Regional Zoning of Dynamic Phenomena in Mines – The Innovative Approaches in Gravimetry

Reservoir compartmentalization is a major uncertainty during appraisal and development. Failure to detect compartmentalization at appraisal can seriously compromise a project’s economics. Traditionally, reservoir compartmentalization is inferred when different fluid properties (e.g. pressure, fluid density, fluid composition), that are not in equilibrium, are observed across a field. The assumption is that fluid properties would have reached equilibrium over geological time unless there is a barrier to flow. Sometimes, however, fluid properties may not be in equilibrium because there has been insufficient time for them to mix since the reservoir filled and/or they were disturbed by another geological process (e.g. uplift, hydrodynamic flow). Thus, spatially varying fluid properties are only indications of compartmentalization if they have existed for longer than the time needed for them to equilibrate. Earlier work, using synthetic data, has demonstrated how mixing times could be used to diagnose compartmentalization and assess, for example the length or permeability of the baffle/barrier. Here we apply reservoir mixing to the identification of barriers/baffles and the quantification of their properties using appraisal data from the Horn Mountain oil field. We compare our results with earlier work using time lapse geochemistry and with assessments of communication based on production data.