bluuebunny/crossref_metadata_2025_split huggingface dataset:
Environmental impacts of coal mining and associated wastes: a geochemical perspective
Authors: Younger Paul L. 
Published: April 2008

Abstract
Ever since the commencement of industrial-scale coal mining (in northeast England around 1600), substantial environmental impacts have been recorded as arising from both the mined voids and from the wastes left behind at the surface. In the early days of coal mining, complaints about such impacts were strident, as the newly established industry adversely affected long-established agricultural interests. When the coal trade had come to dominate regional economies in mining districts, its negative impacts came to be accepted as a necessary byproduct of the generation of coal-based wealth. It has only been since large-scale mine closures began to take place in the major coal-mining economies of the developed world during the last few decades that the negative impacts of coal mining have once more been deemed unacceptable. The environmental impacts arising from coal mining activities are fundamentally attributable to the exposure of reduced earth materials (especially coal, pyrite, siderite, and ankerite) to the oxidizing power of the Earth’s atmosphere. The consequences range from the spontaneous combustion of coal to the release of acidic waters from pyrite oxidation. A typology of the known impacts arising from mine voids and wastes in coal mining districts has been developed, which recognizes many subcategories of impacts under five major headings: air pollution, fire hazards, ground deformation, water pollution, and water resource depletion. A robust understanding of geochemical processes is key to understanding how these impacts arise, and to developing sustainable mitigation strategies. The application of the newly developed typology is illustrated using the case of the Shilbottle Coalfield (Northumberland, UK). Although few demonstrable impacts have arisen in the categories of air pollution, fire hazards, or ground deformation, major problems of water pollution have required both preventative and remedial interventions. For the flooded underground voids, these took the form of a pump-and-treat system, whereas emissions of leachates from surface spoil heaps have necessitated the installation of an innovative ‘hybrid’ passive treatment system, comprising a permeable reactive barrier, oxidation ponds, and a wetland. Inverse geochemical modelling has clarified the linkages between the various types of water encountered in the coalfield, providing a baseline geochemical understanding upon which future investigations of remedial system sustainability can be based.
Waste heat problems and solutions in geothermal energy
Authors: Rybach Ladislaus , Kohl Thomas 
Published: April 2008

Abstract
All heat-power conversion systems produce waste heat, which can attain significant portions. This applies to geothermal power generation too; the waste heat fraction depends on the conversion technology. The more of the waste heat that can be utilized for some useful purpose (and consequently requiring less heat to be rejected), the better economy can be achieved, besides benign environmental effects. The best solution to avoid discharge to the atmosphere or to the hydrosphere is cascaded use. This consist of a chain of applications with stepwise decreasing temperatures, for example, from industrial uses through balneology down to fish farming. Constraints given by environmental legislation can lead to beneficiary solutions like in the case of warm tunnel waters in the Swiss Alps: these would need cooling ponds/towers before being permissible for discharge into local rivers. It is described by several specific examples how the tunnel waters can be used instead.
Modelling near- and far-field processes in nuclear waste management
Authors: Bruno J. , Arcos D. , Cera E. , Duro L. , Grivé M. 
Published: April 2008

Abstract
In this chapter we present some of the recent advances concerning process understanding and modelling of radionuclide migration in nuclear waste disposal systems. The present geochemical modelling approaches used to quantify the processes concerning spent fuel dissolution, radionuclide interactions with the canister materials and the bentonite buffer are thoroughly discussed. Finally, some applications to natural analogue studies of spent nuclear fuel disposal, as testing ground for concepts and models developed for waste management systems, are presented.
Mechanisms of uranyl sorption
Authors: Del Nero M. , Froideval A. , Gaillard C. , Mignot G. , Barillon R. , Munier I. , Ozgümüs A. 
Published: April 2008

Abstract
Detailed knowledge of the reactions at the water/colloid/mineral interface is crucial to model accurately actinide behaviour in nature. In this paper, we review current knowledge of the sorption of actinides and of the mechanisms of sorption, with a particular focus on uranyl. Of major interest is the influence of the aqueous uranyl species (e.g., carbonate complexes, polynuclear species, colloids) on the uranyl sorption species. We present extended X-ray absorption fine structure (EXAFS) and X-ray photoelectron spectroscopy (XPS) studies on the coordination of uranyl onto an amorphous Al phase and onto quartz, respectively. Our XPS investigations show that two components having uranyl ions in very distinct coordination environments co-exist on quartz at high uranyl surface coverage, independently of the presence of uranyl carbonate complexes or uranyl colloids in solution. One component corresponds to polynuclear surface species and/or schoepite-like surface precipitates. In the case of similar uranyl concentrations and of high carbonate solution concentrations, polymeric uranyl species are formed on quartz, whereas no such surface species occurs on the Al phase. Uranyl is found on the Al phase as mononuclear uranyl carbonato surface complexes only. These results are of importance because they suggest that mineral surface characteristics strongly control the uranyl surface species in aquifers.
Secondary mineral formation in coal combustion byproduct disposal facilities: implications for trace element sequestration
Authors: Donahoe Rona J. 
Published: April 2008

Abstract
Coal combustion byproducts (CCBs) are high-volume wastes produced by the electrical power industry and typically disposed of in landfills and lagoon impoundments. In the disposal environment, meteoric water or groundwater may percolate through and interact with the ash materials, producing leachate that contains elevated levels of many trace elements. Various geochemical reactions control the release of solutes and the formation of secondary minerals in CCB disposal facilities during weathering. Concern about the potential release of trace elements into the environment has motivated a large number of studies aimed at predicting the maximum concentrations of elements in leachate solutions. Secondary minerals formed during weathering of CCBs have the potential to limit the mobility of trace elements in an ash disposal facility. Geochemical modelling has been used by many investigators to predict the equilibrium concentrations of solutes in CCB leachate solutions and the stable secondary minerals that will form in weathered ash. Unfortunately, basic kinetic, thermodynamic and adsorption data are lacking for many solid phases, particularly those that may contain trace elements. In addition, secondary solid phases are very difficult to identify by direct analytical methods due to their low abundances and/or amorphous character, so it is often not possible to directly determine the identity and compositions of secondary phases in ash disposal environments. Despite these difficulties, numerous secondary solid phases have been directly observed and/or predicted to form via weathering reactions in CCBs. A tabulation of all secondary phases that have formed or have the potential to form in the CCB disposal environment is given, along with the relevant references. The potential for secondary phases to sequester trace elements via precipitation, adsorption and co-precipitation is discussed. Secondary phases with the greatest potential to limit the mobility of trace elements are amorphous Fe-oxyhydroxide and amorphous aluminosilicate phases, which are metastable precursors to Fe-oxide and clay minerals, respectively.
Effects and impact of early-stage anaerobic biodegradation on Kuparuk River Field, Alaska
Authors: Holba Albert G. , Wright Lisa , Levinson Rick , Huizinga Bradley , Scheihing Mark 
Published: April 2008

Abstract
Anaerobic processes have only recently been recognized as an important mechanism in the biodegradation of crude oils. They are normally invoked to explain extensively biodegraded oils with little or no possibility of contact by oxygenated waters from an active aquifer. This work with Kuparuk Field indicates that early stages of anaerobic biodegradation can be subtle and easily missed, yet have economic impact.
Kuparuk River Field, North Slope of Alaska, comprises two reservoir intervals: vertically stratified and imbricated lower shoreface sandstones (A sands), and overlying shallow marine sandstones with complex permeability structure (C sands). The vertical and lateral distribution of viscous oil (less than 20° API) shows a strong relationship to structure and faulting in the Kuparuk Field. Multiple mechanisms for the origin of tars and viscous oils can be proposed, including early aerobic biodegradation, anaerobic biodegradation, inorganic oxidation and gas deasphalting. This geochemical study, integrated with stratigraphic, structural and production data, was undertaken to help understand the origin and distribution of tar and viscous oil in the field.

Obvious depletion of
n
-alkanes and other paraffins, classically regarded as indicative of early biodegradation, is not observed in examined samples. However, Kuparuk viscous oils show slight to extreme selective depletion in long-chain alkyl aromatic (LCAA) hydrocarbon families (e.g. alkylbenzenes and alkyltoluenes). This is interpreted as indicative of an early stage of anaerobic microbial degradation that likely destabilized the oil to promote subsequent precipitation of asphaltenes as tar.

Depletions in LCAAs in core samples in the field are linked to decreased hydrocarbon/nonhydrocarbon ratio and to an increase in the high molecular weight (>C
50+
) components of Rock-Eval 6 pyrolysates. Using a calibration curve constructed from oil Rock-Eval 6 pyrolysis, the API gravity of core oil plus bitumen can be estimated. Tar-plugged formations with depleted LCAAs have estimated API gravities <8°. Portions of the Kuparuk reservoir with higher iron content tend to show greater depletions in LCAA. Anaerobic biodegradation is likely mediated by dissimilatory iron-reducing bacteria. Biodegradation likely destabilizes the oil with respect to asphaltene precipitation such that later arrival of petroleum leads to tar in the reservoir. Increased tar and depleted LCAAS correspond to intervals with lower productivity indices, thus indicating a significant impact on petroleum producibility.
Rates of reservoir fluid mixing: implications for interpretation of fluid data
Authors: Smalley Craig , England William A. , Muggeridge Ann , Abacioglu Yafes , Cawley Stephen 
Published: April 2008

Abstract

This paper highlights the benefits of using knowledge of the rates of fluid mixing in the interpretation of reservoir fluid data. Comparison of the time it would take for a fluid difference to mix with the actual time available for mixing to occur allows two significant advances over a purely statistical analysis of reservoir fluid data: (1) differentiation of a step in fluid properties, indicative of a barrier to fluid communication, from a gradient indicative of incomplete mixing; and (2) quantitative estimation of the
degree
of compartmentalization that can readily be adapted into models for prediction of reservoir production performance.

We review the existing equations that estimate the mixing times for three main types of variation in fluid properties (fluid contacts, fluid density and fluid chemistry). In addition, a new relationship for fluid pressure mixing is presented. In each case the relationships were validated by comparison with numerical simulation. The different fluid mixing processes were compared by applying the equations to a range of simple fluid scenarios in one simple reservoir description. This shows that mixing times for fluid mixing processes are diffusion > fluid density > fluid contacts > fluid pressure. For each scenario, the processes were analysed in terms of the volume of fluid that must move in order to bring the system to equilibrium and the drive for fluid mixing (pressure difference × permeability/viscosity). Perhaps surprisingly, there is an excellent linear relation between fluid mixing times (a) calculated from the mixing equations and (b) estimated from volume/drive. This indicates that fluid volumes and mixing drive are the main controls on fluid mixing times. This can be used to derive simple interpretation guidelines to estimate mixing rates even in the absence of quantitative modelling. A simple field case study demonstrates how this understanding of fluid mixing times can add value to the interpretation of reservoir fluid data.
Development of a compositional kinetic model for hydrocarbon generation and phase equilibria modelling: a case study from Snorre Field, Norwegian North Sea
Authors: Primio Rolando Di , Skeie Jon Erik 
Published: April 2008

Abstract
The possibility to model petroleum composition during hydrocarbon generation as well as the PVT behaviour of the fluids during migration has only recently become available in modern basin modelling software packages. While various compositional kinetic models of petroleum generation have been published in the past few years, none of the studies presented have attempted to match the composition, physical properties and phase state of known petroleum accumulations. Using compositional data from closed-system non-isothermal pyrolysis experiments, we developed a compositional kinetic model of hydrocarbon generation for a marine Type II source rock, which uses 13 components to describe the generated fluid. The data format selected is compatible with the compositional resolution used in reservoir engineering, thus allowing a direct comparison of predicted compositions and phase behaviour with PVT data of natural fluids. Compositional predictions of the model were tuned to a well-documented maturity sequence from the Tampen Spur, Norway, and the calibrated model implemented in a 2D basin modelling study of the Snorre Field, Norway. The results of the modelling led to an excellent correlation between predicted and reported reservoir fluid properties (formation volume factor, GOR and saturation pressure) for the present-day situation. The results indicate that the Snorre reservoir has received a continuous charge since the late Cretaceous-early Tertiary and that it most likely contained a two-phase system prior to the latest Plio-Pleistocene burial and overpressuring event.
A petroleum charge model for the Judy and Joanne Fields, Central North Sea: application to exploration and field development
Authors: Lines Michael D. , Auld Heather A. 
Published: April 2008

Abstract
There is considerable diversity in petroleum type within the Judy and Joanne Fields of the Central Graben. Superficially, the three major reservoir systems can be considered to contain the following fluid types: gas-condensates in the Pre-Cretaceous, undersaturated black oils in the Chalk and gas-condensates in the Palaeocene. Reality is, however, quite different.
This paper presents the results of several geochemical studies undertaken in the area; oil/condensate analyses to identify differences in maturity and source input, a pressure data review, high resolution GC fingerprinting, strontium isotope analyses to investigate reservoir connectivity/compartmentalization, and 2D basin modelling to determine the timing and extent of petroleum expulsion and migration. These components have been synthesized to produce a composite petroleum charge model which adequately explains the differences observed. This, in turn, enables an assessment to be made of the likely impact, if any, on field development. Furthermore, the petroleum charge model can be applied to predict the charge risk, fluid type and likely petroleum-water contacts in untested parts of the field and in the immediate vicinity.
The results of recent development wells are reviewed in the light of the charge model. Subsequent reservoir geochemistry studies have confirmed the validity of the model and highlight additional applications for reservoir management.
Determination of the orientation of magnetic minerals from the anisotropy of magnetic susceptibility
Authors: Jezek J. , Hrouda František 
Published: April 2008

Abstract

The anisotropy of magnetic susceptibility (AMS) of rocks is controlled by preferentially oriented magnetic mineral grains that carry AMS and, therefore, it contains information about both the grain susceptibilities and the grain orientations. Under certain conditions, information about the grain orientations can be deduced from the AMS. For a multigrain system composed of identical grains that are magnetically uniaxial (for the grain principal susceptibilities it holds that
K
1
>
K
2
=
K
3
, or
K
1
=
K
2
>
K
3
), an exact relationship exists between the AMS and the orientation tensor. We investigate the extent to which the theoretical relationships can be used when grains are generally triaxial. The parallelism of the principal directions of the susceptibility tensor and those of the orientation tensor are well preserved in all basic grain configurations. If grain leading axes have polar or girdle distributions and the two other axes have balanced distributions (similar orientation tensors), the parameters of intensity
I
and shape
T
based on the eigenvalues of the orientation tensor are well estimated. For unbalanced distributions, formulas are found for possible errors of
I
and
T
estimates.
A comparison of anisotropy of magnetic remanence methods — a user’s guide for application to palaeomagnetism and magnetic fabric studies
Authors: Potter David K. 
Published: April 2008

Abstract
Anisotropy of magnetic remanence (AMR) is increasingly being applied to palaeomagnetic and structural fabric studies. AMR techniques measure the anisotropy of the remanence carrying particles, and thus are directly relevant to palaeomagnetic studies concerned with computing the direction and intensity of the Earth’s ancient magnetic field from the natural remanent magnetization (NRM) recorded in anisotropic rocks. This paper provides a comparison of several AMR methods, including some of the less well-known techniques, and highlights the relative merits of each. Results from a strongly anisotropic rock and a pottery sherd are presented. The anisotropies of anhysteretic remanent magnetization (AARM) and isothermal remanent magnetization (AIRM) are currently the most commonly applied types of AMR, since they have provided reasonably good analogues of the anisotropy of thermoremanent magnetization (ATRM) acquired in the Earth’s field. They have also helped to correct for inclination shallowing of detrial remanent magnetization (DRM) in sediments. IRM anisotropy is the most rapid AMR technique, and is particularly useful for very low concentrations of remanence carrying particles. The gyroremanences, gyroremanent magnetization (GRM) and rotational remanent magnetization (RRM), are preferentially acquired by stable single-domain (SD) particles, and are thus directly relevant to the particles of major interest in palaeomagnetism. GRM anisotropy is the most sensitive AMR method. It is essentially the remanence equivalent of the anisotropy of magnetic susceptibility (AMS) delineator, since a single application of an alternating field will only produce a GRM in a sample containing an anisotropic distribution of particles. Static ARM methods need to take account of components of GRM that are simultaneously acquired.
Statistical significance of magnetic fabric data in studies of paramagnetic granites
Authors: Pueyo E. L. , Román-Berdiel M. T. , Bouchez J. L. , Casas A. M. , Larrasoaña J. C. 
Published: April 2008

Abstract

The low anisotropies of paramagnetic granites, due to magnetocrystalline anisotropy, require a statistical treatment of the anisotropy of magnetic susceptibility (AMS) data when systematic fabric studies are performed. Absence of statistical information on these data makes evaluation of their quality difficult. The statistical significance of magnetic fabric in granites is evaluated in this paper. Jelinek’s elliptical confidence angles for the three principal susceptibility axes (E
13
, E
12
, E
23
) of a specimen are used as markers of the quality of the AMS data. Comparing these markers at sample-, site- and massif-scale with the mean AMS axes that result from spherical statistical models helps clarify the reliability of the AMS data. This analysis is presented in detail for the plutons of Veiga and Trives (Spain). It is then applied to seven other massifs from the Pyrenees. We propose the following guides: (1) fabrics with E
13
between 10° and 20° tend to isotropy; the directional data and the shape parameter should be considered with great care; (2) lineation is not reliable when E
12
> 25°, i.e. when
K
max
is almost the same as
K
int
; (3) similarly, foliation is considered as not reliable when E
23
> 25°, i.e.
K
min
does not easily differentiate from
K
int
. Errors attached to the mean
K
max
and
K
min
axes should always be produced, thus allowing further interpretation. In Trives and Veiga, ‘perfect’ triaxiality cannot be automatically assumed since foliation and lineation could be defined simultaneously in only 53% of the cases. Finally, a minimum of three cores (9 specimens) per site would considerably increase the proportion of reliable orientation data.
Magnetic fabric constraints on oroclinal bending of the Texas and Coffs Harbour blocks: New England Orogen, eastern Australia
Authors: Aubourg Charles , Klootwijk Chris , Korsch Russell J. 
Published: April 2008

Abstract
We have carried out a magnetic fabric study on deformed, clay-rich rocks from the Carboniferous Texas beds and Coffs Harbour Association in order to test the hypothesis of oroclinal bending of the Texas and Coffs Harbour blocks of the southern New England Orogen, eastern Australia. The magnetic susceptibility is dominated by paramagnetic phyllosilicates, with site-dependent contributions from the ferromagnetic minerals pyrrhotite, magnetite and hematite. Pyrrhotite is ubiquitous in the Texas block and in the central part of the Coffs Harbour block, and may be important as an indicator of the grade of low-temperature metamorphism. The magnetic fabric results, in general, show good agreement with structural observations in the Texas and Coffs Harbour blocks. The magnetic foliation is related to the pervasive cleavage associated with accretionary deformation prior to oroclinal bending. The magnitudes of the anisotropy parameters and the plunge of the magnetic lineation indicate an increase in the intensity of deformation from east of the Coffs Harbour orocline towards the Texas orocline. An imprint from oroclinal deformation is suggested by a significant increase in the anisotropy parameter and by the development of steeply plunging magnetic lineations towards the hinges of the Texas and Coffs Harbour oroclines. The Terrica beds from the Early Permian (Allandale) Terrica inlier in the Texas orocline also show another, pre-tilt induced, tectonic imprint. Remanence data from volcanics in the Alum Rock inlier (293 Ma) and magnetic fabric data from this inlier tentatively constrain the onset of oroclinal bending as prior to extrusion of the Alum Rocks, and the completion of bending as post-Terrica beds deposition and pre-Illawarra Reversal (est. 265 Ma).