Net Pay and Volume on the Ogbon-1 Well
Learning objectives
- Run the full net-pay flag on the Ogbon-1 oil column
- Integrate porosity and oil fraction into the HC pore thickness
- Compute the STOIIP and feel the cutoff sensitivity on real rock
- See the volumetric handoff as the end of the interpretation chain
One Well, One Number
The chapter, and the interpretation course, ends with one number. On the Ogbon-1 well the shale volume, the porosity, and the Archie saturation are run down the oil column, three cutoffs flag the net pay, and what falls out is the producible rock the whole course was built to find.
The Handoff
The flagged feet, integrated as porosity times the oil fraction, give the hydrocarbon pore thickness; the volumetric equation and the drainage area turn that into the stock-tank oil in place. Every term in the final number, the net-to-gross, the average porosity, the average saturation, the pore thickness, was read from the logs the earlier chapters taught.
Sensitivity on Real Rock
Move the three cutoffs and watch the pay flag, the net-to-gross, and the volume respond, the sensitivity of the chapter made tangible on the Ogbon-1 well. That single STOIIP, carrying the P90-to-P10 spread of its inputs, is the petrophysicist's deliverable to the reservoir engineer, who takes it into recovery factors, development plans, and the reservoir-simulation course downstream. The interpretation chain, from the first gamma-ray kick to the barrels in place, is complete.
References
- Asquith, G. and Krygowski, D. (2004). Basic Well Log Analysis, 2nd ed. AAPG Methods in Exploration 16.
- Tiab, D. and Donaldson, E. C. (2015). Petrophysics, 4th ed. Gulf Professional Publishing.