Abstract
The Controlled Source Electromagnetic Method (CSEM) is used for offshore hydrocarbon exploration. Hydrocarbon detection in seabed logging (SBL) is a very challenging task for deep hydrocarbon reservoirs. The electromagnetic field response of an antenna is unable to detect deep hydrocarbon reservoirs due to a weak electromagnetic signal response in the seabed logging environment. This work premise deals with the comparison of the electromagnetic signal strength of a new antenna with a straight antenna and the orientation of an antenna for deep target hydrocarbon exploration. Antenna position and orientation (Tx and Ty) was studied using Computer Simulation Technology software (CST) for deep targets in marine CSEM environments. The model area was assigned as (40 ′ 40 km) to replicate the real seabed environment. From the results, the new dipole antenna shows an 804% and 278% increase in electric and magnetic field strength than the straight antenna. An electric (E) and magnetic (H) field component study was done with and without the presence of a hydrocarbon reservoir. Ex and Hz field component responses with the new antenna at the1 kmtarget were measured in a deep water environment. It was analyzed that the antenna shows 53.10% (Ex) and 83.13% (Hz) field difference in deep water with and without a hydrocarbon reservoir at the30 mantenna position from the sea floor. From the antenna orientation results, it was observed that, the electric field Ex and magnetic field Hz responses decreased from 18% to 12% and 21% to 16%, respectively but was still able to detect the deep target hydrocarbon reservoir at the4 kmtarget depth. This EM antenna may open new frontiers for the oil and gas industry for deep target hydrocarbon detection (HC).
Highlights
Seabed logging is an application of the control source electromagnetic method which is used to locate an oil reservoir beneath the sea floor by measuring electromagnetic fields [1,2,3,4]
This section focuses on the comparison of the new curved antenna electromagnetic field strength to a straight antenna
Changing of the antenna orientation from the y direction to the x direction caused an electric field response decrease from 18% to 12% and the Hz field strength from 21% to 16% but the hydrocarbon reservoir could still be detected at the 4 km target depth
Summary
Seabed logging is an application of the control source electromagnetic method which is used to locate an oil reservoir beneath the sea floor by measuring electromagnetic fields [1,2,3,4]. In the control source method, a horizontal electric dipole antenna is towed by a surface vessel at a short distance from the sea floor [57]. In a large resistive layer such as hydrocarbon, electromagnetic energy flows along the reservoir (described as a guided wave) and is detected by the stationary sea floor electric or magnetic field detectors which are deployed on the sea floor. A 1D numerical model for a marine CSEM environment with the change of water depth and change of frequency was reported [19]. His proposed model consists of a 1 kmdeep target depth, with a sea water layer of (0.3 Ωm) over a (1 Ωm) half-space. A 100 m thick, 100-Ohm-m resistive layer representing a hydrocarbon reservoir is embedded at 1km below the seafloor for the 1D reservoir
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