CORE DEPTH CORRELATION
Once the core data has been entered into the well log analysis database, the core data must be depth correlated to the well log data. The well log data is always used as the depth reference and the core is depth shifted to match the well log data. Ordinarily, the core porosity is used with reference to the well log analysis porosity for depth correlation purposes. When available, the core gamma ray is digitized to help with the depth correlation and match to the well log gamma ray.
Once depth correlation has been done to the satisfaction of the analyst, the comparison of the core data to the well log data can proceed.
At the most basic a comparison of well log analysis porosity vs. core porosity and well log analysis porosity vs. core permeability maximum are usually undertaken.
The trends of the analysis porosity vs. core permeability maximum (Kmax) can be approximated with a series of line segments. An apparent permeability maximum can then be obtained from the analysis porosity. Given an analysis porosity, go perpendicular to the porosity axis up to intersect the line segment. From the intersection of the line segment go horizontally to intersect the permeability axis to infer the apparent permeability reading.
More complex interpretations using the core data would be to create an apparent core porosity and core permeability for each well over the stratigraphic interval of interest using statistical observation methods
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