The purpose of this presentation is to show how patterns of water pressure, salinity and chemical content within a basin can give much useful information for oil exploration. The Eastern Algerian Sahara is a good example where a substantial increase in exploration efficiency has been achieved by combining regional hydrodynamic studies with classic geological and geophysical studies. This prolific area shows a wide variety of hydrodynamic phenomena. Two distinct areas, each with its own “style” are present.

The Northeast Sahara basin roughly coincides with the limit of Triassic salt occurrence. Within this basin, reservoir beds are sealed both vertically and laterally, and are under abnormally high pressure. No flushing has taken place. The chemical characteristics of underground water are uniform within the basin.

The Southern basin coincides with the Illizi sedimentary basin. Slightly saline water moves hydrodynamically from the outcrops towards the central part of the basin. Hydrodynamic studies are of value here in defining the most prospective zone; in understanding the oil entrapment mechanism, and in facilitating correlations between different reservoirs.