Abstract: Seismic Properties of a Venezuelan Heavy Oil in Water Emulsion

Francisco Maldonado, Yuguang Liu, Gary Mavko, Tapan Mukerji

Several procedures for the production of low-viscosity, surfactant-stabilized, easy-transportable dispersions of heavy crude oil in water--briefly, oil in water (or o/w) emulsions--have been recently patented. Some of them propose to form the o/w emulsion in the reservoir, after the injection of a mixture of water and surfactants, increasing significantly the per well daily production.

Progression of the o/w emulsion front, through the reservoir to the production wells, can be monitored in seismic planar slices with successive 3D seismic surveys (4D seismic), if enough contrast exists between the seismic velocity value of the o/w emulsion and the one of the oil in place.

To facilitate the analysis of the contrast, this study presents high frequency acoustic velocity measurements performed in the laboratory. The experimental setup includes two reflectors and an ultrasonic transducer with double burst train emission. The estimated velocity precision is 0.02%. The measured samples are: a Venezuelan heavy o/w emulsion, a mixture of the same heavy oil and gasoil and a saturated sandstone core containing the o/w emulsion.

Additionally, seismic velocities of the actual pore fluids--live oil and live o/w emulsion--and saturated sandstone are calculated using the above laboratory measurements, Wood's equation, and Gassman's and Biot's models.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela