oa Understanding subsurface pressure data signature in a hydrogeological context

Pressure data are often used to understand the conductive properties of the rock framework, such as compartmentalization and sealing. While using such data is well-justified, the lack of understanding of basinal hydrogeology prevents a more comprehensive and thus accurate interpretation. Using a wealth of pressure data from mature basins and a numerical basin-hydrogeology model, a set of guidelines for understanding the pressure regimes and their implication on the hydrocarbon system are outlined. In subaerially exposed basins, the upper 10,000 ft or so are usually normally-pressured and dominated by a gravity-driven flow system. In these basins groundwater descends starting at topographic highs and then flows laterally before it ascends at<br>topographic lows. Intermediate and local flow systems also develop at a smaller scale due to local topographic variations. Sometimes the flow may be short-circuited by flow conduits between horizons, such as evaporite or shale layers. The gravity-driven flow system is usually superimposed on a deeper, abnormally-pressured system whose genesis can be due to multiple aspects. Among those are compaction, hydrocarbon generation and tectonic compression. The movement of groundwater within these systems and the interaction of such flow systems with the geological framework can generate a multitude of pressure signatures, both on a local and regional scale, which when properly interpreted, can lead to better exploration and development strategies. The<br>developed guidelines are outlined and applied to flow systems observed in the Arabian Platform and the potential implications on understanding the hydrocarbon system is proposed in view of the observed data.