A Nigerian firm, Oranto Petroleum Limited, has successfully completed its seismic data acquisition survey over the Ngassa block located near Uganda’s western border with the Democratic Republic of Congo.

A seismic survey is a technique usually done to explore and appraise oil and gas operations to get a clearer idea of the structures underneath the earth’s surface. It involves the use of energy produced by instruments such as a seismic vibrator (onshore) or an air gun (in water) to generate waves that go through the earth’s layers and “bounce-back” from different rock layers. The reflected and refracted waves are then recorded by receivers (geophones on land or hydrophones in water) to produce the first image of the subsurface.

Oranto contracted the UK-based IMC Geophysical Services Ltd to undertake the survey, which began in mid-April this year and went on until May 18. The Ngassa block lies on the eastern banks of Lake Albert, within the villages of Tonya A, Tonya B, Kijjangi, Mbegu, Kaiso, and Kyehoro, in Hoima and Kikuube districts.

According to energy ministry officials, the Ngassa prospect lies entirely under the lake, and as such, two deviated wells, Ngassa-1 and Ngassa-2, were drilled on land at the periphery of the main structure between 2007 and 2009 to access the reservoirs.

Although the two wells encountered oil and gas, much of this block was not tested, meaning that there was a need for additional exploration work to fully assess the potential of the block. Going forward, the government expects Oranto to process and interpret the acquired data whose results will inform the company’s subsequent activities over the next two years.