Physical Modeling of AVO Responses

Seismic amplitude versus offset (AVO) methods are a well established practice for the direct indication of hydrocarbons, and are proven using both numerical modeling and field data. However, from a laboratory stand-point, AVO techniques have not to date been demonstrated in practice. This paper presents a first case of a physical model which was used to practically demonstrate the use of AVO for the separation of a hydrocarbon (oil) from pure water or brine. The physical model was also used to demonstrate how AVO cannot be used to separate water from a brine (30,000 ppm NaCl). A test using dissolved CO2 in water showed that an amount of 0.1 mol% was inadequate for seismic detection. The physical model was also used to demonstrate the complexities of the oil/gas/water mix, where it was possible to show how under certain circumstances, gas bubbles can remain trapped between oil and water.