June 5, 2026
Revisiting SPE 71431 — An Analytical Solution for the Optimum Number of Development Wells
A twenty-five-year retrospective on SPE 71431. The original equation finds the optimum well count (Wo) at the peak of the NPV curve; this review argues for a Near-Optimum count (Wno) that sits inside a financial safety zone — preserving most of the value with materially less capital at risk.
Richard D. Corrie, SPE — Inepetrol, S.A.
In the early days, oil fields like the one pictured above were developed with little spacing analysis — packing far more derricks into a single area than the economics justified, and tying up capital in wells that added little incremental value. This overdrilling is exactly what the optimum (Wo) and near-optimum (Wno) well-count framework is meant to avoid.