Reducing Facies Uncertainty Distribution in Carbonate Fields Using Forward Stratigraphic Modeling Tool at Appraisal Scale

Abstract

Carbonate ramps are usually very good carbonate reservoirs and could be found all around the world, in South-East Asia and Middle-East. Stratigraphic architecture of these reservoirs is a key feature controlling hydrocarbon occurrence and behaviour. Detailed outcrop studies have been performed during the last decade to understand better the structure and facies distribution of carbonate reservoirs, and have led to a considerable improvement of the sequence stratigraphic conceptual models. These models give geologists new qualitative keys to study outcrops, such as the proportion of surface light or the intensity of waves; they allow them to analyse sedimentary system taking into account the major physical processes such as basin deformation, carbonate production or transport of sediment. Although these models are more and more complex, they are usually limited to a few parameters and cannot provide quantitative evaluation of strata architecture nor address uncertainties. The challenge of our study was thus to achieve fast and accurate stratigraphic numerical models of a carbonate reservoir (average thickness about 200 m) integrated with all the available data, from seismic, wellbore logs and sedimentology, at an appraisal scale (650 km², using a grid point spacing about 200 to 500 m). Modelling the dynamics of sedimentary systems using DionisosFlow, and simulating the filling of sedimentary basins allowed bridging the gap between geological conceptual model and geostatistical simulation. A review of borehole and seismic data, and in particular lithofacies classification (facies type and facies group) and EOD definition (Environments Of Deposition), allowed us to define stratigraphic parameters such as accommodation space, carbonate production laws and sediment transport parameters. A series of numerical simulation were then performed using DionisosFlow and were compared to the data until a best-fit was obtained. This stratigraphic forward modelling approach allowed us to understand better the impacts of sedimentary processes on the large-scale carbonate reservoir architecture and thus reduce uncertainties on the appraisal-scale reservoir characterization

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015