Methods and Apparatus for Determining Downhole Parameters

Abstract

Apparatus and methods for determining downhole fluid parameters are disclosed herein. An example method includes deploying a downhole apparatus into a wellbore. The downhole apparatus includes a sensor having a heater and a temperature sensor. The method also includes traversing the downhole apparatus through the wellbore and obtaining a first response with the sensor in a first position of the wellbore. The method also includes obtaining a second response with the sensor in a second position of wellbore and determining a presence of a boundary between the first and second positions based on the first and second responses.

What is claimed is: 
     
         1 . A method, comprising:
 deploying a downhole apparatus into a wellbore, the downhole apparatus comprising a sensor having a heater and a temperature sensor;   traversing the downhole apparatus through the wellbore;   obtaining a first response with the sensor in a first position of the wellbore;   obtaining a second response with the sensor in a second position of wellbore; and   determining a presence of a boundary between the first and second positions based on the first and second responses.   
     
     
         2 . The method of  claim 1 , further comprising determining a fluid type based on the first or second responses. 
     
     
         3 . The method of  claim 2 , wherein the fluid type comprises one or more of gas, mud, oil, water, or brine. 
     
     
         4 . The method of  claim 1 , further comprising determining a relative position of the boundary based on the first and second positions. 
     
     
         5 . The method of  claim 1 , wherein the first position is associated with a first fluid layer and the second position is associated with a second fluid layer. 
     
     
         6 . A method, comprising:
 determining a first thermal property of a first fluid at a first wellbore position via a sensor of a downhole tool, the sensor comprising a heater and a temperature sensor;   determining a second thermal property of a second fluid at a second wellbore position via the sensor; and   comparing the first and second thermal properties to identify a difference therebetween associated with a boundary.   
     
     
         7 . The method of  claim 6 , wherein the first thermal property comprises a first velocity and the second thermal property comprises a second velocity. 
     
     
         8 . The method of  claim 6 , wherein the sensor comprises a calorimetric sensor. 
     
     
         9 . The method of  claim 6 , wherein determining the first velocity of the fluid at the first wellbore position comprises heating the fluid and determining a temperature of the fluid. 
     
     
         10 . The method of  claim 6 , further comprising determining a thermal conductance between the heater and the fluid. 
     
     
         11 . The method of  claim 6 , further comprising moving the downhole tool from the first wellbore position to the second wellbore position. 
     
     
         12 . The method of  claim 11 , wherein moving the downhole tool comprises moving the downhole tool at a substantially constant rate. 
     
     
         13 . The method of  claim 6 , further comprising generating a profile of the formation based on first and second velocities. 
     
     
         14 . A method, comprising:
 determining a first thermal property of a first fluid at a first wellbore position via a sensor of a downhole tool, the sensor comprising a heater and a temperature sensor;   comparing the first thermal property with thermal properties of reference fluids; and   determining a fluid type of the first fluid based on the comparison.   
     
     
         15 . The method of  claim 14 , further comprising:
 determining a second thermal property of a second fluid at a second wellbore position via the sensor; and   comparing the second thermal property with the thermal properties of the reference fluids; and   determining a fluid type of the second fluid based on the comparison.   
     
     
         16 . The method of  claim 15 , further comprising comparing the first and second thermal properties to identify a difference therebetween associated with a boundary. 
     
     
         17 . The method of  claim 16 , further comprising determining a relative position of the boundary based on the first and second positions. 
     
     
         18 . The method of  claim 15 , further comprising generating a profile of a formation based on first and second thermal properties. 
     
     
         19 . The method of  claim 15 , further comprising moving the downhole tool from the first wellbore position to the second wellbore position. 
     
     
         20 . The method of  claim 19 , wherein moving the downhole tool comprises moving the downhole tool at a substantially constant rate.