Downhole uses of piezoelectric motors

Abstract

A sampling system used in collecting samples of connate fluid from within hydrocarbon bearing formations. The sampling system comprises a sonde disposed within a wellbore formed proximate to the formation of interest. The sonde includes a sample probe insertable into the formation and a drawdown pump in fluid communication with the sample probe. The drawdown pump is motivated by an associated electrically responsive material, where the electrically responsive material can be comprised of a piezoelectric material, a electroactive polymer, or some other electrically responsive material.

1 . A formation fluid testing drawdown pump comprising: 
 a piston;    a cylinder formed to receive said piston therein; and    a motive device operatively coupled to said piston, wherein said motive device is comprised of material responsive to electrical stimuli.    
   
   
       2 . The formation testing drawdown pump of  claim 1 , wherein said material is comprised of a piezoelectric composition.  
   
   
       3 . The formation testing drawdown pump of  claim 2 , further comprising a piezoelectric motor.  
   
   
       4 . The formation testing drawdown pump of  claim 3 , wherein said piezoelectric motor is selected from the group comprising a linear piezoelectric motor and a rotary piezoelectric motor.  
   
   
       5 . The formation testing drawdown pump of  claim 1 , wherein said material is comprised of an electroactive polymer.  
   
   
       6 . The formation testing drawdown pump of  claim 1 , wherein said operative coupling is comprised of a direct mechanical attachment between said motive device and said piston.  
   
   
       7 . The formation testing drawdown pump of  claim 1  wherein said operative coupling is comprised of a hydraulic circuit.  
   
   
       8 . The formation testing drawdown pump of  claim 3 , wherein said piezoelectric composition comprises at least two distinct piezoelectric segments.  
   
   
       9 . The formation testing drawdown pump of  claim 1  further comprising a feed back loop and a pump control, said feed back loop comprising a pressure monitoring device in operative cooperation with the pump control.  
   
   
       10 . The formation testing drawdown pump of  claim 9  wherein said pressure monitoring device provides data representative of fluid pressure within the cylinder and wherein the pump control is programmable for controlling the operation of said drawdown pump in response to the data representative of fluid pressure within the cylinder to ensure the fluid pressure within the cylinder remains above its bubble-point pressure.  
   
   
       11 . A method of sampling connate fluid from within a subterranean formation comprising: 
 inserting a drawdown pump within a wellbore adjacent the subterranean formation;    providing a fluid communicative path between said drawdown pump and the subterranean formation; and    operating said drawdown pump with a motive device, wherein said motive device is operatively coupled to said drawdown pump and comprises material responsive to electrical stimuli.    
   
   
       12 . The method of  claim 11  further comprising providing electrical energy to said motive device.  
   
   
       13 . The method of  claim 11 , wherein said material is comprised of a piezoelectric composition.  
   
   
       14 . The method of  claim 13 , wherein said piezoelectric composition comprises a piezoelectric motor.  
   
   
       15 . The method of  claim 14 , wherein said piezoelectric motor is selected from the group comprising a linear piezoelectric motor and a rotary piezoelectric motor.  
   
   
       16 . The method of  claim 11 , wherein said material is comprised of an electroactive polymer.  
   
   
       17 . The method of  claim 11 , wherein said operative coupling is comprised of a direct mechanical attachment between said motive device and said piston.  
   
   
       18 . The method of  claim 11  wherein said operative coupling is comprised of a hydraulic circuit.  
   
   
       19 . The method of  claim 13 , wherein said piezoelectric composition comprises at least two distinct piezoelectric segments.  
   
   
       20 . The method of  claim 13  further comprising monitoring the pressure within the cylinder.  
   
   
       21 . The method of  claim 20  further comprising controlling operation of the drawdown pump based on the monitored pressure within the cylinder thereby ensuring the pressure within the cylinder remains above the bubble-point pressure of the sampled fluid.  
   
   
       22 . The method of  claim 11 , wherein the operating mode of said drawdown pump is selected from the group consisting of operating at a constant pressure and operating at a constant volumetric flow rate.