Assessment of shallow subsea hydrocarbons as a proxy for leakage at offshore geologic CO2 storage sites

Bureau of Economic Geolog

Assessing risk to fresh water resources from long term CO2 injection- laboratory and field studies

In developing a site for geologic sequestration, one must assess potential consequences of failure to adequately contain injected carbon dioxide (CO2). Upward migration of CO2 or displacement of saline water because of increased pressure might impact protected water resources 100s to 1000s of meters above a sequestration interval. Questions posed are: (1) Can changes in chemistry of fresh water aquifers provide evidence of CO2 leakage from deep injection/sequestration reservoirs containing brine and or hydrocarbons? (2) What parameters can we use to assess potential impacts to water quality? (3) If CO2 leakage to freshwater aquifers occurs, will groundwater quality be degraded and if so, over what time period? Modeling and reaction experiments plus known occurrences of naturally CO2-charged potable water show that the common chemical reaction products from dissolution of CO2 into freshwater include rapid buffering of acidity by dissolution of calcite and slower equilibrium by reaction with clays and feldspars. Results from a series of laboratory batch reactions of CO2 with diverse aquifer rocks show geochemical response within hours to days after introduction of CO2. Results included decreased pH and increased concentrations of cations in CO2 experimental runs relative to control runs using argon (Ar). Some cation (Ba, Ca, Fe, Mg, Mn, and Sr) concentrations increased over and an order of magnitude during CO2 runs. Results are aquifer dependant in that experimental vessels containing different aquifer rocks showed different magnitudes of increase in cation concentrations. Field studies designed to improve understanding of risk to fresh water are underway in the vicinity of (1) SACROC oilfield in Scurry County, Texas, USA where CO2 has been injected for enhanced oil recovery (EOR) since 1972 and (2) the Cranfield unit in Adams County, Mississippi, USA where CO2 EOR is currently underway. Both field studies are funded by the U.S. Department of Energy (DOE) regional carbon sequestration partnership programs and industrial sponsors. Preliminary results of groundwater monitoring are currently available for the SACROC field study where researchers investigated 68 water wells and one spring during five field excursions between June 2006 and July 2008. Results to date show no trend of preferential degradation below drinking water standards in areas of CO2 injection (inside SACROC) as compared to areas outside of the SACROC oil field.Bureau of Economic Geolog

The effect of monitoring complexity on stakeholder acceptance of CO2 geological storage projects in the US gulf coast region

Environmental monitoring at geologic CO2 storage sites is required by regulations for the purposes of environmental protection and emissions accounting in the case of leakage to surface. However, another very important goal of environmental monitoring is to assure stakeholders that the project is monitored for safety and effectiveness. With current efforts to optimize monitoring for cost-effectiveness, the question remains: will optimization of monitoring approaches degrade stakeholder assurance, or do heavily-instrumented sites communicate higher risk to a stakeholder? We report the results of a stakeholder survey in Gulf Coast states of the US where carbon capture and storage (CCS) is developing quickly. We rely on a 2 by 2 factorial experiment in which we manipulate message complexity (complex v. simple) and social norm (support from scientists v. support from community members). Subjects were randomly assigned to one of four conditions: 1) complex message with scientist support; 2) complex message with community member support; 3) simple message with scientist support; or 4) simple message with community member support. In addition to the experimental stimuli, subjects were also asked about their need for cognition, attitudes toward science and scientists, attitudes about climate change and support for carbon capture and storage (CCS). Our sample is drawn from residents in states bordering the western Gulf of Mexico (Texas, Louisiana, Florida) where CO2 geologic storage is being planned both onshore and offshore. The results offer important implications for public outreach efforts to key stakeholders

Improving monitoring protocols for CO2 geological storage with technical advances in CO2 attribution monitoring

Bureau of Economic Geolog

Field assessment of sensor technology for environmental monitoring using a process-based soil gas method at geologic CO2 storage sites

Bureau of Economic Geolog

Detection of anthropogenic CO2 in dilute groundwater: field observations and geochemical modeling of the Dockum aquifer at the SACROC oilfield, West Texas, USA

Bureau of Economic Geolog

Process-based approach to CO2 leakage detection by vadose zone gas monitoring at geologic CO2 storage sites

Bureau of Economic Geolog

Light hydrocarbon and noble gas migration as an analogue for potential CO2 leakage: numerical simulations and field data from three hydrocarbon systems

Bureau of Economic Geolog

Modeling CO2 release experiment in the shallow subsurface and sensitivity analysis

Bureau of Economic Geolog

CO2 solubility in aqueous solutions containing Na+, Ca2+, Cl−, SO4 2− and HCO3-: The effects of electrostricted water and ion hydration thermodynamics

Bureau of Economic Geolog