Method and Apparatus for Evaluating the Potential Effectiveness of Refracing a Well

Abstract

A method for evaluating the potential effectiveness of refracing a previously fracked oil/gas well is accomplished by isolating a plurality of previously fracked zones of an oil/gas well in a formation and measuring the fluid flow rates from the isolated zones using a three phase flow meter positioned within the well at or near the previously fracked zones. The zones may be isolated by an isolation assembly which includes two packers connected by a perforated pipe and attached to a tubular positioned within the well.

What is claimed is: 
     
         1 . A method of evaluating the potential effectiveness of refracing a producing oil/gas well that has already been fracked at a plurality of zones along the length of the well comprising:
 a) isolating a first producing, previously fracked zone in the well,   b) measuring the oil, water, or gas flow rate, from the producing zone while the zone is being produced,   c) calculating a production index for the isolated previously fracked zone, and   d) determining the previously fracked zones that are most likely to exhibit increased productivity due to a refracing procedure based upon the production index.   
     
     
         2 . The method of  claim 1  further including the step of isolating two or more previously fracked zones and measuring the oil flow rate flow from each previously fracked zone. 
     
     
         3 . The method of  claim 1  wherein the previously fracked zone is isolated by placing a packer within the well at the beginning and end of the zone. 
     
     
         4 . The method of  claim 3  wherein the oil, water, or gas flow rate is obtained by placing a three phase flow meter in tubing located within the well, the tubing including a perforated pipe positioned between the packers. 
     
     
         5 . The method of  claim 4  wherein the oil, water, or gas is produced using a jet pump positioned within the production tubing. 
     
     
         6 . The method of  claim 5  wherein the packers are either of the inflatable type or mechanical type and a portion of power fluid for the jet pump is diverted to set the packers. 
     
     
         7 . The method of  claim 1  wherein the well is a horizontal well. 
     
     
         8 . The method of  claim 1  further including measuring the temperature and pressure of fluid within the previously fraced zone. 
     
     
         9 . The method of  claim 1  further including measuring an initial static bottom hole pressure and a flowing bottom hole pressure of the previously fraced zone, measuring a production rate of the previously fraced zone, wherein the production index is calculated by subtracting the flowing bottom hole pressure from the static bottom hoe pressure and dividing the production rate by the result of subtracting the flowing bottom hole pressure from the static bottom hole pressure. 
     
     
         10 . The method of  claim 1  further including the step of refracing the previously fraced zones that are determined to be most likely to exhibit increased productivity.