Ennetbaden, Switzerland
Ennetbaden, Switzerland

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Yamaguchi K.,Mitsubishi Group | Shimoda S.,Mitsubishi Group | Kato H.,Mitsubishi Group | Stenhouse M.J.,INTERA Incorporated | And 5 more authors.
Energy Procedia | Year: 2013

A hypothetical CO2 storage site that has some abandoned wells located near the injection well is considered. Generally, cement plugs are set to cover or isolate porous or productive formations and to isolate usable groundwater from hydrocarbons. When CO2 is injected into a reservoir, supercritical CO2 or dissolved CO2 spreads out in the reservoir. This dissolved CO2 can react chemically with cement seals (plugs and casing cement) in abandoned wells. As a result, minerals in the cement seals (plugs and casing cement) may alter to form other minerals or mineral phases. The first simulations concerning migration of supercritical CO2 and dissolved CO2 in a saline aquifer and a depleted gas field reservoir, were carried out using TOUGH2. The following temperatures and depths of reservoir were selected: 50 °C at E.L.-1,000 m, 60 °C at E.L.-1,500 m and 70 °C at E.L.-2,000 m. Secondly, geochemical reactions of cement seals (plugs and casing cement) were simulated. The results of reservoir simulations were used as boundary conditions for the geochemical calculation of cement seals. Geochemical simulation of the reactions yielded the extent (length) of alteration of cement seals (plugs and casing cement) after long time periods; for example, the alteration length of cement seals after 1,000 years was about one meter. This length is short enough so that the usable cement seals (plugs and casing cement) of abandoned well are able to continue to isolate CO2 in the reservoir from the upper aquifer.

Senger R.,INTERA Incorporated | Romero E.,Polytechnic University of Catalonia | Ferrari A.,Ecole Polytechnique Federale de Lausanne | Marschall P.,National Cooperative for the Disposal of Radioactive Waste
Geological Society Special Publication | Year: 2014

For the characterization of gas migration through a low-permeability clay host rock for deep underground repositories, a comprehensive understanding of the relevant phenomena of gas and fluid flow through low-permeability clay is required. The National Cooperative for the Disposal of Radioactive Waste (Nagra) in Switzerland has developed a comprehensive programme to characterize gas flow in low-permeability Opalinus Clay through laboratory tests and detailed numerical analyses for developing appropriate constitutive models. Laboratory tests were performed on cores by two different laboratories, the Laboratory for Soil Mechanics at EPFL and the Department of Geotechnical Engineering and Geosciences at UPC. Loading tests were performed by both laboratories to study rock compressibility at different stress levels and water permeability dependence on void ratio. The water retention behaviour demonstrated by EPFL and UPC produced comparable results. Water permeability tests and fast controlled-volume air injection experiments were performed in a triaxial cell under isotropic stress conditions on two samples with flow parallel and normal to the bedding planes. A confining stress of 15 MPa was applied during gas testing, corresponding to a lithostatic pressure at a depth of c. 600 m below ground. For detailed analyses, the two-phase flow code TOUGH2 (Pruess et al. 1999) was used. This considers fluid flow in both liquid and gas phases under the influence of pressure, viscous and gravity forces, according to Darcy's law. The standard analyses could not reproduce the measured pressure responses well, and the calibrated hydraulic and two-phase parameters were not consistent with the preceding water test and laboratory analyses. Implementing the non-linear behaviour in terms of the observed relationship between changes in void ratio and associated changes in permeability under different stress conditions significantly improved the simulated results, resulting in a conceptual model that well reproduced the observed injection pressure and outflow responses for both tests, parallel and normal to bedding, using a consistent parameter set. © The Geological Society of London 2014.

Lanyon G.W.,Fracture Systems Ltd. | Senger R.,INTERA Incorporated
Transport in Porous Media | Year: 2011

The generation, accumulation, and release of corrosion gases is an important issue in the assessment of long-term repository performance. For repository concepts in clay-rich rock formations such as the Opalinus Clay of Northern Switzerland the transport path through the Excavation Damage Zone (EDZ) around the emplacement tunnels is of particular interest because the gas transport capacity of the host rock is limited and therefore a significant fraction of the produced gas could be released along the EDZ. This article describes the development of a structured approach to abstract complex geoscientific models of two-phase flow through the EDZ to simplified models suitable for use within a Probabilistic Safety Assessment (PSA). The approach utilizes three different models: a discrete fracture network (DFN) model of the EDZ, an equivalent heterogeneous continuum porous medium (CPM) model and a simplified CPM model suitable for use within PSA. Equivalent properties of the elements of the heterogeneous CPM models are upscaled from DFN realizations. Results from gas injection simulations with the heterogeneous CPM models are then used to derive appropriate parameters for the simplified CPM model. The modeling presented in this article represents the first step in the development of a structured methodology for treatment of gas, solute, and water flow through the EDZ. The emphasis is on methodology development, and both input data and structural models used in this study are of a generic nature and would have to be adapted to the actual conditions at a real repository site. © 2011 Springer Science+Business Media B.V.

Jordan D.L.,INTERA Incorporated | Barroll P.,New Mexico Office of the State Engineer
Journal of the American Water Resources Association | Year: 2013

A time series of estimates of irrigated area was developed for the Lower Rio Grande valley (LRG) in New Mexico from the 1970s to present day. The objective of the project was to develop an independent, accurate, and scientifically justifiable evaluation of irrigated area in the region for the period spanning from the mid-1970s to the present. These area estimates were used in support of groundwater modeling of the LRG region, as well as for other analyses. This study used a remote-sensing-based methodology to evaluate overall irrigated area within the LRG. We applied a methodology that involved the normalization of vegetation indices derived from satellite imagery to get a more accurate estimation of irrigated area across multiple time periods and multiple Landsat platforms. The normalization allows more accurate evaluation of vegetation index data that span several decades. An accuracy assessment of the methodology and results from this study was performed using field-collected crop data from the 2008 growing season. The comparisons with field data indicate that the accuracy of the remote-sensing-based estimates of historical irrigated area is very good, with rates of false positives (areas identified as irrigated that are not truly irrigated) of only about 4%, and rates of false negatives (areas identified as not irrigated that are truly irrigated) in the range of 0.6-2.0%. © 2013 American Water Resources Association.

Kuszmaul J.S.,University of Mississippi | Gunter B.J.,University of Mississippi | Holt R.M.,University of Mississippi | Holtz T.,INTERA Incorporated | And 3 more authors.
Association of State Dam Safety Officials - Dam Safety 2010 Proceedings | Year: 2010

In response to the U.S. Department of Homeland's Security's identified need to inventory and assess the vulnerability of key resources, an ArcGIS-based tool, Water Resources Vulnerability Assessment Tool (WRVAT), has been developed to house a resource inventory and a vulnerability assessment of dams, surface waters, and groundwater resources of Mississippi. WRVAT separately assesses the intrinsic vulnerability (depends on the properties of the resource), extrinsic vulnerability (depends on external factors acting on the resource), and consequences of a failure. For dams, these factors were assessed using the Condition Indexing Method (CIM) that has been used in a range of regions to assess dam vulnerability. CIM was selected because it is well suited to modifications needed for application to large inventories of dams. In our case, CIM was adapted and applied within WRVAT for all applicable embankment dams of Mississippi. In a joint effort with the Mississippi Office of Dam Safety, our assessment method was applied to over 3000 embankment dams. The approach of the CIM was adapted to assess the intrinsic vulnerability of each dam, based on available information about each dam. Extrinsic vulnerability was assessed based on ownership, susceptibility to such factors as poor maintenance and previous record of beaver damage to each dam. Finally, consequences of a failure were estimated using available inundation maps included in Emergency Actions Plans (when available) or more commonly using a newly developed tool designed to provide a conservative estimate of the area potentially at risk of flooding due to the release of reservoir waters. This tool, Vulnerability Assessment Using Simplifying Assumptions (VADUS), was designed for GIS-based estimation of flooding due to sudden release (or failure) of a dam. The GIS database used for WRVAT contained multiple layers to represent population density, infrastructure, and major institutions (e.g., schools, hospitals, etc.). The resulting vulnerability assessments cover all of Mississippi, but excluded some of the larger dams where these simplified methods of analysis were not well suited. The final assessment tools are useful for application to a wide range of dams, where prioritizing is helpful in efficiently identifying the most critical needs.

Clemo T.,INTERA Incorporated | Ramarao B.S.,Intera Inc. | Kelly V.A.,Intera Inc. | Lavenue M.,Intera Inc.
World Environmental and Water Resources Congress 2012: Crossing Boundaries, Proceedings of the 2012 Congress | Year: 2012

A recent publication in Ground Water (Sept-Oct., 2010) highlighted the application of capture functions in the management of groundwater, subject to the constraints on the depletion of surface water supplies. Capture maps are used for optimal location of the pumping wells, their rates of withdrawals, and their timing. The computation of capture functions, in the cited paper, is based on perturbation approach with finite differences. An alternative computational strategy for capture functions, based on the adjoint states, is proposed here and is developed for MODFLOW, a groundwater flow simulator. The new methodology is implemented for one of the examples cited in the above paper, namely that of the San Pedro Model, with over 700,000 nodes, developed by the United States Geological Survey, and compared with their results for capture functions based on their perturbation approach. The comparison shows good agreement between the two methods. The proposed adjoint formulation just uses the same computational time, as for one simulation for the heads, and thus saves computational time, relative to the perturbation approach, by a factor equal to the number of nodes in the model, which is of the order of several hundreds of thousands. Because of its immense savings in computational times, this new strategy for the capture functions makes it feasible to embed the groundwater management problem in a stochastic framework (probabilistic approach) to address the uncertainties in the groundwater model. © 2012 ASCE.

Dompe P.E.,INTERA Incorporated | Gosselin M.S.,INTERA Incorporated | Sheppard D.M.,INTERA Incorporated
Ports 2016: Port Engineering - Papers from Sessions of the 14th Triennial International Conference | Year: 2016

Until recently, few methods existed in the literature for the application of wave loading on horizontal superstructures located in coastal regions. In fact, the U.S. Army Corps of Engineers Coastal Engineering Manual, or CEM (the industry standard for coastal construction), contains no methodologies for calculating loads on horizontal superstructures. Although significant effort has been devoted to the development of predictive equations for wave loads on vertical structures such as piles and seawalls, predictive equations for horizontal superstructures have been limited to offshore platforms in ocean wave conditions. Wave conditions in coastal waters can vary significantly from those in the ocean. Wave periods, and therefore wave lengths, in coastal waters are much shorter. Correspondingly, the ratio of the width of coastal superstructures to the wave length is much greater than those ratios encountered in the offshore environment. Thus, wave-induced water particle velocities and accelerations vary significantly over the width of the structure as compared with offshore structures. This results in corresponding variations in wave forces on the structure. Previous researchers presented a mathematical model applicable to structures in coastal environments. This paper reviews the development of that methodology and presents a case study as well as comparisons with other recently developed methodologies. © 2016 ASCE.

Dompe P.E.,INTERA Incorporated | McBee J.M.,INTERA Incorporated | Demir H.,INTERA Incorporated
World Environmental and Water Resources Congress 2015: Floods, Droughts, and Ecosystems - Proceedings of the 2015 World Environmental and Water Resources Congress | Year: 2015

High winds associated with hurricanes are capable of generating damaging storm surge and waves in both coastal and inland waterbodies posing risks to bridges spanning these waterbodies. Hurricanes Ivan (2004) and Katrina (2005) generated substantial loads that destroyed large portions of the superstructures of several major bridges. The total estimated repair and replacement cost for bridges damaged by Hurricane Katrina exceeded $1 billion. Additionally, traffic/route disruptions attributed to route detours until completion of repairs or replacement further adversely affected local economies. The Louisiana Department of Transportation and Development and the North Carolina Department of Transportation desired a current assessment of the potential vulnerability of their bridges to loading from hurricane generated surge and waves. As part of the assessment, a bridge was categorized as vulnerable when the surge/wave forces or moments exceed the resistive forces and moments (based solely on the span dead weight) on one or more spans. Assessment of structure vulnerability consisted of several phases. The first phase involved examination of the department of transportation databases for the location of all bridges crossing waterways. Aerial photography, U.S. Geological Survey quadrangle maps, and FEMA flood maps provided the means to identify which bridges are protected by limited wave fetches, extensive vegetation canopies (limiting wave growth), and low surge elevations. These bridges were removed from further consideration. The next phase included the development of detailed storm surge and wave model (SWAN+ADCIRC) meshes to adequately resolve remaining potentially-vulnerable bridges' locations. These models simulated all historic hurricanes passing within 50 nautical miles of any bridge within the states. A statistical analysis of the water surface elevation and significant wave height results incorporating each simulation yielded 100-year return period conditions across the entire model domain, including each bridge location. Finally, the ratio of the storm surge and wave forces or moments (along with a load factor) computed via the AASHTO Guide Specifications for Bridges Vulnerable to Coastal Storms to the dead weight of bridge spans determined the vulnerability of each coastal bridge. In Louisiana, 17 of the 100 initially considered bridges proved vulnerable. In North Carolina, 105 of the 222 initially considered bridges proved vulnerable. Accurate determination of coastal storm surge and wave conditions and vulnerabilities of coastal infrastructure leads to targeted retrofitting and replacement priorities. © 2015 ASCE.

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