Cutoffs Interpretation Module
Purpose
The Cutoffs Interpretation module allows users to flag intervals based on specified criteria. This is typically used to flag intervals as gross reservoir, net reservoir, and net pay based on reservoir properties.
Primary Outputs
The following curves are the primary interpretations made in this module.
| Curve Name | Description |
|---|---|
| GROSS_RES | Gross reservoir flag |
| NET_RES | Net reservoir flag |
| NET_PAY | Net pay flag |
Discussion
Criteria can be defined using basic operators. These include:
| Operator | Description |
|---|---|
| < | Less than |
| > | Greater than |
| <= | Less than or equal to |
| >= | Greater than or equal to |
| == | Equal to |
| ! | Not |
| != | Not equal to |
| && | And |
| || | Or |
These operators can be combine in a number of ways. Here are a few examples to help get you started.
- Vclay less than or equal to 30% and not flagged as badhole
@vwcl <= 0.30 && !@badhole
- PhiT greater than 5% and meets the criteria given for gross reservoir
@phit > 0.05 && @gross_res
- Sw less than 65% ore resistivity greater than 10 ohmm and flagged as net reservoir
(Sw < 0.65 || @resd_final >10) && @net_res
In the above examples, you'll notice that for checking if an interval was flagged as net_res we only need to state @net_res and not check if it is equal to one. This is because for binary values, such as those with pay flags or badhole flags it is also treated as boolean.
The Cutoffs module also includes several options that will help control mapping results. These include:
- Map partial zones: Specify if zones with null values be included in summations.
- Limit mapping by data completeness: Specify If mapping should occur only if a certain threshold of data coverage is met.
- Data completeness: Fraction of interval to be covered by data.
- Required curves: Curves that should be considered for data completeness.
For QC'ing the interpretation the following maps are useful:
| Map Name | Description |
|---|---|
| GROSS_RES_SUMMARY | Gross reservoir thickness for selected zone |
| NET_RES_SUMMARY | Net reservoir thickness for selected zone |
| NET_PAY_SUMMARY | Net pay thickness for selected zone |
It is useful to remember:
- When combining criteria with the “OR” operator use parentheses for clarity. For example, how should:
@vwcl < 0.30 || @gr_final < 50 && @phit >= 0.05 || @rhob_final < 2.6
be interpreted? Is it more clear when stated as:(@vwcl < 0.30 || @gr_final < 50) && (@phit >= 0.05 || @rhob_final < 2.6) - When using the Map partial zones parameter, consider pairing it with a data completeness requirement to avoid mapping zones that may only have a few samples available.
For more information, see this tutorial video.
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