Regional hydrogeology of the Arab-D aquifer in Central and Eastern Saudi Arabia with highlighting its environmental and energy potential

Abstract

The Jurassic Arab-D reservoir hosts major oil-producing zone in Eastern Saudi Arabia with production from individual wells exceeding 25000 B/D. From a water supply perspective, Saudi water authorities consider it a minor aquifer with small yields of relatively high salinity; hence, it did not receive much attention in previous studies of aquifers. The present paper describes regional hydrogeological characteristics of the Arab-D in terms of groundwater flow, salinity and temperature, and discusses geological factors controlling these characteristics. Although high groundwater salinity in the Arab-D precludes it from being a potential water supply resource, studying the hydrogeology of Arab-D provides a hydrodynamic tool to oil exploration and development project. It also sets the stage for detailed studies of Arab-D aquifer potential use for industrial effluent disposal and as new geothermal energy source. Most of groundwater flow in Arab-D occurs in the porous and permeable grainy-textured upper zones. The top limit of the groundwater flow domain in Arab-D is the overlying massive Arab-D anhydrite unit. Trends in Arab-D hydraulic head, water salinity and temperature show gravity-driven flow towards the coastal region of Eastern Arabia. Major anomalies in these trends exist near the Ghawar, Summan, Jauf and Yabrin north-south faults. These anomalies are results of fault zone architecture that consists of sealing fault core zones surrounded by conductive fault damage zones. Depth, salinity, and temperature of the Arab-D between north Ghawar and Berri fields show that it has potential uses for industrial effluent disposal and geothermal energy projects.