Wave attenuation in partially saturated rocks

Mavko, G.; Nur, Amos

doi:10.1190/1.1440958

Cited by 411 publications

(255 citation statements)

References 2 publications

Supporting

Mentioning

227

Contrasting

Unclassified

Order By: Relevance

“…Compressional wave velocity changes little until the pore spaces are fully saturated with water because the air in partially saturated pore fluids diminishes the stiffness of the pore fluids and hardly contributes to strengthening the rock frame. On the other hand, when there is an increase in water saturation, the compressional wave attenuation-that is related to energy dissipation-tends to increase more sensitively than velocity (Gardner et al 1964;Toks} oz et al 1979;Mavko and Nur 1979;Murphy 1982;Winkler and Nur 1982;Cadoret et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Effect of Partial Water Saturation on Attenuation Characteristics of Low Porosity Rocks

Kwon

Cho

2010

Rock Mech Rock Eng

View full text Add to dashboard Cite

Section: Introductionmentioning

confidence: 99%

Effect of Partial Water Saturation on Attenuation Characteristics of Low Porosity Rocks

Kwon

Cho

2010

Rock Mech Rock Eng

View full text Add to dashboard Cite

“…It is therefore not surprising that many attempts have been made to incorporate fractures into rock models, and especially models that try to account for partial saturation effects and the possibility that fluid moves (or squirts) during the passage of seismic waves (Budiansky and O'Connell, 1975;O'Connell and Budiansky, 1977;Mavko and Nur, 1979;Mavko and Jizba, 1991;Dvorkin and Nur, 1993). Previous attempts to incorporate fractures have generally been rather ad hoc in their approach to the introduction of the fractures into Biot's theory, if Biot's theory was used at all.…”

Section: Introductionmentioning

confidence: 99%

Elastic wave propagation and attenuation in a double-porosity dual-permeability medium

Berryman

Wang

2000

International Journal of Rock Mechanics and Mining Sciences

228

124

View full text Add to dashboard Cite

To account for large-volume low-permeability storage porosity and low-volume highpermeability fracture/crack porosity in oil and gas reservoirs, phenomenological equations for the poroelastic behavior of a double porosity medium have been formulated and the coefficients in these linear equations identified. This generalization from a single porosity model increases the number of independent inertial coefficients from three to six, the number of independent drag coefficients from three to six, and the number of independent stress-strain coefficients from three to six for an isotropic applied stress and assumed isotropy of the medium. The analysis leading to physical interpretations of the inertial and drag coefficients is relatively straightforward, whereas that for the stress-strain coefficients is more tedious. In a quasistatic analysis, the physical interpretations are based upon considerations of extremes in both spatial and temporal scales. The limit of very short times is the one most pertinent for wave propagation, and in this case both matrix porosity and fractures are expected to behave in an undrained fashion, although our analysis makes no assumptions in this regard. For the very long times more relevant to reservoir drawdown, the double porosity medium behaves as an equivalent single porosity medium. At the macroscopic spatial level, the pertinent parameters (such as the total compressibility) may be determined by appropriate field tests. At the mesoscopic scale pertinent parameters of the rock matrix can be determined directly through laboratory measurements on core, and the compressiblity can be measured for a single fracture. We show explicitly how to generalize the quasistatic results to incorporate wave propagation effects and how effects that are usually attributed to squirt flow under partially saturated conditions can be explained alternatively in terms of the double-porosity model. The result is therefore a theory that generalizes, but is completely consistent with, Biot's theory of poroelasticity and is valid for analysis of elastic wave data from highly fractured reservoirs.

show abstract

“…White's model considers only one dispersion mechanism (mesoscopic flow) and this could lead to an underprediction of the amount of dispersion as a result of partial saturation (e.g., Carcione et al, 2003). An additional mechanism not considered by White's model, but believed to be responsible for the additional dispersion (at partial gas and full water saturation) observed at high frequencies, is squirt or local fluid flow (see Mavko and Nur, 1979, Winkler, 1985, Dvorkin et al, 1994, Carcione et al, 2003. The presence of fractures is also known to cause dispersion in saturated rocks through the squirt flow mechanism (see Chapman, 2003, Gurevich et al, 2009.…”

Section: Insight From Modelling Study and Discussionmentioning

confidence: 99%

Experimental observation of water saturation effects on shear wave splitting in synthetic rock with fractures aligned at oblique angles

Amalokwu

Chapman

Best³

et al. 2014

Geophysical Journal International

View full text Add to dashboard Cite

Contact NOC NORA team at publications@noc.soton.ac.ukThe NERC and NOC trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. SWS is commonly used for fractured rock characterisation and has been shown to be sensitive to fluid type. The presence of partial liquid/gas saturation is also known to affect the elastic properties of rocks. The combined effect of both fractures and partial liquid/gas saturation is still unknown. Using synthetic, silica-cemented sandstones with aligned pennyshaped voids, we conducted laboratory ultrasonic experiments to investigate the effect fractures aligned at an oblique angle to wave propagation would have on SWS under partial liquid/gas saturation conditions. The result for the fractured rock shows a saturation dependence which can be explained by combining a fractured rock model and a partial saturation model. At high to full water saturation values, shear wave splitting decreases as a result of the fluid bulk modulus effect on the quasi-shear wave. This bulk modulus effect is frequency dependent as a result of wave-induced fluid flow mechanisms, which would in turn lead to frequency dependent SWS. This result suggests the possible use of SWS for discriminating between full liquid saturation and partial liquid/gas saturation.3

show abstract

Wave attenuation in partially saturated rocks

Cited by 411 publications

References 2 publications

Effect of Partial Water Saturation on Attenuation Characteristics of Low Porosity Rocks

Effect of Partial Water Saturation on Attenuation Characteristics of Low Porosity Rocks

Elastic wave propagation and attenuation in a double-porosity dual-permeability medium

Experimental observation of water saturation effects on shear wave splitting in synthetic rock with fractures aligned at oblique angles

Contact Info

Product

Resources

About