# Risk*

Risk* is a probability calculator app for Android, aimed at subsurface scientists in oil & gas. It was built in Google App Inventor and made available in the Android Market in August 2011.

## Functionality

Designed primarily as a help app for Volume*.

## Features

Scan the code to visit the Market

### Version 0.2

• First public version
• Five-way prospect risk profile
• Works more or less seamlessly with Volume*
• Automatically recalls whatever was last passed back to Volume*
• On-demand recall of whatever was last passed back, in case you try some other numbers but want to get it back
• Press and hold ('long press') the RESET button to reset the fields
• If you're not using Volume*, the app still works, it's just a bit boring
• If you don't have Volume*, there's a link to the Market to get it

## Parameters

The language used in the qualitative risk pickers (the buttons by the text fields) are based closely on Sherman Kent's words of estimative probability, long used in the US Central Intelligence Agency to describe risk. The only change I made was to make Impossible 0.01 instead of 0, and Certain 0.99 instead of 1.0. I'm just uncomfortable with certainty, but of course there are situations when it is warranted (as for some risk elements in a proven structure or field, for example). I will try to make the list editable in a future release.

In this first public version, there's only one calculation is very simple:

$P_\mathrm{discovery} = P_\mathrm{source} \times P_\mathrm{migration} \times P_\mathrm{trap} \times P_\mathrm{respres} \times P_\mathrm{resqual}$

where Prespres and Presqual are the probabilities for reservoir presence and quality respectively.

Exactly how you use the parameters is up to you of course; most organizations have guidelines for this. If you want fewer than five parameters, just sent one of them to 1.

## Bugs and deficiencies

• The app has only been tested on two devices, both Samsung smartphones; please give us feedback about other devices
• The app has rather limited functionality

## For future release

• Add an option for Bayesian updating with, say, seismic attribute evidence
• Add an option for play risk, probably just for Source, Migration and Reservoir
• Add an option for multiple prospects, or at least two