Application of Simultaneous-Stochastic Inversion to Define the Reservoir Architecture in a Complex Heavy-Oil Province

Abstract

Abstract

A simultaneous-stochastic inversion was performed on a pre-stack seismic dataset to help understand the vertical and lateral variations in a thickly varying complex clastic reservoir in the Llanos Basin. The lithology volume generated from inversion was able to define the subtle changes in rock-properties remarkably well. This volume was used to do a more detailed mapping of the only known operational unit, consisting of three different formations separated by unconformities, fully supported by chronostratigraphic and production data.

Prior to this work, both the stratigraphy and the geophysical signatures of the reservoir packages were poorly understood. Integration of structural, chronostratigraphic and petrophysical data along with seismic inversion results addressed this problem properly. The reservoir was successfully characterized and stratigraphically positioned by integrating the biozonation with the “elastic zones”, thus the relative age of each reservoir package was established. The importance of this result has been emphasized in multiple new comprehensive studies, which have partially finalized the proposal of a new “play” concept, suggesting that the heavy oil producing reservoirs include the Upper Cretaceous, Paleocene and Eocene sandstone stacked intervals stratigraphically trapped. These results match well with the behavior of flow units observed in heavy oil fields and recent discoveries nearby.

Since geo-statistical inversion provided a significant impact on the final interpretation of the reservoir, this methodology may have a broader application to invert a wide-range of analogous datasets to get integrated reservoir characterizations in this heavy-oil province. In addition to the better understanding of geology thus aiding with the regional geologic interpretation, the production data has been better understood, thus enabling more efficient future development strategies.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016