SWP Phase II

Carbon Storage Atlas

Scale-Up to Phase II
Regional Accomplishments
Story of Interest
Research vs. Commercial
Sites
Partners

Scale-Up to Phase II

The Southwest Regional Partnership on Carbon Sequestration (SWP) Phase I project, by definition, was a study in the theoretical availability of carbon dioxide (CO₂) emissions and CO₂ storage capacity of the Southwestern United States. An analysis was conducted for the broad region, with the development of a plan for the implementation of capture, transport, and storage/utilization of CO₂, with existing CO₂ pipelines from natural sources in Wyoming, Colorado, and New Mexico as the backbone. The results of that analysis identified specific areas in the region with unique but ubiquitous geological characteristics that could be utilized as sounding boards (pilots) for larger-scale (commercial) CO₂ capture and storage sites. The most significant storage/utilization option identified within the region, along the CO₂ transport backbone, was CO₂-enhanced oil recovery (EOR), with the Permian Basin of Texas (Scurry Area Canyon Reef Operator’s Committee [SACROC] Unit) being the largest. In Utah, also adjacent to the CO₂ transport backbone, the Paradox Basin (Aneth Field) was a smaller EOR prospect, with geology distinct from the Permian Basin, but more representative of reservoirs within the Colorado Plateau. Enhanced coalbed methane (ECBM) production utilizing CO₂ was attempted as another method of storage within the region. Each of the three pilot projects were able to gather and analyze significant data that expanded on the Phase I dataset.

Regional Accomplishments

The most significant regional-scale accomplishment in the Southwest Regional Partnership on Carbon Sequestration (SWP) region was the initial development of the regional Carbon Storage Atlas, as part of the National Energy Technology Laboratory’s (NETL) National Carbon Sequestration Database and Geographic Information System (NATCARB) effort. This task focused on the major sedimentary basins within the region, identifying significant geologic reservoirs that were sufficiently deep, porous, and permeable, and were capped by impermeable units that would prevent upward migration of injected carbon dioxide (CO₂). Areal and thickness (volume) extents of each significant candidate formation were mapped and combined with porosity values to develop a theoretical CO₂ capacity estimate for reservoirs, basins, individual states, and the entire region. At least 15 large sedimentary basins reside in the Southwest United States, with each basin containing several potential CO₂ reservoirs (saline, oil, gas, coal). The cumulative storage capacity of all reservoirs, in all basins within the SWP region, is conservatively estimated at more than 100 billion metric tons of CO₂. This storage capacity is sufficient for 100% capture from all coal- and gas-fired power plants in the region for the next 100 years (at current emission rates).

Story of Interest

The largest Southwest Regional Partnership on Carbon Sequestration (SWP) Phase II field site was in the Scurry Area Canyon Reef Operator’s Committee (SACROC) Unit of the Permian Basin, Texas. The SACROC Unit is the oldest actively injecting carbon dioxide (CO₂) project in the United States, utilizing CO₂ since 1972. The SWP data collection and analysis of the ongoing CO₂-enhanced oil recovery (EOR) at the SACROC Unit was comprehensive, gathering extensive surface and subsurface geologic, geochemical, and geophysical datasets. These datasets, in turn, fed simulations that evaluated the long-term effects of CO₂ injection, migration, caprock integrity, and trapping mechanisms. One of the conclusions of the simulation activities at the SACROC Unit is the concept of CO₂ injection into deep saline aquifers immediately below an oil reservoir. Carbon dioxide injected below an oil reservoir will mix with the saline water and form a plume that rises due to buoyancy. When the buoyant plume encounters an oil reservoir, simulations indicate most of the CO₂ will dissolve into oil. Although some CO₂ will remain free, it does not tend to migrate vertically because oil density is similar to CO₂ density, causing less buoyancy-driven vertical migration. The free CO₂ behaves more like residual CO₂. Although free CO₂ may reach the top of the target formation, an oil reservoir is always covered by a caprock. Therefore, CO₂ cannot easily escape. Although an oil reservoir provides several advantages for minimizing the potential vertical migration of CO₂, its size and volume are limited for CO₂ storage. In comparison, the potential for CO₂ storage in brine formations is immense.

Research vs. Commercial

The Southwest Regional Partnership on Carbon Sequestration (SWP) Phase II pilot studies were each conducted at existing oil- and gas-producing sites, with the industrial partners and operators having a financial interest in energy extraction rather than carbon dioxide (CO₂) storage. Carbon dioxide was a necessary component of the enhanced oil and gas extraction at each pilot site, with the field operators viewing CO₂ as a valuable resource, much like any fuel. To this end, the operators at each field site tailored CO₂ injection, often combined with water injection (and subsequent co-production and recycling), varied over time and field site, to maximize oil and gas recovery rather than storage. SWP research activities at the Phase II sites, from monitoring, verification, and accounting (MVA) to risk assessment to simulation, had to consider this more complex intermittent injection and constant production when attempting to understand the entire system (reservoir).

Conversely, commercial-scale sites would likely be tailored to maximize CO₂ storage, including nearly constant and consistent injection at dedicated injection wells, with dedicated monitoring wells and other monitoring infrastructure. While attempting to forecast long-term effects of CO₂ at a commercial site is not trivial, the steady-state injection activity reduces much of the complexity of an enhanced oil recovery (EOR) or enhanced coalbed methane (ECBM) site.

Sites

* Lead Organization