South African petrochemicals company Sasol has completed the first ever three-dimensional (3D) onshore seismic programme, in the Inhassoro field, in Mozambique.

This involved acquiring 115 km² of data in the Inhassoro field, which forms part of Sasol’s onshore production sharing agreement (PSA) licence area.

To be developed in phases, the first phase of the PSA licence area development proposes an integrated oil, liquefied petroleum gas (LPG) and gas project adjacent to Sasol’s existing petroleum production agreement (PPA) area.

Sasol has made significant progress on Tranche 1 of the PSA development as approved by the Council of Ministers on January 26.
 
The company had appointed Poland-based Geofizyka Torun to acquire two-dimensional and 3D seismic data using Vibroseis trucks. These send an acoustic wave into the ground and when the wave is reflected at boundaries between rock layers, an image of the subsurface is generated, similar to ultrasound technology used in the medical field.

Future well locations can now be optimised based on the generated images.

The 3D data will significantly enhance Sasol’s understanding of the structure of the oil accumulations, through better resolution and more defined characterisation of the reservoir, the company said on Thursday.

The seismic acquisition programme will now move to the Pande field within the PPA licence area, where 42 km² of 3D seismic data will be acquired.

Meanwhile, Sasol exploration and production VP John Sichinga said the PSA drilling campaign was also progressing well, with the first two wells completed.

“The tests conducted thus far have produced encouraging results. During the course of drilling of the second well, we encountered previously unknown accumulations of hydrocarbons within the development and production area, which indicate the presence of both gas and oil.

“We have issued a notice of discovery to the Mozambican authorities as per the PSA and will continue our evaluation of the data.”