Carbon capture and sequestration (CCS), a technology where carbon emissions are captured at a point source, transported, and injected deep underground into a safe, permitted geologic site for long term storage, was included in the portfolio of climate change mitigation options released in 2005 by the Intergovernmental Panel on Climate Change (IPCC) (IPCC, 2005). The technology continued to be acknowledged and strongly reiterated in successive reports by the International Energy Agency (IEA) (International Energy Agency, 2008a,b, 2011, 2013).
The goal of climate change mitigation is to hold the increase of global average temperature to well-below 2°C above pre-industrial levels (Article 2, United Nations, 2015). Although not explicitly mentioned in the Paris Agreement of November 4, 2016, it is clear that extensive investments in large-scale emission reduction technologies like CCS will be required, at least during a transitional stage (Article 4, United Nations, 2015).
Part of the continued discussion of whether CCS will contribute enough to meet climate targets is the discussion around the role of carbon dioxide enhanced oil recovery (CO2-EOR). Storing captured CO2 through CO2-EOR enters into a category called carbon capture, utilization and storage (CCUS), where the captured CO2 is utilized for a commercial activity, in this case EOR, as it becomes ultimately stored.
A few large-scale CCUS projects are operational today. The Weyburn-Midale Carbon Dioxide Project located in Midale, Saskatchewan, Canada, started CO2 injection in October 2000 and continues to produce oil from Weyburn and Midale oil fields at a rate of 14 thousand barrels of oil per day (Jensen, 2019). The CO2 injected is captured at a lignite-fired synfuels plant in Beulah, North Dakota, U.S., and transported to the fields via a 320 km long transnational pipeline. More recently, a couple of large-scale CCUS projects emerged in the U.S. The Air Products Capture Project injects CO2 captured at a hydrogen production facility in Port Arthur, Texas, into the West Hastings field for EOR, and the Petra Nova project injects CO2 captured at NRG’s Parish Power Plant, southwest of Houston, into the nearby West Ranch oil field, also for EOR.
Figure 2. CO2 trapping mechanisms
Carbon dioxide enhanced oil recovery (CO2-EOR) has been a successful commercial activity in the U.S. since 1972, when it first started in the Permian Basin, more specifically in SACROC Field, Texas. The Permian Basin, by far the most active CO2-EOR region in the world, is located in West Texas and southeastern New Mexico. This oil producing region, the third largest in the U.S., has produced over 30 billion barrels of oil, out of which 1.3 billion have been produced with CO2 (Merchand, 2017). Current EOR activities there produce on average 350,000 barrels of oil per day (BOPD) (the IEA estimates current world CO2-EOR production at 450,000 BOPD). The CO2, mostly naturally sourced, is transported to oil fields through a network of 4,500 miles of pipelines. The development of this vast CO2 supply infrastructure in the region has resulted from the increasing CO2 demand for EOR. CO2 supply has not always met the demand, restricting EOR production. The latter is starting to force a change in the low-cost natural CO2 supply trend, with forecasts including emerging industrial CO2 capture projects.
The U.S. has an oil resource base on the order of ~600 billion barrels of original oil in place. About one-third of this resource base, ~200 billion barrels, has been recovered after primary and secondary oil production. This means that a significant target of ~400 billion barrels of oil are still trapped in the subsurface (Kuuskraa et al., 2009). Not all of the stranded oil can be produced or placed into proved oil reserves, and not all is amenable for CO2-EOR technologies. The same report by Kuuskraa et al. (2009), estimates that from the ~400 billion barrels of oil remaining, ~84.8 billion barrels of oil are technically recoverable through CO2-EOR applications. However, the CO2-EOR market is still large and very attractive to developers. Several screening methodologies to identify candidate oil reservoirs for CO2-EOR exist in the literature, such as Kovscek (2002), Núñez-López et al. (2008), and Bachu (2016). Some methodologies lay out the conditions for miscible displacement (lighter hydrocarbons, higher pressures, lower temperatures), others rely on the estimation of MMP and screen for reservoirs that have pressures above MMP.
Many in the environmental community have argued that CO2-EOR only serves to prolong the use of fossil fuels and, as it produces carbon emitting oil, is not able to reduce emissions. However, a recent study by Núñez-López et al. (2019), shows that, depending on strategic operational choices, the incremental oil produced from CO2-EOR can achieve a net carbon negative status throughout most of the life of the operation (i.e., because a large percentage of the injected CO2 is unavoidably and permanently trapped in the subsurface, as discussed in section Associated Storage of CO2 through EOR). The study uses a novel dynamic lifecycle analysis (d-LCA) that includes greenhouse gas (GHG) emissions at the CO2-EOR site and downstream (including crude oil refining and refined product combustion), and is linked to an operational EOR performance model.
Figure 3. General components of CCUS Systems.
The scale-up problem that CCS faces is largely the result of an insufficient value on carbon—presenting risks to private sector investments and, by proxy banking institutions, which have the potential to be partially alleviated through policy and regulation (Zapantis et al., 2019). The CO2 pipeline infrastructure scale-up needed between customers and suppliers of anthropogenic CO2 to meet a U.S. climate policy case scenario laid out in Wallace et al. (2015) is unprecedented but comparable to pipeline projections in other sectors. Turning the market focus from the value of oil to climate mitigation would likely require additional funding to help offset the “technology valley of death” that many emerging technologies face (i.e., technologies that are technically proven but unable to bridge the gap to commercial-scale). Because companies are already implementing the technology outside of a stable political and economic framework, the private sector is assuming the economic, technical, construction, and operational risks, but these risks could be partially abated by a policy infrastructure.
The lack of a comprehensive CCS regulatory regime has been cited by numerous experts as a primary obstacle to deployment (Davies et al., 2013). The current mix of federal and state policies is what the State CO2-EOR Deployment Work Group 2016) describes as “too cumbersome for project developers to utilize effectively.” The Work Group recommends that Congress establish federal price stabilization contracts, or contracts for differences (CfD) to reduce price volatility between capture facilities and EOR operators (in non-vertically-integrated projects), to make carbon capture eligible for tax-exempt private activity bonds (PABs), and master limited partnerships (MLPs) to provide debt and equity on more favorable terms. There are generalized models of CCS regulatory frameworks that have the potential to support commercial-scale development country-wide (Ekins et al., 2017, p. 83; Jacobs and Craig, 2017).
Source : Frontiers | Potential of CO2-EOR for Near-Term Decarbonization | Climate (frontiersin.org)
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