Incremental RTA (iRTA)
Incremental Rate Transient Analysis (iRTA) automates the continuous update of a Topaze analysis as new production and pressure data become available. Starting from an existing Topaze analysis (the seed document provided by the user), iRTA periodically extends the production history, updates the reservoir model, and optionally improves selected model parameters.
Depending on the available input data, iRTA can either:
Extend an existing history match.
Improve the reservoir model parameters.
Generate production forecasts;
Or estimate production rates from pressure measurements using Virtual Metering.
Typical iRTA Workflow
An iRTA workflow generally consists of the following steps:
Create and validate an initial RTA analysis in Topaze by the engineer.
Upload the Topaze document into KAPPA Automate.
Create an iRTA workflow using the Topaze document as the seed.
Select the desired workflow type and update strategy.
As new pressure and production data become available, iRTA automatically updates the analysis.
The model is extended or improved according to the selected workflow type.
Forecasts and computed channels are updated.
Well properties can optionally be replicated to the Master container (which can serve as the valid results container).
Note
The seed document is the reference RTA analysis used by iRTA. It contains the initial Rate Transient Analysis, the model definition, the fluid properties, and the analysis settings defined by the engineer, which will be applied to subsequent incoming data.
iRTA Workflow Types
There are four types of iRTA workflows available:
Extraction only: This is the only available option if the selected ‘RTA document’ does not contain a model. The data will be sent to the RTA Service which will perform the extraction.
Extraction with model: In addition to Extraction only explained above, the model in the RTA document is extended up to the end of production data. If the seed document contains a model with a forecast of duration dt, the model simulation will continue to end of production data + dt.
Extraction with model + improve: In addition to Extraction with model explained above, if this option is selected, an improve strategy is requested by the user at the time of iRTA creation. The user can specify what model parameters to improve on and their ranges and set the improve targets and their weights. During execution, after the model has been extended to the end of the processed data, an improve of the history plot is performed.
Note
The forecast option is available for iRTA seed files with a model. This feature is enabled when the 'Model' or 'Model + Improve' workflow type is selected.
Virtual Metering: This option is available only when the seed Topaze document has a q(p) model. If the seed document contains a model with a forecast of duration dt, the model simulation will continue to end of pressure data + dt.
This mode is particularly useful when:
Production rates are unavailable.
Flow meters are unreliable.
Production data are delayed.
Temporary metering failures occur.
Since production rates are simulated rather than measured, the accuracy of the results depends directly on the quality of the seed model.
Note
Virtual Metering assumes that the model q(p) remains representative of the well behavior. Significant changes in completion, reservoir conditions, or nearby well interference may reduce the accuracy of the estimated rates.
iRTA Mode | Prerequisite (Seed Document) | What it does |
|---|---|---|
Extraction Only | Must contain an extraction | Extraction is updated to include the new data. |
Extraction with model | Must contain a model | The model in the seed document is extended up to the end of the new data. Forecast is updated. |
Extraction with model + improve | Must contain a model | Improve on rates and/or cumulative data, regressing on user defined parameters. Forecast is updated. |
Virtual Metering | Must contain q(p) model | Works only on update of input pressure data and generates a model-based rate forecast using actual pressure data. |
Gauge Loading Strategy
When the workflow is triggered, the gauge data in the corresponding Topaze needs to be updated first. Two choices are offered:
Append: Only newly available gauges (pressure and productions channels) are added.
Load: Existing gauges are replaced with fresh gauges, containing all the data.
Duration of data to analyze
Since production data may be updated daily or even hourly, executing iRTA after every update would be inefficient.
Therefore, the Duration of data to analyze input defines the minimum amount of newly available production history required before the workflow is triggered.
Users can define a minimum duration of data to analyze (default: 120 days).
iRTA runs only when this duration is reached.
Improve only on new data
By default, the improve process considers the entire production history.
When Improve only on new data is enabled, only the newly acquired data are used as optimization targets. Previous history remains unchanged, allowing incremental model calibration while preserving the original history match.
Document Update Strategy
If the Workflow type is set to Extraction only, Extraction with model or Extraction with model + improve, upon execution, the iRTA workflow will create a new Topaze document containing data from the start of production history up to the end of the extraction.
If the Workflow type is set to Virtual Metering, the iRTA workflow keeps updating the same Topaze document.
Viewing iRTA Results
When an iRTA is first launched, it will create a new container under Well properties node in the field hierarchy, named Container for <iRTA Name>.
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A new folder called Workflows will also be created in the field hierarchy, with the iRTA and any files created by this iRTA listed there. Depending on the selection of output gauges when creating the iRTA, the computed rate, cumulative, and possibly pressure and productivity index are written back under the parent well:
Computed channels are generated by:
Extracting a segment of data of length n (the duration of data to analyze) from each output document.
Combining these segments to produce the computed rates.
If only one output document exists, the computed channel is simply a copy of the simulated channel in Topaze.
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An important assumption of iRTA is that the well is not subject to nearby well interference.
One can run several workflows in parallel and compare them.
It is also possible to copy from in iRTA container into the Master container. If Replicate results to Master flag was enabled when creating the iRTA, this will be done automatically for all shut-ins being processed by the iRTA task.
Alternatively, users can selectively replicate results for some analyses only to the Master well properties container (see [Result Replication into Master Well Properties] for more details).