Regional Hydrodynamic Assessment of the Memouniat Formation in the Murzuq Basin, Libya

By

James Underschultz¹, Julia Davies², Claus Otto¹

(1) CSIRO Petroleum (ARRC), Perth, Australia (2) Woodside Energy Ltd, Perth, Australia

 The Murzuq Basin has a relatively simple tectonic history, complex facies distribution in the Memouniat carrier beds/reservoir horizons and an active groundwater flow system. A hydrodynamic analysis was used to risk areas of hydrocarbon flushing and trap-fill preservation as well as to predict oil migration pathways. The Memouniat can be broadly divided into four geographic regions defined by characteristic hydrodynamic systems:

-         A low flux of formation water migrating to the centre of the Murzuq Basin most likely driven by erosional rebound and dilatation of the Tanezzuft shales;

-         A high flux of formation water from the high elevation Ordovician outcrops on the west side of the basin across the northern rim to low topography discharge in the northeast;

-         A ridge of high hydraulic head originating at Ordovician outcrops on the northern edge of the basin; and

-         A trough of low hydraulic head north of the inferred Memouniat shoreline draining northward into the Ghadamis Basin.

These flow systems together with source rock and carrier bed distribution, control the migration pathways of liquid hydrocarbon within the Murzuq Basin. Estimated hydrodynamic tilts were compared to the structural slope to risk oil charge and trap-fill preservation. The flow systems observed here have had an impact on the distribution of liquid hydrocarbon within the Murzuq Basin, and they are most likely linked to the adjacent Ghadamis and Sirte Basins.