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Geomechanical characterization by estimating the Vp/Vs ratio of sedimentary rock samples

Matuła Rafał, Lewandowska-Śmierzchalska Joanna, Fąfara Zbigniew

AGH Drilling, Oil, Gas

2019

Vol. 36, no. 3

5--14

The velocity ratio Vp/Vs and elastic parameters are effective quantities for describing various physical parameters and lithological properties of rock samples. Ultrasonic measurement was used to evaluate the Vp/Vs ratio. Ultrasonic velocity estimation is widely used in the quantitative evaluation of rock materials. Ultrasonic P and S-wave travel times were studied in one direction of cylindrical core samples with a length and diameter of 100 mm. Wave velocity analysis was carried out on 20 crystalline drill cores taken at depths ranging from 10 m to 80 m. The cores were then tested for their ultrasonic velocity. The studied samples were also geomechanically characterized using ultrasonic testing. In this paper, the method used and a brief description of the measurement geometry are presented. The results of the calculations of P and S wave velocities, Vp/Vs ratio, Young’s modulus and Poisson’s coefficient are given. Finally, the studied samples were geologically classified and the Vp/Vs ratio was discussed.

Upper lithospheric structure in the central Fennoscandian shield: Constraints from P- and S-wave velocity models and Vp/Vs ratio distribution of the BALTIC wide-angle seismic profile

Janik T.

Acta Geophysica

2010

Vol. 58, no. 4

543-586

The paper presents an analysis of the crust and upper mantle structure in the central Fennoscandian shield based on new P- and S-wave 2D velocity models of the BALTIC wide-angle reflection and refraction profiles. Using reprocessing of the old data, new P- and S-wave velocity models and V p /V s ratio distribution were developed. Moving from SW to NE, the thickness of the crust varies strongly, from ∼36 km to extremely thick, 58-64 km, crossing Wiborg rapakivi massif, Saimaa and Outokumpu areas, and Eastern Finland complex. Based on the lateral variations of V p , V p /V s and thickness of the crust, three main blocks of the crust and upper mantle were distinguished from SW to NE: southwestern, associated with Wiborg rapakivi massif; the central, having the highest thickness of the crust; and the northeastern, not well documented, with Archaean basement.