Potentiometric Salinity Mapping of Mishrif Oilfield Waters in (Iraq’s) Southern Oil Fields

The hydrochemistry in the Mishrif reservoir, located at the main productive oilfields at Basrah, southern Iraq, is discussed. Water chemistry coupled with boron isotopes (¹⁰B, ¹¹B) were analyzed using ICP-MS and ICP-SFMS, respectively, and used to determine the subsurface fluid flow direction in the oil traps and interpret the rock-fluid interaction. The presence of boron in brine waters is useful in identifying the sources of water intrusive to oil wells. The δ¹¹B ranged between 33.7 and 35.9‰ with an average of 35.4‰ in the studied oilfields which is lower than that in the Dead Sea (39–57‰), indicating a dilution by the present seawater and injection water. The potentiometric subsurface maps were modelled and super-pressure sites that are of great importance in the oil exploration were marked to pay attention to during future drilling.