Prospect risking

There are a number of different Prospect Risking Schemes implemented in REP, reflecting different (and always strongly held) views on this important aspect of prospect evaluation. The schemes are outlined in 'Prospect Risking Schemes'. It is strongly advised that you decide the way you wish to risk prospects when you first start to use REP (or ask us to implement the way you prefer to do it if none of the existing schemes suit) and then stick to it.

[Note: Scheme 7 is really just a portal to an XL spreadsheet, which can be maintained by you, the user. If you choose this scheme you must enter the filename of the template XL file. See our section on 'XL-based Risking Schemes'.]

Scheme

Enter the style of prospect risking you wish to use. This is used for all exploration risking. See also development risking below

Kent wording

Risks are numeric, but is some schemes are linked to English phrases ("likely", "ambiguous", etc.). Sherman Kent was an American professor who thought deeply about what these words should be, and here they are. His original article of 1964 was originally CIA classified, but is now available here. It an interesting and still relevant read.

Config.

With some schemes you can set the words yourself - click Config. to do this.

XL

Enter the risking XL file (used in Scheme 7)

(XL) Browse

Click to browse for risking XL file

Worksheet

Enter the worksheet name for the worksheet with summary risks

No rounding

Many risking schemes round category chances to the nearest 5%. In some of these (but not all) it is possible to disable the rounding. So if you enter a reservoir chance of 57% that's what you'll get.

Development

The risking scheme to use if your prospect is in developed acreage. This is chosen in Prospect | Resource type

Custom

Disable economic calculations

Check to disable calculations using economic cut-offs. This is an option designed for those companies whose management believes that G&G professionals are sandal-shod dope heads who think that the only purpose of money is to commission really meaningful flower arrangements.

Use Swanson's mean

Swanson's mean is defined as Mean (Mz) = 0.3 x p90 + 0.4 x P50 + 0.3 x P90. This is considered by many authorities (and presumably Swanson himself) as a more robust measure, especially when a results distribution is highly skewed. In REP, log-normal and normal distributions are clipped at 3 standard deviations from the mean (this is a feature of our Monte-Carlo algorithm) so the "true" mean and Swanson's measure rarely differ by much. Swanson's mean is commonly used in the industry and cynics often argue that its importance reflects overuse of the log-normal distribution.

Fractional chances

Check to enter and show chance of success as a fraction rather than a %

Mandatory descriptors

In the normal course of events you can get away with not filling in most of the textural and other descriptive entries in prospect calculations and consolidations. Mandatory description schemes insist that key entries are filled in. This can be important when you are storing the results on a corporate database.

Show net or gross on graphs

You can choose whether to display net (your company's share) or gross (whole trap) quantities on results graphs

Default input units

Choose to set the default unit as oil field or metric (though note that all units can be changed and mixed at any time).

Approvals list

REP allows for a list of appraisers/approvers. For each prospect you can enter the names of these people, and the date when they approved or appraised.  You can enter the titles for these folk, to suit your corporate procedures. Click the right arrow to bring up the list. See Approvals list below

Output

Summary sheet style

Choose a style for the main summary sheet

Summary output

The summary output can be results only or input and results. The standard prospect summary printed report (one page per phase) is printed in either case. In the latter, the input page is also printed.

Name for gross (100%) quantities

Enter the name for gross (100%) quantities on output sheets

Name for (NRI) quantities

Enter the name for net (production interest) quantities on output sheets

Show expectation curve

The expectation curve in a results graph is the risked cumulative reserves probability, and is the unrisked cumulative curve multiplied by the chance of success. It can confuse, so you can choose not to show it.

Don't show risked mean

Some people like to check this option, the risked mean being a value which can - in many cases - never be achieved as well as being a ranking parameter with little reference to value.

Show output SD's

Check if you wish to show the standard deviation of output distributions.

Clipped distribution display

How to display the key points on a clipped distribution: Post-clip shows the effective distribution once the clip has been applied, Pre-clip shows the P90/P50/P10 etc. as the distribution is entered, and before the clip is applied. This is cosmetic only, and affects the summary printout and the input variable table.

Gas-oil equivalence

This is the default factor to apply when converting gas volumes to equivalent oil volumes for the calculation of barrels-of-oil-equivalent (BOE). Most companies use a fixed factor across all assets, but you can set it also on a field-by-field basis if you wish.

[User]

Click to edit the user defaults

Printers

For "advanced" users (geeks) only

Co-ordinate system

The system that will be used to define the location of any new prospect.

Meridian

The zero meridian in UTM eastings.

Southern hemisphere

Check the box if the location is south of the equator.

Spheroid

The projection system controlling latitude and longitude. WGS 1984 is the standard for GPS.

Other

Allow user risking schemes

Most companies choose a risking scheme and stick with it. In this case choice of risking scheme is part of the installation and cannot be changed by individual users. But some consultancies are obliged to mirror their clients' schemes, and individual users can use their own schemes. If so, check this box and set the user scheme in Set-up | User options