Velocity anisotropy and X‐ray imaging of Barnett shale

Peña, Víctor H. de la; Chesnokov, Evgeni M.; Ortíz, Alberto; Kullmann, G.; Dyaur, Nikolay

doi:10.1190/1.3063714

Cited by 3 publications

(2 citation statements)

References 4 publications

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“…The bedding-plane velocities measured on samples should not be considerably different from the velocities measured in situ in this direction, since the bedding plane is not greatly affected by the weight of the overlying rock mass. We discover that the bedding-plane velocities found from the inversion are in good agreement with the velocities measured in this direction by Dyaur et al (2008) on shale samples. These samples represented a shale similar to that occurring at the depth interval 2052-2137 m (productive interval) for a well under study.…”

Section: Figuresupporting

confidence: 80%

Determination of shale stiffness tensor from standard logs

Chesnokov

Bayuk

Ammerman

2010

Geophysical Prospecting

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A B S T R A C TA technique allowing inversion of the shale stiffness tensor from standard logging data: sonic velocities, density, porosity and clay content is developed. The inversion is based on the effective medium theory. The testing of the technique on laboratory measurements of the elastic wave velocities in shale samples shows that the inversion makes it possible to predict the elastic wave velocities V P , V S1 and V S2 in any direction within an error of a few per cent.The technique has been applied for the stiffness tensor inversion along a well penetrating a shale formation of the Mississippian age altered by thin layers of limestone. It is demonstrated that the symmetry of a stiffness tensor inverted at the sonic frequency (2 kHz) is slightly orthorhombic and taking into account the experimental errors, can be related to the vertical transverse isotropy symmetry. For the productive interval of the shale formation, the Thomsen parameters ε, γ , and δ average, respectively, 0.32, 0.25 and 0.21, which indicate anelliptic behaviour of the velocities in this shale. The coefficients of anisotropy of this shale interval are around 24% and 20% for the compressional and shear waves, respectively. The values of the inverted velocities in the bedding plane for this interval are in good agreement with the laboratory measurements. The technique also allows inversion of the water saturation of the formation (Sw) and the inverted values are in agreement with the Sw values available for this formation.A Backus-like upscaling of the inverted stiffness tensors is carried out for the lower and upper bounds of the frequency band used in the crosswell tomography (100 Hz and 500 Hz). These results can serve as an initial velocity model for the microearthquake location during hydrofracking of the shale formation.

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Section: Figuresupporting

confidence: 80%

Determination of shale stiffness tensor from standard logs

Chesnokov

Bayuk

Ammerman

2010

Geophysical Prospecting

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“…For the elastic wave velocities this difference may be as high as 20 -25% [40].We also calculate the velocities in the lateral directions (Vp_x and Vsh_x, Table 3) and compare them with those measured in the bedding plane in laboratory for samples taken from similar formation. Figure 4 shows the experimental data reported by Dyaur et al [41]. As seen, the theoretical values obtained for the lateral direction are in good correspondence with those marked by ellipses in the plot shown in figure 4.…”

Section: Inversion Of Shale's Microstructure Parameterssupporting

confidence: 78%