Sandstone distribution and potential for geopressured geothermal energy production in the Vicksburg formation along the Texas gulf coast

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Geothermal Resources, Vicksburg Formation, Texas Gulf Coast

The potential for discovering geopressured geothermal reservoirs in the Vicksburg Formation is limited to Hidalgo County along the Lower Texas Gulf Coast. In Hidalgo County, an area of approximately 385 square miles (designated the Vicksburg Fairway) contains up to 1,300 feet of geopressured sandstones with fluid temperatures greater than 300°F. In-place effective permeability, however, averages less than 1 millidarcy in the Vicksburg sandstones because of fine grain size and extensive late carbonate cementation. Also, the areal extent of individual reservoirs is limited in a dip direction by growth faults and in a strike direction by the lenticular morphology of the sandstone bodies. In conclusion, under the present specifications set for a geothermal fairway, the Vicksburg has minimal potential because of low reservoir deliverability, which is constrained by low permeability and somewhat limited reservoir continuity. If future tests indicate that lower permeabilities are acceptable, the Vicksburg Fairway should be reconsidered because of the presence of extremely thick sandstone bodies.Bureau of Economic Geolog

Effect of Hydrocarbon Production and Depressurization on Subsidence and Possible Fault Reactivation: Port Acres-Port Arthur Field Area, Southeast, Texas

Subsidence has been extensive in the coastal area of southeast Texas. Despite enormous hydrocarbon production in the area, however, most subsidence has been attributed more to regional shallow groundwater withdrawal than to hydrocarbon production. The impact of hydrocarbon production on subsidence can be accurately quantified only where the effects of groundwater withdrawal are minimal. The Port Acres and Port Arthur field area satisfies this requirement. More than 380 Bcf of gas has been produced from the Port Acres and Port Arthur field area. Pressure in the Hackberry reservoir declined from an original 9,000 psi to less than 3,000 psi by the 1970s, then to less than 2,000 psi by the 1980s. The pressure drop from 9,000 to 1,000 psi could produce a maximum subsidence of 6 percent at reservoir depth. Assuming an average gas column of 50 to 120 ft, estimated compaction of the Hackberry reservoir is 2 to 5 ft (0.61 to 1.63 m), which is consistent with reported surface subsidence.Bureau of Economic Geolog

Geopressured Geothermal Fairway Evaluation and Test Well Site Location Frio Formation, Texas Gulf Coast

Tertiary strata of the Texas Gulf Coast comprise a number of terrigenous depositional wedges, some of which thicken abruptly at their downdip ends as a result of contemporaneous movement of growth faults and underlying salt. The Frio Formation, one of these wedges, has been studied regionally by means of a grid of correlation cross sections aided by micropaleontological control. By means of these sections, the Frio was subdivided into six map units; maps of sandstone distribution within these units delineate principal elongate sandstone trends parallel to the Gulf Coast composed of deltaic, barrier-bar, and strandplain sandstones. These broad regional studies, followed by detailed local investigations, were pursued in order to delineate prospective areas for the production of geopressured geothermal energy. A prospective area must meet the following minimum requirements: reservoir volume of 3 cubic miles, minimum permeability of 20 millidarcys (md), and fluid temperatures of 300°F. Several geothermal fairways were identified as a result of this Frio study.Bureau of Economic Geolog

Sandstone Consolidation Analysis to Delineate Areas of High Quality Reservoirs Suitable for Production of GeoPressured Geothermal Energy Along the Texas Gulf Coast

Analysis of reservoir quality of lower Tertiary sandstones along the Texas Gulf Coast delineatesareas most favorable for geopressured geothermal exploration. Reservoir quality is determined by whole core, acoustic log, and petrographic analyses. Wilcox sandstones exhibit no regional reservoir quality trends. In the Lower and parts of the Middle and Upper Texas Gulf Coast, the sandstones are relatively well consolidated, but in other parts of the Middle and Upper Texas Gulf Coast, they show a reversal toward increased porosity at depth. Vicksburg sandstones have the poorest reservoir quality of sandstones of any formation prospective for geothermal energy. Frio sandstones show a systematic increase in reservoir quality from the Lower to the Upper Texas Gulf Coast. This increase in reservoir quality correlates to changes in rock composition and cementation. Acoustic log analysis substantiates a progression of greater consolidation from the Upper to the Lower Texas Gulf Coast. Wilcox sandstones are poorly to moderately sorted, fine-grained, quartzose lithic arkoses, becoming more quartz-rich from the Upper to the Lower Texas Gulf Coast. Most rock fragments are metamorphic and volcanic. Vicksburg sandstones are poorly sorted, fine-grained lithic arkoses. Rock fragments are mainly volcanic clasts with lesser carbonate and minor metamorphic clasts. Frio sandstones range from poorly sorted, fine-grained, feldspathic litharenites to lithic arkoses in the Lower Texas Gulf Coast to poorly sorted, fine-grained, quartzose lithic arkoses to subarkoses in the Upper Texas Gulf Coast. Volcanic rock fragments predominate in all areas; carbonate rock fragments are common in the Lower Texas Gulf Coast.Bureau of Economic Geolog

Evidence-Based Professional Development of Science Teachers in Two Countries

The focus of this collaborative research project of King?s College London, and the Weizmann Institute, Israel. project is on investigating the ways in which teachers can demonstrate accomplished teaching in a specific domain of science and on the teacher learning that is generated through continuing professional development programs (CPD) that lead towards such practice. The interest lies in what processes and inputs are required to help secondary school science teachers develop expertise in a specific aspect of science teaching. `It focuses on the design of the CPD programmes and examines the importance of an evidence-based approach through portfolioconstruction in which professional dialogue pathes the way for teacher learning. The set of papers highlight the need to set professional challenge while tailoring CPD to teachers? needs to create the environment in which teachers can advance and transform their practice. The cross-culture perspective added to the richness of the development and enabled the researchers to examine which aspects were fundamental to the design by considering similarities and differences between the domains

Healthier prisons: The role of a prison visitors' centre

Since the inception of the prison as a ‘setting’ for health promotion, there has been a focus on how the health of those men and women who spend ‘time inside’ can at least be maintained and if possible, enhanced, during their prison sentence. This paper presents findings from a mainly qualitative evaluation of a prison visitors' centre in the UK. It reports experiences of prisoners' families, prisoners, prison staff, the local community and the ways in which the visitors' centre has contributed positively to their health and well-being. In addition, key stakeholders were interviewed to ascertain the role this visitors' centre has in policy frameworks related to re-offending. The findings from this evaluation underscore how the visitors' centre improved the quality of visits, and contributed towards the maintenance of family ties through the help and support it provides for families and prisoners. The paper concludes by suggesting that visitors' centres are an essential part of a modern prison service helping to address the government's health inequalities agenda

Professional decision making and women offenders : containing the chaos?

This article draws on the findings from research undertaken in south-east Scotland in 2008 which sought to identify the characteristics of female offenders and to document the views of policy makers and practitioners regarding the experiences of women involved in the Scottish criminal justice system. Despite Scotland having retained a stronger 'welfare' focus than elsewhere in the UK (e.g. McAra, 2008), this is not reflected in the treatment of women who offend, with the rate of female imprisonment having almost doubled in the last ten years and community based disposals falling short of a welfare-oriented system. This article explores why the treatment that women offenders receive in the criminal justice system may be harsh and disproportionate both in relation to their offending and in relation to the treatment of men. It is argued that interventions with women need to be initiated earlier in their cycle of offending and at an earlier stage in the criminal justice process but also that the wide-ranging health, welfare, financial and behavioural needs of women who offend cannot be met solely within an increasingly risk-averse and punitive criminal justice environment

Fermi Surface as the Driving Mechanism for Helical Antiferromagnetic Ordering in Gd-Y Alloys

The first direct experimental evidence for the Fermi surface (FS) driving the helical antiferromagnetic ordering in a gadolinium-yttrium alloy is reported. The presence of a FS sheet capable of nesting is revealed, and the nesting vector associated with the sheet is found to be in excellent agreement with the periodicity of the helical ordering.Comment: 4 pages, 4 figure

Learning to Teach Argumentation: Research and development in the science classroom

The research reported in this study focuses on an investigation into the teaching of argumentation in secondary science classrooms. Over a one-year period, a group of 12 teachers from schools in the greater London area attended a series of workshops to develop materials and strategies to support the teaching of argumentation in scientific contexts. Data were collected at the beginning and end of the year by audio and video recording lessons where the teachers attempted to implement argumentation. To assess the quality of argumentation, analytical tools derived from Toulmin's argument pattern (TAP) were developed and applied to classroom transcripts. Analysis shows there was development in teachers' use of argumentation across the year. Results indicate that the pattern of use of argumentation is teacher-specific, as is the nature of change. To inform future professional development programmes, transcripts of five teachers, three showing a significant change and two no change, were analysed in more detail to identify features of teachers' oral contributions that facilitated and supported argumentation. The analysis showed that all teachers attempted to encourage a variety of processes involved in argumentation and that the teachers whose lessons included the highest quality of argumentation (TAP analysis) also encouraged higher order processes in their teaching. The analysis of teachers' facilitation of argumentation has helped to guide the development of in-service materials and to identify the barriers to learning in the professional development of less experienced teachers