Enhanced Oil Recovery (EOR) or “Tertiary Oil Recovery”, as the name suggests, is the third and final stage implemented in recovering all the crude oil possible from an oil reservoir.
There are a number of techniques currently used for Enhanced Oil Recovery, each of which has varying implications on cost, efficiency and safety. Of all the techniques, Surfactant EOR is receiving more attention in recent years, primarily due to its increasing cost effectiveness against the backdrop of rising oil prices.
Types of Enhanced Oil Recovery
Oil production can be broken down into three phases: Primary, Secondary and Tertiary (or Enhanced Oil Recovery). Each phase requires an increasing amount of technology and energy to recover the oil. This, in turn, increases the cost of well production. With increasing global demand and oil prices the costs associated with more expensive techniques are fast becoming less of an issue.
Primary & Secondary Recovery
Primary recovery relies on naturally occurring pressure within the oil reservoir to drive oil to the surface. This method typically leaves around 85%-95% of the oil behind.
Secondary oil recovery introduces external energy to the oil reservoir when naturally occurring pressure is no longer sufficient to bring oil to the surface. It does this by injecting water (water-flooding) or by pumping compressed gasses into the reservoir. The success of secondary oil recovery is limited by the characteristics of the oil reservoir itself and can become ineffective early on. Secondary oil recovery leaves anywhere between 50% – 80% of the oil unrecovered.
The Global Need for Enhanced Oil Recovery
As global demand for oil increases so does its value, and this makes more expensive oil extraction techniques more and more viable. In the long term, fossil fuels will need to be replaced by renewable energy sources. In the mean time, however, Enhanced Oil Recovery offers the only viable solution for retrieving anywhere up to 80% of the world’s oil reserves.
When oil prices are low the general practice has been to extract somewhere between 20-50% of the oil through primary and secondary processes and then abandon it. Generally speaking establishing new wells has been a cheaper production method than EOR and that’s why it has been slow to take off.
It is only now with improved bio-based surfactant systems that can be used at lower concentrations, the decline in new oil field discovery and rising oil prices that EOR is becoming economically viable.
Relieving the tension on global oil supply in the near and medium term is vital in securing the futures of developed and emerging economies. Whilst enhanced oil recovery is more costly, at a practical level it means the difference between expensive oil and no oil at all.
Enhanced Oil Recovery is a grouping of various methods including:
- Thermal EOR
- Gas EOR
- Chemical EOR
- Hyrdodynamic EOR
- Combined EOR (a combination of the above)
With new advances in chemical research Chemical EOR (which includes Surfactant EOR) is fast gaining well-deserved attention as a long-term option for almost complete oil field extraction.
Chemical EOR first came to forefront during the oil crisis of the 1970’s and 80’s when increasing oil prices allowed initial EOR research to flourish. It is only now, however, that these original breakthroughs are re-emerging on the world’s short-list of options for securing oil supply in the 21st century.
Recent developments in Chemical EOR have made even further developments making the processes safer, cleaner and more cost efficient that ever.
EOR is not Fracking
Enhanced Oil Recovery is not the same as “Fracking” which is part of a group of methods known as “Oil Production Intensification”. The aim of fracking is to locally increase oil flow by changing the nature of the underlying rock strata.
EOR does not do this and, instead, relies on changing the nature of water and oil which impacts the way it flows through the oil field. The underlying structure of the rock is left in place. For this reason EOR does not represent any of the same risks or attract the controversy currently associated with Fracking.
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