System and method for determining forces on a load-bearing tool in a wellbore

Abstract

A system and method for sensing forces on a load-bearing tool located in a wellbore, according to which forces acting on the tool are sensed, and other conditions in the wellbore are measured. The forces on the tool caused by the measured conditions are subtracted from the sensed forces to determine the direct force acting on the tool.

1 . A method of determining a direct force acting on a load-bearing tool connected to a workstring, comprising the steps of: 
 sensing a total force acting on the tool when located in a wellbore, wherein the total force comprises the direct force acting on the tool and additional forces acting on the tool;    measuring at least one condition in the wellbore that causes the additional forces;    calculating the additional forces from the measured condition; and    subtracting the additional forces from the sensed total force to determine the direct force acting on the tool.    
   
   
       2 . The method of  claim 1  wherein the measured condition is the temperature in the wellbore around the tool.  
   
   
       3 . The method of  claim 1  wherein the measured condition is the differential pressure across the tool.  
   
   
       4 . The method of  claim 1  wherein the measured condition is the pressure in the workstring.  
   
   
       5 . The method of  claim 1  wherein the steps of calculating and subtracting are done by a processor that receives signals corresponding to the sensed total force and measured conditions.  
   
   
       6 . The method of  claim 1  wherein the direct force is a tensile or compressive stress on the tool.  
   
   
       7 . The method of  claim 1  wherein the tool comprises a packer, and the direct force is a force used to set the packer.  
   
   
       8 . A system for determining a direct force acting on a load-bearing tool connected to a workstring, comprising: 
 at least one sensor for sensing a total force acting on the tool when located in a wellbore, wherein the total force comprises the direct force acting on the tool and additional forces acting on the tool;    at least one gauge for measuring at least one condition in the wellbore that causes additional forces on the tool; and    a processor for calculating the additional forces on the tool resulting from the measured conditions, and subtracting the additional forces from the sensed total force to determine the direct force.    
   
   
       9 . The system of  claim 8  wherein the measured conditions include the temperature in the wellbore around the tool.  
   
   
       10 . The system of  claim 8  wherein the measured conditions include the differential pressure across the tool.  
   
   
       11 . The system of  claim 8  wherein the measured conditions include the pressure in the workstring.  
   
   
       12 . The system of  claim 8  wherein the processor receives signals corresponding to the sensed total force and measured conditions.  
   
   
       13 . The system of  claim 8  wherein the direct force is a tensile or compressive stress on the tool.  
   
   
       14 . The system of  claim 8  wherein the tool comprises a packer, and the direct force is a force used to set the packer.  
   
   
       15 . A processor readable medium comprising a plurality of instructions for execution by at least one processor, wherein the instructions are for: 
 receiving an input corresponding to a total force acting on a tool when located in a wellbore, wherein the total force comprises a direct force acting on the tool and additional forces acting on the tool;    receiving an input corresponding to at least one measured condition in the wellbore that causes the additional forces on the tool;    calculating the additional forces resulting from the measured condition; and    subtracting the additional forces from the total force to determine the direct force acting on the tool.    
   
   
       16 . The medium of  claim 15  wherein the measured condition is the temperature in the wellbore around the tool.  
   
   
       17 . The medium of  claim 15  wherein the measured condition is the differential pressure across the tool.  
   
   
       18 . The medium of  claim 15  wherein the measured conditions include the pressure in a workstring connected to the tool.  
   
   
       19 . The medium of  claim 15  wherein the direct force is a tensile or compressive stress on the tool.  
   
   
       20 . The medium of  claim 15  wherein the tool comprises a packer, and the direct force is a force used to set the packer.  
   
   
       21 . A system of determining a direct force acting on a load-bearing tool connected to a workstring, comprising: 
 means for sensing a total force acting on the tool when located in a wellbore, wherein the total force comprises the direct force acting on the tool and additional forces acting on the tool;    means for measuring at least one condition in the wellbore that causes the additional forces; and    means for calculating the additional forces resulting from the measured condition and subtracting the additional forces from the total force to determine the direct force.    
   
   
       22 . The system of  claim 21  wherein the measured condition is the temperature in the wellbore around the tool.  
   
   
       23 . The system of  claim 21  wherein the measured condition is the differential pressure across the tool.  
   
   
       24 . The system of  claim 21  wherein the measured condition is the pressure in the workstring.  
   
   
       25 . The system of  claim 21  wherein the means for calculating and subtracting is a processor that receives signals corresponding to the total force and measured conditions.  
   
   
       26 . The system of  claim 21  wherein the direct force is a tensile or compressive stress on the tool.  
   
   
       27 . The system of  claim 21  wherein the tool comprises a packer, and the direct force is a force used to set the packer.