Acoustic and dielectric properties and network models of tight-gas sandstones. Annual report, July 1985-June 1986

Technical Report · Tue Jul 01 04:00:00 EDT 1986

OSTI ID:6048790

Nur, A

Nuclear magnetic resonance (NMR) data were inverted to obtain the surface area to volume ratio (S/V) of the pore space of a sandstone. The variation of S/V with water saturation (Sw) shows the increasing importance of surface effects as Sw decreases. Ultrasonic compressional and shear velocities were measured as functions of differential pressure to 50 MPa and Sw on 80 sandstone samples with porosity ranging from 0.02 to 0.50 and volume clay ranging from 0.0 to 0.50. Vp and Vs for clean sandstones exhibit a linear dependence on porosity. Vp and Vs data for sandstones containing clay are noticeably distinct from those for clean sandstones and show a linear dependence on porosity and clay content. The presence of water causes a decrease in the shear and bulk moduli and consolidated shaly sandstones, but an increase in these moduli in unconsolidated shaly sandstones. An apparatus was built to measure complex shear and compressional moduli of rocks over the frequency range of 5 kHz to 1 MHz. Data collected using a sample of Vycor porous glass show effects due to geometrical dispersion and due to frequency-dependent moduli. The low-velocity and large-moduli dispersion at frequencies below 100 KHz are interpreted as due to the influence of adsorbed water films.

• Research Organization: Stanford Univ., CA (USA). Dept. of Geophysics
• OSTI ID: 6048790
• Report Number(s): PB-87-207155/XAB
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
030900* -- Natural Gas-- Artificial Stimulation
Plowshare-- (-1989)
DIELECTRIC PROPERTIES
ELECTRICAL PROPERTIES
ENHANCED RECOVERY
GEOLOGIC DEPOSITS
HYDROGEN COMPOUNDS
ISOTHERMS
MAGNETIC RESONANCE
MATHEMATICAL MODELS
MINERAL RESOURCES
NATURAL GAS DEPOSITS
NUCLEAR MAGNETIC RESONANCE
OXYGEN COMPOUNDS
PERMEABILITY
PHYSICAL PROPERTIES
RECOVERY
RESONANCE
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SURFACES
WATER