On the Eexploration of Mud Volcanoes using Electromagnetic Techniques: a Case Study from Azerbaijan

Abstract

3 mud volcanoes in Perekishkul close to Baku/ Azerbaijan were chosen in order to study their conductivity structures by using shallow and deep electromagnetic techniques. Radiomagnetotelluric (RMT) and transient electromagnetic methods were applied to study the depth range up to 150 m. In order to examine depths up to 6 km, the so called long offset transient electromagnetic (LOTEM) method was used. RMT data were observed at 536 stations on 16 profiles crossing the mud volcanoes. The RMT data were then interpreted by 2D conductivity models. A 50m x 50m loop as transmitter and a 20m x 20 m receiver loop were used at 72 stations on 6 profiles for the TEM measurements. A laterally constrained inversion technique was applied on the TEM data to derive a quasi-2D conductivity model.750 m dipole was used as a galvanic source for the LOTEM method and a 33 A current was injected. Ex and dHz/dt components were measured at the receivers on a profile of the mud volcanoes. The 1D joint inversion of the LOTEM Ex and TEM data clearly resolve the conductivity structure up to a depth of 5 km indicating a relative high resistive hydrocarbon containing layer at this depth range.