Thirty-three oil/condensate samples, representing most of the known petroleum accumulations in the Haltenbanken region, were analysed by a comprehensive geochemical scheme to determine possible genetic relationships. The organic geochemistry of the samples is comparatively invariate if one excludes the characteristics attributed to maturity differences and phase-induced fractionation. On this basis, in a gross sense, the C 10+ fractions of most of the petroleum samples are suggested to be derived from the Spekk Formation. However, the ratio of pristane to phytane and the stable carbon isotope composition of the petroleums proved useful to differentiate this picture. The database was subjectively divided into three main genetic groups which show dependence on the geographical location of the fields. Group 1, comprising the samples from Njord, Smørbukk Sør well 6506/12-5, Tyrihans N, Tyrihans S, Trestakk and the 6506/12-3 DST 6 sample above the Smørbukk Sør main reservoir, is clearly differentiated from Group 2, comprising samples from Midgard, 6407/2-2 DST 1 and from Alve 6507/3-1 DST 3. Group 3, comprising samples from Draugen, Heidrun, Mikkel plus the Smørbukk Sør petroleum 6506/12-3 DST 1, forms an intermediate population between Groups 1 and 2. In general, Group 2 is confined to the easterly, more proximal part of the basin, while Group 1 fields have drainage areas in distal, more deeply buried regions of the basin. Available data on the geochemistry of the two major source rocks in the region, the Spekk Formation and the deeper Åre Formation, lead us to conclude that the C 15+ fractions of the Group 1 petroleums are derived predominantly from a distal marine anoxic facies of the Spekk Formation. Group 2 forms the other end member, supposedly sou rced mainly from more terrestrially influenced proximal marine (partly dysaerobic?) isotopically heavier shales of the Spekk Formation. Group 3 contains characteristics of both source-rock facies. We see no evidence in biomarker distributions of the current database for significant contributions to the heavy ends of the reservoired petroleums from Åre coals. However, we cannot, based on our limited source-rock database, exclude contributions in some localities from Åre Formation shales. Furthermore, we have no evidence to exclude contributions to the light hydrocarbon range from the Åre Formation, e.g. condensate/gas contributions. We feel that the Spekk Formation varies significantly in geochemistry, both laterally and vertically, i.e. according to Walters law, and that this formation is less homogeneous with respect to geochemistry and the depositional and early diagenetic environment than commonly described. The metal composition of the petroleums generally substantiates these interp retations on laterally varying dysaerobic/anoxic conditions of the Spekk Formation, even if it proved difficult in cases to compare metal distributions in petroleums with drastically different gas/oil ratios. Because most fields, despite overall similarities, contain petroleum with specific singular minor characteristics, we suggest that, with the exception of the Draugen and Midgard Fields, lateral migration has been predominantly short- to medium-range with respect to intra-field distances. A core extract from well 6609/11-1 (Helgeland basin) deserves special attention, as our data suggest that this core at 2561 m contains a zone of terrestrially derived oil, possibly lacushine, most likely sourced from a Triassic or Palaeozoic formation.

A simple flow injection system, the FIAstar unit, was used to inject samples of seawater into a flame atomic-absorption instrument allowing the determination of cadmium, lead, copper and zinc at the parts per million level at a rate of 180-250 samples per hour. Further, on-line flow injection analysis pre-concentration methods were developed using a microcolumn of Chelex-100 resin, allowing the determination of lead at concentrations as low as 10 parts per los (p.p.b.) and 1 p.p.b. for cadmium and zinc. The sampling rate was between 30 and 60 samples per hour and the readout was available within 60-100 s after sample injection; the sampling frequency depended on the pre-concentration required.Atomic-absorption spectrophotometry (AAS) is a well established, extremely valuable technique for the determination of trace amounts of metals. Since its introduction by Walsh,l the method has gone through a number of development stages aiming at obtaining an increase in reliability, ease of operation and, above all, improvement in the limit of detection. Hence, atomisation by a flame has been supplemented or replaced by the graphite furnace technique, background correction has been introduced to compensate for non-specific absorption phenomena and most recently background correction has, by exploiting the Zeeman effect, become more sophisticated by incorporating a polariser and a magnetic field into the commercial instruments.However, despite all these improvements, the assay of trace amounts of metals in samples with high salt content, such as seawater, still remains a time-consuming and difficult task. Because the high salt content in evaporated samples might result in clogging of the burner, or poisoning of the inner surface of a graphite tube, heavy metals generally have to be preseparated from the salt matrix either by solvent extraction or by ion exchange. While diethyldithiocarbamate extraction into isobutyl methyl ketone is widely used, this method is far from ideal because besides being laborious, it also requires very careful work if blank values are to be kept low. Further, analysis of a large number of samples yields, along with the analytical results, considerable volumes of used organic solvents that have to be disposed of in environmentally acceptable ways. Therefore, there is a marked tendency to use another preconcentration technique, that is, ion exchange on Chelex-100 resin,2 which is efficient and yields low blanks3 A recent paper by Danielssen et and an older, yet much more detailed, paper by Kingston et aZ.,5 have summarised the present state of seawater assays based on ion exchange. Thus, a typical procedure requires 100-500 ml of seawater, which is to be passed through a column containing 5 g of Chelex-100, at a rate of 2 ml min-l, followed by elution into 10 ml of 5 M nitric acid. Hence, pre-concentration of a single sample by a factor of ten will require over 1 h, while one 1-1 sample volumes have to be pre-concen-* Present address: ReagentsAll chemicals were of analytical-reagent grade and re-dist...

Condensates and naphtha are petroleum samples with largely gasoline-range components (C 5 -C 10 ). Metal organic complexes are source inherited components of oils which are associated with the polar components and asphaltenes of oils. Because of the very low levels of biomarkers such as hopanes and steranes in condensates, they present a special correlation problem. Geochemically significant metals, such as V and Ni, can be measured in some condensates using conventional Meinhardt-Scott chamber inductively coupled plasma mass spectrometry (ICP-MS). In order to increase the sensitivity and the range of condensates which can be analysed, the Cetac U-6000 AT Ultrasonic nebuliser-desolvation system was tested. The Cetac system improved the sensitivity for V and Ni by a factor of about 40. Valuable information for relating these difficult samples to each other and to heavier oils in a basin can thus be supplied to exploration geochemists. The influence of organic matrix on the analytical signal was investigated. Matrix effects are more pronounced for the Cetac system than for the conventional ICP-MS system. For both systems, the use of an In internal standard was found to be necessary for compensating for differences in nebulisation and combustion behaviour caused by variations in the nature of the sample. The use of ICP-MS for the analysis of toxic metals such as Hg and Pb in condensates and naphthas is also discussed. The results are compared with those obtained using electrothermal atomic absorption spectrometry and cold vapour atomic absorption spectrometry in an interlaboratory study of naphthas. Conventional Meinhardt-Scott chamber ICP-MS provided good accuracy and precision of analysis compared with the other techniques during this study. Volatile species such as Et 4 Pb and Me 2 Hg were lost in the desolvation unit when using the Cetac system. Volatilisation effects were not observed when using the conventional Meinhardt-Scott chamber ICP-MS system.

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One important issue in the design and optimization of a superconducting cable conductor is the control of the current distribution between single tapes and layers. This presentation is based on a number of experiments performed on a 4-layer three meter long prototype superconducting cable conductor.The self and mutual inductances of the layers are studied theoretically. The current distribution between the superconducting layers is monitored as a function of transport current. The results are compared with the expected current distribution given by our equivalent electrical circuit model.The AC-losses are measured as a function of transport current and a given current distribution and compared with the monoblock model. Recommendations for design of future cable conductor prototypes are given.