Lithology on the Ogbon-1 Well
Learning objectives
- Read the logs as a continuous lithology, foot by foot
- Combine the gamma ray, photoelectric factor, and porosity tools into mineral volumes
- See the litho-density track as the chapter's deliverable
- Place lithology beside saturation and permeability in the evaluation
The Logs as Rock
The chapter ends by turning the whole log suite into a picture of the rock itself. The gamma ray gives the clay, the photoelectric factor names the matrix mineral, and the density-neutron pair sets the porosity; folded together by the multimineral idea, they resolve every foot into volume fractions of quartz, calcite, clay, and pore.
Reading the Track
Drawn as a stacked litho-density track, the Ogbon-1 well reads at a glance: clean quartz sands through the oil column, a limestone streak the photoelectric curve flags near 5, the shale breaks swelling with clay, and the porosity ribbon down the right edge. The curve beside it is the independent check, sitting near 1.8 in the sands and climbing toward 5 in the carbonate, exactly the lithology indicator the chapter opened with.
The Third Pillar
This continuous mineralogy is the deliverable of the lithology chapter. It stands beside the water-saturation log of Chapter 7 and the permeability log of Chapter 9 as the third pillar of a formation evaluation, all three read from the same handful of curves. The chapters that follow turn these into net pay and a hydrocarbon volume, and finally into the full Ogbon-1 evaluation, end to end.
References
- Schlumberger (2009). Log Interpretation Charts. Schlumberger Educational Services.
- Asquith, G. and Krygowski, D. (2004). Basic Well Log Analysis, 2nd ed. AAPG Methods in Exploration 16.