MICROORGANISMS AND HYDROCARBONS IN THE NORTH SEA DURING JULY-AUGUST 1975

1977 ◽  
Vol 1977 (1) ◽  
pp. 593-609 ◽  
Author(s):  
C. H. Oppenheimer ◽  
Wilfried Gunkel ◽  
G. Gassmann

ABSTRACT The 1975-1976 North Sea Oil Ecology Investigation is designed to determine the dynamics of oil pollution in the North Sea and to serve as a baseline study at the start of the rather extensive oil exploitation of the seabed of the North Sea. In designing the experiment, particular attention has been paid to the 1974-1975 research effort of the Gulf Universities Research Consortium directed towards determining the effect, if any, of offshore oil exploitation in Louisiana on the area's ecology. As a result, both projects address the distribution of hydrocarbons and their possible concentration in the water, sediment, and living organisms, and the determination of the rates of degradation and effect of hydrocarbons on the food web. Preliminary analyses and study of cruise data taken in the North Sea during July-August 1975 indicates that there appears to be a tendency for higher numbers of microorganisms to be associated with the most active oil field, “Ekofisk;” there is also some indication of microbial response to outflow from the Elbe River. The uniform low levels of hydrocarbons in the sediment suggest that microorganisms are active as shown by ratios of higher hydrocarbon bacteria to heterotrophs in the “Ekofisk” area.

Chemosphere ◽  
2001 ◽  
Vol 45 (3) ◽  
pp. 245-259 ◽  
Author(s):  
O.P Heemken ◽  
H Reincke ◽  
B Stachel ◽  
N Theobald

1977 ◽  
Vol 1977 (1) ◽  
pp. 45-52 ◽  
Author(s):  
D. R. Blaikley ◽  
G. F. L. Dietzel ◽  
A. W. Glass ◽  
P. J. van Kleef

ABSTRACT The reasons are introduced for the development of a simulator sufficiently simple to enable weather data normally acquired for E & P operations to be used. “SLIKTRAK,” developed by Shell, applies a slick description and combat concept, developed within the E & P Forum for well blowouts in the North Sea, but applicable to other areas. This concept includes costs for cleanup, damages and the effect of phenomena such as evaporation and natural dispersion. These factors are based on industry experience and vary primarily with sea conditions. The computer programme simulates the continued creation of an oil spill and applies weather data to predict movements of each day's spillage for successive days at sea and quantities of oil left after each day until the oil either disappears or reaches a coastline. Cumulative probability curves for the oil volumes cleaned up, oil arriving at specified shores, total costs, etc., are produced by random selection of input variables such as well location, weather data, the possibility of well bridging etc., and repetition of simulated spill incidents over a large number of cycles. Trace-plots of individual spills may also be generated. In association with the E & P Forum's position as technical advisers to the North West European Civil Liability Convention for Oil Pollution Damage from Offshore Operations, a study based on the North Sea areas has been made. These results and further developments of the program are discussed.


2021 ◽  
Vol 9 (3) ◽  
Author(s):  
Marcio Soares Pinheiro ◽  
Paulo Roberto Duailibe Monteiro

Brazil began to explore its seas in the 60’s of the XX Century looking for petroleum. This journey began in the Northeast and the first oil field produced offshore was the Guaricema Field, in the State of Sergipe. During the 70’s, Petrobrás found oil in the Campos Basin, between the States of Espírito Santo and Rio de Janeiro, that became the most important oil province in Brazil until the discovery of the Pre-Salt province, in the Santos Basin. As these fields are producing for a long time, many of them are already completely depleted or their production is in way of to be not commercial anymore, and their facilities need to be decommissioned. This review of decommissioning practices of fixed offshore platforms carried out worldwide has focus on the removal of topside with special vessels designed for this purpose or with conventional methods (crane vessels + barge). It will show the benefits of using specialised heavy lift vessels to remove the topsides and move it to shore for dismantling / recycling / reuse / disposal. The cases for study were the successful decommissioning projects in the North Sea: Brent B/D, Valhall QP, Viking, Curlew, Eider A, Golden Eye and Leman, Iwaki-Oki, Halfweg Q1, Yme and Ninian North.


Author(s):  
Beatriz Alonso Castro ◽  
Roland Daly ◽  
Francisco Javier Becerro ◽  
Petter Vabø

Abstract The North sea Yme oil field was discovered in 1987, production started in 1996 and ceased after 6 years when it was considered no longer profitable to operate. In 2007 a new development was approved, being Yme the first field re-opened in the Norwegian Continental Shelf. The concept selected was a MOPUStor: comprising a jack-up unit grouted to a subsea storage tank. Due to compromised structural integrity and lack of regulatory compliance that came to light shortly after installation, the platform was required to be removed [1]. The remaining riser caisson and the future 1050 t wellhead module required a support to allow the re-use of the facilities and tap the remaining oil reserves. The innovative tubular frame support was designed as a braced unit, secured to the existing MOPUstor leg receptacles and holding a grouted clamp larger than typical offshore clamps for which design guidance in ISO is available. The existing facilities had to be modified to receive the new structure and to guide it in place within the small clearances available. The aim of this paper is to describe the solutions developed to prepare and verify the substructure for installation; to predict the dynamic behavior of a subsea heavy lift operation with small clearances around existing assets (down to 150 mm); and to place large volume high strength grouted connections, exceeding the height and thickness values from any project ever done before. In order to avoid early age degradation of the grout, a 1 mm maximum relative movement requirement was the operation design philosophy. A reliable system to stabilize the caisson, which displacements were up to 150 mm, was developed to meet the criteria during grouting and curing. In the stabilizer system design, as well as the plan for contingencies with divers to restart grouting in the event of a breakdown, the lessons learned from latest wind turbine industry practices and from the first attempt to re-develop the field using grouted connections were incorporated. Currently the substructure is secured to provide the long term integrity of the structure the next 20 years of future production in the North Sea environment.


1973 ◽  
Vol 13 (1) ◽  
pp. 3
Author(s):  
P. E Kent

The paper gives the case histories of discovery in three major oil field areas-Iran, northern Alaska and the North Sea. These areas differ in their regional features and in the consequent requirements for geological and geophysical investigation and delineation. In Iran the earlier discoveries were based entirely on surface geology; geophysics became important with the need for deep survey. In northern Alaska structures mapped at surface gave only minor shows. Seismic surveys following geological deductions on reservoir development led to discovery of the giant Prudhoe Bay field near the Arctic coast. In the North Sea, in the much more complex extension of Permian-Mesozoic basins already well known on land, location of structures has been entirely by seismic survey.There is no close relation between the new Global Tectonics and the location of major oil field belts. The factors controlling the latter are multiple and complex. Resolution of the relative importance of vertical (epeirogenic) displacement as against the effect of lateral plate movement is nevertheless critical, particularly in Alaska.There is at present a large unresolved discrepancy between the times at which some continental margins developed (North Atlantic, East and West Indian Ocean) and with the physical evidence of sea floor spreading. In the three areas quoted, breakdown of the continental margins by vertical movements started in the Permian (—280 million years), but spreading is dated as beginning only in the late Cretaceous (—70 million years). It is the earlier movements, unexplained by current global theories, which have most relevance for petroleum exploration.


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