ANALOG SITE DATABASE: DESCRIPTION AND USE

The Analog Site Database was developed to provide information on the release of CO2 from existing injection sites and natural releases. The analog site database is a compilation of studies performed at other CO2 storage locations and from sites with natural CO2 accumulations and releases. Since there is limited information on leakage rates from deep saline injection projects, the analog site search was extended to existing CO2 injection sites, natural CO2 sites, and VHM CO2 emission sites. While it is recognized that, by their very nature, VHM sites are not good analogs for CO2 releases from sedimentary basins, releases from VHM sites provide valuable information on CO2 attenuation and dispersion in the near surface and surface environment, and the potential impact of CO2 emissions on human health and the environment.

The analog site database currently includes information that has been obtained from four existing CO2

injection sites¹ (i.e., Rangely, Weyburn, In Salah, and Sleipner), 16 natural CO2 sites in sedimentary rock formations, and 17 sites in VHM areas (Table 5-1). These sites have been identified in several natural analog investigations for CO2 sequestration (e.g., Benson et al., 2002; IEA Greenhouse Gas R&D Program, 2005 and 2006a; IPCC, 2005; Streit and Watson, 2004).

Table 5-1. Sites Included in Analog Sites Database

Location/Site Site Type

Existing CO2 Injection Sites

Sleipner, North Sea Sedimentary

Weyburn, CO₂ Project, Canada Sedimentary Rangely CO2 EOR Project, CO Sedimentary In Salah, CO₂ Project, Algeria Sedimentary

Natural CO2 Sites

Crystal Geyser-Ten Mile Graben (Fault Zone), UT Sedimentary

Teapot Dome, WY Sedimentary

Farnham Dome, UT Sedimentary

Otway (Penola), Australia Sedimentary

Otway (Pine Lodge, Permeable Zone), Australia Sedimentary Otway (Pine Lodge, Fault), Australia Sedimentary

Springerville, AZ Sedimentary

St. Johns Dome, AZ-NM Sedimentary

Vorderrhon, Germany Sedimentary

Jackson Dome, MS Sedimentary

McElmo Dome, CO Sedimentary

Bravo Dome, NM Sedimentary

Big Piney – La Barge Area, WY Sedimentary

Gordon Creek, UT Sedimentary

Escalante, UT Sedimentary

Sheep Mountain, CO Sedimentary

1 Teapot Dome is also an experimental CO₂ injection site, but injection did not start until mid 2005, well after the CO₂ flux measurements were made. Therefore, Teapot Dome is not considered a CO₂ injection site within the context of this analog database.

Table 5-1 (continued). Sites Included in Analog Sites Database

Location/Site Site Type

Volcanic/Geothermal Sites

Mesozoic carbonate, Central Italy Sedimentary -hydrothermal Mammoth Tree Kill Area, CA Volcanic

Matraderecske, Hungary (Permeable Zone) Volcanic - hydrothermal Matraderecske, Hungary (Fault) Volcanic - hydrothermal Masaya volcano, Nicaragua Volcanic

Alban Hills, Italy Volcanic - hydrothermal

Latera, Tuscany, Italy Volcanic - hydrothermal Poggio dell’Ulivo, Italy Volcanic - hydrothermal Yellowstone volcanic system, WY Volcanic - hydrothermal Dixie Valley Geothermal Field, NV Volcanic - hydrothermal

Poas volcano, Costa Rica Volcanic

Arenal volcano, Costa Rica Volcanic Oldoinyo Lengai volcano, Tanzania Volcanic

Solfatara crater, Italy Volcanic

Vulcano Island, Italy Volcanic

Cerro Negro, Nicaragua Volcanic

Miyakejima volcano, Japan Volcanic

The most relevant natural analogs for geologic containment over the long-term are CO2 and CO2 -rich natural gas fields (Benson et al., 2002). The types of information collected, listed in Table 5-2, were selected based upon the following criteria:

• Data and information requested in the geologic storage qualifying criteria and geologic storage scoring criteria given in the FutureGen request for proposals;

• Data and information identified as key factors in the geologic carbon sequestration health, safety, and environment screening and ranking framework developed by LBNL (Oldenburg, 2005);

• Data and information defined as key factors controlling the potential for CO2 leakage and the magnitude of CO2 leakage in recent CO2 risk assessments and risk assessment guidelines (Benson et al., 2002; IPCC, 2005); and

• Data and information defined as important factors in recent analog studies (Streit and Watson, 2004; IEA Greenhouse Gas R&D Program, 2005 and 2006a).

Table 5-2. Parameters Compiled in Analog Site Database General Site Information

Location/Site

General Site Type (Volcanic/Geothermal or Sedimentary) Area (sq km)

Description of CO₂ Zone Depth (m)

Areal Extent (sq km) Structural Closure (m) Lithology

CO2 Origin CO₂ Age (years) Net Thickness (m) Gross Thickness (m)

Gas Composition ( percent CO2) Porosity (Fraction)

Permeability (mD) Pressure Gradient (psi/ft) Fracture Gradient (psi/ft)

Reservoir Water Chemistry TDS (mg/L)

Description of CO₂ Flux Rates & Reservoir Volume CO₂ Zone Regional Flow Rate (m/year)

CO₂ Production Rate (cu m/year) CO2 Reservoir Volume (cu m)

Description of Leakage Event CO₂ Leakage Rate (gm/sq m/day)

Event Triggering Leakage Pathway for Leakage Type of Release

Surface Topographic Slope (m per m) Average Surface Wind Speed (m/sec) Average Atmospheric Stability Class Surface Climate Type (arid; semi-arid, etc) Surface CO₂ Concentration (ppm)

Known Human Impacts from CO₂ Releases Known Ecosystem Impacts from CO₂ Releases

Table 5-2 (continued). Parameters Compiled in Analog Site Database Description of Primary and Secondary Seals

Lithology

Zone Areal Extent (sq km) Zone Gross Thickness (m) Porosity (fraction)

Permeability (mD)

Capillary Entry Pressure (Mpa)

Description of Secondary Porous Zone Lithology

Zone Areal Extent (sq km) Depth (m)

Gross Thickness (m) Porosity (fraction) Permeability (mD)

Capillary Entry Pressure (Mpa)

Description of Groundwater (GW) Regional Flow (m/year)

Pressure (kPA) TDS (mg/L)

Major Cation (Type-mg/L) Major Anion (Type-mg/L)

Primary Storage Formation - Regional Flow (m/year) Description of Vadose Zone Thickness (m)

Porosity (fraction) Permeability (mD) CO₂ Concentration (ppm)

Surface Water Information Depth (m)

Lake HCO₃ (mg/L) River HCO₃ (mg/L)

Information on Faults Number of Tectonic Faults

Number of Normal Faults Number of Strike-Slip Faults Fault Permeability (mD)

Table 5-2 (continued). Parameters Compiled in Analog Site Database Nearby Wells

Number of Deep Wells Number of Shallow Wells Number of Abandoned Wells

Injection Wells Number of Injection/Disposal Wells Injection Rate (MMT/year)

Total Reinjected (MMT)

Radon Information References

Not all information was pertinent for a given site and not all the information could be obtained. The CO2

release rates are expressed as g/m²-year (or micromoles per meter squared-second [µmol/m²-s]), so that the relative leakage rates could be compared among the sites. References are included in the database.

The Analog Site Database was used to identify sites where CO2 has been released, and that had measured or estimated release rates, and information on effects on human health and the environment. The database was used to identify realistic CO2 migration pathways and factors that influence those pathways for use in formulating the conceptual model (Figure 5-2). These pathways provide the basis for the description of potential release scenarios for the FutureGen sites. Comparison of information from the System Model and the parameter values in the Site-Analog Database was then used to identify analogs for the proposed injection sites, which are in turn used to estimate both the probability of releases and the magnitude of releases at the proposed sites.

The first step in applying the Analog Site Database is to conduct a qualitative review of the geologic setting and a quantitative analysis of the FutureGen site database to assess the similarity of each FutureGen site and determine the most appropriate (set of) analog site(s). Then, where known release estimates are available from the selected analog site, the release estimates are extrapolated from the analog site to the candidate site.