A METHOD OF GEOMETRICAL FACTORS IN THE THEORY AND INTERPRETATION OF FORMATION DENSITY LOGGING

An interpretational model based on the "radial geometrical factors concept" is developed to describe the count-rate of a formation density logging (FDL) multi-spaced tool. The interpretational model includes two metrological parameters for each detector-source pair of a multi-spaced sonde, which are: sensitivity to formation density S and radial sensitivity a. Apart from its universal application, the algorithm also allows some diagnoses of the intermediate zone to be made; that is to reveal zones of consolidation and fracturing. It is shown that empirical algorithms realizing different forms of "spine and ribs" charts are derived from the general algorithm. There is a practical possibility of resolving problems associated with the vicinity of the borehole wall by means of a three-spaced FDL tool. It is given a corresponding algorithm and a metrological optimization procedure. The validity of the relations established is substantiated by physical measurements and by Monte-Carlo modeling.