COMSATS Institute of Information Technology Defence Road, Off Raiwind Road, Lahore, Pakistan
May 27, 2015
COMSATS Institute of Information TechnologyDefence Road, Off Raiwind Road, Lahore, Pakistan
Enhanced Oil Recovery
Steam Injection
What is Enhanced Oil Recovery (EOR) ?
• A generic term for increasing the amount of crude oil extracted from an oil reservoir
• Also referred to as ‘improved oil recovery’ or ‘tertiary oil recovery’
• Using EOR, oil extraction rate can exceed up to 60% compared to primary and secondary oil recovery methods (20-40% recovery)
Methods of EOR
• Gas injection methods• Chemical injection methods• Thermal methods– Steam injection– Fire flooding
Steam Injection
• One of the methods included in EOR
• Applies the use of steam for recovering oil
• Has several different forms but two main ones– Cyclic Steam Stimulation– Steam Flooding
Cyclic Steam Stimulation
• Also known as “Huff-and-Puff” method
• Sometimes applied to heavy-oil reservoirs
• Assists natural reservoir energy by lowering viscosity of oil
• Commonly used for a formation of oil-wells but can be applied to a single-well procedure
Cyclic Steam Stimulation (contd.)
• The cycle may be repeated until the recovery response becomes minimum due to decrease in pressure and increase in water production
• Accompanied by continuous steam-flooding to continue the supply of heat and to replace declining pressure of reservoir
Steam Flooding
• Most commonly used in heavy-oil reservoirs having high viscosity
• High-temperature steam is continuously ejected into the reservoir which,– Loses heat to formation of water and condenses– The hot water produced coupled with continuous
steam supply acts as a driving force to move the oil to the production wells
Advantages• Steam floods are easier to control than fire-floods
• Steam floods do not cause cracking of oil and no environmentally objectionable flue gases are produced
• Steam injection wells are subject to much lower temperature than fire injection wells
• Steam flooding can be applied to reservoirs containing high API gravity oils
• Flushing of liners and casing perforations, as well as the reduction of deposits that may build up in the wells
Disadvantages
• Heat losses are high through injection lines, wellbores and oil well formation
• Steam flooding requires large supply of high quality fresh water
• Steam injection can’t be performed at depths below 5000 ft because of high reservoir pressure
Economic Considerations
• Capital investment is lower
• Fuel consumption per barrel of oil produced is higher
References
• http://en.wikipedia.org/wiki/Steam_injection_%28oil_industry%29
• www.netl.doe.gov/technologies/oil-gas/publications/eordrawings/BW/bwsf.PDF
• www.netl.doe.gov/technologies/oil-gas/publications/eordrawings/BW/bwcyclic_stm.PDF
• www.most.gov.mm/techuni/media/PE_05045_2.pdf