A New Approach to Quantifying Uncertainties, from Seismic Characterisation to Hydrocarbons in Place

摘要

The field presented is a gas accumulation situated in the UK. Three individual sandslayers have been identified at the 4 wells. The total reservoir thickness is underseismic vertical resolution over most of the field's extension.An AVO seismic attribute obtained by combination of the near and far substacksexhibited a very good correlation with Net Sand Thickness at well locations.An AVO versus net sand cross plot was generated from a massive modelling study. Itwas used to generate 200 possible Net Sand thickness maps by bivariate non linearcollocated co-simulation.200 top reservoir maps were simulated within the estimated uncertainty range. Theywere used to flex the geological 3D model.For each of the 200 models, the porosity and permeabilities were produced bygeostatistical simulation. The Gas Water Contact was randomly drawn within theuncertainty range, based on the interpretation of RFT data. The water saturationtransition zone was defined by a J function and the associated uncertainty wasmodelled.The resulting Gas in Place distribution was used to provide a set of realistic data asinput for a range of reserves case scenarios and for key decision making.