f Subsalt imaging using Non-Seismic methods in the Northern part of the Gulf of Suez, Egypt

Magnetic and MT soundings are important non-seismic methods, used to image the subsurface basement structures in the northern part of the Gulf of Suez. The Pre-rift Nubia Sandstone reservoir is considered as a main target for hydrocarbon exploration in the offshore Gulf of Suez. It is unconformably overlies the Precambrian basement rocks. The seismic data in this region is very difficult to interpret below the salt - anhydritic formations due to the poor reflections received from the deeper sediments, resulting in a very obscure lithological succession. However, the magnetic data and the MT soundings synthetic models are integrated with the available geological information to delineate the basement structural framework of the study area. The geophysical data include a total field intensity aeromagnetic map, three MT soundings synthetic models, in addition to borehole data from available twenty five drilled wells in the area. Qualitative and Quantitative interpretation of magnetic data are carried out, including the RTP, Residual-Regional separation using lease square polynomial, and Second Vertical Derivative (SVD) techniques. Trend analysis of the magnetic maps reveals four major dominant fault trends N45o W (Suez or Clysmic), N5o - 20o W (East African), W 10o - 30oE (Aqaba) and N 80o - 90o E (Mediterranean) trends. Depth to the Precambrian basement surface is estimated on selected profiles. The Results indicated that the thickness of the sedimentary cover ranges between 2.3 and 3.8 Km. Magnetic modeling for three selected profiles confirms the basement structures in the area. Fifteen structural cross sections are constructed. MT synthetic models are produced and correlated with the available seismic sections and the geological column of the area. The results from the three MT models show perfect correlation with the geologic column. As well as, some of thin events (less than 20 meters), that are not clear or do not appear on the seismic sections have also been indicated with the MT models. Finally, after this integration the basement structures are outlined and the Nubia Sandstone structure contour map is constructed. The study revealed that the area lies above a faulted basement block tilted to the northeast and bounded to the west by zigzag fault pattern. Three door trap structures are found at the edges of the block (denoted 1 to 3) due to the intersection between clysmic and oblique faults. Another block bounded by west dipping fault is believed to exist in the area based on the interpreted magnetic data. Detailed investigation will help to identify the hydrocarbon potentiality of this block. Further, exploration is advisable for Nubia Sandstone to the west in the up dip direction, where western sealed fault traps are expected.