Units of measurement
The Unit Definition window contains the list of available units of measurement and their settings. It can be opened only from the Variable Definitions window. The list of available units of measurement is fixed, and default system units cannot be edited. If you would like to use a unit which is not on the default list, select the Custom option from the Select Unit list and specify the settings.
The top part of the window contains the basic settings of the selected unit (see the following table), and the bottom part contains conversion factors for different unit systems.
| Field | Description |
|---|---|
| Is Currency Unit | Indicates whether the selected unit is a monetary unit; it is always grayed out. |
| Timescale Consolidation Method | Method used to calculate values for different periodicities (see the table below). |
| Aggregation Method | Calculation method used for ringfencing. The number of items on the list changes depending on other variable properties. |
| Back Allocation Method | Method used to split between projects after ringfenced calculations. The number of items on the list changes depending on other variable properties. NoSplit back allocates the aggregated value to all projects within the calculation. EvenSplit back allocates the aggregated value divided by the number of projects within the calculation. WeightedSplit back allocates the aggregated value to individual projects based on the weighting variable factors among the projects being back allocated. |
Example 1: In the image above, the basic unit for oil volume is one thousand barrels in the Imperial unit system. Other acceptable units are barrels and millions of barrels. Since one thousand barrels is the basic unit, 1 is set as the medium-scale conversion factor. One thousand barrels contains 1000 barrels, thus the small-scale conversion factor is 1000. And one million barrels contains 1000 thousands of barrels, thus the large-scale conversion factor is 0.001. The labels for the unit are: bbl, MSTB and MMSTB.
The following example describes conversion from the Imperial unit system into Metric.
Example 2: One thousand barrels is 0.1589873 m3, thus the conversion factor for the medium scale is 0.1589873. Then, this conversion factor is multiplied by small- and large-scale factors specified in the Imperial unit system (1000 and 0.001 respectively), which gives coefficients of 158.9873 and 0.0001589873. The labels for the unit are: m3, E3m3 and E6m3.
The following table explains timescale consolidation methods.
| Method | Description |
|---|---|
| Sum | When converting from smaller periodicities to larger periodicities, values of all periods are summed up; for example, when converting from Monthly to Annually, a year will get the sum of values of all months in that year. When converting from larger periodicities to smaller periodicities, the value is divided between smaller periods; for example, when converting from Annually to Monthly, all months will get an equal share of value assigned to that year. |
| Sum – Time Weighted | When converting from smaller periodicities to larger periodicities, values of all periods are summed up; for example, when converting from Monthly to Annually, a year will get the sum of values of all months in that year. When converting from larger periodicities to smaller periodicities, the value is divided between smaller periods weighted by the number of days in the period; for example, when converting from Annually to Monthly, each month will get a share of value assigned to that year weighted by the number of days in each month. This method is usually used for production volumes. |
| Average | When converting from smaller periodicities to larger periodicities, values of all periods are averaged; for example, when converting from Monthly to Annually, a year will get the average of values of all months in that year. When converting from larger periodicities to smaller periodicities, the value is assigned to all periods as it is; for example, when converting from Annually to Monthly, each month will get the same value as that assigned to that year. |
| Average – Time Weighted | When converting from smaller periodicities to larger periodicities, an average of values of all periods is calculated, weighted by number of days; for example, when converting from Monthly to Annually, a year will get the average of values of all months in that year, weighted by the number of days. When converting from larger periodicities to smaller periodicities, the value is assigned to all periods as it is; for example, when converting from Annually to Monthly, each month will get the same value as that assigned to that year. This method is usually used for production rates such as bbl/d. |
| Last Period | When converting from smaller periodicities to larger periodicities, the value of the last period is used; for example, when converting from Monthly to Annually, a year will get the value from December of that year. When converting from larger periodicities to smaller periodicities, the value will be assigned to the last period; for example, when converting from Annually to Monthly, December will get the value of that year and all other months will get zeros. This method is usually used for cumulative values. |
| First Period | When converting from smaller periodicities to larger periodicities, the value of the first period is used; for example, when converting from Monthly to Annually, a year will get the value from January of that year. When converting from larger periodicities to smaller periodicities, the value will be assigned to the first period; for example, when converting from Annually to Monthly, January will get the value of that year and all other months will get zeros. This method is usually used for opening balances. |
| Compounded |
Values are compounded using the compounding formula when converting both from smaller periodicities to larger periodicities and from larger periodicities to smaller periodicities. For example, when converting from Monthly to Annually, the following formula will be used (Ry is the annual value and Rm is the monthly value):
And when converting from Annually to Monthly, the following formula will be used:
This method is usually used for interest rates and inflation. |
| Equal Allocation Balance | When converting from smaller periodicities to larger periodicities, the value of the last period is used; for example, when converting from Monthly to Annually, a year will get the value from December of that year. When converting from larger periodicities to smaller periodicities, the value is assigned to all periods as it is; for example, when converting from Annually to Monthly, each month will get the same value as that assigned to that year. |
