AVO and seismic inversion has been successfully applied during the exploration phase of the Late Messinian Abu Madi Formation in the central Nile Delta of Egypt. Several gas condensate discoveries were made using this technique as a Direct Hydrocarbon Indicator (DHI) and risk mitigation tool. Deterministic inversion was further employed to delineate the overall lateral extent of the field and gross reservoir character during the appraisal phase of one particular field. A comprehensive well data acquisition programme for several wells revealed a complex lateral and vertical reservoir stacking patterns with highly heterogeneous reservoir parameters. The reservoir sequence is attributed to lacustrine turbidities deposited in semi-isolated Late Messinian Basins. Informally, the Abu Madi Formation can be subdivided in to upper and lower members. Intraformational shale barriers and baffles are commonplace. The stacked reservoir sands cannot be visualised and differentiated by the existing deterministic inversion products but each sand package displays complex vertical and lateral pressure trends. This paper describes an AVA Geostatistical Inversion process integrated with rock physics modelling (using differential effective medium theorem) of the wells to generate high resolution multiple rock property models with the aim of capturing reservoir heterogeneity and the observed pressure trends. The probabilistic representations of lithology, water saturation, permeability and effective porosity captured the range of uncertainty remaining after appraisal drilling to provide equi-plausible models to further de-risk future development of the field. Flow simulation modelling is used to monitor and predict pressure depletion trends to optimise further infill drilling and effectively manage the reservoir. Introduction The Late Messinian Abu Madi Formation is a prolific producing reservoir in the Nile Delta of Egypt. The first discoveries were made from the late 1960's onwards focused along the Abu Madi Valley trend (Rizk, 2002). A number of fields were subsequently discovered within this north-south trending incised valley trend. More recently exploration focused to the west of the Abu Madi Valley trend in the central Nile Delta area. Despite near-continuous exploration from the mid-1960's the area yielded no commercial discoveries. Following a phase of extensive 3D seismic acquisition and interpretation several fields were discovered from 2007 onwards. Most discoveries have made on structurally robust traps which usually comprises some stratigraphic trapping elements (facies changes and sand pinch-out). All discoveries were supported by positive AVO responses which generally conform to the mapped structural traps.

The Cowms Rocks landslide was the result of a translational movement which occurred downslope of a stream junction but involved part of the tributary valley side. Its morphology is described and a Gradient Index has been used to identify the component slide units. Slippage occurred on a 7° planar surface at about 40 m below the original ground surface, and consequent upon slope failure the main slump moved en masse. The tensional stresses controlling the slide were not uniform and a series of upslope‐facing escarpments developed within the main slump with some toppling and flexuring taking place at the slump's inner edge. At its margins, the slump broke into several blocks, some of which were tilted or deformed during the slip movement. The dominant factor leading to slope failure was rock (mass) creep which developed when periglacial climates prevailed in Pleistocene times. This led to differential weakening of the rocks within the slope but the exact timing for this deterioration is not known. The ultimate failure was delayed until some time in the Flandrian when stream undercutting was the ‘trigger’ mechanism.

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Building a reservoir model by integrating seismic angle stacks and well data has been challenging for oil and gas companies. Seismic data contain very detailed information of reservoir properties lateraly but lack vertical resolution while well data provide very detailed information vertically but lack horizontal information. One established method of integrating these two kinds of data is deterministic seismic inversion. Deterministic seismic inversion has proven to be a good method in delineating the reservoirs at seismic resolution but it has limitation in analyzing thin reservoirs and it only pruduced one result. Geostatistical seismic inversion method has the ability to integrate many types of data and produce multiple relaizations of the results. The realizations are at much higher details than seismic data and are able to capture thin reservoirs.An AVA geostatistical seismic inversion workflow was successfully implemented to produce highly detailed reservoir models of Abu Madi reservoir sands in Nile delta, Egypt. Abu Madi Formation is composed of lacustrine turbidite deposits in semi-isolated basin and can be subdivided into Upper and Lower reservoirs. Intraformational shale baffles occur quite commonly within Abu Madi Formation which acted as barriers of pressure depletion between the Upper and Lower reservoirs. Well data analysis has demonstrated the complex pattern of the stacked reservoir sand zones of heterogeneous reservoir parameters and pressure trends. The main objective of the study was to produce reservoir models that could be used to understand the observed pressure depletion trends within the Upper and Lower Abu Madi reservoirs which have great significance for effective field management.Seismic angle stacks and well data were integrated through AVA geostatistical inversion to produce highly detailed lithotype and elastic property results at 0.5 ms vertical sampling. Thesse models have successfully captured the shale baffles. Lithotype and elastic property realizations were used to cosimulate for reservoir (engineering) properties of Effective Porosity and Volume of Clay. The Effective Porosity and Volume of Clay realizations were then ranked to provide the P10, P50 and P90 models to be used as input for dynamic flow simulation. Five permeability rock types were derived based on extensive SCAL database and used to define the permeability and saturation models. These detailed engineering models were used for dynamic flow simulation and successfully predicted the pressure depletion trends in the Abu Madi reservoirs.

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