with at least one of carbon dioxide, water, ammonia, diethyl ether, methane, ethane, propane, ethylene, propylene, methanol, ethanol, Freon, acetone and mixtures of thereof. 
   
   
       16 . The method as recited in  claim 14  wherein the step of filling a fluid spring with a phase change fluid at the surface further comprises filling the fluid spring such that the first pressure is less than about 1,500 psi. 
   
   
       17 . The method as recited in  claim 14  wherein the step of pressurizing the phase change fluid in the fluid spring downhole further comprises increasing the pressure in an annulus surrounding the downhole tool. 
   
   
       18 . The method as recited in  claim 14  wherein the step of releasing the energy stored in the fluid spring to actuate the downhole tool further comprises reducing the pressure in an annulus surrounding the downhole tool. 
   
   
       19 . The method as recited in  claim 14  further comprising repeating the steps of pressurizing the phase change fluid in the fluid spring downhole and releasing the energy stored in the fluid spring to actuate the downhole tool through a plurality of positions by sequentially increasing and decreasing the pressure in an annulus surrounding the downhole tool. 
   
   
       20 . A fluid spring for actuating a downhole tool in a wellbore, the fluid spring comprising:
 a housing defining a fluid chamber; and   a phase change fluid disposed within the fluid chamber, the phase change fluid in a first phase at a first pressure at the surface and in a second phase at a second pressure in the wellbore, the second pressure being greater than the first pressure.   
   
   
       21 . The fluid spring as recited in  claim 20  wherein the first phase is a liquid phase. 
   
   
       22 . The fluid spring as recited in  claim 20  wherein the second phase is one of a gas phase and a supercritical fluid phase. 
   
   
       23 . The fluid spring as recited in  claim 20  wherein the first pressure is less than about 1,500 psi. 
   
   
       24 . The fluid spring as recited in  claim 20  wherein the second pressure is greater than about 10,000 psi. 
   
   
       25 . The fluid spring as recited in  claim 20  wherein the fluid is at least one of carbon dioxide, water, ammonia, diethyl ether, methane, ethane, propane, ethylene, propylene, methanol, ethanol, Freon, acetone and mixtures of thereof.