Structural and stratigraphic study of the Sharyoof oil field, Block 53, in Say’un-Masilah basin using seismic reflection and well logging methods, Yemen

The Say’un-Masilah basin is one of the most prolific sedimentary basins in Yemen, and therefore it has attracted the attention of geologists and geophysicists for hydrocarbon prospection and exploration. The main objective of this research is to study the structural and stratigraphic subsurface features as well as to determine the lithological contents of the Sharyoof oil field, Block 53, in the Mesozoic rift basin, eastern Yemen, using seismic and well log data. The basic inputs in this study include log data, collected from six wells, such as gamma ray (GR), caliper, deep, and shallow laterlog resistivity (LLD, LLS), micro-spherically focused log (MSFL), photoelectric absorption index (PEF), and porosity tools (density, neutron, and sonic). In addition, seismic sections including 15 lines 2D, well tops, bottom, sheck shot, well header, and deviations were used to accomplish this study objective. The obtained results from the seismic profiles interpretations demonstrated the existence of a series of normal faults dissecting most of the mapped horizons toward NE-SW (major faults) and NW-SE and W-E (secondary faults) creating several graben and horst structures. Moreover, results analysis of the well log data indicates that the main lithology content is dominated by the presence of the carbonates (limestone and dolomite) in the Sa’ar Formations and Qishn Carbonates Member while the sandstones for the Qishn Clastics, Harshiyat, and Mukalla Formations. The lithostratigraphy succession consists of rock units ranging in age from Early to Upper Cretaceous age (from Sa’ar to Mukalla Formations). Furthermore, seismic section data allowed determining the subsurface feature styles from reflections maps of both isochronous (two-way travel time) on the tops of the Sa’ar to Mukalla Formations. They reflect the occurrence of several distinct structures (anticlines, synclines, and faults), added to trends of faulting (NW-SE dissected by NE-SW). The novel contribution of the present work consists in the identification of the structural characteristics of the Lower and Upper Cretaceous formations of Block 53 using new seismic lines. Therefore, the obtained results of this study allow determining the sections and composition holding the hydrocarbon reservoir characteristics. As such, this research can be used as a reference study.