Investigation of the Cretaceous total petroleum system using wireline logs, core, and geochemical data in Bahrah Field, Northern Basin, Kuwait

Abstract

We used wireline logs, seismic, core data, fluid analysis, and geochemical data to investigate the total petroleum system in the Cretaceous period. Also, we used thin sections and fluid analysis throughout the investigation. Python’s 1-D backstripping technique was used to determine the abrupt changes in subsidence rates and their effect on the reservoir’s quality. The results defined that the potential reservoirs include, from top to bottom, Mauddud, Upper Burgan, Lower Zubair, and Ratawi Limestone. The reservoir facies reflect different environments between the carbonate ramp (Mauddud, Ratawi Limestone, and Minagish reservoirs), delta plain (Zubair reservoir), and margin shelf (Burgan reservoir), and its quality is graded from Mauddud to Ratawi Limestone from top to bottom. The field lies up-dip under Kuwait Bay and represents the continuation of super-giant Greater Burgan Field. It filled with the spilled oil from the down-dip Raudhatain and Sabriyah fields through a structural saddle. Two major tectonic events subsided the deposited sediments by 0.25 mm/year, besides three minor events; however, these events did not affect all Cretaceous reservoirs but only according to their deposition times. Furthermore, according to burial history, thermal maturity, and reservoirs’ fluid geochemical analysis, the Sulaiy (Makhoul) and Minagish formations are likely the primary sources for all Cretaceous reservoirs.