East Africa – Phase I – Reservoirs and Seals Tanzania

Core Laboratories is pleased to announce a significant series of rock based, geological studies in East Africa, providing dataset generation and detailed evaluation of reservoir, source and seal rocks across the region. Phase I – Tanzania is presented in this proposal for your consideration.

Tanzania Petroleum Development Corporation (TPDC)) will provide access to national archives of cuttings, conventional cores, fluids, electric logs and technical geological well reports for study purposes. Approximately 20 wells will be selected from national archives and a number of recently drilled wells will be added subject to operator agreement.

All major coastal basins in Tanzania will be included in the study, including the Selous and Ruvu Basins, the Coastal Basins (Mandawa, Ruvuma, Rukwa and offshore basins) and the Deep-Water Basins. Reservoir targets include continental deposits of the Paleozoic-Mesozoic Karroo Group, Lower Jurassic clastics, evaporites and carbonates and Cretaceous-Tertiary fluvial, deltaic, lacustrine and marine sediments.

The pre-rift and synrift stratigraphic units, from the top of basement to the end of Early Jurassic, are best represented in the Selous, Ruvu, Mandawa, and Ruvuma basins of eastern Tanzania, and in the Rukwa Basin in the southwest. In the Selous Basin, reservoir targets occur within the Karoo Group which comprises approximately 10 km of fluvial, deltaic, continental and lacustrine deposits. In the Mandawa Basin, the reservoir targets include pre-rift, syn-rift and post-rift clastic and carbonate sediments. The coastal basins were established from Middle Jurassic onwards as the continental shelf of a passive margin. These basins formed major depositional depocentres in the Mesozoic and Tertiary, accumulating > 8000 m of deltaic and marine sediments that provide multiple reservoir intervals with proven oil-prone sources and seals.

The primary objective is to undertake a full evaluation of reservoir quality of all major reservoir intervals that are penetrated in the study wells, integrated with an evaluation of associated seal rock lithologies, together with an evaluation of regional sources units and thermal maturity. All fluid occurrences will be characterized and correlated. The establishment of a regional sequence stratigraphic framework will also be a major component of the study.

The key components of the study are as follows:

  • Reservoir Description and Rock Properties Evaluation of all major reservoirs:
  • Rock Typing of uncored sections;
  • Seal Atlas of major seal lithologies;
  • Regional Source Rock evaluation and thermal maturity
  • Fluid characterization and correlation
  • Biostratigraphy/Sequence Stratigraphy of key wells;
  • Digital Database of laboratory and well data, including LAS files of the electric logs;
  • HTML browser of the study dataset and report.

The study is scheduled for a mid 2008 completion.