3-D Reservoir Modelling with GEOLOGIX and MONARCH

M. Budding, H. Davies, P. Davies, J. Fowles, J. v.d. Vorst

Three-dimensional reservoir models of over 50 oil and gas fields and outcropping analogues have been generated during the past five year using the Shell proprietary programs GEOLOGIX and MONARCH.

GEOLOGIX is a well-log correlation system used for analysing well data and constructing stratigraphic correlation models. In the first instance the relationship between core and wireline log data is established with the resultant lithofacies scheme correlated within a hierarchial stratigraphic framework. The hierarchical nature of the modelling system allows the application of current stratigraphic modelling techniques whilst honouring reservoir heterogeneity on variable scales.

MONARCH is an object orientated modelling system which integrates deterministic and stochastic techniques whilst honouring well log, core and geophysical data to generate hierarchical 3-D lithofacies models. The geometry and distribution of lithofacies bodies is constrained by the stratigraphic correlation framework and user-defined geological parameters. The resultant reservoir model is converted to a 3-D grid mate and deformed to its present-day structural configuration using horizon and fault grids derived from seismic.

Reservoir properties derived from core, log and or geophysical data are assigned to the structured model through interpolation, object-based, map-based, or depth dependent attribute allocation techniques. Effective properties such as volumes in place and connected volumes are calculated and analysis is made of the sensitivity of the model to geological and geophysical input parameters. Models resulting from different scenarios are screened and ranked using field performance indicators including well tests, production data and material balance calculations.

The presentation will highlight the applications of the modelling system with studies from fluvio-estuarine oil reservoirs in S.E. Asia, aeolian-lacustrine gas reservoirs in N.W. Europe and outcrop analogue fluvio-deltaic deposits in Kentucky, USA.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995