Fluid substitution: Estimating changes in V{sub P} without knowing V{sub S}
- Stanford Univ., CA (United States). Rock Physics Lab.
Two methods are presented for estimating the change of seismic P-wave velocity that accompanies pore fluid changes in a rock in the common situation when S-wave velocity is unknown. In contrast, Gassmann`s relation operates on the rock bulk modulus, which can only be calculated when both V{sub P} and V{sub S} are measured. The first method operates directly on the P-wave modulus and is equivalent to replacing the bulk moduli of the rock and mineral in Gassmann`s relation with the corresponding P-wave moduli. The second method uses a graphical construction to estimate the decomposition of the measured P-wave modulus into bulk and shear moduli, when then allows the conventional Gassmann`s formula to be used. When applied to a large set of sandstone data, the predictions of both methods, computed with V{sub P} only, are within a few percent of the Gassmann`s relation, using both V{sub P} and V{sub S}.
- OSTI ID:
- 175957
- Journal Information:
- Geophysics, Journal Name: Geophysics Journal Issue: 6 Vol. 60; ISSN 0016-8033; ISSN GPYSA7
- Country of Publication:
- United States
- Language:
- English
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