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Universidade Fernando Pessoa

Porto, Portugal

This is the Home Page of the notes on "Sismo - Sequential Interpretation".

If you click on the interlinks (underlined text and bots), you can navigate and you will find a text and the majority of the plates shown during the course.

This interpretation of a seismic line of the deep-offshore of Angola was performed in terms of stratigraphic cycles, that is to say, seismic intervals deposited during eustatic cycles with different time durations. Some of these cycles correspond to sequence cycles deposited during 3rd order eustatic cycles (time duration between 0.5 My and 3-5 My), while others correspond to continental encroachment subcycles deposited during 2sd order eustatic cycles (time duration between 3-5 My and 50 My). The boundaries of these cycles correspond to unconformities (erosional surfaces) created by relative sea level falls, which displace seaward and basinward the coastal onlaps. Such a displacement exhumes the continental shelf creating lowstand geological conditions (sea level below the shelf break). The internal configuration of the seismic intervals does not allow a systems tract interpretation and so any lithological prediction can be advanced. Notice the seaward dipping reflectors (SDRs), which are deposited imediately above the breakup unconformity (BUU), correspond to lava flows "mise en place" by subaerial spreading centres. The SDRs thin landward, that is to say, eastward and cover the distal rift-type basins in which organic rich lacustrine shale (potential source rocks) are often deposited. They are fossilized by onlapping of the basal sediments of the Cretaceous transgression induced by the eustatic sea level rise created by the breakup and dispersion of the Gondwana Supercontinent, which decrease the volume of the oceanic basin. In this offshore (Atlantic-type margin overlying rift-type basins), as well as in other sedimentary basins, the understanding of petroleum systems is based on a sequential interpretation of seismic data, which in many instances requires a low hierarchic level approach (sequence cyle) in which lithological predictions are possible. The basic principles of the sequential interpretation will be abridged on these notes.

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Seismic-Sequential Interpretation

Carlos Cramez

In addition to these notes on "Sequence Stratigraphy " the following courses are or will be sooner available:

- Glossary of Salt Tectonics;
- Basic Principles in Tectonics;
- Bassins Sédimentaires et Systèmes Pétroliers;
- Salt Tectonics;
- Systemic Stratigraphy Seminar;
- Volume Problems;
- Hydrodynamism;
- Sequence Stratigraphy;
- Geological setting & Seismic Interpretation; 
- Offshores Profonds;
- Glossary in Sequential Stratigraphy;
- Probabilistic Reserves Assessment;
- Geological Setting & Seismic Interpretation.

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