Dynamic multi-parameter interpretation of dual-detector carbon/oxygen measurements

摘要

Traditional C/O interpretation methods that rely on a limited set of data can not provide the fidelity and accuracy needed to interpret C/O data in complex completions, mixed lithology, or under variable holdup conditions. New interpretation methods based on computer modeling can now furnish accurate C/O response data, not only for applying sequential environmental corrections, but even for treating simultaneous variations in the logging conditions. In this paper, we present new concepts of interpreting C/O data that fully utilize the power of computer modeling. The C/O response is dynamically generated at every depth level of the log based on a non-linear model that simultaneously accounts for variations in completion geometry, borehole diameter, formation porosity and mineralogy, and borehole holdup. The model also allows for normalizing the C/O response in a shale or a low-porosity zone. A new treatment for dual-detector instruments is also presented that takes advantage of the precision and sensitivity of the two detectors rather than simply using one or the other. Data from the two detectors are combined in such a way that the error of the measured saturation is minimized, which should provide an optimum measurement under any condition.