Elastic anisotropy of source rocks: Implications for hydrocarbon generation and primary migration

Journal Article · Mon Apr 01 04:00:00 EST 1996 · AAPG Bulletin

OSTI ID:249786

Vernik, L ^[1]; Landis, C ^[2]

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1. Stanford Rock Physics Lab., CA (United States)
2. ARCO Exploration and Production Technology, Plano, TX (United States)

We combined acoustic velocities and anisotropy measurements with x-ray diffraction mineralogy, Rock-Eval organic geochemical analyses, vitrinite reflectance, and scanning electron microscope observations on 69 cores of hydrocarbon source rocks collected from eight sedimentary basins. The velocity data indicate the lamellar distribution of solid organic matter (kerogen) in compacted black shales and show a strong correlation between their elastic anisotropy and organic richness. The experimental results are consistent with the two-component anisotropic model of black shales with a continuous kerogen network in both bedding-parallel and bedding-normal directions beginning from relatively low TOC values. The strong elastic anisotropy of tight, thermally mature source rocks is further enhanced by overpressure-induced bedding-subparallel microcrack development during the main stage of hydrocarbon (HC) generation and primary migration at R{sub o} greater than 0.75%. In agreement with published petrographic observations, these microcracks significantly aid primary HC migration, particularly horizontally. Elastic anisotropy of medium to high-porosity illite/smectite shales is weaker than in lower porosity, predominantly illite shales; however, the overall positive trend of elastic anisotropy with kerogen content remains unchanged.

• OSTI ID: 249786
• Journal Information: AAPG Bulletin, Journal Name: AAPG Bulletin Journal Issue: 4 Vol. 80; ISSN 0149-1423; ISSN AABUD2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
36 MATERIALS SCIENCE
ACOUSTIC MEASUREMENTS
ELASTICITY
EXPLORATION
HETEROGENEOUS EFFECTS
HYDROCARBONS
MIGRATION
ORIGIN
SOURCE ROCKS