Assessment of Fracture Properties from P-Wave Velocity Distribution

2011 ◽  
pp. 109-116 ◽  
Author(s):  
Jan Vilhelm ◽  
Vladimír Rudajev ◽  
Roman Živor
Keyword(s):  
Velocity Distribution ◽  
Wave Velocity ◽  
P Wave ◽  
Fracture Properties ◽  
P Wave Velocity

P‐wave velocity and permeability distribution of sandstones from a fractured tight gas reservoir

Geophysics ◽  
2002 ◽  
Vol 67 (1) ◽  
pp. 241-253 ◽  
Author(s):  
Helmut Dürrast ◽  
P. N. J. Rasolofosaon ◽  
Siegfried Siegesmund
Keyword(s):  
Velocity Distribution ◽  
Wave Velocity ◽  
Confining Pressure ◽  
P Wave ◽  
Tight Gas ◽  
Rock Fabric ◽  
The Core ◽  
Wave Velocities ◽  
P Wave Velocity ◽  
Tight Gas Reservoir

Fractures are an important fabric element in many tight gas reservoirs because they provide the necessary channels for fluid flow in rocks which usually have low matrix permeabilities. Several sandstone samples of such a reservoir type were chosen for a combined study of rock fabric elements and petrophysical properties. Geological investigations of the distribution and orientation of the fractures and sedimentary layering were performed. In addition, laboratory measurements were carried out to determine the directional dependence of the permeability and P‐wave velocities. Higher permeability values are generally in the plane of the nearly horizontal sedimentary layering with regard to the core axis. With the occurrence of subvertical fractures, however, the highest permeabilities were determined to be parallel to the core axis. Compressional wave velocities were measured on spherical samples in more than 100 directions to get the VP symmetry without prior assumptions. Below 50 MPa confining pressure, all samples show a monoclinic symmetry of the P wave velocity distribution, caused by sedimentary layering, fractures, and crossbedding. At higher confining pressure, sedimentary layering is approximately the only effective fabric element, resulting in a more transverse isotropic VP symmetry. Using the geological‐petrophysical model introduced here, the complex symmetry of the VP distributions can only be explained by the rock fabric elements. Furthermore, water saturation increases the velocities and decreases the anisotropy but does not change VP symmetry. This indicates that at this state, all fabric elements, including the fractures, have an influence on P‐wave velocity distribution.

Fine structure of P-wave velocity distribution along the Atotsugawa fault, central Japan

2009 ◽  
Vol 472 (1-4) ◽  
pp. 95-104 ◽  
Author(s):  
Takashi Iidaka ◽  
Aitaro Kato ◽  
Eiji Kurashimo ◽  
Takaya Iwasaki ◽  
Naoshi Hirata ◽  
...  
Keyword(s):  
Fine Structure ◽  
Velocity Distribution ◽  
Wave Velocity ◽  
P Wave ◽  
Central Japan ◽  
P Wave Velocity ◽  
Atotsugawa Fault

The effect of rock fabric on P-wave velocity distribution in amphibolites

1999 ◽  
Vol 114 (1-2) ◽  
pp. 39-47 ◽  
Author(s):  
V Vajdová ◽  
R Přikryl ◽  
Z Pros ◽  
K Klı́ma
Keyword(s):  
Velocity Distribution ◽  
Wave Velocity ◽  
P Wave ◽  
Rock Fabric ◽  
P Wave Velocity
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