An Innovative Methodology to Update Dalia Lower Main Channel Geological Model

Eric Vacheresse¹, Eric Zuckmeyer¹, Joao Guerra¹, Emmanuelle Brechet¹, Marie Pascale Perruchot², and Dominique Pourtoy^3
1Total E & P Angola, Luanda, Angola
²Total E & P Indonesia, Kaltim, Indonesia
³SINCOR, Caracas, Venezuela.

The Dalia field is located offshore Angola in Block 17 in water depth greater than 1200m. Oil reserves are close to 1 billion bbl in four major Miocene accumulations. The information brought by the development wells implies a refining of the Architectural Elements (AE) with more heterogeneities and new distributions of sands inside. A new methodology was then developed in order to distribute these heterogeneities inside the model. The Lower Main Channel (1/3 of the accumulation) with seven new penetrations was chosen for the first implementation of this workflow in the model. A seismic dataset with 3D HR and two generations of inversion of high quality as well as an exhaustive geological database (9 wells) were available. Rock Type (RT) definition was slightly reviewed. RT were populated per AE inside the 3D grid using IP/IS seismic trend finalized with an in-house reservoir characterization software. RT is characterized by petrophysics such as porosity, irreducible water saturation and permeability. Then the Net-To-Gross (NTG) was dependant from the RT of each AE and in line with well results.

On a static point of view, the obtained model is more heterogeneous at a finer scale, and more precise in terms of local sand prediction as it has been proven by results of seven wells drilled later on. On a dynamic point of view, this new version of the reservoir model is a marked improvement for simulation of detailed fluids behavior inside the reservoir. It is an important step towards a reliable history matched model.

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