Sonic/Acoustic Logs

Sonic log data give us the speed of elastic waves in the rock around the borehole - but not directly. Extracting wavespeeds is a complex procedure which to a large extent relies on an interpretation.

An operating company may wish to verify a previous processing, or reprocess a log with a specific purpose in mind, for example to extract mechanical properties.

Eriksfiord carries out quality control, data analysis and processing of sonic logs, and calculate mechanical rock properties from density and sonic information.

Of particular interest is the shear wave speed which can be measured either from a non-directional (monopole) source, or inferred from the flexural wave from a directional (dipole) source.

The shear wave will be polarized in an anisotropic rock. Hence both the speed and the direction of the shearwave can be extracted. Under certain favourable circumstances, information about microfracturing, rock texture and rock stress can be gained.

Dipole processing, when done uncritically, can give misleading results. Conversely, interesting information may remain hidden in the data. Eriksfiord therefore performs a thorough and independent quality control, and provides an extensive documentation of the processing.