221213000685 - Proposed 3D Seismic Survey covering Blocks 2713, 2712A, 2712B, 2812B, and 2812A and Portions of Blocks 2813B, 2813A, 2814B, 2714B, 2714A, 2614 2613, 2612A and 2612B, Orange and Lüderitz Basins, Offshore Southern Namibia

The ECC is required by the Proponent for the proposed 3D Seismic Survey covering Blocks 2713, 2712A, 2712B, 2812B, and 2812A and Portions of Blocks 2813B, 2813A, 2814B, 2714B, 2714A, 2614 2613, 2612A and 2612B, Orange and Lüderitz Basins, Offshore Southern Namibia. Water depths of the area of interest ranges from ca-500m to -4000m from east to west respectively. Seismic survey is a key tool that resources companies exploring for hydrocarbons (oil and natural gas) use to map the subsurface and kilometres below the ground on land (onshore) or in the sea (offshore). The basic principle of seismic survey method is the application of controlled generation of sound / acoustic waves by a seismic source to obtain an image of the subsurface. The generated acoustic wave that travels deep into the earth, is reflected by the various rock formations of the earth and returns to the surface where it is recorded and measured by receiving devices called hydrophones. Airguns are the most common sound source used in modern offshore seismic surveys. An airgun is an underwater pneumatic device from which high-pressure air is released suddenly into the surrounding water. On release of pressure the resulting bubble pulsates rapidly producing an acoustic signal that is proportional to the rate of change of the volume of the bubble. The frequency of the signal depends on the energy of the compressed air prior to discharge. Arrays of airguns are made up of towed parallel strings. A single airgun could typically produce sound levels of the order of 220 - 230 dB re 1 mPa @ 1 m, while arrays produce sounds typically in the region of 250 dB re 1 mPa @ 1 m. Most of the energy produced is in the range of between 0 - 120 Hz bandwidth, although energy at much higher frequencies is also produced and recorded. High-resolution surveys and shallow penetration surveys require relatively high frequencies of between 100 – 1, 000 Hz, while the optimum wavelength for deep seismic work is in the 10 - 80 Hz range. During the survey operation, the seismic vessel records the data from all the hydrophones, including accurate coordinates of the vessel and its hydrophones. The proposed 3D seismic survey will employ numerous streamers and multiple hydrophones, providing enough data to give a detailed subsurface profile of the rock layers of the area of interest. The depths of the reflecting layers are calculated from the time taken for the sound to reach the hydrophones via the reflector. By analysing the time, it takes for the seismic waves to travel between the rock formations and the surface, geophysicists, geologists, and petroleum engineers use sophisticated software to create subsurface images /maps showing potential drill-ready subsurface geological structures called reservoirs that may contain hydrocarbons.