Hierarchical Outcrop Reservoir Modeling of a Shallow Marine Deltaic Complex from the Eocene Roda Sandstone, Spain

Håvard H. Enge¹, Beate L.S. Leren¹, Simon Buckley¹, John A. Howell², and Allard W. Martinius^3
1 Centre for Integrated Petroleum Research, University of Bergen, Bergen, Norway
² University of Bergen, Bergen, Norway
³ Statoil, Trondheim, Norway

The accurate geological and petrophysical modelling of shallow marine depositional systems remains a key challenge. 3D modelling of outcrops can provide important insight on the controls of both facies geometries and modelling strategies on fluid flow within analogous reservoirs. Laser scanning (LIDAR) and the creation of virtual geological outcrops provide a means for the rapid collection and interpretation of large volume of accurate geometric data.

Outcrop data have been collected from the Eocene shallow-marine Roda Sandstone which crops-out in the Spanish Pyrenees. The Roda is a well studied, tidally influenced Gilbert type delta which shows a complex stacking of delta lobes and tidally reworked delta toe-sets. Laser scanning and traditional field techniques have been used to collect a high resolution data set from the outcrops. A work flow for producing usable virtual outcrops from the high volumes of point cloud data has been developed. This work flow has been used to map surfaces and to build a variety of geocellular models from the facies (c. 100m) up to the oil-field (c. 5km) scales.

Although cellular, the models are heavily based on stratigraphic surfaces. A hierarchy of surfaces include cross-bed set bounding surfaces, through clinoforms to parasequence boundaries. Flow simulation results from the fine scale models have been used to populate the petrophysical properties of highly irregular grids, defined between key stratigraphic surfaces in the broader scale models. Comparative flow simulations have been used to test the effects of grid structure and modelling strategy on simulated production.