3-D visualization of the 45-degree isosurface of the invariant phase. Each voxel corresponds to one frequency at one station, here converted to a pseudodepth. Phoenix calculates 40 frequencies in the MT spectrum, so there are approx. 32 x 32 x 40 voxels, each with many MT parameters. In this simple presentation, all voxels are shown as the same size.
Plan view of the MT parameter
Uzbekneftegaz, the state-owned oil and gas company of Uzbekistan, carried out several large 3-D MT surveys during 2008, using a multichannel Phoenix MT system. These results were first reported at the First Uzbekistan Electroprospecting Conference in Bukhara last November. One 3-D MT survey, in a mountainous area in southern Uzbekistan, comprised 1,020 MT stations on a nearly regular 12 km x 13 km grid (approx. 32 x 32 stations). Seismic is difficult and expensive in this type of terrain. The target gas-bearing formation is approx. 3,000 m deep, in an anticline approx. 10 km x 3 km, with 250 m relief. Several rounds of drilling and geophysical work have resulted in repeated revisions to the model of the complicated geological structure since its discovery with 2-D seismic in 1983.
Uzbekneftegaz used 3-D MT to help plan a future 3-D seismic survey. The innovative MT survey yielded a rich data set suitable for 3-D visualization and manipulations.
The figures at right are excerpted from 3-D MT Survey in Uzbekistan by Babadjanov et al., presented by Olex Ingerov at the MT seminar in Beijing in February