Estimated Ultimate Recovery (EUR): Finding Minimum Data Requirements
Tuesday January 26, 2016
On my first day at Drillinginfo, I was greeted by a smiling Mark Nibbelink. “You must be the mystery man I’ve heard so much about,” he said with a calm demeanor. A month prior Mark reached out to my advising professor, Dr. Larry Lake, and requested candidates for a database analysis project. The Drillinginfo staff sought to determine the minimum amount of wells needed to predict estimated ultimate recovery (EUR) baskets for acreage grades within a play, specifically the Eagle Ford. Acreage grades measure an area of land’s potential production and are determined using a statistical model that also takes engineering parameters into consideration (azimuth, lateral length, etc).
When solving any problem, I constantly ask myself a universal set of questions:
- What do I know?
- What do I need to know?
- Which pertinent method(s) should I use?
These prompts help streamline a bulky framework, permit a fluid approach, and ensure a thorough solution.
WHAT DO I KNOW?
The Eagle Ford Shale ranks among the most heavily invested plays in the world.Surprisingly, the Eagle Ford is mainly comprised of carbonate sediments rather than shales. With estimated proved reserves of 5,172 MMbbl and 23.7 Tcf, the Eagle Ford will remain relevant until hydrocarbons are no longer our primary energy source (EIA).
The table below showcases data gathered from DI Desktop, DI Analytics, and DI Classic
Unfortunately, the Texas Railroad Commission only requires operators to report liquid and gas production on a per lease basis, and does not require operators to report monthly produced water data. Drillinginfo estimates production rates for each well using a robust algorithm, however, we must make a mental note that some error is already present before we begin our analysis. The data’s interconnectivity presented a challenge. Each database possessed random instances of blank entries. Once I removed all extreme outliers (points outside of Q1-3*IQR and Q3+3*IQR) and ensured continuity, the dataset for analysis was reduced in size. (IQR=interquartile range)