M. Batzle

Fluids and frequency dependent seismic velocity of rocks

Summary Compressional and shear velocities of rocks are dependent on frequency and this dispersion may be significant even within the seismic band. The amount and position of dispersion will be largely a function of fluid properties, distribution, and motion in the pores. Velocities are thus directly coupled to rock permeability and pore compliance. Propagation often will be in the high frequency regime, even at a few tens of Hertz. Static, or low frequency models such as Gasmann will fail under such conditions. In addition, Biot theory will not correctly model wave propagation in many cases.

Heavy oils: A worldwide overview

Heavy oil is defined by the U.S. Department of Energy as having API (American Petroleum Institute) gravities that fall between 10.0° and 22.3° (Nehring et al., 1983). Extra-heavy oils are defined as having API gravities less than 10.0° API. Heavy oils are classified as such using API gravity rather than viscosity values. Two important distinctions must be made between API gravity and viscosity. First, viscosity determines how well oil will flow while API gravity typically determines the yield from distillation. Additionally, temperature and paraffin content can have a large effect on viscosity values while API gravity is not affected by these parameters.

CO2 velocity measurement and models for temperatures up to 200°C and pressures up to 100 MPa

Studies on how the velocity of C O2 is affected by temperature and pressure are important for understanding seismic properties of fluid and rock systems with a C O2 component. We carried out laboratory experiments to investigate velocity of C O2 in temperatures ranging from −10°C to 200°C and pressures ranging from 7 MPa to 100 MPa , in which C O2 is in a liquid phase. The results show that under the above conditions, in general, the velocity of C O2 increases as pressure increases and temperature decreases. Near the critical point ( 31.1°C and 7.38 MPa ), the velocity of C O2 reaches a minimum and has a complicated behavior with temperature and pressure conditions due to the C O2 transition between gas and liquid phases. We also developed preliminary empirical models to calculate the velocity of C O2 based on newly measured data.

Shear velocity as the function of frequency in heavy oils

The velocity behavior in heavy oil depends on oil phase (Han et. al, 2006). As shown in Figure 1, heavy oil in the liquid phase at a higher temperature, S-wave velocity is negligible and P-wave velocity shows negligible frequency dependent, similar as conventional liquid oil. We have found a threshold of viscosity for the liquid phase of heavy oil is ~ 10 cp) there are both Pand S-wave velocities which have negligible frequency dependent dispersion, similar as an elastic solid. However, there is transition zone called quasi-solid phase for heavy oils. In this phase, viscosity of heavy oil is high enough to bear the shear stress. In addition, both shear rigidity and bulk modulus of the heavy oil are frequency dependent: high at ultrasonic, but low at sonic and seismic (Han et. Al., 2005). Clearly, we need to quantify the velocity dispersion behavior.

Velocities of deepwater reservoir sands

Deepwater reservoirs, those in water depths ranging from 1000 m to more than 3000 m, often consist of young turbidite sediments associated with early hydrocarbon charge, overpressure buildup, and seal with retarded diagenesis. Deepwater sands maintain shallow properties even at great depths (e.g., 18 000 ft) but these weakly cemented sands—with a history of progressive compaction and cementation—differ from surface sediments.

Velocity And Dispersion of Heavy Oils

Acoustic properties of heavy oils have been investigated based on laboratory measurement and modeling studies. Based on newly measured shear velocity data in extended low temperature, we have revealed a full spectrum of shear velocity of heavy oils as function of temperature, which we have applied to calibrate viscosity of heavy oils. A series of models has been developed to describe both Sand P-wave velocities of heavy oils as function of temperature and frequencies

CO2 Velocity Measurements and Models for Temperatures down to -10 °C and up to 200 °C and Pressures up to 100 MPa

Summary Studies concerning how CO2 velocity is affected by a wide range of temperatures and pressures are important in understanding CO2 behavior in fluid and rock systems. Three laboratory experiments were carried out to investigate the effect of temperature and pressure on CO2 velocity for the range and 7

CO2 velocity measurement and models for temperatures up to 200°C and pressures up to 100 MPaCO2 velocity measurement and models

Studies on how the velocity of C O2 is affected by temperature and pressure are important for understanding seismic properties of fluid and rock systems with a C O2 component. We carried out laboratory experiments to investigate velocity of C O2 in temperatures ranging from −10°C to 200°C and pressures ranging from 7 MPa to 100 MPa , in which C O2 is in a liquid phase. The results show that under the above conditions, in general, the velocity of C O2 increases as pressure increases and temperature decreases. Near the critical point ( 31.1°C and 7.38 MPa ), the velocity of C O2 reaches a minimum and has a complicated behavior with temperature and pressure conditions due to the C O2 transition between gas and liquid phases. We also developed preliminary empirical models to calculate the velocity of C O2 based on newly measured data.

velocity measurement and models for temperatures up to and pressures up to 100 MPa

Studies on how the velocity of C O2 is affected by temperature and pressure are important for understanding seismic properties of fluid and rock systems with a C O2 component. We carried out laboratory experiments to investigate velocity of C O2 in temperatures ranging from −10°C to 200°C and pressures ranging from 7 MPa to 100 MPa , in which C O2 is in a liquid phase. The results show that under the above conditions, in general, the velocity of C O2 increases as pressure increases and temperature decreases. Near the critical point ( 31.1°C and 7.38 MPa ), the velocity of C O2 reaches a minimum and has a complicated behavior with temperature and pressure conditions due to the C O2 transition between gas and liquid phases. We also developed preliminary empirical models to calculate the velocity of C O2 based on newly measured data.

Seismic signature of reservoir recovery processes

Summary Recovery processes are complex and usually oversimplified in geophysics. Time lapse seismic monitoring of these different processes will often be complicated and lead to conflicting interpretations. Pressure, temperature, or density changes can out weigh effects due to fluid replacement. Small concentrations of free gas can appear even during liquid or supercritical injection and will lower velocities unexpectedly. Fluid compositional and phase analysis can help predict the seismic response.