| Building a Decline Set |  |
Well potential production can be defined in the Decline Tab. Alternatives are the Decline/AOF URL on the Network Tab, Production on the Data Tab and the Data Menu - Decline/AOF, but these do not display the decline graph in the dialog they access. After selecting the well, to add a decline for any product, select the product(s) to add. This will open up a further section for the product (oil, gas, water, etc) that will allow you to put in the data for the decline.
The Decline tab or dialog will allow you to choose the type of production forecast to use and insert the associated data. The forecast method can be either Decline (the default), Ratio, Array(Time), Array(Cum), or Function. If we choose Decline or Ratio, a predetermined analytic form is implied. We select the method (Exponential, Hyperbolic, Harmonic, Linear, or Flat for a Decline; Semi-log or Linear for a Ratio) and then enter the appropriate parameters.
Production Forecasts can also be entered as array data. The distinction between Array(Time) and Array(Cum) is purely the format of data input; in calculations both are treated as a potential rate vs cumulative primary fluid production relationship. See Using a Type Well for more details.
The Function option allows a completely free entry of any allowed calculation that can be constructed with WellSpring’s Function Builder (see Function Reference Library ). In the spirit of the type curve approach, this is more likely to remain rate vs cumulative but the cumulative may not necessarily be for the primary product. For example, water oil ratio of an oil well might depend on cumulative water injection instead of or in addition to cumulative oil production.
Taking a hyperbolic decline as an example, you would select the forecast method and decline method.
