System and method for monitoring strain & pressure

Abstract

A method for monitoring a well treatment, comprising the steps of installing at least one distributed acoustic strain sensor in at least one monitoring well, said monitoring well being a known distance from the treatment well, initiating a well treatment on the first well, monitoring the formation surrounding the monitoring well using the distributed acoustic strain sensor, and using the distributed acoustic strain sensor, detecting a change in strain at a first location in the monitoring well, using the change in strain to make determinations about the well treatment. The sensor may comprise a fiber optic cable. The change in strain may be used as an indicator that the effect of the well treatment has extended beyond a predetermined preferred treatment zone, the treatment may be a fracture treatment, and the well treatment may be controlled or ceased based on the determinations made in step e).

1 . A method for detecting the effect of a well treatment performed in a first well, comprising the steps of:
 a) installing at least one distributed acoustic strain sensor in at least one monitoring well, said monitoring well being a known distance from the first well;   b) initiating a well treatment on the first well;   c) monitoring the formation surrounding the monitoring well using the distributed acoustic strain sensor;   d) using the distributed acoustic strain sensor, detecting a change in strain or pressure at a first location in the monitoring well; and   e) using the change in strain detected in step d) to make determinations about the well treatment in step b).   
     
     
         2 . The method according to  claim 1  wherein distributed acoustic strain sensors are installed in at least two monitoring wells. 
     
     
         3 . The method according to  claim 1  wherein each monitoring well is between 50 m and 5000 m from the first well. 
     
     
         4 . The method according to  claim 1  wherein the distributed acoustic sensor comprises a fiber optic cable. 
     
     
         5 . The method according to  claim 1  wherein the change in strain detected in step d) indicates that the effect of the well treatment has extended to or beyond the limit of a predetermined preferred treatment zone. 
     
     
         6 . The method according to  claim 1  wherein the well treatment is a fracture treatment. 
     
     
         7 . The method according to  claim 1  further including the step of controlling the well treatment based on the determinations made in step e). 
     
     
         8 . The method according to  claim 1 , further including the step of ceasing the well treatment based on the determinations made in step e). 
     
     
         9 . The method according to  claim 1  further including the step of detecting, at one or more locations that are vertically spaced from the first locations, further changes in strain that are related to the change in strain detected in step d). 
     
     
         10 . The method according to  claim 8  further including the step of using the change in strain detected in step d) to determine information about the formation between the first well and the monitoring well.