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SPE/IADC 119942 Kicks in Offshore UK Wells--Where Are They Happening, And Why? This paper was selected for presentation by an SPE/IADC program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers or the International Association of Drilling Contractors and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers or the International Association of Drilling Contractors, its officers, or members. Abstract The first well on the UK Continental Shelf was spudded 44 years ago and the area has long been considered a mature province. Despite this, kicks are still a frequent occurrence.
The development of subsea facilities to improve the economics of marginal oilfield developments has focused attention on the need to develop single and combination production chemicals that can function in subsea environments, Figure 1. The recent development of long ( 20km) subsea tiebacks in the North Sea, Gulf of Mexico, Brazil and West Africa has focused attention on long-term product stability at seabed temperatures and the associated product specification required for this kind of service. The deepwater developments of Gulf of Mexico, Brazil and Angola with water depth of 750meter have brought new challenges of fluid viscosity and hydrostatic pressure to be considered in the Capex phase of such projects. The following sections outline some of the technical challenges and current methods that can be utilized to eliminate or at least reduce the risk to flow assurance (in scale control, hydrate and wax inhibition) by using such chemicals and the technical consideration to be taken into account during the selection program. Technical issues Figure 2 shows the principle factors that have an impact on the selection of suitable scale, wax and hydrate inhibitors for a subsea application. The most effective way to evaluate the impact of these factors is to discuss each in terms of site-specific examples where these factors have been critical to product selection for applications within the North Sea, Gulf of Mexico, Brazil and West Africa. Inorganic Scale Control Specific factors that are significant to inorganic scale revolve around brine chemistry as this impacts the type and amounts of scales that form. Brine compatibility with chemical is also important.
The search for hydrocarbons in Middle Eastern and North African (MENA) countries began essentially as an exploration for giant oil fields, and several exploration wells may have been suspended, plugged and abandoned and declared "dry" under giant-prone early exploration strategies, obsolete logistics, drilling technology, and production methods. Some of these "dry holes" are now proven oil producers or "undiscovery wells".
Geothermal gradient anomalies associated with hydrocarbon traps have been recognised since the early days of modern hydrocarbon exploration. The goals of this study are: (1) mapping the geothermal gradients of North Arabia, (2) delineating geothermal gradient fairways and anomalies of oil and gas traps, then (3) identifying and reviewing similar anomalies in the same area as they may be indications of un-drilled, under-rated or bypassed hydrocarbon traps.
In this study an exclusive computer programme was used to create BHT database, correct, test the statistical significance of BHT measurements, calculate and plot Compensated Geothermal Gradients (CGG) and Extrapolated Surface Temperature Intercepts (ESTI) of 50 exploration and development wells in the study area covering onshore Kuwait, NW Saudi Arabia, Iraq, and parts of W. Iran, E. Jordan and E. Syria (Long. 39.00 ºE to 48.00 ºE and Lat. 29.00 ºN to 37.00 ºN).
The study recognised 30 Proven geothermal gradient anomalies of hydrocarbon entrapment (i.e. associated with proven oil and gas fields), and used their model to identify and delineate 3 Potential, 6 Probable and 5 Possible geothermal gradient anomalies of hydrocarbon entrapment in the area.
There are thousands of BHT data dormant in borehole records of every producing basin that can be used in similar analysis to investigate old dry holes for commercially producible traps.
Global hydrocarbon exploration history recorded many cases of early "dry holes" or "dry" anomalies becoming hydrocarbon producers at later dates. Examples are numerous; such as well K1-13 of Libya, which was classified as "dry hole" at completion date, then proved to be an oil producer at later dates is probably one of many potential "undiscovery wells" in Middle Eastern and North African (MENA) countries.
Geological and Geothermal Frameworks
Bottom-hole temperature (BHT) recordings using maximum recording mercury-in-glass thermometers is one of the oldest geophysical well logging tools, and early exploration BHT measurements are correlatable with present-day BHTs irrespective of the BHT logging device (e.g. optical fiber sensors, Carnahan et al, 1999). At present there are thousands of BHT readings in records of old suspended, P&A, wet, tight or dry boreholes in every producing basin. Temperature data can be used as a quick look method to investigate early dry holes as some of these wells may be commercially producible now.
The studied area is located northeast of the Proterozoic Arabian Shield, on the northeastern Arabian Shelf and south-southwest of the Late Tertiary Taurus-Zagros suture zone (Long. 39.00 ºE to 48.00 ºE and Lat. 29.00 ºN to 37.00 ºN). More than 150 oil and gas fields have been discovered within the study area.
An exclusive computer programme was used to create BHT database, correct, test the statistical significance of BHT measurements, calculate and plot Compensated Geothermal Gradients (CGG) and Extrapolated Surface Temperature Intercepts (ESTI) of 50 exploration and development wells in the study area.
Published geothermal studies on Northern Arabia include a generalized geothermal gradient map (Klemme, 1975), a geothermal gradient contour map of South Iraq (Ibrahim, 1984), and a geothermal gradient and heat flow maps of southern Turkey (Unlan and Ungur, 1979). Sporadic geothermal gradients and BHT data were published by Al Saad (1986) and Ibrahim (1994b) on southern Iraq, Al-Habba et al (1994) on Western Iraq and Al Shadidi et al (1995) on Northern Iraq. Beydoun et al (1994) and Abu Ajemieh (1989) published some geothermal gradients and BHT data on eastern Jordan, Abu Rabee (1986) on Kuwait, Cole et al (1994) on northern Saudi Arabia and Sirriya (1986) on Syria.
Temperature data obtained in boreholes serve as critical input to many fields of engineering, exploration, and research in (1): well completions, (2) gas and fluid production engineering, (3) the exploration for hydrocarbons and ore minerals, and (4) testing hypotheses concerning the evolution of the Earth's crust and tectonic processes. Wireline-conveyed maximum-recording thermometers and continuous-reading thermistors are used to measure absolute temperatures, differential temperatures, and temperature gradients at depth. Temperature logs can detect thermal anomalies produced by temperature contrasts between the borehole fluid and the formation fluid or formation (also cement behind casing). A variety of information can be obtained from the identification and interpretation of these anomalies. High-resolution temperature- gradient logs can be used for detailed lithologic identification and correlation, of similar quality to other electric and nuclear well logs. The intent of this paper is to provide a general introduction to the diverse applications of these data.
A Reservoir Modelling workstation that allows fast access to, and integrated interpretation of data from the disciplines of Geophysics, Geology and Reservoir Engineering is being developed. Currently, from an initial overall reservoir 3-D geometry description (derived from seismic and log data), the model is elaborated to include more geological detail through the extension of single well geology diagnostic to the entire reservoir. A longer term objective is to integrate pressure and flow information with this static description to produce a 3-D dynamic reservoir model. Some of the techniques that have evolved during development of the static model have been applied to a North Sea oil field. Data used in this study included 3-D surface seismic, VSP surveys from 12 wells, and well log information from 28 wells.
The computational heart of the workstation is a VAX II optionally equipped with an array processor. The main user interface, however, is through a Scientific Information Processor. This machine is ideally suited for the manipulation of objects (or sets of symbols) rather than the more traditional arithmetic approach.
Extensive use is made of this object oriented programming environment for the construction of knowledge bases, which contain information concerning specific aspects of a reservoir, such as Top of the A sand, average porosity of the C member and so on. Other knowledge bases contain the more traditional (quantitative) data such as surface seismic, open hole well logs, pressure and flow test information, as well as conventional core analysis and, more generally, the geological framework of the basin.
The structural nature of the underlying system allows efficient communication between the various knowledge bases such that the user can interact with all available data in a truly synergetic manner. Data communication between the symbolic and arithmetic processors is via a 10Mb Ethernet link. The same connection may be used to tie back the workstation to a mainframe machine, thus permitting easy access to large volumes of archived data (either raw or processed). In stand-alone operation, the workstation is currently equipped with 380Mb of hard disk, and reservoir data can be loaded into the system via a tri-density tape drive attached directly to the workstation. Graphics displays are routed through a graphics processor equipped with two high resolution colour monitors for 2D and 3D manipulations. The electronics are packaged such that the entire workstation can be moved easily from one installation to another.
A separate interface allows a digitising table to be connected either directly to the workstation or to an adjacent larger machine. Both colour and black-and-white continuous feed hardcopy are available; the former 15" wide and the latter 11"or 22" wide.
A study has been made on an oil-field that is located in a graben in the Northern North Sea (Fig. 1). The graben is part of a major rift system lying along a line of incipient crustal divergence between the British Isles and Norway. The field produces primarily from the Brent Group of sandstones. It appears that the reservoir sandstones of the Brent Group were deposited as part of a northward prograding deltaic complex. Their gross external geometry is controlled by faulting, fault-block rotation, and truncation at the top by a major erosional unconformity.
THE BRITISH PETROLEUM INDUSTRY AND ITS PLACE IN THE WORLD PART I. HISTORICAL D. C. Ion, Chairman, British National Committee, WPC, Village Farm House, The Green, Bledington, Nr. Kingham, Oxford, OX7 6XQ. PART II. CURRENT AND FUTURE STATUS A. T. Gregory, President, Institute of Petroleum, 61 New Cavendish Street, London W1 M 8AR. Abstract. The petroleum industry in Britain has grown through this century as demand for oil increased, and as several major international oil groups, British or with very substantial British shareholdings, extended their world-wide operations. In the decades following the Second World War, Britain was effectively the centre for the Eastern Hemisphere operations of the international oil industry generally. Since 1965 this historical development has been transformed by the exploration for and development of major oil and gas reserves in the UKCS. Currently Britain thus stands as a country exceptionally well endowed both in actual and potential oil and gas reserves, and well equipped as a source of longstanding and rapidly evolving petroleum technology in all phases of the industry. Britain has reached this position partly by the good fortune of natural endowment and by strenuous development of its own scientific and technological resources, but also by maintaining a policy of non-discrimination against foreign companies. The skills and experience thus nurtured in Britain will be of increasing service in the development of oil and gas resources, and in all phases-both up and downstream-of the world-wide industry. Résumé. L'industrie pétrolière britannique a connu une forte croissance au cours de ce siècle avec l'augmentation de la demande de pétrole et avec le développement des activités mondiales de plusieurs groupes pétroliers internationaux, soit britanniques soit comportant une part importante de participation britannique. Dans les décennies ayant suivi la guerre de 1939-1945, la Grande-Bretagne était effectivement pour l'hémisphère Est le centre des opérations de l'industrie pétrolière en général. Depuis 1965 cette tendance historique a été modifiée par l'exploration et le développement des réserves importantes de pétrole et de gaz dans le plateau continental britannique. La Grande-Bretagne est donc actuellement un pays doté de réserves exceptionnelles de pétrole et de gaz et bien équipé en technologies pétrolières, aussi bien éprouvées que dernier cri, dans tous les secteurs de l'industrie. La Grande-Bretagne a atteint cette position en partie par sa bonne fortune de posséder des ressources naturelles et par le développement énergique de ses propres ressources scientifiques et technologiques, mais aussi par le maintien d'une politique de non discrimination envers les compagnies étrangères. Les compétences et l'expérience ainsi encouragées en Grande-Bretagne seront d'une utilité croissante dans le développement des ressources de pétrole et de gaz ainsi que da
The following Cumulative Index is organized similar to the specific subject section of the KWIC Index. Additional titles and sub headings have been used. The papers are indexed both according to subject and to author. When applicable, the papers are listed under two subject references. Papers represented by only an abstract in the symposia transactions are labeled as such. There is a Subject Index followed by an Author Index. Following are explanations of the Publication Reference Codes and the Paper Subject Classification.