Method and apparatus for placing and interrogating downhole sensors

Abstract

A method and system to passively monitor cement integrity and reservoir/formation parameters near the wellbore at all depths and orientations outside a wellbore. Different types (pressure, temperature, resistivity, rock property, formation property etc.) of sensors are “pumped” into place by placing them into a suspension in the cement slurry at the time a well casing is being cemented, by placing them in gravel pack used in frackpacking, or by a deflected drilling tool. The sensors are either battery operated, or of a type where external excitation, (EMF, acoustic, RF etc.) may be applied to power and operate the sensor, which will send a signal conveying the desired information. The sensor is then be energized and interrogated using a separate piece of wellbore deployed equipment whenever it is desired to monitor cement or formation conditions. This wellbore deployed equipment could be, for example, a wireline tool.

We claim:  
     
         1 . A method of placing sensors in a borehole, the steps comprising: 
 drilling a borehole with a drill apparatus;    forming a well casing therein; and    placing at least one remote sensor into cement slurry as the well casing is being cemented.    
     
     
         2 . The method as recited in  claim 1 , wherein the at least one remote sensor comprises a transducer.  
     
     
         3 . The method as recited in  claim 1 , wherein the at least one remote sensor comprises a pressure measurement device.  
     
     
         4 . The method as recited in  claim 1 , wherein the at least one remote sensor comprises temperature measurement device.  
     
     
         5 . The method as recited in  claim 1 , wherein the at least one remote sensor comprises a resistivity measurement device.  
     
     
         6 . The method as recited in  claim 1 , wherein the at least one remote sensor measures rock properties.  
     
     
         7 . The method as recited in  claim 1 , wherein the at least one remote sensor measures formation properties.  
     
     
         8 . The method as recited in  claim 1 , wherein the at least one remote sensor measures paramagnetic properties.  
     
     
         9 . The method as recited in  claim 1 , wherein the at least one remote sensor measures magnetic fields.  
     
     
         10 . The method as recited in  claim 1 , wherein the at least one remote sensor measures pulse eddy current.  
     
     
         11 . The method as recited in  claim 1 , wherein the at least one remote sensor measures polar spin.  
     
     
         12 . The method as recited in  claim 1 , wherein the at least one remote sensor measures magnetic flux leak.  
     
     
         13 . The method as recited in  claim 1 , wherein the at least one remote sensor measures well integrity.  
     
     
         14 . The method as recited in claim l, wherein the at least one remote sensor measures casing wear.  
     
     
         15 . A method of placing sensors in a geologic formation, the steps comprising: 
 drilling a wellbore with a drill apparatus;    placing a at least one sensor outside said borehole; and    placing a wellbore device into said wellbore to interrogate said at least one sensor.    
     
     
         16 . The method as recited in  claim 15 , wherein said at least one sensor is powered by external excitation.  
     
     
         17 . A method of placing sensors in a geologic formation, the steps comprising: 
 drilling a wellbore with a drill apparatus;    removing formation material in a direction away from said wellbore to produce a sensor placement area; and    placing a sensor into said sensor placement area.    
     
     
         18 . The method as recited in  claim 17 , wherein said removing formation material step comprises using a side bore coring tool.  
     
     
         19 . The method as recited in  claim 17 , wherein said removing formation material step comprises fracturing and packing the formation with a slurry and wherein said placing step comprises placing said sensor in said slurry prior to packing the formation with said slurry.  
     
     
         20 . An apparatus for placing a sensor in a geologic formation, comprising: 
 a first tube,    a second tube attached to said first tube wherein the end of said second tube opposite from end attached to said first tube comprises a nozzle for expressing fluid and wherein said second tube comprises clasping means for attaching a sensor thereto; and    deflectors attached to the outside surface of said first tube for deflecting said second tube away from said first tube.