Uncertainty Matters

Patrick Corbett

Nothing better than stochastic simulation
Give me your range,
Monte will throw dice
Are you feeling lucky today, punk?

Don’t want you to tell me THE answer
I want P10, P50 and P90.
You mean greater than or less than?
Are you feeling lucky today, punk?

Those oil reserves you quoted
Are they proven, probable or possible
I’m confused, Carlo; P1, P2 or 2P?
Are you feeling lucky today, punk?

Bosses took a long time before
Realising the computer is only as
Good as the human input estimations
Are you feeling lucky today, punk?

When the world is all-known
The input distributions will collapse
Upon a single point solution!
Will you feel lucky that day, punk?

The Science

If estimating volumes of hydrocarbons buried in the Earth’s subsurface is anything other than educated guess work, then it is to the science of Uncertainty Quantification that we look to. Properties are estimated from various remote sensing techniques and borehole samples. Minimum, most likely and maximum values for a range of parameters are estimated. These are then combined using Monte-Carlo procedure and the P10 (Less Than) identified as Proven (P1), P50, Proven (P1) plus Probable (P2), or 2P, and P90 (LT) Proven plus Probable plus Possible. All these terms are confusing, even for many industry professionals! These are the basis of estimates for the World’s hydrocarbon reserves – which are uncertain – and will be until we stop producing them. Thanks for inspiration to my friend Mike Christie, Prof Emeritus of Uncertainty at Heriot-Watt University and fan of Clint Eastwood.

The Poet

Patrick Corbett is a Professor of Petroleum Geoengineering at Heriot-Watt University, and also the first University Poet. The latter is a voluntary role promoting the use of poetry as a form of communication in branches of science such as geology and energy. His poetry awakening coincided with embarking on a slow, interrupted walk around the UK coastline, which gave space for thinking and refreshing new ideas. He has recently developed a web page at www.geopoetrick.co.uk to capture some of these thoughts and consequent activities.

Next poem: Uncertainty of knowing by Wendy Lowe