Best Fit or Refit a Decline from a Point

Best fitting data from a point involves selecting a point in the production history. Value Navigator determines the best decline rate (Di) based on the production history from that point forward, ignoring the history before it.

Refitting data from a point involves selecting a point in the production history. Value Navigator determines the best decline rate (Di) based on the production history from that point forward while maintaining the current N value.

Best Fit and Refit from Point looks for all segments between the start point and most current date, then chooses the best segment to determine the best initial rate and create the forecast. The points used to create the forecast are indicated with a row of small black dots, and the backfit is visible as a semi-transparent line.

To best fit or refit data from a point in production history you can click the mouse at any point in history while holding the Alt button or Ctrl button, respectively. The resulting decline type depends on which button you hold.

• Alt + Click (best fit): Value Navigator determines whether the decline should be hyperbolic, harmonic or exponential.
• Ctrl + Click (refit): Value Navigator maintains the current decline type (N value).

To best fit or refit data from a point in production history

1. On Predictions | Declines, right-click the graph you want to edit.
2. In the menu, point to the decline type you want to fit and select the Fit from Point option you want to perform.
   Your mouse pointer turns into a hand.
3. Use your mouse pointer to click the point in history you want to use. Value Navigator best fits or refits the well based on the point you selected.

OR

1. On Predictions | Declines, hold the Alt key (best fit) or the Ctrl key (refit).
2. On the graph, click the point in history you want to use.