Insights into Cold Water Injection Stimulation Effects through Analytical Solutions to Flow and Heat Transport

Wells in traditional hydrothermal reservoirs are used to extract heat and to dispose of cooled water. In the first case, high productivity (the ratio of production flow rate to the pressure differential required to produce that rate) to is preferred in order to maximize power generation, while minimizing the parasitic energy loss of pumping. In the second case, high injectivity (the ratio of injection flow rate to the pressure differential required to produce that rate) is preferred, in order to reduce pumping costs. In order to improve productivity or injectivity, cold water is sometimes injected into the reservoir in an attempt to cool and contract the surrounding rock matrix and thereby induce dilation and/or extension of existing fractures or to generate new fractures. Though the increases in permeability associated with these changes are likely localized, by improving connectivity to more extensive high-permeability fractures they can at least temporarily provide substantially improved productivity or injectivity

Final Report - Assessment of Testing Options for the NTR at the INL

One of the main technologies that can be developed to dramatically enhance the human exploration of space is the nuclear thermal rocket (NTR). Several studies over the past thirty years have shown that the NTR can reduce the cost of a lunar outpost, reduce the risk of a human mission to Mars, enable fast transits for most missions throughout the solar system, and reduce the cost and time for robotic probes to deep space. Three separate committees of the National Research Council of the National Academy of Sciences have recommended that NASA develop the NTR. One of the primary issues in development of the NTR is the ability to verify a flight ready unit. Three main methods can be used to validate safe operation of a NTR: 1) Full power, full duration test in an above ground facility that scrubs the rocket exhaust clean of any fission products; 2) Full power , full duration test using the Subsurface Active Filtering of Exhaust (SAFE) technique to capture the exhaust in subsurface strata; 3) Test of the reactor fuel at temperature and power density in a driver reactor with subsequent first test of the fully integrated NTR in space. The first method, the above ground facility, has been studied in the past. The second method, SAFE, has been examined for application at the Nevada Test Site. The third method relies on the fact that the Nuclear Furnace series of tests in 1971 showed that the radioactive exhaust coming from graphite based fuel for the NTR could be completely scrubbed of fission products and the clean hydrogen flared into the atmosphere. Under funding from the MSFC, the Center for Space Nuclear Research (CSNR) at the Idaho National laboratory (INL) has completed a reexamination of Methods 2 and 3 for implementation at the INL site. In short, the effort performed the following: 1) Assess the geology of the INL site and determine a location suitable SAFE testing; 2) Perform calculations of gas transport throughout the geology; 3) Produce a cost estimate of a non-nuclear , sub-scale test using gas injection to validate the computational models; 4) Produce a preliminary cost estimate to build a nuclear furnace equivalent facility to test NTR fuel on a green field location on the INL site. The results show that the INL geology is substantially better suited to the SAFE testing method than the NTS site. The existence of impermeable interbeds just above the sub-surface aquifer ensure that no material from the test, radioactive or not, can enter the water table. Similar beds located just below the surface will prevent any gaseous products from reaching the surface for dispersion. The extremely high permeability of the strata between the interbeds allows rapid dispersion of the rocket exhaust. In addition, the high permeability suggests that a lower back-pressure may develop in the hole against the rocket thrust, which increases safety of operations. Finally, the cost of performing a sub-scale, non-nuclear verification experiment was determined to be $3M. The third method was assessed through discussions with INL staff resident at the site. In essence, any new Category I facility on any DOE site will cost in excess of$250M. Based on the results of this study, a cost estimate for testing a nuclear rocket at the INL site appears to be warranted. Given the fact that a new nuclear fuel may be possible that does not release any fission products, the SAFE testing option appears to be the most affordable

Laparoscopic colectomy for colonic neoplasms in a developing country

AbstractAimTo report the outcome of patients treated for colonic neoplasms using a laparoscopic assisted technique since its introduction at the University Hospital of the West Indies, Jamaica.Subjects and MethodsAll consecutive patients undergoing laparoscopic assisted colectomy were entered into a prospective database and this data analysed. Data collected included patient demographics, pre-operative diagnosis, operative events, post-operative morbidity and outcome.ResultsOver the thirty-six months period July 1, 2005–December 31, 2005 and July 1, 2006–December 31, 2008, thirty patients each underwent laparoscopic assisted colectomy for a colonic neoplasm. Their mean age was 63 years with M: F ratio of 1:2. Seventy-four per cent of the patients had carcinomas which was located on the right and sigmoid colon in 17 and 10 patients respectively. Mean operative time was 98 min for patients with right-sided lesions and blood loss for the entire group was minimal. Two patients were converted to open resections. Median duration of hospitalization was five days. There was no mortality but three patients had complications. After median follow-up of 30 months, there was no local or systemic recurrence.ConclusionsAppropriately selected patients with colonic neoplasms can be safely subjected to a laparoscopic assisted resection and expect to enjoy the advantages of this technique even in a developing country setting.The outcome of thirty consecutive laparoscopic assisted colectomies is reported demonstrating that this technique can be safely applied to selected patients with colonic carcinomas in developing countries

Hand ischemia associated with elbow trauma in children

ObjectivesPrevious observational studies suggest that children with hand ischemia following elbow trauma can be safely observed if Doppler signals are present in the wrist arteries (pink pulseless hand, PPH). Nonoperative management of PPH is predicated on the assumption that PPH results from local arterial spasm, but the mechanism of arterial compromise has not been investigated. We hypothesized that PPH signifies a brachial artery injury that requires surgical repair.MethodsRetrospective review of operations performed on children with hand ischemia following elbow trauma at a level I trauma center pediatric hospital.ResultsBetween 2003 and 2010, 12 children (seven males, mean age 7.4 years) underwent brachial artery exploration for hand ischemia following elbow trauma (11 supracondylar fractures, one elbow dislocation) due to falls (n = 10) or motor vehicle crashes (n = 2). At presentation, three subjects had normal radial pulses, eight subjects had Doppler signals but no palpable pulses, and one had weak Doppler flow with advanced hand ischemia. Six of the nine subjects without palpable pulses also had neurosensory changes. All 12 subjects underwent brachial artery exploration either initially (n = 2) or following orthopedic fixation (n = 10) due to persistent pulselessness. At operation, eight of 12 patients (67%) had focal brachial artery thrombosis due to intimal flaps, and four had brachial artery and median nerve entrapment within the pinned fracture site. At discharge, all 12 subjects had palpable radial pulses, but three with entrapment had dense median nerve deficits. One of the three subjects with dense neurologic deficit had complete recovery of neurologic function at ten months. The other two subjects had residual median nerve deficits with partial recovery at 5 and 6 months follow-up, respectively. No patient developed Volkman's contracture.ConclusionsBrachial artery injuries should be anticipated in children with hand ischemia associated with elbow trauma. Neurovascular entrapment at the fracture site is a possible complication of orthopedic fixation. Absence of palpable wrist pulses after orthopedic fixation should prompt immediate brachial artery exploration. PPH should not be considered a consequence of arterial spasm in these patients

Late Quaternary glacier sensitivity to temperature and precipitation distribution in the Southern Alps of New Zealand

Glaciers respond to climate variations and leave geomorphic evidence that represents an important terrestrial paleoclimate record. However, the accuracy of paleoclimate reconstructions from glacial geology is limited by the challenge of representing mountain meteorology in numerical models. Precipitation is usually treated in a simple manner and yet represents difficult-to-characterize variables such as amount, distribution, and phase. Furthermore, precipitation distributions during a glacial probably differed from present-day interglacial patterns. We applied two models to investigate glacier sensitivity to temperature and precipitation in the eastern Southern Alps of New Zealand. A 2-D model was used to quantify variations in the length of the reconstructed glaciers resulting from plausible precipitation distributions compared to variations in length resulting from change in mean annual air temperature and precipitation amount. A 1-D model was used to quantify variations in length resulting from interannual climate variability. Assuming that present-day interglacial values represent precipitation distributions during the last glacial, a range of plausible present-day precipitation distributions resulted in uncertainty in the Last Glacial Maximum length of the Pukaki Glacier of 17.1 km (24%) and the Rakaia Glacier of 9.3 km (25%), corresponding to a 0.5°C difference in temperature. Smaller changes in glacier length resulted from a 50% decrease in precipitation amount from present-day values (−14% and −18%) and from a 50% increase in precipitation amount (5% and 9%). Our results demonstrate that precipitation distribution can produce considerable variation in simulated glacier extents and that reconstructions of paleoglaciers should include this uncertainty

Resilience in a Watershed Governance Context: A Primer

Watersheds are complex systems involving social, economic, and ecological dimensions that are constantly interacting and influencing each other, and governance of these systems involve a large and diverse cast of actors that add to the complexity and difficulty in deciding what is best for the watershed and people. Resilience thinking offers a way to understand and navigate the uncertainty, dynamics and complexity of watershed governance. This primer describes key ideas associated with resilience: more inclusive participation; building a shared understanding; inclusion of ecosystem services and functions in long-term planning; strong leadership; institutional and decision making flexibility; and, a decentralized system. This primer is an initial effort to translate the scholarly understanding of these key ideas and initiate a dialogue about their application in the context of watershed governance.Social Sciences and Humanities Research Council of Canada through the Water Economicsw, Policy and Governance Network Social Sciences and Humanities Research Council Insight Development Gran

Multiphase Carbon-14 Transport in a Near-Field-Scale Unsaturated Column of Natural Sediments

Wastes buried at the Subsurface Disposal Area (SDA) of the Idaho National Engineering and Environmental Laboratory include activated metals that release radioactive carbon-14 (14C) as they corrode. To better understand 14C phase partitioning and transport in the SDA sediments, we conducted a series of transport experiments using 14C (radio-labeled sodium carbonate) and nonreactive gas (sulfur hexafluoride) and aqueous (bromide and tritiated water) tracers in a large (2.6-m high by 0.9-m diameter) column of sediments similar to those used as cover material at the SDA. We established steady-state unsaturated flow prior to injecting tracers into the column. Tracer migration was monitored using pore-water and pore-gas samples taken from co-located suction lysimeters and gas ports inserted at ~0.3-m intervals along the column’s length. Measurements of 14C discharged from the sediment to the atmosphere (i.e., 14CO2 flux) indicate a positive correlation between CO2 partial pressure (pCO2) in the column and changes in 14CO2 flux. Though 14CO2 diffusion is expected to be independent of pCO2, changes of pCO2 affect pore water chemistry sufficiently to affect aqueous/gas phase 14C partitioning and consequently 14C2 flux. Pore-water and -gas 14C activity measurements provide an average aqueous/gas partitioning ratio, Kag, of 4.5 (±0.3). This value is consistent with that calculated using standard carbonate equilibrium expressions with measured pH, suggesting the ability to estimate Kag from carbonate equilibrium. One year after the 14C injection, the column was cored and solid-phase 14C activity was measured. The average aqueous/solid partition coefficient, Kd, (1.6 L kg-1) was consistent with those derived from small-scale and short-term batch and column experiments using SDA sediments, suggesting that bench-scale measurements are a valid means of estimating aqueous/solid partitioning at the much larger spatial scale considered in these meso-scale experiments. However, limitations at the bench scale prevent observation of spatially- and temporally-varying parameters that affect contaminant transport in the natural environment. In addition to a temporally-variable 14CO2 flux, in response to changes of pCO2, we observed non-uniformities in Kag and Kd that were not observed in bench-scale studies. Our results suggest that 14C transport is effectively controlled by gas diffusion with minimal retardation by partitioning onto the solid phase, and little long-term retention. The implication for the SDA is that 14C released via corrosion of activated metals is primarily transported by gas-phase diffusion rather than by liquid-phase advection. Calculations show that, because the atmospheric boundary is so much closer than the aquifer boundary at the SDA, most of the 14C will diffuse upward to the atmosphere

Loss of TaIRX9b gene function in wheat decreases chain length and amount of arabinoxylan in grain but increases cross-linking

Wheat contains abundant xylan in cell walls of all tissues, but in endosperm there is an unusual form of xylan substituted only by arabinose (arabinoxylan; AX) that has long chains and low levels of feruloylation, a fraction of which is extractable in water (WE-AX). WE-AX acts as soluble dietary fibre but also gives rise to viscous extracts from grain, a detrimental trait for some non-food uses of wheat. Here we show that a glycosyl transferase family 43 wheat gene abundantly expressed in endosperm complements the Arabidopsis irx9 mutant and so name the three homoeologous genes TaIRX9b. We generated wheat lines with a constitutive knock-out of TaIRX9b by stacking loss-of-function alleles for these homeologues from a mutagenized hexaploid wheat population resulting in decreases in grain extract viscosity of 50-80%. The amount and chain length of WE-AX molecules from grain of these triple stack lines was decreased accounting for the changes in extract viscosity. Imaging of immature wheat grain sections of triple stacks showed abolition of immunolabelling in endosperm with LM11 antibody that recognises epitopes in AX, but also showed apparently normal cell size and shape in all cell types, including endosperm. We identified differentially expressed genes from endosperm of triple stacks suggesting that compensatory changes occur to maintain this endosperm cell wall integrity. Consistent with this, we observed increased ferulate dimerisation and increased cross-linking of WE-AX molecules in triple stacks. These novel wheat lines lacking functional TaIRX9b therefore provide insight into control of wheat endosperm cell walls

Solution Geochemistry of the Water of Limestone Terrains

Limestone groundwater flows mainly in openings it has solutionally enlarged, thus an understanding of the water\u27s state of saturation relative to calcite (the principal mineral component of limestone) is fundamental to an understanding of the nature and evolution of the limestone aquifer. This study investigated the Mammoth Cave-Sinkhole Plain (MCSP) and Cave Hollow (CH) aquifers in Kentucky, both in Missippian limestones. Both aquifers were always undersaturated with calcite. Except for completely ventilated vadose flows (usually) and some vadose seepage (occasionally), all recharges sampled (sinking streams, vadose flows, and vadose seepage) were also undersaturated. The lack of saturation in the MCSP aquifer was due to the introduction of carbon dioxide into the water in amounts difficult to explain by the carbon dioxide content of the above recharges. In both vadose flows and seepage, undersaturatlon tended to correlate directly with flow volume, and there was an inverse correlation between the amount of carbon dioxide and calcite saturation in most of the waters sampled. In vadose seepage this relationship was so strong as to suggest seasonal invariance of carbon dioxide content of the water prior to out gassing. Results suggest solutional enlargement is greatest near recharge points in ventilated aquifers (CH) but the carbon dioxide introduction phenomenon (MCSP) allows solution over wide areas in unventilated aquifers