Delineation of Hydrocarbon with Variation of Overburden Thickness for Sea Bed Logging Applications

Abstract

There are various methods being used to model and study behavior of electromagnetic (EM) waves in controlled source electromagnetic (CSEM) environment. Sea Bed logging (SBL) is using CSEM technique in detecting and characterizing hydrocarbon bearing reservoirs in deep water areas. It uses a mobile horizontal electric dipole (HED) source called transmitter that transmits low frequency of 0.1Hz to 10Hz, 30m - 40m above sea bed and an array of seafloor electric field receivers. These signals depend on the resistivity structure beneath the sea bed as hydrocarbon is known to have high resistivity value of 30 500 Ωm in contrast to sea water layer of 0.5 2 Ωm and sediments of 1-2 Ωm. Array of seafloor receivers detect EM energy that propagates through the sea and subsurface. Data collected is used for processing and modeling purposes to predict depth of resistive bodies. In this paper, synthetics data generated from developed simulator that is able to replicate SBL environment is compared to synthetics data generated from Computer Simulation Software (CST) and COMSOL software with same parameter setting to study trends between them. Percentage differences between data with hydrocarbon and without hydrocarbon are calculated and comparisons are made. Overburden thickness is varied from 1000m to 3000m (incremented by 500m) at frequency of 0.125Hz. It was found that all the data generated either from simulator, CST software and COMSOL showing the same trends. From these findings it shall conclude that the simulator is a reliable tool to model any sea bed logging environment and predicting present of hydrocarbon reservoir in SBL environment.