Building a Mineral Componential Model of Formation Based on C/O and Other Through-Casing Logs

Proposed is a decomposition of measured C/O-spectra into a series of elementary spectra. As far as it is impossible measure such elementary spectra in formation calibration models, authors propose compute such spectra by the Monte-Carlo mathematical simulation. Verification of Monte-Carlo computations is performed by processing the results of C/O-log in calibration models. As a result of this approach the concentration of elements in rocks are produced. To derive oil saturation of rocks from concentrations of elements a technique for building the mineral-componential and fluidal models of formation is used. To this end such logs as spectral gamma log, neutron-neutron, and pulsed neutron-neutron logs are run. Petrophysical characteristics are computed based on the extended analysis of core samples of studied deposits. The mineral-componential and fluidal models of formation allows compute the oil-saturation index and estimate the share of movable oil, i.e., predict the oil recovery of a reservoir. The use of detailed mineral-componential and fluidal models for interpreting logs run in cased wells allows to monitor the current oil saturation of beds and identify previously bypassed interlayers. Presented are examples of applying this technique to interpreting logs acquired in the wells of Vartovsk arch, West Siberia