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Building on Drillinginfo posts about Enhanced Oil Recovery (EOR) earlier this year in these times of low commodity prices, I wanted to touch on the subject of EOR affordability and access for the operators who manage the hundreds of thousands of underappreciated stripper wells across the US.

The National Stripper Well Association (NWSA) states that there are an estimated 771,000 marginal wells in production. Combined they make up 11.3% of the US oil production and 8.3% of the US gas production. These wells are described as marginal because they are marginally economic to produce. The NWSA website states that in that last 10 years, over 131,000 of these oil wells and 48,000 gas wells have been plugged and abandoned. Many of these wells are plugged without ever having undergone waterfloods or tertiary production so they are being abandoned with a significant % of the original oil still in place.

With the recent drastic reduction in oil prices, some operators of these marginal wells are laying off, cutting back and shutting in wells in an attempt to just break even, while others are doing the bare minimum to maintain mineral rights. Few of them are focused on technologies which can economically extend the lives of their fields because to date, the cost of stepping up to field wide water, CO2 or nitrogen floods is too cost prohibitive. Other than periodic mini-fracs, hot oiling or paraffin treatments, not much is done to these wells to increase production rates. The day-to-day focus is on reducing repair and maintenance expenses.

The Three P’s

When you look at shallow stripper wells, what is holding them back from continued profitability is primarily what I call the three P’s –  Pressure, Permeability and Paraffin. As these fields are produced, the wells undergo severe pressure depletion and a corresponding reduction in production rates. With the amount of thermal energy entering the wellbore drops with production rates. Wells get to the point where oil crosses its cloud point threshold and paraffin crystals start to precipitate when the oil moves from the pore space to the open wellbore. If a well’s flowrate is high enough,...