A METHOD OF THROUGH-CASING GAS DETECTION

摘要

In the field of through-casing gas detection related to oil production there is a need to identify the presence of gas in a formation. A gas detection method includes carrying out respective neutron and densi ty logs, using neutron (12) and density (13) detectors, along a length of well. The density log is corrected for the dimensions and properties of the we ll casing. The corrected density log is then combined with the neutron log to compensate for regions of artificially high density outside the casing. The compensated density log is continuously calibrated against the neutron log. The dynamically calibrated density and neutron logs are inspected for crossovers that signify the presence of gas in a formation.