Alternate Stratigraphic Play for Santonian Aged Turbidite Lobes in Central Santos Basin, Brazil
Lauren J. Stiles
University of Louisiana at Lafayette/Woodside Energy (USA), Inc
Rifting of Africa from South America began the formation of the Santos Basin. The complex fill history of the basin was strongly influenced from uplifting of the Serra do Mar coastal mountain ranges in the Upper Cretaceous and organization of the Paraiba do Sul drainage system. The increased sediment influx in the Upper Cretaceous forced shelf progradation and deep-water turbidite sedimentation. Reorganization of Aptian aged salt due to sediment loading influenced local sand deposition. Upper Cretaceous Santonian aged turbidites filled accommodation space created by salt withdrawal. Amalgamated turbidite lobes were deposited in the lows and pinched out on the structural highs. These pinchouts against updip structural highs create the potential for a hydrocarbon trap.
Three exploration wells drilled on updip and downdip structural highs are located within the area of study. The two updip wells were drilled along the crest of a northeast-southwest structural ridge outside the turbidite lobes. The wells penetrated slightly older water-bearing Santonian aged sands. The downdip well was drilled on a four-way structural closure and penetrated the distal edge of the turbidite sand lobes. An oil column was found at the top of the interval. There are seismic amplitudes in the area of the well that extend updip above the oil water contact and stop before reaching the updip wells. This area of higher amplitude may represent a stratigraphic hydrocarbon trap. This study is the first step in evaluating additional hydrocarbon potential. Further amplitude analysis needs to be completed to de-risk the play concept.
AAPG Search and Discovery Article #90182©2013 AAPG/SEG Student Expo, Houston, Texas, September 16-17, 2013