Offshore gravity and magnetic surveys

Fig.1. Seismic-gravity profile
Calibration of seismic reflectors with special points calculated with the use of an algorithm of standardized gradient of gravity
Fig.2. Example of reflection of a seabed mine
(magnetic mass about 100 kg, elevation above the seabed about 0.8 m, amplitude of local magnetic anomaly – 6 nTl, distance to the item – 6 m)
Fig.3. Photograph of the seabed mine
(reflected by the anomaly from Fig.2)

These methods, based on natural geophysical fields measurements, permit reduce the costs and always carried out with regard to environmental safety are usually perform as a part of:

  • Oil & gas exploration
  • Site surveys

We provide our Customers with:

  • Instruments tests and calibration
  • surveys with permanent quality control;
  • Obtained data P&I;
  • geological reports preparation

During oil & gas exploration, the results of gravity and magnetic surveys, combined with seismic data, provide more accurate interpretations and significant costs reduction related to subsequent drilling. Therefore, JSC YUZHMORGEOLOGIYA is actively cooperating with energy companies, providing them with high quality gravity and magnetic data:

 

  • Lukoil (2000 – 2001.– the Volga delta – Middle Caspian),
  • Total Fina Elf (2003, the Black Sea),
  • Priazovneft,
  • Chernomorneftegas (2003- 2006, Sea of Azov).

 

Active development of the shelf areas, construction of ports and hydrotechnical infrastructure in the areas of previous military actions, stimulates the application of geophysical techniques for HSE protection during geotechnical surveys. The development of unexploded ordnance (UXO) detection technologies based on high precision magnetic surveys that has been previously used only by military specialists is an innovative and dynamic service trend of JSC YUZHMORGEOLOGIYA.

The first successful surveys were carried out by JSC YUZHMORGEOLOGIYA

in 2004 under Sakhalin-1 project and covered the area of 2 km2 with about 500 UXOs detected. But in 2005 we took part in large-scale site surveys in the construction area of a new port in the Zhelezniy Rog Cape (Black Sea) and surveyed an area of 50 kmwith about 5000 potentially dangerous UXOs indificated.

At present, UXO identification is one of the most efficiently performed tasks for JSC YUZHMORGEOLOGIYA specialists. Our techniques help us accurately identify the location of buried seabed mines, shells, air bombs, anchors, metal and ferroconcrete debris and sunken ships with a minimum size of 1m and minimum magnetic mass of 20 kg. The tests conducted with use of the 300М Sea Spy Marine Magnetics magnetometer and the C-MAX side scan sonars proved a detection confidence of buried metal objects within a minimum distance of about 10 m.