Palaeohydrology of hydrocarbon maturation, migration and accumulation in the Dead Sea rift

It is proposed that hydrocarbon maturation, migration and accumulation in the Dead Sea rift, which took place during the last 3-6 Myr, were significantly affected by density-driven groundwater flow, from the rift westwards through deep aquifers. To test this hypothesis, a quantitative feasibility study was carried out using numerical modelling, which assesses the effects of structural evolution, groundwater flow, heat transport and salinity redistribution on hydrocarbon migration. Results indicate that a significant fraction of hydrocarbons have escaped to the land surface within the graben. Oil that has been forced westward into the rift flanks with the migrating brine is still moving. However, gas that has been forced westward has been trapped and forms the three small commercial gas fields: Zohar, Kidod and Haqanaim. A significant portion of the oil has biodegraded forming heavy oils and asphalts due to subsequent flushing by meteoric water. Simulations indicate that flow-field configurations of both groundwater and hydrocarbons have changed during the structural evolution of the rift, illustrating the interrelationships between basin formation, palaeohydrology and hydrocarbon reservoir formation.