Applicability of slug interference tests under Hanford Site test conditions: Analytical assessment and field test evaluation

Slug interference testing may be a useful technique for characterizing the hydraulic properties of high conductivity formations where problems associated with disposal of contaminated ground water make pumping tests undesirable. The suitability of the slug interference method for characterizing the unconfined aquifer at the Hanford Site was evaluated in a two-phase investigation. The first phase consisted of an analytical assessment. Slug interference responses were predicted over the range of conditions expected for the aquifer. The effects of partial penetration, delayed-yield and aquifer anisotropy on expected test results were also evaluated and possible analytical corrections are presented. The field test evaluation was conducted at a site with two observation wells and a stress well. Results verified the analytical evaluation and gave reasonable values of hydraulic conductivity and storativity. Test design considerations that optimize the observed response are discussed

The Wallula basalt sequestration pilot project

AbstractThe U.S. Department of Energy Big Sky Regional Carbon Sequestration Partnership completed drilling the world’s first continental flood basalt sequestration pilot borehole to a total depth (TD) of 1253 m at a paper mill site near the town of Wallula located in Southeastern Washington State. Site suitability was assessed prior to drilling by acquisition, processing and analysis of a four-mile, five-line, three component seismic swath, which was processed as a single data-dense line. Analysis of the seismic survey data indicated absence of major geologic structures that would preclude CO2 injection at the site. Drilling of Wallula pilot borehole was initiated on January 13, 2009 and reached TD on April 6, 2009. Hydrogeologic information was obtained primarily during borehole drilling/advancement utilizing a progressive drill-and-test characterization strategy. A general decreasing transmissivity trend with depth pattern was observed, which is consistent with results exhibited for Columbia River basalt interflow zones at a number of other deep wells in the region. Based on the comparative results from 10 test intervals, a candidate injection test zone was identified between the general depth interval of ∼828 and 875 m bgs. Over this interval, three brecciated interflow zones were intersected and isolated for CO2 injection. The flow tops have moderate permeability (75 to 150 millidarcies) and are bounded by thick flow interiors that have extremely low (microdarcy) permeability. The borehole configuration established at the Wallula pilot site provides a unique opportunity to scientifically study the reservoir behaviour of three connected reservoir intervals confined between primary and secondary caprock zones. The permitting process for the CO2 injection has proceeded in accordance with formal rules for geologic sequestration projects enacted in June 2008 into the underground injection control program administered by the Washington State Department of Ecology. The permitting process is expected to conclude in October 2010 and injection would begin soon thereafter. Post-injection monitoring includes long-term sampling of water retrieved from the injection zone, shallow groundwater and soil gas monitoring, and PSInSAR

Calculation of groundwater discharge to the Columbia River in the 100-N Area

A computer code called WATDIS (an acronym for water discharge) was developed that, when used with the commercially available software, WATER-VEL{trademark}, calculates the volumetric discharge to a specific cross-sectional area of the aquifer. This report describes the development of the WATDIS code and its application. The development of this code is Phase 1 of a two-phased project whose objective is to estimate the amounts of radionuclides reaching the Columbia River through the unconfined aquifer as a result of natural'' conditions