Analyzing Multilayer Wells

Harmony’s default analysis mode is for single-layer wells (i.e., wells that intersect one layer / one formation). To analyze these wells, properties for the single layer are entered, the well entity is launched from the entity viewer, and analysis worksheets are created. Rate forecasts are generated in these analysis worksheets, and represent the rates being produced from that single layer, and therefore of that well.

Occasionally a well is drilled that intersects and combines the flows of two or more reservoirs. Such a well is called a multilayer well or a commingled well. For these wells, the reservoir dynamics cannot be sufficiently modeled using just one set of reservoir properties or just one analytical model*The “Multilayer” Analytical Model can still be used, but its main limitation is that every layer must have an identical initial pressure. The new Multilayer Analysis procedure explained in this topic is more general, and allows every layer to have its own unique initial pressure. .

To analyze a multilayer well:

1. Create a single-layer well. See Adding an Entity for additional information.

2. Import the commingled production rates, and if available, the wellhead flowing pressures. See Importing Well Data for additional information.

3. Add overall fluid properties details in the Properties Editor.

4. Add layers to that well to make it a multilayer well. See Adding a Layer Entity for additional information.

5. Add wellbore details in the Wellbore Editor.

Note:   You need to enter perforated interval and temperature information according to the rules for multilayer wells.

6. Allocate the commingled production to each layer using the Multilayer Allocation Editor.

7. Calculate the flowing pressures for each layer.

8. Select layers one-by-one, entering their reservoir and fluid properties in the Properties Editor.

9. Analyze each layer as if it was its own well: perform a history match, and forecast the rates from that layer. See Performing an Analysis for additional information.

10. To obtain a forecast for the well, sum all of the layer forecasts together by launching the well for analysis, and perform a Forecast Consolidation.

Multilayer Wells: Key Differences

To adapt to the requirements of multilayer wells, changes had to be made to the way that some features work in Harmony. The following changes are listed, or linked to, on a tab-by-tab basis:

• Attribute Tab
• Editors Tab
• GIS Tab
  The multilayer well on the GIS tab will still be displayed as if the well is a single-layer well, as long as the multilayer well’s well-entity contains valid values for its wellhead latitude and longitude attributes, or a valid universal well identifier (either with DLS or NTS).
  

Note:   Selecting layers in the Entity Viewer will have no bearing on the selection of wells in the GIS tab.