"Seismic Properties of Hydrocarbon Fluids" 

De-hua Han, University of Houston

ABSTRACT

“Who care geophysics and seismic, all we care are hydrocarbon fluids”. This statement has been made 20 years ago (1995) by Dr. Michael Batzle as we facilitate support for the “Fluids/DHI” consortium. It seems too extreme; however it is true then, now, as long as we, geophysicists, have worked for hydrocarbon reservoir exploration and production.

Understand of seismic properties (velocity and density) of hydrocarbons and their effects on seismic data are essential to bridge seismic data with properties of hydrocarbon reservoirs.  In comparison with porous rocks, hydrocarbon fluids appear to be simple as elastic (infinity Q) and uniform (scaleless), but complicated with dynamic phases. Hydrocarbon fluids in a single phase are usually composed of different compounds, especially gas can dissolve into oil, which called under-saturated. With pressure decreases below the bubble pressure, gas can bubble out of oil, became gas-oil (two saturated fluid phase) mixture. Properties of two phase mixture can be calculated by the Wood equation (1955) based on properties of each single phase. Therefore, we measured properties of hydrocarbon fluids in a single phase with ultrasonic technique on samples with a minimal volume (~30 cc).

We have measured hundreds hydrocarbon fluids samples from worldwide reservoirs at in situ conditions: pressure up to ~25000 Psi and temperature from sub-zero to over 200 °C.  In this presentation, I will present measured data and developed models of hydrocarbon fluids include mainly brine, gas and oil, as well as their applications for quantitative seismic interpretation and reservoir monitoring.