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Abstract: Time-Lapse Resistivity Log Responses in Horizontal Wells, Namorado Reservoir, Albacora Field, Campos Basin, Offshore Brazil

GOMES, RICARDO M. R., Colorado School of Mines, Dept. of Geology and Geological Engineering, Golden, CO

The Campos Basin is located offshore of the Southeastern Brazilian coast. The Upper Cretaceous sand-rich turbidites of the Namorado reservoir accounts for 22% of the total oil equivalent recoverable in the Albacora Field.

A development strategy using horizontal wells was delineated for the Namorado reservoir. The first horizontal well presented abnormal resistivity "horns" in the logged reservoir interval and higher resistivity readings than logs from previous vertical wells. The second horizontal well was drilled using a LWD 2MHz resistivity tool and seven time-lapse logs were obtained. These logs show a growing pattern for the resistivity "horns" with the increment in the time lapse.

The main purpose of this thesis is to explain the anomalous resistivity response in the horizontal wells of the Namorado reservoir, improving the knowledge of the principal effects acting in the horizontal well log environment.

The research will include the discussion of the principal features acting in the horizontal environment and their influence on log interpretation. A detailed reservoir characterization for the Namorado turbidite deposits will allow the establishment of a precise layering framework in order to construct stratigraphic profiles along the azimuth of the two horizontal wells. Detailed analysis of the time-lapse logs will provide important clues for this interpretation.

The interpretation will be checked using the tool response modeling technique. The quality of the adjustment between the real and simulated logs will support the proposed geologic model for the reservoir.

AAPG Search and Discovery Article #90931©1998 AAPG Foundation Grants-in-Aid