CO2 Enhanced Oil Recovery involves injecting CO2 into a depleted oil reservoir to increase the amount of oil that can be extracted from it. ‘Miscible flooding’ is a general term for an injection process that introduces miscible (or ‘mixable’) liquids or gases, such as CO2, into a reservoir. The miscible liquids or gases combine with oil in the reservoir and cause a reduction in the oil’s viscosity, so it becomes easier to flow. This helps unlock the remaining oil in the reservoir that couldn’t be extracted using conventional methods.
CO₂ EOR Explained
The most effective permanent safe storage is in sites of sufficient depth (typically deeper than 800 meters) with adequate capacity and an overlying sealing system to ensure containment of fluids.
By undertaking the CO2 EOR project, Enhance can help to reinvigorate communities with the addition of jobs, increasing the standard of living for all Albertans and positively impacting the lives of all Canadians. A 2009 Canadian Energy Research Institute (CERI) Study found a total of 30,000 person-years of Canadian employment would result from the initial phase of the ACTL project which represented an impact on Canada’s GDP of almost $6 billion.
At Clive, Enhance has found a permanent home for CO2 while generating a low carbon fuel source that can supply the energy and products driving our economy and quality of life.
Carbon emissions of EOR and other fuel types
The net CO2 emissions per unit of energy for fossil fuel energy sources are compared to those from oil produced from CO2 EOR, incorporating the impact of extraction, processing and fuel combustion. The chart also shows that oil produced from EOR+ can store more CO2 per unit of energy than is emitted during extraction, processing and combustion, thereby resulting in net negative carbon emissions.
EOR Basics at Clive
Discovered in 1952, only three years after the first Leduc discovery, the Clive field was rapidly developed to produce high quality light oil. As the oil is produced, salty water from the underlying Leduc aquifer begins to move into the micro-sized pore spaces in the rock to fill the voids left by the oil.
Fast forward to 2018, when millions of barrels of oil have been produced from Clive, but the remaining wells are producing mostly water. At the pore-scale, the salty aquifer waters have created channels through the more viscous oil. The oil has been bypassed and no amount of pumping will recover it.
Enhance Energy’s injection wells are pumping CO2 into the Leduc which, at a depth of 2km, can be absorbed into the oil. The CO2/oil combination becomes less viscous and expands to push out the water and close the channels. By alternating water injection with CO2, banks of fluid pick up and move previously unrecovered oil towards an awaiting production well.
CO₂ Enhanced Recovery is Proven Technology
CO2 injection into oil reservoirs is a widely-used, proven and safe technique for EOR, and has been used by the oil industry for more than 45 years.
As of 2012, it is estimated that CO2 EOR operations in North America inject up to 65 million tonnes per year of CO2 through more than 7,200 injection wells. Cumulative CO2 injection in the United States is estimated to be 800 to 900 million tonnes. Today, there are over 136 registered CO2 floods in North America producing greater than 400,000 barrels per day of oil.