The Petrophysics Workflow
Learning objectives
- See the whole course as a single interpretation workflow
- Trace what each stage consumes and what it produces
- Place every chapter on the chain from logs to a decision
- Recognize how the advanced logs refine the saturation spine
The Whole Course Is One Chain
Every chapter of this course was one link in a single chain that turns raw logs into a development decision. This map lays the chain out in interpretation order, so the through-line is visible at last: quality-control the logs, strip the shale, find the porosity and the lithology, read the resistivity, solve for water saturation, estimate permeability, place the contacts and the structure, apply the cutoffs for net pay, and finally compute the volumes and the decision.
Each Stage Feeds the Next
Step through the stages and watch the dependencies. The shale volume gates the porosity; the porosity and the resistivity feed Archie for the saturation; the saturation and the porosity set the net pay; the net pay sets the volumes. Nothing downstream is trustworthy if an upstream stage is wrong, which is why a single bad Rw or a mis-set cutoff can ripple all the way to the oil in place.
The Spine and Its Refinements
The core spine is short: shale, porosity, saturation, permeability, net pay, volumes. The advanced chapters refine it. Lithology sharpens the porosity by naming the matrix; capillary pressure carries the saturation away from the well into the reservoir; the image logs and the pressures supply the structure and the fluid contacts; and for source rocks, the same logs run the unconventional workflow. Learn the spine first, then add the refinements, and the whole of formation evaluation is this one map.
References
- Asquith, G. and Krygowski, D. (2004). Basic Well Log Analysis, 2nd ed. AAPG.
- Rider, M. and Kennedy, M. (2011). The Geological Interpretation of Well Logs, 3rd ed. Rider-French.