PAY Prospect Area Yield

Prospect volumetrics the other way round: start from the reasonable closure area, multiply by a mid-case area yield, and let a lognormal distribution anchored on that upside and on a downside volume give the full range. The method is described in Quirk and Schmid (2021), The Prospect Area Yield (PAY) method, a remedy for over-optimistic volumetric estimations in conventional petroleum exploration.

Project

Prospect name Evaluator(s) Date

Additional information

Upside inputs

What is the reasonable closure area?

The footprint area of the discovery if the interpretation model works as expected. Delineate it on the best interpretation map of top reservoir in depth, agreed with peers from an assessment of spill points and leak points, bearing in mind reservoir extent, potential waste zones, seal limits, down-dip dry wells and possible geophysical anomalies. A hydrocarbon column beyond the reasonable closure area can be regarded as unlikely. Check the area against the statistical P10 footprint area of discoveries in the relevant play for the appropriate period.

Reasonable closure area (RCA), km² Contour defining the RCA, m Constrained by a robust anomaly? Limited by column height? Limited by dry wells?

Additional information

Mid-case area yield, MMboe/km²

Where does the P50 area yield come from?

Either from historical statistics of the same or an analogue play, or calculated from the median (P50) values of the key reservoir and fluid parameters.

Historical statistics Calculation

P50 area yield, MMboe/km² From (play, source of the statistics)

Inputs given as Reservoir thickness as

	P90	P10	P50	distribution
Area yield, MMboe/km²	product of the P90s	product of the P50s

Prospect size

Upside volume, MMboe (URR) RCA × P50 area yield of MMboe/km²

Probability of the upside volume Downside volume, MMboe (URR), the P99

	MMboe, URR	Probability of exceeding, %