AMT and CSAMT methods for hydrocarbon exploration at Nile Delta, Egypt

摘要

The offshore Nile Delta Basin, Egypt, has been known for a long time as a significant source of gas and oil. The study area is located on the Middle Eastern part of the Nile Delta near Mansoura City. The magnetotelluric method (MT) has emerged as a promising tool for oil exploration than any other geophysical technique. Hydrocarbon reservoirs typically exhibit higher electromagnetic resistivity than their surroundings. In this paper, the MT method was used to investigate the resistivity subsurface structure that related to hydrocarbon exploration, and the results were integrated with seismic data collected in the same area. The MT survey was performed using two frequency ranges: high (10 Hz to 100 kHz) and low (0.1 Hz to 1 kHz). Low-frequency natural MT waves were recorded using AMT only, and the measurement was then repeated using an artificial signal source for CSAMT. These surveys were carried out along three profiles having 22 sites. The recorded time-series data were transformed to the frequency domain and processed to determine apparent resistivities and phases at each site in which the determinant average of the impedance tensor was then used for 1D and 2D inversion. A good coherence was found between the electromagnetic and seismic profiles and shows that the hydrocarbon is exiting in the Abu Madi and Qawasim channel which represent the main gas-containing layers in the Nile Delta. The depth and extension of these layers were estimated and imaged with a maximum thickness of 4,000 m at profile 1 in the northwestern part of the study area.