Tomographic Imaging of Fracture - Fault Permeability Zones During Cementing Operations

Abstract

Disclosed are various embodiments of methods for identifying faults and fractures, and other permeable features, within geologic layers during a drilling operation comprising; recording microseismic data during a drilling operation; recording times and positions of a drill bit in a well bore during the drilling operation; processing microseismic data at a plurality of selected times and locations to image microseismic events and identifying faults and fractures, and other permeable features, from corresponding images of microseismic events. In other embodiments, the integrity of a cementing operation may be verified by recording microseismic data during a cementing operation; recording times and positions of a cementing operation in a well bore during the cementing operation; processing microseismic data at a plurality of selected times and locations to image microseismic events and identifying faults and fractures, and other permeable features, within the cemented zone from corresponding images of microseismic events.

What is claimed is: 
     
         1 . A method for monitoring the progress and success of a cementing operation and verifying the integrity of cementing in a well bore comprising:
 recording microseismic data during a cementing operation;   recording times and positions corresponding to such times of a cement slug in a well bore during the cementing operation;   processing microseismic data at a plurality of selected times and locations proximate the well bore to image microseismic events and   identifying faults and other natural or induced fractures associated with the cementing operation from images of microseismic events.   
     
     
         2 . The method of  claim 1 , wherein the cementing times and corresponding positions are substantially continuously recorded. 
     
     
         3 . The method of  claim 1 , wherein recording microseismic data during a cementing operation further comprises continuing to record microseismic data after cessation of cementing until microseismic activity resulting from the cementing operation has substantially ceased. 
     
     
         4 . The method of  claim 1 , wherein the microseismic data are processed with SET software. 
     
     
         5 . The method of  claim 1 , wherein the microseismic data are processed using an estimated velocity model derived using SET processing of the microseismic data to image a plurality of positions of the drill bit corresponding to known times and positions of the drill bit. 
     
     
         6 . The method of  claim 1 , wherein the microseismic data are processed using an estimated velocity model derived from analysis of conventional surface seismic data. 
     
     
         7 . The method of  claim 1 , wherein the microseismic data are processed using an estimated velocity model derived from analysis of well log data. 
     
     
         8 . The method of  claim 1  wherein the plurality of selected times is determined by selecting a predetermined time increment during the cementing process. 
     
     
         9 . The method of  claim 1  wherein the plurality of selected times is determined by selecting times corresponding to a predetermined depth increment during the cementing process. 
     
     
         10 . The method of  claim 1  wherein the plurality of selected times is determined by selecting times corresponding to a predetermined set of time or depth values during the cementing process. 
     
     
         11 . The method of  claim 1  wherein the plurality of selected times is determined by selecting times corresponding to events observed during the cementing process. 
     
     
         12 . The method of  claim 11  wherein the events observed during the cementing process further comprise a loss of cement. 
     
     
         13 . The method of  claim 1  further comprising monitoring the progress and success of a cementing operation and verifying the integrity of cementing by identifying faults and fractures or the lack thereof from corresponding images of microseismic events. 
     
     
         14 . The method of  claim 1  further comprising monitoring the progress and success of a cementing operation and verifying the integrity of cementing by identifying subsurface zones that carry cement away from the well bore.