Time-Depth Conversion with Uncertain and/or Incomplete Data

Abstract : It is common during the exploration phase or at the early stage of a field development to work with a few of or even no well data, with uncertain Time or Velocity maps and with doubts about fault location. Lack of data and uncertain data decrease the robustness Depth-converted structural maps used in estimation of the field economic potential. Geostatistical methods developed in the framework of the UncerTZ R&D consortium can help dealing with uncertain data and with a few data when calculating depth maps: The paper describes the combined use of advanced geostatistical techniques which offer a solution for generating realistic depth maps at exploration or delineation phases: • Misties can be fixed and uncertain markers at wells (or estimated markers when wells are missing) can be managed with kriging with measurement error method; • Stochastic conditional simulations allow integrating uncertainty on Time or Velocity maps and on fault location. They also allow quantifying the global uncertainty resulting from all the uncertainties on data. With these methods, it is possible to get usable results from which the uncertainty on extension and volumes of petroleum traps can be estimated, allowing stakeholders to take the most appropriate decisions about field development.