--> --> Pore Pressure Evolution in Offshore Suriname as Indicated by Well Analysis and 3-D Basin Modeling

2018 AAPG International Conference and Exhibition

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Pore Pressure Evolution in Offshore Suriname as Indicated by Well Analysis and 3-D Basin Modeling

Abstract

Pore pressure evolution is one important process characterizing petroleum systems in a basin. For instance, reservoir quality and seal capacity are closely related to development of pore pressure and effective stress history. As present-day state of pore pressure and effective stress are not necessarily representative their entire history, it is worth assessing pore pressure development through geological time. In this study, mega-regional scale pore pressure evolution was reconstructed in offshore Suriname by a combination of well analysis and 3D basin modeling. Well analysis revealed that three mechanisms contributed to overpressure generation in the study area: (1) disequilibrium compaction, (2) smectite to illite transformation, and (3) hydrocarbon generation. All the processes were taken into account in the 3D basin modeling. As a result of the combined approach, pore pressure evolution was reconstructed from Mesozoic through present-day. It was indicated that overpressure currently developed in the Upper Jurassic - Miocene units in outer shelf to deepwater offshore Suriname. The current overpressure was mainly caused by a high sediment input during Pliocene - Pleistocene. Disequilibrium compaction is the most contributing factor for overpressure generation. Hydrocarbon generation also plays a certain role by adding further overpressure in the deeper part of the basin. Effect of clay mineral transformation is relatively minor in the study area. As overpressure developed in the latest stage of the burial history, effective stress within the Mesozoic units reached its maximum value before Pliocene – Pleistocene overpressure generation. Therefore, present-day effective stress in the Pliocene – Pleistocene depocenter does not represent the historical maximum value. The pore pressure evolution reconstructed in the present study revealed complex effective stress history. It provides an insight into the petroleum systems in offshore Suriname, especially for understanding their elements such as reservoir quality and seal capacity.