Methods and Means for Simultaneous Casing Integrity Evaluation and Cement Inspection in a Multiple-Casing Wellbore Environment

Abstract

An x-ray based cement evaluation tool for measurement of the density of material volumes within single, dual and multiple-casing wellbore environments is provided, wherein the tool uses x-rays to illuminate the formation surrounding a borehole, and a plurality of detectors are used to directly measure the density of the cement annuli and any variations in density within The tool uses x-rays to illuminate the casing surrounding a borehole and a plurality of multi-pixel imaging detectors directly measure the thickness of the casing The tool includes an internal length having a sonde section, wherein the sonde section further includes an x-ray source; a radiation shield for radiation measuring detectors; sonde-dependent electronics; and a plurality of tool logic electronics and PSUs. Other systems and subsystems appropriate for carrying out the foregoing are also disclosed, as are a plurality of example methods of use therefor.

1 . An x-ray based cement evaluation tool for measurement of the density of material volumes, wherein the tool uses x-rays to illuminate a formation surrounding a borehole and a plurality of detectors are used to measure the density of the cement annuli and variations in density within, said tool further comprising:
 an internal length comprising a sonde section, wherein said sonde section further comprises an x-ray source;   a radiation shield for radiation measuring detectors;   sonde-dependent electronics;   and a plurality of tool logic electronics and PSUs.   
     
     
         2 . The tool of  claim 1 , further comprising a detector that is used to measure casing standoff such that other detector responses are compensated for tool stand-off and centralization. 
     
     
         3 . The tool of  claim 1 , wherein said shield further comprises tungsten. 
     
     
         4 . The tool of  claim 1 , wherein the tool is configured so as to permit through-wiring. 
     
     
         5 . The tool of  claim 1 , wherein a plurality of reference detectors is used to monitor the azimuthal output of the x-ray source. 
     
     
         6 . The tool of  claim 1 , wherein the shortest-axial offset imaging detector array is configured to distribute incoming photons into energy classifications such that photoelectric measurements may be made. 
     
     
         7 . The tool of  claim 1 , wherein the x-ray source energy is capable of being modulated to modify the optimum-detector axial offset in order to assist with the creation of response sensitivity functions. 
     
     
         8 . The tool of  claim 1 , wherein the tool is combinable with other measurement tools comprising one or more of neutron-porosity, natural gamma and array induction tools. 
     
     
         9 . The tool of  claim 1 , wherein an azimuthally segmented acoustic measurement is integrated into the tool. 
     
     
         10 . The tool of  claim 1 , wherein the tool determines the position, distribution and volume of fractures, either natural or artificial, within the formation surrounding the cased wellbore. 
     
     
         11 . The tool of  claim 1 , wherein the tool is integrated into a logging-while-drilling assembly. 
     
     
         12 . The tool of  claim 1 , wherein the tool is powered by mud-turbine generators. 
     
     
         13 . The tool of  claim 1 , wherein the tool is powered by batteries. 
     
     
         14 . The tool of  claim 1 , wherein the tool is configured so as to permit through-wiring. 
     
     
         15 . The tool of  claim 1 , wherein a plurality of reference detectors is used to monitor the output of the x-ray source. 
     
     
         16 . The tool of  claim 1 , wherein the shortest-axial offset detector is configured to distribute incoming photons into energy classifications such that photoelectric measurements may be made. 
     
     
         17 . The tool of  claim 1 , wherein the x-ray source energies are modulated to modify the optimum-detector axial offset in order to assist with the creation of response sensitivity functions. 
     
     
         18 . The tool of  claim 1 , wherein the tool is combinable with other measurement tools comprising one or more of neutron-porosity, natural gamma and array induction tools. 
     
     
         19 . The tool of  claim 1 , wherein azimuthally segmented acoustic measurements are integrated into the tool. 
     
     
         20 . The tool of  claim 1 , wherein the tool determines the position, distribution and volume of fractures, either natural or artificial, within the formation surrounding the cased wellbore. 
     
     
         21 . The method of x-ray based cement evaluation for measuring the density of material volumes within single, dual and multiple-casing wellbore environment, wherein said method comprises:
 illuminating the formation surrounding a borehole using x-rays;   using a plurality of detectors to measure the density of the cement annuli and any variations in density within; and   illuminating the casing surrounding a borehole using x-rays and then using a plurality of multi-pixel imaging detectors to measure the thickness of the casing.   
     
     
         22 . The method of  claim 21 , further comprising: measuring casing standoff such that other detector responses can be compensated for tool stand-off and centralization. 
     
     
         23 . The method of  claim 21 , further comprising using a plurality of reference detectors to monitor the azimuthal output of the x-ray source. 
     
     
         24 . The method of  claim 21 , further comprising: configuring the shortest-axial offset imaging detector array to distribute incoming photons into energy classifications such that photoelectric measurements may be made. 
     
     
         25 . The method of  claim 21 , further comprising modulating the x-ray source energy source to modify the optimum-detector axial offset to aid the creation of response sensitivity functions. 
     
     
         26 . The method of  claim 21 , further comprising combining the tool with other measurement tools comprising one or more of neutron-porosity, natural gamma and array induction tools. 
     
     
         27 . The method of  claim 21 , further comprising integrating an azimuthally segmented acoustic measurement into the tool. 
     
     
         28 . The method of  claim 21 , further comprising determining the position, distribution and volume of fractures, either natural or artificial, within the formation surrounding the cased wellbore. 
     
     
         29 . The method of  claim 21 , further comprising using a plurality of reference detectors to monitor the output of the x-ray source. 
     
     
         30 . The method of  claim 21 , further comprising configuring the shortest-axial offset detector to distribute incoming photons into energy classifications such that photoelectric measurements may be made. 
     
     
         31 . The method of  claim 21 , further comprising modulating the x-ray source energies so as to modify the optimum-detector axial offset in order to aid the creation of response sensitivity functions. 
     
     
         32 . The method of  claim 21 , further comprising determining the position, distribution and volume of fractures, either natural or artificial, within the formation surrounding the cased wellbore.