capture cross section u03c3 or sigma and the resistivity r the collocation of sensors on the tool allows the measurements to be taken substantially in the same formation zone of investigation and substantially at the same time a downhole assembly of tools as opposed to a single integrated tool may also be used if it is capable of making substantially simultaneous disparate measurements in one or more zones of interest in a subsurface formation the single integrated tool or the assembly of tools may be disposed on a wireline a drill string or some other conveyance mechanism using those measurements one may solve certain equations e g sigma and resistivity simultaneously to obtain for example estimates of water salinity and saturation that are mutually consistent with the measurements in another embodiment one may generate and display the solution graphically for the example given if invasion is negligible the results are representative of the virgin zone water saturation s w interpretations from stand alone sigma and resistivity computations rely on among other presumably known inputs a water salinity input to derive sigma water u03c3 w and a water resistivity r w input the sigma equation can be written as u03c3 u03c3 m 1 u2212.