The purpose of this article is to explain the options under the DCA Wrangler Decline Parameters menu.
Decline Parameters Menu
The Parameters menu is used to adjust the parameters and thresholds of the decline algorithm.
|Decline||Pressing the Decline button will generate declines for the wells that are currently marked.|
|Reset||Reset will reset all parameter in the submenus to the DCA Wrangler defaults.|
|Submenus||Submenus are dropdown menus that allow for user adjustment of each parameter.|
Oil, Gas, Water, GOR, Yield, WOR, Forecast, Normalize, Fluid Limits, and Type Curve submenus are more fully described below.
The Oil, Gas, Water, GOR, Yield, and WOR submenus are used to select the decline algorithm for the streams. The algorithm's parameter thresholds are also set in these submenu.
IMPORTANT NOTE: The submenus for Oil, Gas, and Water are the same. The submenus for GOR, Yield, and WOR are the same.
|Dropdown||The dropdown will select the decline algorithm for the stream.|
See below for the options:
|Modified Arps (Auto)|
|Linear Piecewise (Auto)|
Forecast parameters determine the length of the decline and if the decline will use a previous output to anchor against.
The DCA Wrangler uses declines stored in the database to “anchor” the autocasting engine. Using anchoring, the engine will attempt to “update” the previous stored forecast using new data since the model was saved. In updating, the engine will employ the Eliot Tie method, which:
- Ties the updated forecast to the most recent data (changing Qi and start date)
- Adjusts effective decline to handle latest data
- Does not change b-factor
If the change in data is too great (5%), the engine will honor the previous forecast decline rather than the data.
|Years||Number of years the decline algorithm will forecast past last date of production.|
|Anchor||Determines if the decline to be run will be anchored on previous results if they exist in the project. To Anchor, previous results must be saved as Official (using Save) to the Petro.ai Engine and then pulled back into the DCA Wrangler via the Sync Button.|
Options: Latest Official, Models, or None
When creating and comparing type wells, it is important to normalize the production data against a common differing property associated with the well or its location. DCA Wrangler can normalize by linearly scaling individual well history based on a normalization column and value.
|Main Fluid||The Main Fluid for the well.|
Options: Auto, Oil, Gas
|Normalize||Determines where normalization for the decline curve will begin.|
Options: Start, Local Peak, Global Peak, Manual
|Start Date||When the Normalize option Manual is selected, this date will be the Start Date of the decline curve.|
|GOR Thresh||Threshold as a percentage for declaring the Gas as Main Fluid.|
|Target Value||Value to use in normalization against a normalization column.|
Fluid Limits Submenu
Fluid Limits are economic thresholds that will end a decline if the decline curve forecast moves outside of the specified range.
|Oil||Range of limits for Oil (bbls) stream.|
|Gas||Range of limits for Gas (mcf) stream.|
|GOR||Range of limits for GOR stream.|
|Oil TTD||Range of limits for Oil TTD (cumulative bbls) stream.|
|Gas TTD||Range of limits for Gas TTD (cumulative mcf) stream.|
IMPORTANT NOTE: TTD is Total To Date.
Type Curve Submenu
A type well is a pseudo well that is usually created by averaging the production rate from many wells. Its intended use is to determine the production rate that can be expected from a new well(s) based on the performance of analogous wells. It may also be used as a benchmark to provide confidence in individual well forecasts for a group of similar wells. These use cases make Type Wells necessary for portfolio management, play inventory ranking, budgeting and forecasting processes, and business case analyses.
DCA Wrangler offers a Type Curve mode to create average, P10, P50 and P90 type wells for a given group of wells. We use the following formula to create the average Type well for a given group of wells.
|Min Well Count||Sets the cut off on the type curve fit based on well count. When Min Well Count is less than 1, it is taken as the fraction of the total wells for each group (e.g. 0.43 = 43% of the wells in the group).|
|Days Bin||The number of days to bin for type curve aggregation of Avg, P10, P50, P90.|
|Start Date||Start Date of the Type Curve.|
|All Group Name||Name for the Type Curve Group if no other Group options have been specified.|