Hierarchical benchmark case study for history matching, uncertainty quantification and reservoir characterisation

Benchmark problems have been generated to test a number of issues related to predicting reservoir behaviour (e.g. Floris et al., 2001, Christie and Blunt, 2001 and Peters et al., 2010). However, such cases are usually focused on a particular aspect of the reservoir model (e.g. upscaling, property distribution, history matching, uncertainty prediction, etc.) and the other decisions in constructing the model are fixed by log values that are related to the distribution of cell properties away from the wells, fixed grids and structural features and fixed fluid properties. This is because all these features require an element of interpretation, from indirect measurements of the reservoir, noisy and incomplete data and judgments based on domain knowledge.Therefore, there is a need for a case study that would consider interpretational uncertainty integrated throughout the reservoir modelling workflow. In this benchmark study we require the modeller to make interpretational choices as well as to select the techniques applied to the case study, namely the geomodelling approach, history matching algorithm and/or uncertainty quantification technique. The interpretational choices will be around the following areas:(1)Top structure interpretation from seismic and well picks.(2)Fault location, dimensions and the connectivity of the network uncertainty.(3)Facies modelling approach.(4)Facies interpretations from well logs cutoffs.(5)Petrophysical property prediction from the available well data.(6)Grid resolution-choice between number of iterations and model resolution to capture the reservoir features adequately.A semi-synthetic study is based on real field data provided: production data, seismic sections to interpret the faults and top structures, wireline logs to identify facies correlations and saturation profile and porosity and permeability data and a host of other data. To make this problem useable in a manageable time period multiple hierarchically related gridded models were produced for a range of different interpretational choices.

► We made a case study which requires the inclusion of interpretational uncertainties.
► Solution space described by 81 different available realisations.
► The model is not one of the provided scenarios.
► We have tried to match the reservoir using 2 simple approaches with some success.
► Challenge to match and will require approaches that look at all the solution space.