Down Hole Subsurface Wave System with Drill String Wave Discrimination and Method of Using Same

Abstract

A system, method and tool for measuring subsurface waves from a wellbore is provided comprising a source for propagating at least earth waves and a drilling tool. The drilling tool may include a drill string comprising a number of drill pipe sections positionable in the wellbore and a bottom hole assembly. The bottom hole assembly may include a sensor package containing a strain gauge to determine strain measurements of the drill string and a subsurface sensor to determine subsurface measurements of earth waves passing through the earth and drill string waves passing through the drill string. Embodiments of the system may compare the strain measurements to the subsurface measurements in order to distinguish drill string waves from earth waves.

What is claimed is: 
     
         1 . A system for measuring subsurface waves from a wellbore, the system comprising:
 a source for propagating at least earth waves;   a drilling tool comprising;
 a drill string comprising a plurality of drill pipe positionable in the wellbore; and 
 a bottom hole assembly comprising;
 a sensor package comprising;
 a strain gauge to determine strain measurements of the drill string; and 
 a subsurface sensor to determine subsurface measurements of earth waves passing through the earth and drill string waves passing through the drill string; and 
 
 
   wherein the strain measurements are compared with the subsurface measurements to distinguish the drill string waves from the earth waves.   
     
     
         2 . The system of  claim 1 , further comprising a subsurface unit comprising a strain gauge tool to receive the strain gauge measurements and a subsurface sensor tool to receive the subsurface measurements. 
     
     
         3 . The system of  claim 2  wherein the comparison between the subsurface measurements and the strain measurements occur down hole. 
     
     
         4 . The system of  claim 1 , wherein the subsurface sensor comprises;
 at least one of a hydrophone or a geophone; and   the subsurface measurements comprises at least a corresponding one of a hydrophone measurement or a geophone measurement.   
     
     
         5 . The system of  claim 4 , further comprising a subsurface unit comprising at least one of a corresponding hydrophone tool to receive the hydrophone measurements or a geophone tool to receive the geophone measurements. 
     
     
         6 . The system of  claim 5  wherein the comparison between the strain measurements and the at least one of the corresponding hydrophone measurements or the geophone measurements occurs down hole. 
     
     
         7 . The system of  claim 1 , wherein the source comprises an air gun. 
     
     
         8 . The system of  claim 1  further comprising a source sensor operatively connected to the source. 
     
     
         9 . The system of  claim 1 , further comprising a surface clock and a down hole clock. 
     
     
         10 . The system of  claim 1 , further comprising a down hole sensor, the down hole sensor measuring at least one down hole parameter comprising a temperature, a pressure or a density. 
     
     
         11 . The system of  claim 1 , wherein the drilling tool comprises one of a drilling tool or a drill stem tester. 
     
     
         12 . A method of measuring subsurface waves from a wellbore comprising:
 advancing a drilling tool to form the wellbore, the drilling tool comprising a drill string, and a bottom hole assembly comprising a sensor package comprising a strain gauge and a subsurface sensor;   taking strain measurements of the drill string with the strain gauge and taking subsurface measurements of earth waves passing through the earth and drill string waves passing through the drill string with the subsurface sensor; and   discriminating the drill string waves from the earth waves via comparisons between the strain measurements and the subsurface measurements.   
     
     
         13 . The method of  claim 12 , further comprising determining a down hole break time for the earth wave when the subsurface measurement records the earth wave but the strain gauge does not. 
     
     
         14 . The method of  claim 13 , further comprising determining a transit time for the earth wave by differencing the down hole break time with a surface break time established at an activation of a source. 
     
     
         15 . The method of  claim 12 , further comprising activating a source during an addition or subtraction of a drill pipe section to the drill string. 
     
     
         16 . The method of  claim 12 , further comprising determining wellbore parameters via a down hole sensor. 
     
     
         17 . A wellbore tool comprising:
 a strain gauge configured to detect strain signals traveling within the tool;   a subsurface wave sensor configured to detect subsurface waves;   wherein noise in a subsurface wave measurement is reduced by discriminating out the impact of strain signals on the subsurface wave sensor.   
     
     
         18 . The tool of  claim 17 , wherein the subsurface wave sensor is at least one of a hydrophone or a geophone. 
     
     
         19 . The tool of  claim 17 , wherein the subsurface waves comprise earth waves traveling through earth and drill string waves traveling through the tool, and wherein the strain signals are drill string waves. 
     
     
         20 . The tool of  claim 17 , wherein the wellbore tool further comprises a down hole clock for determining a down hole break time.