The Resource Ledger
An oil field needs six separate things to line up; miss one and the same organic-rich rock yields nothing.
Phase 0 · The phenomenon
Same rock, different fortunes
A layered cross-section. At the bottom is a dark, organic-rich source shale. Above it a yellow sandstone reservoir bends up into an arch on the left, capped by grey shale, with black oil pooled at the top of the arch and a well drilled into it. On the right the sandstone has no cap rock, oil droplets rise through it to small seeps at the surface, and a second well there is marked dry.
Two exploration wells are drilled 30 kilometres apart into the same layer of black, organic-rich shale. Both cores smell of petroleum. One well flows oil for thirty years.
The other is dry. The shale is just as rich there, and buried just as deep. The difference is not the source rock at all.
In this lab you will build a petroleum system piece by piece, find out why one missing piece is fatal, and then use the numbers to judge how long a find will last.
Why does the same organic-rich rock yield an oil field in one place and nothing in another — and how do geologists weigh whether a resource is worth developing?
What this lab works toward
HS-ESS3-1Explain how natural resources, natural hazards and climate change have shaped human activity.HS-ESS3-2Weigh competing ways to develop and use energy and mineral resources by comparing their costs and benefits.
Plain-English summaries. The course maps these performance expectations to this lab; the official wording is published at nextgenscience.org.
The stations
- Oil WindowHow deep must a source rock be buried to make oil?
- Reservoir VolumeHow do porosity and thickness decide how much oil a reservoir holds?
- Petroleum SystemWhat happens when any one of the six petroleum-system elements is missing?
- Supply LedgerHow long does a resource last when demand keeps growing?
Each station runs the same loop: predict before you see any data, investigate the model and record runs, reveal what the measurements show, then explain the gap between your prediction and the result. A claim-evidence-reasoning checkpoint and an exit ticket close the lab.
- Maturation is read from temperature alone. Real maturation depends on temperature AND time: a rock held at 90 °C for 100 million years matures further than one there for 1 million years.
- Oil in place uses the standard volumetric formula with a fixed 25% water saturation, a volume factor of 1.2 and a 35% recovery factor; real fields vary widely.
- The six petroleum-system elements are treated as independent yes/no events with equal chances. Explorers estimate a different chance for each.
- The supply ledger ignores new discoveries, price changes and improving technology — all of which change real reserve lifetimes.