Oil and gas exploration in the Rovuma (also spelled Ruvuma) River Basin started almost 50 years ago but early wells were either dry or gas prone. This led to the region being largely ignored for several decades. Upstream investments remained relatively small until 2005 when Wentworth bid for and won concessions in three Rovuma Basin blocks. At that time the Company was partnered with Anadarko and the national oil company in the onshore and offshore Rovuma concessions in Mozambique and held an 80% interest in the Mnazi Bay Concession in southern Tanzania with that country's national oil company.
Work began in all three concession areas in 2006 and by 2008 new seismic had been acquired in Mnazi Bay, Tanzania and onshore and offshore Rovuma, Mozambique. One well re-entry, two appraisal wells, and one exploration well were drilled in the Mnazi Bay Concession and all four wells flowed natural gas. For a period of time following the global financial collapse in 2008 work in the area slowed but resumed in 2009 with the drilling of the Mecupa-1 well in the Onshore Rovuma concession, Mozambique. Anadarko's initiative to drill deep-water wells in the Offshore Rovuma Area 1 concession began in late 2009 and the success of those wells would go on to change perceptions of the East African margin and the Rovuma Basin's prospectivity forever.
To date Anadarko has drilled more than a dozen deep-water wells with: six significant natural gas discoveries; five appraisals of discoveries; and one well with a 125' column of oil and gas saturated sands. The oil encountered in this well is the first known occurrence of liquid hydrocarbons in deep-water offshore East Africa. To the east of the Offshore Area 1 concession ENI has drilled two major natural gas discovery wells and appraisals of those wells in the Offshore Rovuma Area 4 concession.
In addition to current and committed future drilling, emphasis by operators is shifting to how they are going to monetise what is currently estimated to be in the region of 175Tcf of gas. Liquefied Natural Gas or LNG is the logical solution but for concessionaires with smaller known or expected resources, alternative monetisation solutions have to be considered. In the case of Wentworth and the Mnazi Bay concession, there are currently two monetisation schemes under consideration and development:
In the case of the latter project Wentworth commissioned and completed a pre-feasibility study to look at and consider multiple monetisation solutions. The results of this study point to the production of methanol and ammonia/urea as the optimal solution. Wentworth, with the support of the Tanzanian government, is pursuing the development of this project and expects a Final Investment Decision immediately after the outcome of new exploration and appraisal drilling is known.