The innovative application of horizontal drilling technology has made the Petrozuata development project in Venezuela a great success. Petrozuata is the first of four strategic associations implementing an integrated development in the Faja trend, which contains 1.36 trillion barrels of oil in place and is one of the world’s largest heavy oil accumulations. The joint venture of Petroleos de Venezuela, S.A. (PDVSA) and Conoco, Inc., drilled 101 single lateral and 140 multi-lateral horizontal wells in the Zuata Field from 1998 to 2001 as a means of delivering production rates of up to 3000 BOPD per well from reservoir sands of 8° to 10° API oil.

Well test interpretation and analysis techniques have been applied to both single and multi-lateral horizontal wells. This paper summarizes the methodology developed to analyze pressure build up (PBU) tests in the single lateral horizontal wells and recent experiences with the application of state of art PBU analysis techniques in the Zuata field wells.

Because of the geological complexity of the fluvial-deltaic reservoir sands and the peculiar transient pressure behavior, it was necessary to integrate analytical techniques that identified the various flow regimes with numerical analysis that further quantified the analytic interpretation. The integrated approach allowed for improvements in the conventional analytical interpretation and provided a basis of incorporating refinements in the reservoir description when combined with geological and petrophysical data and interpretation.

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