Enhanced oil recovery
Enhanced oil recovery (abbreviated EOR), also called tertiary recovery, is the extraction of crude oil from an oil field that cannot be extracted otherwise. Although the primary and secondary recovery techniques rely on the pressure differential between the surface and the underground well, enhanced oil recovery functions by altering the chemical composition of the oil itself in order to make it easier to extract. EOR can extract 30% to 60% or more of a reservoir's oil,[1] compared to 20% to 40% using primary and secondary recovery.[2][3] According to the US Department of Energy, carbon dioxide and water are injected along with one of three EOR techniques: thermal injection, gas injection, and chemical injection.[1] More advanced, speculative EOR techniques are sometimes called quaternary recovery.[4][5][6][7]
This article is about processes applicable to conventional oil fields. For processes applied to oil sands, see oil sands.Economic costs and benefits[edit]
Adding oil recovery methods adds to the cost of oil—in the case of CO2 typically between 0.5–8.0 US$ per tonne of CO2. The increased extraction of oil on the other hand, is an economic benefit with the revenue depending on prevailing oil prices.[33] Onshore EOR has paid in the range of a net 10–16 US$ per tonne of CO2 injected for oil prices of 15–20 US$/barrel. Prevailing prices depend on many factors but can determine the economic suitability of any procedure, with more procedures and more expensive procedures being economically viable at higher prices.[34] Example: With oil prices at around 90 US$/barrel, the economic benefit is about 70 US$ per tonne CO2. The U.S. Department of Energy estimates that 20 billion tons of captured CO2 could produce 67 billion barrels of economically recoverable oil.[35]
From 1986 to 2008, the quote oil production deriving from EOR has increased from 0.3% to 5%, thanks to an increasing oil demand and a reduction of oil supply.[36]
EOR projects with CO2 from carbon capture[edit]
Boundary Dam Power Station, Canada[edit]
SaskPower's Boundary Dam Power Station project retrofitted its coal-fired power station in 2014 with carbon capture and sequestration (CCS) technology. The plant will capture 1 million tonnes of CO2 annually, which it sold to Cenovus Energy for enhanced oil recovery at its Weyburn Oil Field,[37] prior to the sale of Cenovus's Saskatchewan assets in 2017 to Whitecap Resources.[38] The project is expected to inject a net 18 million ton CO2 and recover an additional 130 million barrels (21,000,000 m3) of oil, extending the life of the oil field by 25 years.[39] There is a projected 26+ million tonnes (net of production) of CO2 to be stored in Weyburn, plus another 8.5 million tonnes (net of production) stored at the Weyburn-Midale Carbon Dioxide Project, resulting in a net reduction in atmospheric CO2 by CO2 storage in the oilfield. That's the equivalent of taking nearly 7 million cars off the road for a year.[40] Since CO2 injection began in late 2000, the EOR project has performed largely as predicted. Currently, some 1600 m3 (10,063 barrels) per day of incremental oil is being produced from the field.
Petra Nova, United States[edit]
The Petra Nova project uses post-combustion amine absorption to capture some of the carbon dioxide emissions from one of the boilers at the W.A Parish power plant in Texas, and transports it by pipeline to the West Ranch oil field for use in enhanced oil recovery.
Kemper Project, United States (canceled)[edit]
Mississippi Power's Kemper County energy facility, or Kemper Project, was to have been a first-of-its-kind plant in the U.S. that was expected to be online in 2015.[41] Its coal gasification component has since been canceled, and the plant has been converted to a conventional natural gas combined cycle power plant without carbon capture. The Southern Company subsidiary worked with the U.S. Department of Energy and other partners with the intention to develop cleaner, less expensive, more reliable methods for producing electricity with coal that also support EOR production. The gasification technology was designated to fuel the integrated gasification combined cycle power plant.[35] Additionally, the unique location of the Kemper Project, and its proximity to oil reserves, made it an ideal candidate for enhanced oil recovery.[42]
CO2 EOR in the United States[edit]
The United States has been using CO2 EOR for several decades. For over 30 years, oil fields in the Permian Basin have implemented CO2 EOR using naturally sourced CO2 from New Mexico and Colorado.[46] The Department of Energy (DOE) has estimated that full use of 'next generation' CO2-EOR in United States could generate an additional 240 billion barrels (38 km3) of recoverable oil resources. Developing this potential would depend on the availability of commercial CO2 in large volumes, which could be made possible by widespread use of carbon capture and storage. For comparison, the total undeveloped US domestic oil resources still in the ground total more than 1 trillion barrels (160 km3), most of it remaining unrecoverable. The DOE estimates that if the EOR potential were to be fully realized, state and local treasuries would gain $280 billion in revenues from future royalties, severance taxes, and state income taxes on oil production, aside from other economic benefits.
In the US, regulations can both assist and slow down the development of EOR for use in carbon capture & utilization, as well as general oil production. One of the primary regulations governing EOR is the Safe Drinking Water Act of 1974 (SDWA), which gives most of the regulatory power over EOR and similar oil recovery operations to the EPA.[47] The agency in turn delegated some of this power to its own Underground Injection Control Program,[47] and much of the rest of this regulatory authority to state and tribal governments, making much of EOR regulation a localized affair under the minimum requirements of the SDWA.[47][48] The EPA then collects information from these local governments and individual wells to ensure they follow overall federal regulation, such as the Clean Air Act, which dictates reporting guidelines for any Carbon Dioxide sequestration operations.[47][49] Beyond the atmospheric concerns, most of these federal guidelines are to ensure that the Carbon Dioxide injection causes no major damage to America's waterways.[50] Overall, the locality of EOR regulation can make EOR projects more difficult, as different standards in different regions can slow down construction and force separate approaches to utilize the same technology.[51]
In February 2018, Congress passed and the President signed an expansion of the carbon capture tax credits defined in section 45Q of the IRS' Internal Revenue code. Previously, these credits were limited to $10/ton and capped at a total of 75 million tons. Under the expansion, carbon capture and utilization projects like EOR will be eligible for a tax credit of $35/ton, and sequestration projects will receive a $50/ton credit.[52] The expanded tax credit would be available for 12 years to any plant constructed by 2024, with no volume cap. If successful, these credits "could help sequester between 200 million and 2.2 billion metric tons of carbon dioxide"[53] and bring down carbon capture and sequestration costs from a currently estimated $60/ton at Petra Nova to as low as $10/ton.
Environmental impacts[edit]
Enhanced oil recovery wells typically pump large quantities of produced water to the surface. This water contains brine and may also contain toxic heavy metals and radioactive substances.[54] This can be very damaging to drinking water sources and the environment generally if not properly controlled. Disposal wells are used to prevent surface contamination of soil and water by injecting the produced water deep underground.[55][56]
In the United States, injection well activity is regulated by the United States Environmental Protection Agency (EPA) and state governments under the Safe Drinking Water Act.[57] EPA has issued Underground Injection Control (UIC) regulations in order to protect drinking water sources.[58] Enhanced oil recovery wells are regulated as "Class II" wells by the EPA. The regulations require well operators to reinject the brine used for recovery deep underground in Class II disposal wells.[55]