Statoil and the University of Liverpool stratigraphy group have carried out an extensive analysis of the lower Jurassic Lajas outcrop in Argentina, a continuous 18-kilometre exposure of tidally-influenced, coastal embayment sandstones and mudrocks.
Field geologists studying muddy tidal flat sediments overlain by a sharp-based tidal channel sandstone complex (Lajas Formation, Argentina).
These sediments are thought to be extraordinarily similar to those comprising the notoriously complex lower Jurassic reservoirs off mid-Norway, in the Halten Bank area of the Norwegian Sea.
The challenge was to find a way of transferring this knowledge from the Andean foothills to Norwegian offshore field developments.
The procedure was as follows:
- create a detailed computer-based model of the outcrop
- import petrophysical properties into the model from the Heidrun oil field operated by Statoil on the Halten Bank
- simulate the production performance of this pseudo-reservoir.
The results have been used to upgrade reservoir models of the Heidrun and Smørbukk fields and to assist the successful submission of a field development plan for Kristin.
Important understanding has also been gained about:
- the architecture of the larger-scale reservoir components
- their vertical connectivity
- the need to represent permeability properly in order to improve predictions of the stage when production wells are liable to start yielding large quantities of formation water along with the oil.