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3rd EAGE North African/Mediterranean Petroleum and Geosciences Conference and Exhibition
- Conference date: 26 Feb 2007 - 28 Feb 2007
- Location: Tripoli, Libya
- ISBN: 978-90-73781-42-9
- Published: 26 February 2007
1 - 20 of 100 results
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Outcrop Investigation of the Lower Palaeozoic Succession of Kufra Basin, SE Libya - First Steps of Targeting Effective Hydrocarbon Plays
Authors K. Tawengi, Y. Ismail, S. Shabbo, A. Al-Madhuni, E. Abushaala, J.L. Tornero, M. Kresta, Y. Al-Shagruni and J. Hernan-GomezThe Kufra basin located in the southeastern part of Libya is an elongate SW-NE trending (?Hercynian) depression defining a zone of crustal weakness of the trans-Africa lineament (Turner, 1980; 1995). The basin covers an aerial extent of approximately 400,000 sq km extending into Chad, Sudan and Egypt. Two major tectonic elements are known to have significantly controlled the structural style of the basin and consequently affected lithology distribution namely the Hercynian and the Caledonian events of Early Carboniferous and Late Silurian age respectively (Bellini and Massa, 1980). The basin fill consisting of a clastic Mesozoic and essentially Palaeozoic sequence attains an approximate thickness of 4000 m in basin centre. Lower Palaeozoic strata are exposed in three major outcrops surrounding the basin; Jabal Dalma in the NE, Awaynat massif including Jabal Asba in SE and Jabal Eighe in the W-SW. The existence of these outcrops provided ideal opportunity to examine the Palaeozoic succession from within a sedimentological/stratigraphic framework. As the only non-producing basin of Libya, Kufra Basin has recently re-captured the intention of oil companies for a detailed work in a bid to solve uncertainties still surrounding the basin hydrocarbon potential. In the same context, Remsa has conducted a field campaign to the area with the aim of investigating the depositional packages of the Lower Palaeozoic sequence as the main possible hydrocarbon plays may have exist in the subsurface counterpart. Two separate campaigns have been carried out during March-April 2005/2006 in the NE of Kufra (Jabal Asba, Arkunu and Garda area) and in the NE of Kufra (Jabal Dalma area) during which more than 80 localities were visited. Lower Palaeozoic sequence is investigated including the InfraCambrian, Cambrain Hassawna Fm, Ordovician sequence of Hawaz, Melaz Shugran, and Mamuniyat Fms, Silurian Tanezzuft and Akakus Fms and the Devonian sequence of Tadrat/Oan Casa Fms and the Binem (Blitah Fm). Packages are dealt with in a large-scale architecture i.e. facies associations without considering details of facies scale. The aim is to predict depositional mode and palaeogeographic reconstruction within a sequence stratigraphic approach applying method of facies recognition, stacking pattern, palaeoflow data, surface logging and composite log reconstruction. The field campaign is augmented in some instances by geochemical, petrographic and petrophysical analysis for units of interest in addition to shallow hole drilling. The systematic and/or genetic evolution of the Lower Palaeozoic succession of the Kufra Basin seems to have been largely affected by the interaction of tectonics and sea level changes demonstrating a pronounced variation in facies architecture and stacking pattern as it varies from proximal in the SE “Awaynat Massif-Jabal Asba outcrops” into distal setting of the “Jabal Dalma outcrop” which provided the key of reconstructing the palaeogeography of individual time slices and their inferred depositional models.
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A Recipe for Exploration Success in the 21st Century - Exploration Ingredients that Led to BP’s Deep Raven Success Story
Authors T. Afifi and M.V. ShannThis oral presentation discusses a holistic set of ingredients used to deliver deep water gas exploration success in the Nile Delta of Egypt. An exemplary of BP's renown exploration method as applied in North Africa.
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An Early Miocene Play Fairway Opener in the Nile Delta, Egypt
More LessThis describes the technical background that led to the 2004 Raven deepwater exploration success in the offshore Nile Delta, Egypt. Presented by the lead explorer involved in the discovery. Pulls together regional synthesis, seismic imaging technology and an in depth set of exploration results from an important deep play opener that is critical in underpining the future exploration potential offshore North Africa.
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Hydrocarbon Prospectivity and Play Types of the Levantine Basin from Modern Seismic Data
Authors D. Rowlands, G. Roberts and D. PeaceThe paper describes the regional tectonic setting and evolution of the Levantine basin in the Eastern Mediterranean. Thereafter the majority of the paper focuses on the hydrocarbon prospectivity and play types in the basin derived from an interpretation of 20,000 km of modern, high quality seismic data.
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Structural Style Associated Structures on Occidental Saharan Atlas and Petroleum Implications (Algeria)
By H. BechiriThe study area is located at west of Algeria, straddling two different geological domains, the Saharan Platform in the south and the Alpine domain in the north. Two major Faults (South Mesitian Fault and South Atlasic Fault) subdivide the area in three geodynamically and tectonically distinct domains, High Plateaus, Occidental Saharan Atlas and Saharan Platform (or Bennoud Trough). Three stratigraphic columns are build to illustrate the stratigraphic series' nature and thickness variation of the geodynamic provinces. So as to set off the geometry of the Saharan Atlas associated structures, we've draw up dips domains sections perpendicular to the tectonic transport direction. The interpretation of these sections in depth, including wells and seismic data, permitted us to set up three regional equilibrated structural sections. These shows that the present structure of the Saharan Atlas is the result of regional NW-SE and N-S compressional direction which prevails since the Late Eocene and it illustrated by Fault-bend fold and Fault-propagation fold. Salt tectonic, in some cases, complicate structures. In Bennoud Trough, the two established regional transect evidencing two distinct zones; a calm zone in the south and a structured one in the north near the Saharan Atlas. The majors faults had an important role in the provinces' geodynamic evolution created during the distension stage (Trias-Upper Cretaceous). Each province had his own subsidence ratio and petroleum system. So, the discovery of hydrocarbons in the Occidental Saharan Atlas is possible if the structural style is taken into consideration. Structures geometry in depth must be defined before drilling, because the appearance and disappearance of traps depends on the evolution of the folds. Hydrocarbons accumulations can be trapped at the top of the major fold or in it's slices.
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Genetic Basin Analysis and Paleoenvironmental Reconstructions of the Mesozoic and Cenozoic Strata of the Libya Region
Authors K.M. Bohacs and W. HeinsOur analysis of the Libya region was built on foundation of previous proprietary and published studies and employed recent proprietary research on concepts and tools and newly available data and a new age model that included significant thicknesses of Mesozoic strata offshore. These allowed calibration of the seismic character of source and reservoir facies and their stratal packaging in proven onshore areas, and extrapolation to similar seismic facies & stratal packaging seen in offshore data. We concluded that the Libya region was in a favorable setting for accumulating source, reservoir, and seal-prone strata throughout the Mesozoic and Cenozoic, due to the: 1) common occurrence of shelfal water depths and paleogeographic restriction, 2) low-latitude setting, 3) warm, dry to sub humid paleoclimate, commonly with low seasonality, 4) some coastal upwelling, along with water mass mixing under ITCZ & tropical cyclones, 5) dominantly quartz-sand-prone provenance lithotypes, and 6) late development of shelf-bypass clastic dispersal systems. The incorporation of paleo-environmental reconstructions is a powerful tool in exploration, enabling evaluation of numerous frontier areas in less than 10 weeks of work by using our fundamental understanding of the dynamics of basin formation integrated with the regional paleo-environmental context.
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The Murzuq Basin, Libya - A Proven Petroleum System
Authors I. Sarkawi, G. Abeger, J.L. Tornero and E. AbushaalaThe Murzuq Basin is located to the southwest of Libya. The basin is a foreland intracratonic trough which was formed during the Pan-African orogeny. It has evolved through several tectonic events from Pan African to Alpinian. The complex glacial influence sedimentation and erosion have been recognized in the Ordovician Hawaz and Mamuniyat sediments. The Hawaz Fm. has been deeply eroded forming a spectacular terrain of escarpments and incised valleys where later filled by Melaz Shuqran and Mamuniyat Formations. Restricted basin during the early Silurian favored the deposition of organic rich Base Tanezzuft “Hot Shale”. A combination of both Ordovician Hawaz and Mamuniyat as reservoir with the Lower Silurian Tanezzuft Hot Shale creates the main play in the area. The presence of active petroleum system and hydrocarbon potential in the Murzuq Basin has been support by oil fields and discoveries. A total of 18 oil fields have been discovered with recoverable reserves exceeding 1.9 billion barrels.
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Mesozoic Tectonism in Northeast Africa
By W. BosworthMesozoic tectonism in NE Africa was locally, but significantly, impacted by older Neoproterozoic and Hercynian structures. During the Permo-Triassic to Neocomian, the dominant control on deformation was the newly formed Neotethyan margin to the north. From the late Aptian onward, stress fields represented the combined effects of distant plate boundaries, producing both extensional and compressional deformation.
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The Opening of the Eastern Mediterranean and its Impact on the Tectonics of North Africa
By J. HossackThe opening of the Eastern Mediterranean had a large impact on the structure of the North African passive margin. The first extension event that lead to the formation of the ocean can be traced back to the Permian. A Permian rift system is preserved in the subsurface of Tunisia, north of the Jefarra uplift. Renewed rifting occurred in the Triassic. Triassic rifts are preserved in the Atlas, Sicily, Sirt, and Levant margins. A phase of Jurassic rifting is observed in the Nile Delta and Sicily but a possible occurrence of rifting in the Sirt basin is obscured by younger Cretaceous rifting. Jurassic rift structures also occur in the Atlas. The North African margin rifted again in the Early Cretaceous when the Sirt Basin formed on the site of earlier Triassic rifts. The Sirt rift faults form a 3 armed system where the eastern faults trend E-W parallel to the earlier Triassic rift system. A southern arm trends SSW and a NW branch continues offshore across the passive margin. Early Cretacous rifts occur extensively in North Africa and are known to be related to South Atlantic spreading.
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Petroleum Geology in the NC41 Area (Western Libyan Offshore)
More LessThe NC41 area belongs to a polyphasic pull-apart basin in the western side of the Libyan offshore. The early stage of the basin was upper Cretaceous in age. The local troughs of the pull-apart were affected by restricted conditions that gave origin to the cretaceous source-rock (Kef Fm.). The deposition of the cretaceous source is a peculiar feature of the deepest part of the Sabratah-Misrata basin. The geochemical properties and evolution of the cretaceous source led to the generation of gas that largely contributed to most important accumulation of the area. The trap-forming processes started during the late Cretaceous transpressional phase. The early faults were reactivated later, sometime evolving into attractive exploration features. The present structural style, characterized by faulted anticlines, results in particular from late Cretaceous and Oligocene events. The two major exploration plays are the Eocene shallow-water carbonates and the Cretaceous carbonate platform. The former is the most successful play of the area. The latter is presently largely unexplored in spite of the close concurrence of effective source and reservoir units but it shall represent a challenging target for next future exploration.
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Regional Seismic Attribute Mapping for Nile Delta Deep Water Reservoir Imaging
Authors K.B. Halleland, J. Cotton and I. HanbalSixteen surfaces were mapped on a regional basin scale. The strategic focus for the mapping study was to identify the prospectivity in the Pre Pliocene section, so the horizons mapped were focused in this interval. Three areas of seismic mapping have been critical to completion of this phase of regional work : 1. Deep 2D seismic for basement structure as well as petroleum charge 2. Very large 3D mega merges for reservoir / seal definition & detailed lead mapping 3. Onshore & peripheral 2D mapping to extend the mapped key horizons both up dip & outward across the full project AOI. In addition several deeper surfaces were mapped carefully to calibrate the petroleum charge system.
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Pre-Screening Tectonic Heat Flows for Basin Modelling - Some Implications for Deep Water Exploration in the Mediterranean
Authors J.D. van Wees, G. Bertotti, P. David, F. van Bergen and S. CloetinghBasin modelling results can be very sensitive to (paleo-)temperature uncertainties. For frontier basins, in particular for deep water settings, the thermal signature of the basin is poorly constrained, as data from wells are lacking. This may lead to wrong heat flow assumptions if these are extrapolated from the shallow offshore or onshore. Furthermore large uncertainties can exist when dealing with constructing paleo-heat flow. The potential errors in spatial and temporal extrapolations are especially large in settings with strong spatial and temporal variations in tectonic regime. This is in particular true for the Mediterranean and North Africa. Heat flow modeling can be improved considerably through numerically modeling lithospheric processes underlying basin deformation. For this purpose we have developed a probabilistic tool which is capable of calculating tectonic heat flows calibrated to observed data and which can be used as input for maturation modelling. For various basin settings we will show the effect of adopting tectonic heat flows for improving spatial and temporal constraints on the temperature and maturation history in deep water exploration settings. Case studies include the Morrocan Atlantic margin and the Valencia Through (Spain).
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Crustal Structure and Early Opening of the Eastern Mediterranean Basin - Key Observations from Offshore Northern Egypt
Authors P.A. Bentham, I. Hanbal, J. Cotton, M.B. Longacre and R. EdwardsA significant body of literature has been published on the post-Paleozoic evolution of the Eastern Mediterranean Basin (EMB) however, many contrasting opinions are presented, and much is poorly understood about this particularly complex piece of the Tethyan system. Even the highest order aspects of the evolution of the continental margin of NE Africa are subject to debate and reinterpretation. Using recently-acquired industry data from the offshore Northern Egypt, we document results that address the fundamental questions concerning (1) the crustal structure underlying the EMB, and (2) the tectonic evolution associated with the early basin history. A synthesis of these results has been used to test existing plate tectonic models for the early Mesozoic evolution of the region and a preferred opening geometry is presented.
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The Petroleum System Knowledge Today and Tomorrow
Authors J.J. Biteau, G. Choppin de Janvry, J.J. Jarrige and F. ReverdyIn Basin and prospect evaluations we always deal with the assessment the Petroleum System elements. The Petroleum System is defined as the sequence of all the geological combined elements and processes which, from a source rock to one or several reservoir / seal pairs and using a common plumbing system leads to the formation of a genetically related family of hydrocarbon accumulations. We need to improve the seal efficiency studies: investigate the sealing sections as carefully as we do for reservoir intervals by a detailed mapping of their petrophysical parameters, thicknesses, the occurrence of hydrocarbon shows from mudlogs etc. We must also progress on hydrocarbon type predictions: We can use sophisticated simulators and calculators but only as sensitivity tools thanks to computers becoming more and more powerful, but we must not forget the geological and naturalist reasoning for helping to find new hydrocarbons! We need to come back to the geologic reflexion, following the key steps of the evaluation workflow and gather and integrate the knowledge and data even it becomes more and more complex to manage.
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Regional Hydrocarbon Charge in the Sirte Basin, Libya – Integration of Geochemistry, Basin Modeling and Regional Geology
Authors G.P.A. Muscio, N.D. Rodriguez and L. LiuA regional evaluation of hydrocarbon charge was undertaken in the Sirte Basin, Libya in order to improve the understanding of the general hydrocarbon charge system and to determine robustness of hydrocarbon charge in different areas in the basin. Geochemical data derived from crude oils and source rock extracts as well as source rock samples were integrated with regional map-based charge modeling and paleofacies mapping. Four main oil families and additional sub-families were identified, and correlated with the source rocks. Integration with maturity and lithofacies maps highlights that the Upper Cretaceous Rachmat Formation source rock appears to be the principal contributor to the resource-base (as opposed to the Sirte Shale). Moreover, this approach also reveals that the East Sirte Basin is more robust in terms of hydrocarbon charge than the West Sirte Basin.
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Looking for Hydrocarbons in Dry Holes - Application of Fluid Inclusion Chemistry in North Africa/Mediterranean
Authors P.J.R. Nederlof, A. Bell and D. HallFluid inclusions can provide hard evidence for the presence of hydrocarbons in a ‘dry’ hole and fluid inclusion screening of cuttings forms a routine part of a dry hole analysis in many oil companies. Subsequent microscopic and chemical analyses provide additional compositional information via cryo-optical and quantitative fluorescence techniques, constrain the timing of migration or reservoir filling (from paired analyses of coeval petroleum and aqueous inclusions) and can identify the source of the hydrocarbons via GCMS and/or isotopic methods. A particularly useful technique is compound specific isotope analyses (CSIA) of the gas components of the fluid inclusions. For instance, in many basins in North Africa and the Mediterranean, there is uncertainty about the presence of the Silurian Tannezuft (Qusaiba) source rock. This source rock was deposited after the Silurian deglaciation and source rock quality depends on the anoxia and stratification of the water column, which varied regionally with the topography at that time of deposition. With CSIA analyses of fluid inclusions, the presence of Silurian generated gas is easily recognized from the carbon isotopes that are characteristic for the Silurian generated gases. In this presentation, we describe recent applications of the fluid inclusion geochemistry from Libya, Syria and Oman.
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An Overview of North African Petroleum Systems as Revealed by Petroleum Geochemistry
More LessPredictions of source rock type, geologic age, and thermal maturity can be made based on biomarkers from migrated crude oils whilst natural gas origin and maturity can be deduced from stable isotopic compositions. Various petroleum systems are mapped across northern Africa, based upon the predicted source rock type and age. The solid component of petroleum, asphaltenes, can be used as source rock kerogen surrogates to determine generation kinetic characteristics.
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Geochemical Evaluation of Source Rocks in Block NC98, and the Relationship between Petroleum Habitat in Block NC98
More LessIdentifying of source rocks is essential for the evaluation of the petroleum potential of the sediments dominated by terrestrial organic matter in exploration areas. This will improve the modeling of the generation history of the source rock sediments.The knowledge of the petroleum generation and the characteristics of the source rock sediments is one of the main factors in the exploration success of an area. Geochemical data were used to examine the amount, type, and maturation of organic matter and Hydrocarbon potentials of source rocks within the Block NC98. Block NC98 source rock intervals have been identified in Lower and Upper Cretaceous group. The source rocks have been determined by identification of various organic Geochemical and palyonologyical methods and techniques. The data obtained indicates that both petroleum systems have a very good source section with high potential for oil and gas generation. Both petroleum systems have organic facies derived from marine and terrestrial organic input. This was confirmed by the optical examination, and organically rich TOC. The Geochemical analysis including carbon isotope, GC, and GC - MS indicates that the Hydrocarbon extracted from Lower Cretaceous group have a positive correlation with Hydrocarbon found in the Upper Nubian sandstone.
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Global Neoproterozoic Petroleum Systems - Snowballs, Source Rocks and the search for “Old Oil” in North Africa and Middle East
By J. CraigThe Neoproterozoic eon, stretching from 1000 Ma to the base of the Cambrian at 542 Ma, is relatively poorly known from a petroleum perspective despite the existence of proven plays in many parts of the world including Oman, Mauritania, Siberia, India, Pakistan, Australia and the United States. Many of the proven “Infracambrian” (Neoproterozoic to Early Cambrian) hydrocarbon plays around the world depend on the presence of prolific “Infracambrian” source rocks. There is increasing evidence that deposition of many of these organic-rich units was triggered by strong post-glacial sea level rises, on a global scale, following the “Snowball Earth” type glaciations, coupled, in some areas at least, with basin development and rifting on a more local scale. Neoproterozoic to Early Cambrian organic-rich strata were deposited in both high latitudes (e.g. Mauritania) and low latitudes (e.g. Oman) along the North Gondwana Margin. Some of the black shales encountered on the West African Craton may be as old as 1000 Ma and clearly predate the Pan-African orogenic event. These are substantially older than the majority of the Infracambrian organic-rich units that occur across much of North Africa and the Middle East (including those in Oman) which predominantly range from c. 850 - c. 540 Ma in age.
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The Eocene Ramp Complex of Al Jabal al Akhdar, Cyrenaica, NE Libya - A Surface Analogue for Nummulite Reservoirs
Authors A.S. El-Hawat, S. Jorry, O. Hammuda, A. Obeidi, H. Barghathi and B. CalineForty eight high resolution stratigraphic sections and more than 850 thin sections were used to study the Eocene of Cyrenaica. Sections are located on the northern limb of Al Jabal al Akhdar inversion anticlinorium that formed a series of submerged Cretaceous structural highs and islands. These played an important role in the development of the Eocene nummulitic ramp complex. Evolved regionally parallel facies belts consisted of outer ramp mudstone clinoforms and mass transported facies, mid-ramp nummulite facies and inner ramp miliolid-orbitolites, coral-coralgal and skeletal facies respectively. Progradation of these belts led to an upward shallowing mega-sequence constituting Apollonia and Dernah Formations. It consisted of three correlatable nummulite dominated sequences in Ras al Hilal area. The top two of which pass eastward into structurally controlled reefal-coralgal-discocyclinid dominated facies. Reworking of nummulite bodies by waves and currents over structural highs led to improvement of primary porosity. Syndepositional reactivation of the structures not only triggered mass transport of the mid-ramp deposits, but also controlled nummulite body geometry, internal heterogeneities and diagenesis by spatially shifting high-energy and subaerial exposure zones through time. There no single nummulite ramp model that would characterize this active inversion setting, as depositional parameters changes in space and time.
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