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GEOREF RECORD

Seismic properties of pore fluids

M. L. Batzle and Zhijing Wang
Seismic properties of pore fluids
Geophysics (November 1992) 57 (11): 1396-1408

Abstract

Pore fluids strongly influence the seismic properties of rocks. The densities, bulk moduli, velocities, and viscosities of common pore fluids are usually oversimplified in geophysics. We use a combination of thermodynamic relationships, empirical trends, and new and published data to examine the effects of pressure, temperature, and composition on these important seismic properties of hydrocarbon gases and oils and of brines. Estimates of in-situ conditions and pore fluid composition yield more accurate values of these fluid properties than are typically assumed. Simplified expressions are developed to facilitate the use of realistic fluid properties in rock models.Pore fluids have properties that vary substantially, but systematically, with composition, pressure, and temperature. Gas and oil density and modulus, as well as oil viscosity, increase with molecular weight and pressure, and decrease with temperature. Gas viscosity has a similar behavior, except at higher temperatures and lower pressures, where the viscosity will increase slightly with increasing temperature. Large amounts of gas can go into solution in lighter oils and substantially lower the modulus and viscosity. Brine modulus, density, and viscosities increase with increasing salt content and pressure. Brine is peculiar because the modulus reaches a maximum at a temperature from 40 to 80 degrees C. Far less gas can be absorbed by brines than by light oils. As a result, gas in solution in oils can drive their modulus so far below that of brines that seismic reflection bright spots may develop from the interface between oil saturated and brine saturated rocks.


ISSN: 0016-8033
EISSN: 1942-2156
Coden: GPYSA7
Serial Title: Geophysics
Serial Volume: 57
Serial Issue: 11
Title: Seismic properties of pore fluids
Affiliation: ARCO Exploration and Production Technology, Plano, TX, United States
Pages: 1396-1408
Published: 199211
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 54
Accession Number: 1992-066294
Categories: Applied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: 1 table
Secondary Affiliation: CORE Laboratories, CAN, Canada
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 1992
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