Characterization of the Jurassic reservoir potential in the Eastern Levant margin using reconstruction of the depositional environment and the diagenetic history. A poster for Israel Geology Society conference, 2017.

Structural and seismic studies of the Levant Basin margins indicate a variety of potential structural and stratigraphic oil-traps offshore Israel. Several offshore and onshore boreholes showed oil marks and oil accumulation in the Jurassic section, especially in the Barnea, Sderot and Zohar formations. Nevertheless, the diagenetic history of the cements in the Jurassic section has never been studied. The current study focuses on the diagenetic evolution of potential reservoir rocks within the Jurassic sedimentary section along the Levant margin in Israel in order to track evidence for the accumulation of hydrocarbons within these rocks. Paragenetic sequence study is a useful tool for the reconstruction of burial history of sedimentary rocks. Guided by lithostratigraphic description and electric logs, sampling efforts targeted rock cuttings and drill cores from the richest clastic intervals recovered from boreholes in the coastal plain and offshore central Israel. A petrographic examination of the cement phases suggests their relative age and paragenetic sequence. Twenty-seven samples had been studied, using optical polarizing microscope, Scanning Electron Microscope (SEM) and specialized cathodoluminescence microscope (CL). Massive cement is noticed in most of the samples and the porosity in most of the samples is very low, and no hydrocarbons have been detected in them. Among the observed authigenic minerals, the most significant are the carbonate minerals. Four authigenic carbonate minerals were observed: calcite, siderite, ankerite and dolomite. Calcite is the most common cement mineral, and appears in different phases, of eogenetic and mesogenetic formation to late fracture-filling cementation. The other three carbonate cement minerals are of eogenetic to mesogenetic formation. Additional authigenic minerals are: pyrite, quartz, chalcedony, oligoclase, clay minerals and gypsum. Comparing the Jurassic cementation of the current study and the Lower Cretaceous rocks cementation of the Heletz Formation, it seems that the Jurassic rocks had experienced most of the cementation in its early burial stages, and prior to the Middle Cretaceous burial cementation found at the Heletz-Kokhav oil field. The Jurassic rocks diagenesis shows signs of ferrous-dolomitization in places, though it is considerably less than the hydrocarbon-related ferrous-dolomitization that the Heletz Formation diagenesis recorded.