Effect of kerogen on velocity anisotropy in source rocks

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:80222

Vernik, L; Liu, X; Nur, A ^[1]

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1. Stanford Univ., CA (United States)

A diverse collection of hydrocarbon source rocks have been studied to estimate the effect of organic richness (kerogen content) on their velocity anisotropy. The maximal values of P-wave and S-wave intrinsic anisotropy, respectively {var_epsilon} = 0.40 and {gamma} = 0.45, as measured at ultrasonic frequencies and under the effective pressure of 70 MPa in low-porosity source rocks, are reached at kerogen volumetric concentrations of 24 to 33% (the TOC range of 9 to 13%). The velocity variation with kerogen content for bedding-normal and bedding-parallel propagation was successfully modeled using a modification of the Backus averaging principle to account for the lenticular microstructure of source rocks dominated by the network of kerogen separating lens-like clay and siliceous particles. Anisotropy of high-porosity source rocks shows much lower absolute values and much weaker dependence on kerogen content. The organic richness of shales is a strong factor affecting the velocity versus porosity relation of these rocks and should be taken into account in lithology prediction problems.

• OSTI ID: 80222
• Report Number(s): CONF-941015--
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
58 GEOSCIENCES
ANISOTROPY
ATTENUATION
DATA ANALYSIS
GEOCHEMISTRY
NATURAL GAS DEPOSITS
PETROLEUM DEPOSITS
RESPONSE FUNCTIONS
SEISMIC SURVEYS
SEISMIC WAVES
SOURCE ROCKS
WAVE PROPAGATION