Interpreting laboratory velocity measurements in partially gas-saturated rocks

Journal Article · Fri Jul 01 04:00:00 EDT 1994 · Geophysics; (United States)

DOI:https://doi.org/10.1190/1.1443666· OSTI ID:6954558

Gist, G A ^[1]

---

1. Exxon Production Research Co., Houston, TX (United States)

It is an old problem in rock physics that the saturation dependence of high-frequency laboratory velocities does not match the Biot-Gassmann theory commonly used to predict the effects of gas on seismic velocities. A new interpretation of laboratory velocity data shows that the saturation dependence is controlled by two previously published high-frequency acoustic mechanisms: (1) a gas pocket model that describes pressure equilibration between liquid and gas-saturated regions of the pore space, and (2) local fluid flow, induced by pressure equilibration in pores with different aspect ratios. When these two mechanisms are added to Biot theory, the result describes published velocity versus gas saturation data for a wide range of rock types. These two mechanisms are negligible at the lower frequencies of seismic data, so the saturation dependence of laboratory velocities cannot be used to predict the saturation dependence at seismic frequencies. The one laboratory measurement that is relevant for predicting the seismic velocity is the ultrasonic velocity of the dry rock. The dry-rock velocities should be used in the Biot-Gassmann theory to predict the full saturation dependence of the seismic velocities.

• OSTI ID: 6954558
• Journal Information: Geophysics; (United States), Journal Name: Geophysics; (United States) Vol. 59:7; ISSN GPYSA7; ISSN 0016-8033
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200 -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
58 GEOSCIENCES
580000* -- Geosciences
BENCH-SCALE EXPERIMENTS
CORRECTIONS
DATA ANALYSIS
DATA PROCESSING
GAS SATURATION
GEOLOGIC DEPOSITS
GEOPHYSICAL SURVEYS
MINERAL RESOURCES
NATURAL GAS DEPOSITS
PETROLEUM DEPOSITS
PROCESSING
RESOURCES
SATURATION
SEISMIC SURVEYS
SONIC LOGGING
SURVEYS
WELL LOGGING