KAMPALA – Oranto Petroleum Limited (OPL) has successfully completed a Two Dimensional (2D) seismic data acquisition survey over the Ngassa block in the Albertine Graben.
Through Petroleum Authority of Uganda [PAU], OPL contracted IMC Geophysical Services Limited from the United Kingdom to undertake the survey, which commenced on 15 April and was completed on 18 May.
According to PAU, the survey involved the acquisition of 326 line kilometres of offshore (on Lake Albert) 2D seismic data over the Ngassa Contract Areas.
A seismic survey is a method, typically used during the exploration and appraisal phase of oil and gas operations and this method gives a clearer idea of the structures underneath the earth’s surface (subsurface).
According to Mr. Dozith Abeinomugisha, Director Exploration at the Petroleum Authority of Uganda (PAU) the method involves the use of energy produced by instruments such as a seismic vibrator (on land/ onshore) or an airgun (in water/ offshore) to generate waves that go through the earth’s layers and “bounce-back” from different rock layers. The reflected and refracted waves are recorded by receivers (geophones on land or hydrophones in water) to produce the first image of the subsurface.
“The conclusion of this exercise represents an important step by the licensee in fulfilling its obligations for the first two-year exploration phase that runs from October 2017 to October 2019,” said Mr Abeinomugisha.
He explained that the two stratigraphic licenses of Ngassa Deep Play and Ngassa Shallow Play Contract Areas were awarded to Oranto Petroleum Limited from Nigeria in October 2017 by the Minister of Energy and Mineral Development, for a period of four (4) years.
“This is the first time Uganda undertook stratigraphic licensing, where two licenses are issued vertically over the same block and this is to ensure that all potential oil and gas zones in the area are fully evaluated through the implementation of the work programmes approved by the PAU,” added Mr Abeinomugisha.
The Ngassa block, which was initially part of Exploration Area 2 licensed to Tullow Uganda Operations Pty Limited, reverted to Government after the expiry of Tullow’s appraisal period and this block is covered by good quality 2D seismic data acquired between 2003 and 2008 and a third of the block is covered by 3D seismic data.
The Block [Ngassa] 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.
“Oranto Petroleum Limited will now process and interpret the acquired data and the results will inform the subsequent activities during the next two-year phase of the exploration period. We expect Oranto Petroleum Limited to revert to the PAU by October 2019, with a detailed work programme for drilling at least one exploration well on Lake Albert within the next two years,” said Mr. Abeinomugisha.
He said the acquired data will be analysed together with the pre-existing 2D and 3D data to better define the North Eastern part of the Ngassa mega-prospect and that OPL has also undertaken other technical studies as part of the exploration work programme, including reprocessing of the existing seismic data, Amplitude Versus Offset (AVO) and petrophysical studies over the Ngassa 1 and 2 wells to evaluate the quality of the reservoir horizons penetrated by these wells as well as studies related to a drilling solution on Lake Albert.
Mr. Abdul Byakagaba Bazara, the General Manager, OPL, described the exercise as a big success for Uganda.
“We have received great support from the government, the local leaders and communities in the area where we are operating. The UPDF and Uganda Police have provided us with security throughout this exercise, which has been undertaken without incident,” he said.
A Joint Security Team that comprised the Uganda People’s Defence Forces (UPDF), Uganda Police Force (UPF) and the Internal Security Organisation (ISO) led by Brig. Michael Nyarwa, the Commandant of the UPDF Marine Unit, oversaw the security for the exercise.
“We secured the operations on land, water and air, and our team also worked closely with the local community for intelligence gathering,” said Brig. Nyarwa.
Mr. Ali Tinkamanyire, the LC3 Chairperson for Buseruka Sub-county in Hoima district expressed happiness that the data acquisition survey provided employment opportunities.
“I thank OPL for using labour from the local communities during this exercise and I hope, in the future, even more, people benefit from the opportunities created by oil and gas activities,” he said. Mr. Tinkamanyire.
The PAU is mandated to monitor and regulate petroleum activities in the country; this includes approving the licensees’ work programmes and ensuring that these are undertaken in an efficient manner.
The PAU’s regulatory role also includes monitoring of national content development in the oil and gas sector.
“Over 70% of the workforce employed during the survey were Ugandans. In addition, OPL has subcontracted Uganda firms to provide legal services, security services, camping, catering and general maintenance services”, Mr. Byakagaba added.
WHAT IS A SEISMIC SURVEY?
A seismic survey is a method, typically used during the exploration and appraisal phase of oil and gas operations. This method gives a clearer idea of the structures underneath the earth’s surface (subsurface).
The method involves the use of energy produced by instruments such as a seismic vibrator (on land/ onshore) or an airgun (in water/ offshore) to generate waves that go through the earth’s layers and “bounce-back” from different rock layers. The reflected and refracted waves are recorded by receivers (geophones on land or hydrophones in water) to produce the first image of the subsurface.
This technique allows for interpretation of what may lie underneath the ground or seabed (oil, gas, water, faults, folds etc) without having to drill into the earth. The acquired data is used by companies to make decisions of a suitable location where to drill a well.
The onshore seismic operations usually use specialised trucks that carry a heavy plate that is vibrated to generate a seismic signal.