The purpose of this article is to explain the options under the DCA Wrangler Parameters menu.



Parameters Menu


The Parameters menu is used to adjust the parameters and thresholds of the decline algorithm.


Option Description
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, GOR, Yield, Forecast, Normalize, Fluid Limits, and Type Curve submenus are more fully described below. 




Oil, Gas Submenus


The Oil and Gas submenus are used to select the decline algorithm for the streams. The algorithm's parameter thresholds are also set in this submenu.


IMPORTANT NOTE: The submenu for Oil and Gas are the same.



Option Description
Dropdown The dropdown will select the decline algorithm for the stream.

Options include: None or Modified Arps

None No decline for this stream will be produced.
Modified Arps
A Modified Arps Hyperbolic decline algorithm will produce the stream's decline. Parameters are defined below. 

Qi Range for Qi (Initial Rate) value. If less than or equal to 2, takes the percent of global maximum rate, else takes the absolute rate values.
De Range for initial decline parameter, De .
B Range for constraining the B value.
Dmin Range for limiting decline rate Dmin (D lim). Set as both numbers to same to enforce a hard limit.




GOR, Yield Submenus


The GOR and Yield submenus are used to select the decline algorithm for the streams. The algorithm's parameter thresholds are also set in this submenu.


IMPORTANT NOTE: The submenu for GOR and Yield are the same.



Option Description
Dropdown The dropdown will select the decline algorithm for the stream.

Options include: None or Linear Piecewise

None No decline for this stream will be produced.
Linear Piecewise A Linear Piecewise decline algorithm will produce the stream's decline. Parameters are defined below.

No. Segments Number of segments to be used in the continuous Linear Piecewise model.
Initial Range for Initial GOR value. If less than or equal to 2, takes the percent of average GOR for the initial period, else takes the absolute GOR values.
Segment Time (days) Range for guessing the length of linear segment in days.
Segment Change (%) Range for guessing the change in slope of model when switching.
Outlier SD Standard deviation (from mean data fit) for declaring data points as outliers.
Initial Period (days) Defines the initial period starting from the peak production rate for primary fluid.



Forecast Submenu


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.



Option Description
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

Latest Official
Anchor on Latest Official declines that have been synced with the project from Petro.ai.
Models If other models have been brought into the project using the Sync button, the user can anchor on those models.


None
Do not Anchor on previous forecasts.




Normalize Submenu


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.


Option
Description
Main Fluid The Main Fluid for the well.

Options: Auto, Oil, Gas

Auto Determines the Main Fluid based on GOR Threshold parameter, set below.
Oil Selects Oil as the Main Fluid.
Gas Selects Gas as the Main Fluid.

Normalize Determines where normalization for the decline curve will begin.

Options: Start, Local Peak, Global Peak, Manual 

Start
Decline Curve will begin at the start of production history.
Local Peak
Decline Curve will begin at the last local maximum.
Global Peak
Decline Curve will begin at the last global maximum.
Manual
Decline Curve will begin at the user-defined date in Start Date

Start Date When the Normalize option Manual is selected, this date will be the Start Date of the decline curve.
GOR Thresh Threshold 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. 


Option
Description
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.




Option
Description
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.