Analytical solution for Joule–Thomson cooling during CO2 geo-sequestration in depleted oil and gas reservoirs

Mathematical tools are needed to screen out sites where Joule–Thomson cooling is a prohibitive factor for CO₂ geo-sequestration and to design approaches to mitigate the effect. In this paper, a simple analytical solution is developed by invoking steady-state flow and constant thermophysical properties. The analytical solution allows fast evaluation of spatiotemporal temperature fields, resulting from constant-rate CO₂ injection. The applicability of the analytical solution is demonstrated by comparison with non-isothermal simulation results from the reservoir simulator TOUGH2. Analysis confirms that for an injection rate of 3 kg s^?1 (0.1 MT yr^?1) into moderately warm (>40 °C) and permeable formations (>10^?14 m² (10 mD)), JTC is unlikely to be a problem for initial reservoir pressures as low as 2 MPa (290 psi).     

Land Use,Geology, Enrichment,and Stream Biota in the Eastern Ridge and Valley Ecoregion: Implications for Nutrient Criteria Development1

Abstract: The eastern panhandle region of West Virginia is entirely within the Appalachian Ridge and Valley ecoregion. It is underlain by limestone in the eastern part and by shale and sandstone in the western part. Agricultural and urban development has affected the condition of the streams of this region. We examined samples from 165 stations in the Ridge and Valley, collected from 1998 to 2004. Land use, geological characteristics, physical and chemical parameters, and algal and macroinvertebrate assemblages were used to identify potential stressors that affect streams in the region. Our analyses indicated that both human land uses and ecoregional differences led to elevated nutrient concentrations in streams of the study areas. Multiple regression analyses indicated that both agricultural and urban land use in the watershed were associated with high nutrient concentrations (NO₂₊₃, total nitrogen, and total phosphorus) in streams. These elevated nutrient concentrations have led to increased algal biomass, increased trophic state, and degradation of macroinvertebrate community in the streams. Values of the West Virginia Stream Condition Index, as well as several other benthic macroinvertebrate metrics, decreased with increased nutrient concentrations and conductivity, especially in the limestone region. When regional differences were partitioned out in the analysis, nutrient concentrations became the strongest stressor in the limestone region while conductivity exhibited less of an effect on macroinvertebrate metrics. Meanwhile, periphyton diagnostic metrics also responded to increased nutrient concentrations, suggesting nutrients could be a cause of biological degradation in the Eastern Ridge and Valley region. Multiple approaches and multiple lines of evidence (reference approach and stressor‐response approach) were applied to develop nutrient benchmarks for different geological regions in the study watershed.     

Crosslinking and stabilization of high fractional free volume polymers for gas separation

Crosslinkable poly(4-methyl-2-pentyne) (PMP) membranes were cast from carbon tetrachloride solutions containing PMP and either 4,4′-diazidobenzophenone or 4,4′-(hexafluoroisopropylidene)diphenyl azide. The composite membranes were transparent and homogeneous and were crosslinked by UV irradiation at room temperature or thermal treatment at 180 °C. Low levels of the bis(aryl azide) (1–4.5 wt%) were effective in rendering the membranes insoluble in cyclohexane and carbon tetrachloride, both are good solvents for PMP, thus PMP can easily be converted to mechanically stable membranes with permeabilities and selectivities comparable or higher than those of the well-known poly(dimethylsiloxane) (PDMS). The permeabilities of O₂, N₂, H₂, CH₄ and CO₂ were measured. Compared to pure PMP, the crosslinked membranes containing bis(aryl azide) had lower permeabilities and higher selectivities, consistent with a reduction in free volume.     

Biomonitoring of airborne mercury with perennial ryegrass cultures

A biomonitoring network with grass cultures was established near a chlor-alkali plant and the mercury concentration in the cultures were compared with the average atmospheric total gaseous mercury (TGM). Biomonitoring techniques based on different exposure periods were carried out. When comparing the mercury concentration in the grass cultures, both the average atmospheric TGM concentration during exposure and the exposure time determined to a large extent the accumulation rate of TGM. The maximum tolerable level of mercury in grass (approximately equal to 110 microg kg(-1) DM) corresponds with an average TGM concentration of 11 ng m(-3) for 28 days exposure. The background concentrations in grass were on an average 15 microg kg(-1) DM and the effect detection limit (EDL) was 30 microg kg(-1) DM. This value corresponds with an average TGM concentration of 3.2 and 4.2 ng m(-3) for 28 and 14 days exposure, respectively, which is in turn the biological detection limit (BDL) of ambient TGM. Exposures for 7 days were less appropriate for biomonitoring.     

Safety culture aboard fishing vessels

Safety at sea is a serious issue for the commercial fishing industry. Injury and fatality rates are between 25 and 40 times the national average in many European counties, Australia and the USA. A 50-item safety culture questionnaire was developed, using items from published research combined with some original items. The questionnaire was distributed to fishermen who completed the responses. A total of 209 questionnaires were collected. Principal Component Analysis (PCA) revealed nine factors, all with a Cronbach’s Alpha higher than 0.68. The factors were tested using ANOVA, t-tests, correlations and regression analysis.The findings indicate significant differences between age groups, vessel types, occupations, and whether or not a close family member is a fisherman. It was also found that the safety attitude of management had a strong influence on a company’s safety policy. Fishermen who had sought medical attention during the preceding year as a result of an accident showed a significantly less positive attitude to rules and regulations and had a less positive safety attitude in general. Fishermen who had been involved in a serious accident/incident showed a significantly more positive attitude to rules and regulations.     

Community-based energy policy: A practical approach to carbon reduction

Whilst the existence of global climate change is no longer seriously contested and most governments are seeking to adopt appropriate responses, the rate of engagement with these measures is slow. Top-down policies and reliance on market mechanisms are failing to produce the reductions in energy demand and shifts away from fossil fuel reliance that are required. This paper outlines an example of a research programme that seeks to deliver more rapid change. It focuses on the potential for carbon emission reduction in a deprived community in South Yorkshire, UK, and reports on an approach that could be replicated elsewhere. The method includes estimation of baseline energy demand, energy efficiency potential and renewable energy resource assessment as a precursor to action. An innovative community-based energy service company is described and the benefits of a community-based bottom-up approach to carbon reduction are outlined.     

Hydrology and Water Budget for a Forested Atlantic Coastal Plain Watershed,South Carolina1

Abstract: Increases in timber demand and urban development in the Atlantic Coastal Plain over the past decade have motivated studies on the hydrology, water quality, and sustainable management of coastal plain watersheds. However, studies on baseline water budgets are limited for the low‐lying, forested watersheds of the Atlantic Coastal Plain. The purpose of this study was to document the hydrology and a method to quantify the water budget of a first‐order forested watershed, WS80, located within the USDA Forest Service Santee Experimental Forest northeast of Charleston, South Carolina. Annual Rainfall for the 2003 and 2004 periods were 1,671 mm (300 mm above normal) and 962 mm (over 400 mm below normal), respectively. Runoff coefficients (outflow as a fraction of total rainfall) for the 2003 and 2004 periods were 0.47 and 0.08, respectively, indicating a wide variability of outflows as affected by antecedent conditions. A spreadsheet‐based Thornthwaite monthly water balance model was tested on WS80 using three different potential evapotranspiration estimators [Hamon, Thornthwaite, and Penman‐Monteith (P‐M)]. The Hamon and P‐M‐based methods performed reasonably well with average absolute monthly deviations of 12.6 and 13.9 mm, respectively, between the measured and predicted outflows. Estimated closure errors were all within 9% for the 2003, 2004, and seasonal water budgets. These results may have implications on forest management practices and provide necessary baseline or reference information for Atlantic Coastal Plain watersheds.