Petrophysical properties of shallow marine sediments offshore Haifa Bay, Northern Israel
High-resolution geophysical data from the continental shelf offshore Haifa Bay identified a 72 m2 gas reservoir at water depths of ~40 to 110 m below sea-level. Postulating that fluid flow plays an important role in localizing free gas, along with the question whether the sedimentary record can serve as a basis for identifying stratigraphical levels in the overburden, the aim of this study is to investigate the petrophysical and sedimentary properties of the shallow sediments (<5 m deep) and to evaluate their potential to transmit fluids towards the seafloor. To achieve the previously specified goals, piston cores were subjected to a suite of petrophysical, and sedimentological analyses using analytical nondestructive high resolution X-Ray Computed Tomography (CT), Multi Sensor Core Logging (MSCL, that includes gamma-density and magnetic susceptibility) and using two empirical equations to evaluate permeability. Core splitting, smear slide and granulometry measurements were also executed. By juxtaposing the study over the active gas systems (seal failure) and over the stable area, the study shows a spatial overview of the above mentioned measurements. Integration of all measured parameters identify three lithological units: LU1 (0-0.8 m), LU2 (0.8-2.56 m), and LU3 (2.57-3.9 m), which is also supported by CT analysis of three different marine environments; littoral zone, bathyal zone, and sub-littoral zone. A NE-SW transect reveals a possible change in deposition and north to south Israel continental shelf properties shows a higher permeability in the south than the north. Burrowing prints and the calcite clay fraction present in the sedimentary column are thought to be the main mechanisms in transmitting fluids and both are favorable pathways and the cause of anisotropy affecting permeability values at the micro-scale. The contribution of this study to the current theoretical knowledge gaps in flow patterns and their controls is valuable, though needs to be furthered studied especially via true conditions experiment to resemble the subsurface and to keep the clay undisturbed.
This project is funded by the National Infrastructures, Energy and Water Resources.