Orca operates a license in Tanzania which has a total area of approximately 170 km2. The blocks are located in shallow water 15 km off the coast of Songo Songo Island and 200 km south of Dar es Salaam.
The license contains the large Songo Songo gas field which lies in the southern area of the offshore Tanzanian Coastal Basin. The field is positioned on and slightly offshore Songo Songo Island (SSI). The main reservoir is developed in Lower Cretaceous aged Neocomian to Albian sandstones (Neocomian), while Upper Cretaceous aged Cenomanian sands that lie unconformably on the Lower Cretaceous sandstone provide an additional reservoir when developed. The source rocks are overlain by a thick section of late Cretaceous and Paleogene shales, forming an excellent top seal.
The gas in the Songo Songo reservoir is categorised as either Protected Gas or Additional Gas. Protected Gas is owned by Tanzania Petroleum Development Corporation (TPDC) and is sold by them under a 20-year gas agreement to Songas Limited, and to the Tanzania Portland Cement Company. Songas utilizes the Protected Gas for its gas turbines at Ubungo. Protected Gas is supplied at a maximum of 45 MMscfd and Orca is obligated to make it available through to 31 July 2024. Additional Gas is the gas in the Discovery Blocks that is in excess of Protected Gas. Orca is entitled to produce and sell all Additional Gas until October 2026.
As at 31 December 2018, the independent petroleum engineers, McDaniel and Associates Consultants Limited, assessed the Additional Gas proven (1P) and proven and probable (2P) Songo Songo reserves available to Orca to the end of the licence period at 261 Bcf and 293 Bcf respectively.
Songas owns the infrastructure that enables the natural gas from the Songo Songo field to be transported to Dar es Salaam where it is consumed by power and industrial customers. This includes a 110 MMcfd gas processing facility, a 25 km 12″ offshore pipeline and a 207 km 16″ onshore pipeline.
Orca operates the 8 wells in the Songo Songo field (4 offshore and 4 onshore) and the gas processing facility on SSI on behalf of Songas. Orca also owns and operates a 50 km downstream distribution network and a compressed natural gas facility in Dar es Salaam.
The Songo Songo project was Tanzania’s first natural gas development and East Africa’s first gas to power project.