Abstract. Lithocodium aggregatum Elliott (with its synonyms, Bacinella irregularis Radoiĉić and Pseudolithocodium carpaticum Miŝík), Radoicicinellopsis sterni (Radoiĉić) and Bacinellacodium calcareus Dragastan are referred to the new subfamily Lithocodioidea of the family Codiaceae (marine, chlorophycean, calcareous algae). The significance which has been ascribed to these taxa by past authors is assessed. Radoicicinellopsis is proposed as a new genus. Lithocodium is redescribed and its diagnosis is emended. The importance of this alga in palaeoenvironmental interpretation and fossil hydrocarbon accumulation is noted.

This paper discusses current water quality assessment methods and some of the parameters that can affect the suitability of North Sea water as an injection fluid. Also included are general comments on the North Sea and its biomass. Examples are drawn from tests carried out during the commissioning of the Forties field seawater injection system in 1976-78.

The Tukang Besi Platform, an Australian microcontinental fragment, began docking with Sundaland in the Pliocene, impacting on east Buton (SE Sulawesi). Fortuin et al. (1989; Journal of SE Asian Earth Sciences, 4, 107-124) postulated that south Bnton had rotated clockwise through about 60 ° relative to central/north Buton in response to the Tukang Besi collision. A palaeomagnetic investigation was carried out to test this model. Some 41 (of 72) palaeomagnetic sites from the upper Neogene Tondo and Sampolakosa Formations on Buton yielded interpretable data. Sites from south Buton record locally consistent directions, but at sampling localities < 25 km apart deflections are between 0 ° and 35 ° clockwise. There is no trend in these data with respect to the broad geotectonic setting. In central Buton declination offsets are negligible. In north Buton localized (kilometre scale) large (30-60 °) clockwise and counterclockwise declination offsets are observed. Effectively the Buton data provide spot markers on cover sequences that have been locally deformed as 'thin-skin' sheets. The underlying basement may have experienced the large relative motions proposed by Fortuin et al. (1989) but the upper Cenozoic cover has not been deformed in such a simple way. This study demonstrates that thinskin sheets associated with continental collision may undergo 30-60 ° rotations within very short intervals (< 2-3 Ma).

No abstract

As a result of core injectivity tests and alternative filtration trials carried out on Forties platforms it became apparent that certain components of the North Sea biomass have a direct bearing upon the ultimate quality of North Sea injection water. This view is substantiated by the continuous monitoring of the fine filters currently in use in the Forties Water Injection System. This paper discusses those species which according to test data and observations of the fine filters are considered most likely to influence water quality. Their seasonal frequency and lateral and vertical distribution in the North Sea are also commented upon. The conclusion is drawn that filtration of North Sea Water is necessary prior to well injection Introduction Sea Water injection of the Forties oilfield commenced in December 1976 and is currently going ahead at a rate of approximately 125,000 b/d for each of the four platforms. The details of the Forties water injection system have been published and will not be mentioned here in any detail. published and will not be mentioned here in any detail. Suffice to say that the sea water is won from a depth of 200 ft below sea level and is filtered before being pumped down to the aquifer at a well-head pressure of 1,200 psi. An initial coarse filtration of the water is obtained by a 80 um stainless steel screen. Fine filtration down to 5 um is achieved by backwashable. Plenty cartridge filters containing replaceable fibre elements which are positioned upstream of the main injection pumps. The decision to filter the sea water prior to injection was based upon information gained from numerous on-site tests which in turn were followed by filtration trials to ensure the selection of the most efficient fine filter element available for use in the Forties environment. The current paper which is a sequel to one published in 1978 is limited to a discussion of the organic content of the injection water and its relationship to the fine filters.