Impact of Velocity Uncertainties to Estimate GRV in Structural Complexities Scenarios

Abstract

All exploration-appraisal-development project portfolio manages and evaluates several inherent uncertainties, analyzing risk elements with highest impact on the volumetric evaluation. Oil in Place (OIP) estimation is influenced by some well information, such as porosity, oil saturation and Net to gross is usually predicted by deterministic and stochastics methods, as well as seismic surveys interpretation that generates framework, a key issue to assessment of gross rock volume. The TWT structural interpretation brings uncertainties related to seismic resolution, and time-depth conversion through velocity models constitutes a fast and precise evaluation method in order to improve GRV calculation with better time interpretation. Structural scenarios from different individual compartments types, such as stratigraphic, fluid, and fault blocks allow assessment of velocity uncertainty and its impact on GRV distributions. Usually, when estimating OIP, there is a concern regarding the variation of internal properties within a GRV, such as porosity, NTG and saturation. However, the greatest impact is related to the velocity model, since higher or lower velocity can directly change the final portfolio volume. In compressional settings, the uncertainties associated with velocity models become even greater. The present study uses a methodology in which a depth-based framework is populated with time-domain inputs (horizons and faults) and dynamically converted on the fly to depth. Then it uses different models for conversion, creating different scenarios in which the results are compared and evaluated.

AAPG Datapages/Search and Discovery Article #90326 © 2018 AAPG Latin America & Caribbean Region, Optimizing Exploration and Development in Thrust Belts and Foreland Basins. Santa Cruz de la Sierra, Bolivia, June 6-8, 2018