Creating a Gas Deliverability Analysis using the Simplified Equation
The Simplified equation (C, n) is a widely accepted method for determining a well's deliverability (absolute open flow - AOF) potential. The calculation methods use the information provided to determine the well's AOF at the sandface. From here, further analysis may be performed, such as determining the well’s wellhead deliverability potential, or comparing well performance scenarios by determining operating points along the deliverability curve(s) with the use of tubing performance curves.
To create a gas deliverability analysis using the Simplified equation:
1. Launch an entity for analysis.
2. Click the Gas AOF / TPC thumbnail.
3. Add the Gas-Deliverability Simplified (C,n) analysis to the worksheet. See Adding an Analysis for details.
4. Select a Calculation Method in the Analysis Parameters pane.
Base your selection on the type of information that you have available:
| Calculation Method | Required Information | Description |
|---|---|---|
| Use Sandface AOF |
|
Harmony calculates either a resulting Sandface AOF, or Sandface C value when either of the other entered. |
| Use Sandface Flowing Pressure |
|
Harmony calculates a resulting Sandface C and Sandface AOF. |
| Use Wellhead Flowing Pressure |
|
Calculate Wellhead AOF is enabled as Harmony uses the wellbore and Liquid Ratio information to calculate the SF Flowing Pressure used to determine the Sandface AOF value. |
| Use Wellhead Quiet (Non-Flowing) Pressure |
|
Calculate Wellhead AOF is enabled as Harmony uses the wellbore and Liquid Ratio information to calculate the SF Flowing Pressure used to determine the Sandface AOF value. The Average Liquid Gradient is applied to the height of the liquid column from the Liquid Level (LL) to the Datum depth. |
5. Continue with the analysis:
- (Optional) Click the Calculate Additional AOF Curves option; then enter depleting reservoir pressures. (The Calculate Wellhead AOF option converts the sandface deliverability curve to wellhead, and calculates the resulting Wellhead AOF and Wellhead n values based on the selected Wellbore, Configuration, and if applicable, entered Liquid Ratios.)
Assuming the well has reached stabilized deliverability (no longer transient), Harmony can calculate additional Sandface AOF values and display their corresponding deliverability curves. This option can be used to help determine future AOF curves with a depleting reservoir pressure.
- (Optional) Click the Calculate Wellhead AOF option; select the relevant wellbore and configuration, and enter the liquid ratio (if applicable).
The Wellhead Deliverability curve is displayed, and it shows at which point the well is operating above (solid portion), or below (diamond portion) the critical gas rate required to effectively lift the liquid at the wellhead.