Publications Database - List of storage publications

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    January, 2009

The CO₂ Capture Project Phase 2 (CCP2) Storage Program: Progress in Geological Assurance in Unmineable Coal Beds

Dan Kieke, Scott Imbus, Karen Cohen, Chris Galas, Erika Gasperikova, William Pickles, Eli Silver

The CO₂ Capture Project’s (CCP) Phase 2 program made significant progress addressing issues to facilitate assurance of the safety and security of geological storage of CO₂. This work included stakeholder assurance of CO₂ storage in unmineable coal beds. Simulation studies of CO₂ injection into coal beds were designed to identify operating conditions that will minimize leakage of CO₂ and maximize production of methane. Geophysical models were used to simulate gravity and electromagnetic responses from coal beds containing CO₂. Hyperspectral remote sensing was evaluated for its ability to detect leakage of CO₂ and CH₄ to the surface.

© 2008 Elsevier Ltd. All rights reserved.

Keywords: CO₂; coal bed; ECBM; monitoring; EM; gravity; MASTER; remote sensing.

Source: Greenhouse Gas Control Technologies (GHGT) conference, 16-20 November 2008

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    January, 2009

Modeling the effects of topography and wind on atmospheric dispersion of CO₂ surface leakage at geologic carbon sequestration sites.

Fotini K. Chow, Patrick W. Granvold, Curtis M. Oldenburg

Understanding the potential impacts of unexpected surface releases of CO₂ is an essential part of risk assessment for geologic carbon sequestration sites. We have extended a mesoscale atmospheric model to model dense gas dispersion of CO₂ leakage. The hazard from CO₂ leakage is greatest in regions with topographic depressions where the dense gas can pool. Simulation of dispersion in idealized topographies shows that CO₂ can persist even under high winds. Simulation of a variety of topographies, winds, and release conditions allows the generation of a catalog of simulation results that can be queried to estimate potential impacts at actual geologic carbon sequestration sites.

© 2008 Elsevier Ltd. All rights reserved.

Keywords: atmospheric dispersion, dense gas, leakage and seepage, carbon sequestration.

Source: Greenhouse Gas Control Technologies (GHGT) conference, 16-20 November 2008

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    January, 2009

Pressure perturbations from geologic carbon sequestration: Area-of-review boundaries and borehole leakage driving forces

Jean-Philippe Nicot, Curtis M. Oldenburg, Steven L. Bryant, and Susan D. Hovorka

We investigate the possibility that brine could be displaced upward into potable water through wells. Because of the large volumes of CO₂ to be injected, the influence of the zone of elevated pressure on potential conduits such as well boreholes could extend many kilometers from the injection site—farther than the CO₂ plume itself. The traditional approach to address potential brine leakage related to fluid injection is to set an area of fixed radius around the injection well/zone and to examine wells and other potentially open pathways located in the “Area-of-Review” (AoR). This suggests that the AoR needs to be defined in terms of the potential for a given pressure perturbation to drive upward fluid flow in any given system rather than on some arbitrary pressure rise. We present an analysis that focuses on the changes in density/salinity of the fluids in the potentially leaking wellbore.

© 2008 Elsevier Ltd. All rights reserved.

Keywords: pressure profile, water density, AoR, brine leakage, USDW, TDS.

Source: Greenhouse Gas Control Technologies (GHGT) conference, 16-20 November 2008

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    January, 2009

Probability Estimation of CO₂ Leakage Through Faults at Geologic Carbon Sequestration Sites

Yingqi Zhang, Curtis M. Oldenburg, Stefan Finsterle, Preston Jordan, and Keni Zhang

Leakage of CO₂ and brine along faults at geologic carbon sequestration (GCS) sites is a primary concern for storage integrity. The focus of this study is on the estimation of the probability of leakage along faults or fractures. This leakage probability is controlled by the probability of a connected network of conduits existing at a given site, the probability of this network encountering the CO₂ plume, and the probability of this network intersecting environmental resources that may be impacted by leakage. This work is designed to fit into a risk assessment and certification framework that uses compartments to represent vulnerable resources such as potable groundwater, health and safety, and the near-surface environment. The method we propose includes using percolation theory to estimate the connectivity of the faults, and generating fuzzy rules from discrete fracture network simulations to estimate leakage probability. By this approach, the probability of CO₂ escaping into a compartment for a given system can be inferred from the fuzzy rules. The proposed method provides a quick way of estimating the probability of CO₂ or brine leaking into a compartment. In addition, it provides the uncertainty range of the estimated probability.

© 2008 Elsevier Ltd. All rights reserved.

Keywords: Leakage risk; Connectivity of faults and fractures; Probabilitly estimation.

Source: Greenhouse Gas Control Technologies (GHGT) conference, 16-20 November 2008

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    January, 2009

Sensitivity of CO₂ migration estimation on reservoir temperature and pressure uncertainty

Preston Jordan and Christine Doughty

The density and viscosity of supercritical CO₂ are sensitive to pressure and temperature (PT) while the viscosity of brine is sensitive primarily to temperature. Oil field PT data in the vicinity of WESTCARB’s Phase III injection pilot test site in the southern San Joaquin Valley, California, show a range of PT values, indicating either PT uncertainty or variability. Numerical simulation results across the range of likely PT indicate brine viscosity variation causes virtually no difference in plume evolution and final size, but CO₂ density variation causes a large difference. Relative ultimate plume size is almost directly proportional to the relative difference in brine and CO₂ density (buoyancy flow). The majority of the difference in plume size occurs during and shortly after the cessation of injection.

© 2008 Elsevier B.V. All rights reserved.

Keywords: geologic carbon storage, pressure temperature sensitivity, buoyancy-driven flow.

Source: Greenhouse Gas Control Technologies (GHGT) conference, 16-20 November 2008

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    January, 2009

Wellbore integrity analysis of a natural CO₂ producer

Walter Crow, Brian Williams, J. William Carey, Michael Celia, Sarah Gasda

The long-term integrity of wellbores in a CO₂-rich environment is a complex function of material properties and reservoir conditions including brine and rock compositions, CO₂ pressure, and formation pressure and temperature gradients. Laboratory experiments can provide essential information on rates of material reaction with CO₂. However, field data are essential for assessing the integrated effect of these factors in subsurface conditions to provide a basis for validation of numerical models of wellbore behavior. We present a comprehensive study and conclusions from an investigation of a 30-year old well from a natural CO₂ production reservoir. The wellbore was exposed to a 96% CO₂ fluid from the time of cement placement. This site is unique for two reasons: it represents a higher, sustained concentration of CO₂ compared to enhanced oil recovery fields and the reservoir and caprocks are clastic materials that will possess less buffering capacity than carbonate reservoirs. A sampling program resulted in the recovery of 10 side-wall cement cores extending from the reservoir through the caprock. The hydrologic, mineralogical and mechanical properties of these samples have been measured and those results are combined with an in-situ pressure-response test to investigate cement integrity over larger length scales. Fluid sampling was conducted with pressure and temperature measurements for geochemical analysis of the cemented annulus and the adjacent formation. These combined data sets provide an assessment of well integrity including original cement seal and the impacts of CO₂. Cement evaluation wireline surveys indicate good coverage and bonding, consistent with observations from sidewall cement core samples that have tight interfaces with the casing and formation. Although alteration of the cement samples is present in all cores in varying degrees, hydraulic isolation has prevented leakage based on the pressure gradient measured between the caprock and CO₂ formation. Effective cement placement was a key element to create the performance of the barrier system. Simulation of test data indicates the best match for effective permeability of the barrier is 20 micro-darcies (μD) near the top of the caprock. The types of information collected in this survey permit analysis of individual components (casing, cement and reservoir fluid and pressure measurements) for comparison to the larger scale system including the interfaces. The results will be used as part of the CO₂ Capture Project’s effort to develop a long-term predictive simulation tool to assess wellbore integrity performance in CO₂ storage sites.

© 2008 Elsevier Ltd. All rights reserved.

Keywords: CO₂ Storage; well integrity; cement barrier; cement capillary pressure; effective permeability; vertical interference test; cement mineralogy.

Source: Greenhouse Gas Control Technologies (GHGT) conference, 16-20 November 2008

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    January, 2009

Wellbore flow model for carbon dioxide and brine

Lehua Pan, Curtis M. Oldenburg, Yu-Shu Wu, and Karsten Pruess

Wellbores have been identified as the most likely conduit for CO₂ and brine leakage from geologic carbon sequestration (GCS) sites, especially those in sedimentary basins with historical hydrocarbon production. In order to quantify the impacts of leakage of CO₂ and brine through wellbores, we have developed a wellbore simulator capable of describing non-isothermal open-well flow dynamics of CO₂-brine mixtures. The mass and thermal energy balance equations are solved numerically by a finite difference scheme with wellbore heat transmission handled semi-analytically. This new wellbore simulator can take as input the pressure, saturation, and composition conditions from reservoir simulators and calculate CO₂ and brine fluxes needed to assess impacts to vulnerable resources. This new capability is being incorporated into the Certification Framework (CF) developed for risk assessment of GCS sites.

© 2008 Elsevier Ltd. All rights reserved.

Keywords: Geologic carbon sequestration; Well leakage, Wellbore flow, Risk assessment.

Source: Greenhouse Gas Control Technologies (GHGT) conference, 16-20 November 2008

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    January, 2009

Case studies of the application of the Certification Framework to two geologic carbon sequestration sites

Curtis M. Oldenburg, Jean-Philippe Nicot, and Steven L. Bryant

We have developed a certification framework (CF) for certifying that the risks of geologic carbon sequestration (GCS) sites are below agreed-upon thresholds. The CF is based on effective trapping of CO₂, the proposed concept that takes into account both the probability and impact of CO₂ leakage. The CF uses probability estimates of the intersection of conductive faults and wells with the CO₂ plume along with modeled fluxes or concentrations of CO₂ as proxies for impacts to compartments (such as potable groundwater) to calculate CO₂ leakage risk. In order to test and refine the approach, we applied the CF to (1) a hypothetical large-scale GCS project in the Texas Gulf Coast, and (2) WESTCARB’s Phase III GCS pilot in the southern San Joaquin Valley, California.

© 2008 Elsevier Ltd. All rights reserved.

Keywords: Geologic carbon sequestration; Risk assessment; Leakage risk; Well leakage; Case studies.

Source: Greenhouse Gas Control Technologies (GHGT) conference, 16-20 November 2008

(1989 Kb)      View   Download

    May, 2008

The CO₂ Capture Project Phase 2 Storage Program: Progress in Geological Assurance

Dan Kieke, Scott Imbus, Chevron Energy Technology Co

Presented at the 7th Annual Conference on CO₂ Capture and Sequestration, Pittsburgh PA. Covers storage, moitoring and verificiation including certification framework, wellbore integrity field study, geochemical-geomechanical simulation, CO₂ ECBM operations and geophysical monitoring, and remote sensing.

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    June, 2007

Storing CO₂ Underground

IEA Greenhouse Gas R&D Programme

CO₂ capture and geological storage could contribute a significant part of the solution to the global warming problem. The required technology has been used by the oil and gas industry for many years - it is proven and available today. CCS could therefore play a significant role in helping to reduce CO2 emissions over the coming decades. However, CCS is a relatively new concept and therefore not specifically addressed by most laws and regulations (both globally and locally). Commercial organisations will invest in CCS projects when they are legal and financially viable. In order for CCS to be implemented on a widespread scale, work needs to be done soon to develop appropriate regulations and commercial frameworks for CCS.

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