The examination of production history from hydrocarbon fields composed of turbidite deposits indicates that fluid flow behaviour is often more complex than expected. The cause is commonly linked to the presence of fine-scale sedimentary heterogeneities, which complicate the reservoir. This is especially true in the case of turbiditic submarine channel complexes with final channel-filling stages composed of lateral migration deposits. These fine-scale heterogeneities are usually below seismic resolution and are rarely represented in initial reservoir models designed for such fields. Thus, it is difficult to match the production history or identify methods to improve production and reduce associated risks. The various depositional patterns recognized in channel migration and aggradation packages from the Oligocene Malembo Formation of the Congo Basin, offshore Angola, exhibit different dynamic responses when modelled in a reservoir simulator. These dynamic differences are related to the different preservation rates of bank collapse sediments within isolated channel bodies, hereafter referred to as ‘elementary channels’. According to these preservation differences, the vertical stacking pattern of channels results in better connectivity than the true lateral migration. This effect has been incorporated into a full-field simulation model by applying petrophysical upscaling methods. The recognition and modelling of detailed sedimentological heterogeneities, and their distribution along full-field models produces a better history match when the inherent uncertainties have been taken into account. Incorporating all available data and concepts to define reservoir architecture is essential in understanding the impact that fine-scale heterogeneities have on reservoir management. As the lateral extent and areal distribution of heterogeneities is still unknown, our modelling workflow incorporates uncertainty in the form of multiple realizations to identify and measure all uncertainties that might impact dynamic response.

The variation of sediment supply through time is assumed to be the most critical parameter for the sequential evolution of deep-sea fans. It includes sea-level fluctuations (eustatic or tectonically induced), and the rate and source of sediment supply. The deformation is most of the time only described as critical for gravity flow sediment confinement. Although the effect of the deformation on a single flow is well established, only few studies investigate the influence of a deforming seafloor on turbiditic sedimentation at larger scale of space (10–100 km in length) and time (0.5–10My). The main objective of this study is to document the influence of seafloor deformation on the morphology of gravity flow deposits, both at regional (×100 km) and local (1–10 km) scales and for 0.5–10My periods, taking into account the tectono-stratigraphic evolution of the basin.Using seismic (2D and 3D) data calibrated on well data, the parameters controlling the morphology of two major turbiditic systems of the Lower Congo basin are investigated over a large area (5000 km2) and for a large period of time (Oligocene to Middle Miocene, about 10My). Studied turbiditic systems can be described by three main depositional architectures: (1) an erosive morphology characterized by a well-developed basal erosional surface, (2) a constructive morphology characterized by well-developed external levees, and (3) a depositional morphology characterized by lobes. The first turbiditic system (Chattian) is almost exclusively composed of turbiditic deposits (stacked channel-levee complexes). The geometry of the channel-levee complexes is mainly constructive and their spatial distribution is controlled, at the scale of the study area, by autocyclic sedimentary processes (mostly compensation phenomenon). In contrast, the second turbiditic system (Burdigalian-Langhian) is made up of erosive channel complexes and lobes isolated within a hemipelagic background. The geometry of turbiditic deposits is partly controlled, at the scale of the study area, by seafloor deformation related to growth structures (major and secondary faults, turtle-back anticline) rather than sedimentary topography. The two turbiditic systems are separated by hemipelagic deposits of Aquitanian age (Lower Miocene), related to a high eustatic sea-level, whereas turbiditic systems are related to eustatic sea-level lows. However, even though both are associated with eustatic sea-level lows, similar climatic contexts, and similar distances from source, the Chattian and Burdigalian–Langhian systems exhibit different morphology.We relate this difference to both regional (×100 km) and local deformation (×10 km). The regional deformation, related to the Miocene West African margin uplift, explains the more erosive character of the Burdigalian–Langhian system. We propose a model based on the ratio of sedimentation rate versus local deformation (S/D ratio) to explain the origin of the topography that controls the morphology of the systems. During periods of high S/D ratio (equal or larger than 1), sedimentation may smooth seafloor topography and, consequently, turbiditic complexes are controlled by the topography of previous complexes (compensation phenomenon). During periods of low S/D ratio (lower than 1), deformation related to growth structures is not obliterated by sediment deposition (Aquitanian) and may control turbiditic complex geometry (Burdigalian–Langhian).

D010 DEFORMATION AND SEDIMENT TRANSFER ALONG THE WEST AFRICAN MARGIN: I. ARCHITECTURE OF TURBIDITIC SYSTEMS. ROUBY D. 1 BROUCKE O. 2 TEMPLE F. 3 GUILLOCHEAU F. 2 ROBIN C. 1 DAUTEUIL O. 1 GUIRAUD M. 4 ELLOUZ N. 5 1 Géosciences Rennes UMR CNRS 6118 Université de Rennes 1 Campus de Beaulieu 35042 Rennes France 2 TOTAL 2 place de la Coupole 92078 Paris France 3 TOTAL CSTJF avenue Larribau 64018 Pau Cedex France 4 Biogéosciences-Dijon UMR CNRS 5561 6 Bd Gabriel Université de Bourgogne 21 000 Dijon France 5 Institut Français du Pétrole 92852 Rueil Malmaison France Introduction The

A013 3D MODELLING OF STACKED TURBIDITE CHANNELS - IMPACT ON DYNAMIC RESERVOIR SIMULATIONS Summary 1 AUTHOR(S) R. LABOURDETTE 1 J. SEGUIN 1 P. BIVER 1 F. TEMPLE 1 and J-A. HEGRE 2 Address 1 Total Geoscience Technologies Dept ISS CSTJF Avenue Larribau 64018 Pau Cedex France 2 Total E&P UK plc - Geoscience Research Centre Based on the production from fields consisting of turbidite deposits it is evident that fluid flow behaviour is more complex than anticipated. The cause is linked to the fine-scale sedimentary heterogeneities which complicate the reservoir characteristics especially in turbiditic channel complexes having a laterally offset