CO₂ is injected into a carefully selected hydrocarbon reservoir, which results in oil being flushed from the pore spaces in the reservoir rock and ‘pushed’ to the production wells where it is pumped to the surface and recovered, thereby increasing the quantity of oil that is ultimately recovered from the reservoir.
Utilization: Enhanced Oil Recovery
Enhanced Oil Recovery (EOR)
CO₂ Enhanced Oil Recovery is a technique of injecting CO₂ into an oil reservoir to increase the amount of oil that can be extracted from the field and has been used throughout North America for nearly 50 years. ‘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 is easier to flow. This technique is also called ‘tertiary recovery’ and helps unlock oil that is still in the reservoir but was not able to be extracted using primary or secondary methods (see below for more detail on each method). CO₂ EOR represents the utilization component of CCUS and is a technique already used in CO₂ floods worldwide.
CO₂ EOR Recovers as much oil as primary or secondary recovery.
Tertiary (CO₂ EOR)
The Clive reservoir will be developed in phases where paired injection and production wells will be drilled and their associated production and injection flowlines will be installed. Over time it is anticipated that the entire Clive field will be under CO₂ EOR development.
CO₂ is pumped under high pressure into the reservoir through injection wells, and mixes with the remaining oil in the reservoir to make it more mobile. At this depth, the formation pressure and temperature will keep the injected CO₂ fluid miscible (mixed) with the oil in a dense, liquid phase. This helps flush the oil from the reservoir rock and push it towards the producing wells where it can be pumped to the surface.
Clive Development Plan
Stages of Oil Recovery
Primary oil recovery represents the first stage of petroleum and natural gas production. Crude oil extraction from a new well relies on oil naturally rising to surface due to pressure differences between the oil field and the bottom-hole of the well. Artificial or mechanical lift devices such as pump jacks help to bring oil to the surface in primary recovery.
Secondary enhanced recovery is the recovery of oil or gas from a reservoir over and above what is recovered through normal flowing and pumping operations under primary recovery. Secondary recovery techniques involve injecting water, immiscible gas or other substances into the formation to maintain or enhance the reservoir pressure as a driving force to bring oil or gas to the surface to be produced.