Jiajin Liu

Seismic properties of heavy oils—measured data

Seismic techniques hold great potential for characterization and recovery monitoring of heavy oil reservoirs. However, to be more effective, we must understand the seismic properties of the heavy oils and the heavy oil sands because this knowledge of in-situ properties is key to linking the seismic response to reservoir properties and changes. In this article, we examine the seismic properties of heavy oils in detail.

Acoustic property of heavy oil - measured data

Summary Heavy oils are viscous fluid having three phases: fluid, quasi-solid and glass solid depended on temperature. We have measured ultrasonic velocities on 10 heavy oil samples at different phases. Measured data suggest that heavy oil properties are similar to the light oil properties if temperatures are higher than the liquid point. With temperature decreases below the liquid point, heavy oil transfers from liquid phase to a quasi-solid phase with drastic increase of viscosity, S-wave velocity appears measurable and P-wave velocity deviated up from the light oil trend. P- and S-wave velocities of heavy oils show a systematic relation to API gravity, temperature, pressure, GOR, and appear dispersive as heavy oil in the quasi-solid state. densities, gas-oil ratios and bubble points may not apply well to heavy oils. Heavy oil at high temperatures can be characterized similar as light oil. However, at low temperatures, viscosity of heavy oils increases drastically and properties of heavy oils are significantly different. We need study properties of heavy oil thoroughly in order to build a proper rock physics model for heavy oil reservoirs.

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.

Application of Spectral Decomposition to Detect Deepwater Gas Reservoir

In this paper, spectral decomposition techniques are applied to deepwater seismic data from Gulf of Mexico to examine the gas associated spectral anomalies. In the first case, thick gas sand with nearly constant P-impedance is encased in shale with non-symmetric P-impedance, and gas reservoir are bright at low-frequency iso-frequency sections; Commercial gas sand and low-gas saturated sand also show apparently different spectral characteristics. In the second case, gas reservoir includes two consecutive up-fining sand intervals with gradually changed P-impedance in each sand interval. Spectral anomalies of gas sand occur at highfrequency iso-frequency sections. Detailed forward modeling is analyzed to help understand the underlying physical mechanisms. Reservoir thickness and Pimpedance structure are the first order factors to control the spectral decomposition responses of the above two gas reservoirs. Systematic synthetic model based on reservoir properties is needed to select optimal frequency range to directly detect hydrocarbon for specific reservoir.

Viscosity model of Heavy Oil with calibration of shear velocity data

New data of the shear wave velocity of heavy oils using the transmission wave at low temperature combined with the data using reflection wave at high temperature provides the probability to build a complete model of shear velocity from liquid phase to solid phase. To get the more reasonable viscosity of heavy oils at low temperature, we modified the existing viscosity models with calibration by glass and liquid points from the shear velocity model. The HN frequency model with new optimal parameters can be used to fit the data with updated viscosity from the modified model. The HN model gives the estimation of shear properties of heavy oils including attenuation in frequency domain.

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

Measurement of shear wave velocity of heavy oil

It is well known that the fluids have no shear modulus and therefore no shear wave can propagate through fluids. But heavy oils have properties that are much complex than lighter oils. At low temperatures, heavy oils are extremely viscous and begin to act like solids. An effective shear modulus appears allowing propagation of shear waves. The bulk moduli of heavy oils increase since the bulk and shear moduli are related with each other. Therefore, it is observed that the compressional wave velocity of heavy oils increases faster than that of light oils at low temperatures.

Light Oil Measurement: Density, Velocity And Modulus From 23 to 200?C And At Pressures Up to 150 MPa

Summary A new density vessel has been made and calibrated. And meas urement procedures have been improved for measuring density and velocity of hydrocarbon fluids at temperature up to 200

Velocity and density of CO2 -oil miscible mixtures

Summary Different structure of CO2 from hydrocarbon gases and oils has a significant impact on properties of CO2-oil miscible mixtures in comparison with “live” oil with dissolved hydrocarbon gases. We have systematically investigated velocity and density of CO2 with different oil (API) mixtures above their bubble point. The measurement condition is ranged with CO2 GOR up to 310L/L, temperature from 40°C to 100°C, and pressure from 20MPa to 100MPa. Based on our updated database we have developed preliminary models for the velocity and density of the CO2-oil miscible mixtures.

Improvement of Density Model for Oils

We have developed a density model (Han and Batzle, 2000) to replace the one developed by Batzle and Wang (1992) for under-saturated oil with dissolved gas based on the engineering concept (McCain, 1973, 1990). In 2002, we had made the improvement of the model with new correction to cover pressure higher than 10,000 Psi (69 MPa). In order to apply the density model to “live oil” with high GOR at HTHP conditions, we have to further improve the model.