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Integrated Prospect Evaluation Using Electromagnetic, Seismic, Petrophysical, Basin Modeling, and Reservoir Engineering Data

Elizabeth Lorenzetti Harvey, Odd-Petter Skogly, Tracy Burke, and Luiz Amado
Shell International Exploration and Production Inc, Houston, TX

A deepwater prospect in the Campos Basin, Brazil, was evaluated using a combination of geophysical and geological technologies including controlled-source electromagnetic data, seismic amplitude-vs.-offset and inversion data, basin- and prospect-scale modeling of hydrocarbon generation and migration, and petrophysical input to reservoir engineering models. The integration of these disciplines produced a consistent story for the prospect that reduced the uncertainty of the interpretation. Key uncertainties were the presence of reservoir and the presence, quality, and producibility of hydrocarbons. Many of the analyses, considered alone, were inconclusive or highly uncertain. Combining the analyses increased confidence in the interpretation, and several scenarios were dropped. For example, seismic forward modeling results using petrophysical trend data were ambiguous regarding the presence of reservoir and hydrocarbons. Reservoir engineering and offset well data suggested a likelihood of heavy oil with a seismic response similar to brine. Seismic AVO analysis indicated a weak response at the crest of the structure. Seismic inversion results supported the presence of reservoir, but indicated a wet response in all but the most crestal areas of the prospect. Prospect-specific basin modeling indicated that hydrocarbon migration into the prospect was unlikely, although an oil discovery was located only a few kilometers away. Electromagnetic data were acquired over the prospect and showed a negative response. This result was used to downgrade scenarios that could not be discounted with other data types. The integration of these data and methods has served to downgrade a prospect that has been in the exploration portfolio inventory for five years.