Cerro Negro is a heavy oil strategic association, located in the eastern portion of the ‘Orinoco Heavy Oil Belt’, of Venezuela. The 700-feet thick reservoir sands are assigned to the early and middle Miocene Morichal Member of the Oficina Formation. The Morichal is a transgressive fluvial to estuarine and marine sedimentary sequence, and is informally divided in to Lower, Middle and Upper units. Sands were deposited in valley fairways and show a high degree of lateral variability. This stratigraphic variability has an important impact on the seismic response. This reponse, or acoustic impedance, is directly proportional to the density and velocity differences of the lithological units. Most of the seismic impedance contrast in Cerro Negro is caused by ‘tuning effects’, due to thickness variations of the reservoir units. The use of the seismic data was instrumental for deciphering the complex relationships in the reservoir, and designing a 121 horizontal well drilling program. The integrated team approach, and the use all the well and seismic data available, was critical in the success of the first phase of the project.

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