Low oil prices may not be the biggest threat to the long-term sustainability of the North American shale business.
Some are more concerned about the low recovery rates of horizontal shale wells, estimated to be about 7% on average—far short of the 40% achieved through primary and secondary (waterflooding) production in conventional reservoirs.
Refracturing has been touted as the next big thing to improve ultimate recovery, but such operations remain relatively expensive and may only temporarily reset production to initial rates once or twice in a well’s life.
To see long-term results and a doubling or tripling of current recovery rates, a number of experts say enhanced oil recovery (EOR) technologies must be developed to work in tight shale reservoirs. And due to persistently low natural gas prices, current efforts appear to be exclusively focused on oil and condensate producing wells.
It is early days for this area of EOR research. There is no consensus on which approaches will work best, how much they may cost, what the most pressing challenges are, or exactly when an EOR operation should begin.
“Our understanding is really small,” said Todd Hoffman, an assistant professor of petroleum engineering at Montana Tech University. “We’re coming from the conventional world where ‘this’ is how we did EOR and we may just have to throw all that out.”
