Kola Superdeep Borehole at UWYO

Analysis of log and seismic data from the world's deepest Kola Borehole

The Kola Superdeep Borehole (KSDB, also often referred by its Russian acronym as SG-3) is the world’s deepest borehole. Since the beginning of drilling in 1970, this borehole has been a site of extensive geophysical studies [Kozlovsky, 1987]. KSDB was cored nearly continuously from the surface to its total depth of 12.26 km. This extent of geophysical logging is an outstanding feature of KSDB, considering that the second deepest scientific borehole, KTB in Germany, was hardly cored below 4 km [Lüshen et al., 1996]. By correlating the KSDB log data with the results of the recent CDP and VSP seismic experiments carried out by the University of Wyoming, we arrive at significant conclusions about the physical state of deep crystalline rocks and about the nature of deep seismic reflections.

Geological sketch map of the Pechenga region; the borehole labeled as KSDB.

Geological section of the KSDB derived from nearly continuos core extraction.

KSDB log data:

Sonic, caliper, resistivity, gamma, and density logs within 0-11.4 km depth range:

Four geophysical KSDB logs. Note sharp change in the character of all four logs at the depth of the LFZ (4.5-km).

Research targets:

The cause of log fluctuations: compositional or structural variations?

The nature of discordant subhorizontal reflections imaged in the CDP and VSP sections

Physical state of rocks

The role of fluids in the deep crust

Causes of seismic reflections; how well the reflectivity can be deduced from crustal logs?

Fractal properties of rock fracturing

Techniques applied in our data analysis:

Transformation of the 4-component records from Gal'perin VSP tool to standard Cartesian coordinates

Polarization analysis of VSP wavefield.

Statistical cross-log correlation.

Log attribute panels

Spectral analysis of log data

Hurst fluctuation range analysis

Igor Morozov | Yuri Ganchin | UWyo Seismology Group