Changes

===Wireline log calibration and correlation===

===Wireline log calibration and correlation===

Interpretations of depositional environment based on individual well data are transformed into a three-dimensional picture of the reservoir by wireline log correlation and, where possible, by three-dimensional seismic data.

Interpretations of depositional environment based on individual well data are transformed into a three-dimensional picture of the reservoir by wireline [[log correlation]] and, where possible, by [[3-D seismic: the data cube|three-dimensional seismic data]].

Wireline logs to be used for facies analysis should, whenever possible, always be calibrated by core. This calibration involves (1) shifting core to log depths (see [[Preprocessing of logging data]] and [[Core-log transformations and porosity-permeability relationships]]) and (2) establishing a relationship between lithofacies associations and curve shape. Core gamma scans, obtained by passing the core through a device that measures the natural radioactivity of the rock, are particularly useful for shifting cores to logs. The calibration of wireline log shape by core is particularly important for firmly establishing the log response and the identity of vertical sequences on these logs.

Wireline logs to be used for facies analysis should, whenever possible, always be calibrated by core. This calibration involves (1) shifting core to log depths (see [[Preprocessing of logging data]] and [[Core-log transformations and porosity-permeability relationships]]) and (2) establishing a relationship between lithofacies associations and curve shape. Core gamma scans, obtained by passing the core through a device that measures the natural radioactivity of the rock, are particularly useful for shifting cores to logs. The calibration of wireline log shape by core is particularly important for firmly establishing the log response and the identity of vertical sequences on these logs.