Patent ID: 8805615
Filing Date: 2014-08-12
Classification: E21B,G01V

Abstract:
1. For use in conjunction with a fractureable subterranean formation traversed by a borehole, a well logging method comprising the steps of: performing a before-frac logging operation and an after-frac logging operation with one or more logging tool apparatuses having a neutron emitting source and a plurality of thermal neutron or capture gamma ray logging detectors located at different distances from the neutron emitting source, wherein performing each of the before-frac and after-frac logging operations comprising moving the logging tool apparatus through the borehole and respectively generating a) a before-frac near detector count rate log and a before-frac far detector count rate log (“BF count rate logs”), and b) an after-frac near detector count rate log and an after-frac far detector count rate log (“AF count rate logs”); generating a before-frac near/far-count-rate-ratio-log (“BFN/F ratio log”) based on the BF count rate logs; generating an after-frac near/far-count-rate-ratio-log (“AFN/F ratio log”) based on the AF count rate logs; generating Corrected BF count rate logs by correcting the BF count rate logs to account for any changes in one or more of borehole fluid, logging tools, and neutron source output between the before-frac and after-frac logging operations; generating a Corrected BF ratio log by correcting the BFN/F ratio log to account for any changes in one or more of borehole fluid, logging tools, and neutron source output between the before-frac and after-frac logging operations; comparing the AFN/F ratio log and the Corrected BF ratio log to determine near/far count rate ratio differentials (“N/F ratio differentials”); computing near detector and/or far detector count rate differentials as lithology-independent and/or borehole condition independent, and hydrogen index-corrected count rate differentials based on the determined N/F ratio differentials; combining the computed near detector and/or far detector count rate differentials with the corresponding Corrected BF count rate logs—to yield modified before-frac near detector and/or far detector count rate logs that are a lithology-independent and/or borehole condition independent and hydrogen index-corrected before-frac count rate logs; and comparing the modified before-frac near detector and/or far detector count rate logs with the corresponding AF count rate logs to determine the heights/locations of high thermal neutron capture cross-section material-containing proppant in formation fractures and/or a borehole region adjacent to the fracturable subterranean formation.