MercoPress. South Atlantic News Agency

Oil electromagnetic imaging survey in Falklands' waters

Rockhopper Exploration plc will be undertaking a 2D survey in the North Falklands Basin starting on Monday the 23rd of January.

It is the first survey of this type to be conducted in the Falkland Islands and is expected to be watched closely by the exploration industry, the Falkland Islands Government and investors alike. Dave Pratt, OHM's CEO said; "By undertaking CSEM surveys Rockhopper Exploration are progressing exploration in the Falklands, de-risking their exploration prospects ahead of any drilling programme and ultimately protecting their shareholders interests.

"In remote locations such as the Falkland Islands OHM's CSEM imaging technology is especially valuable. Mobilizing exploration drilling rigs to such frontier areas, especially at times of very high rig rates, is expensive. As the cost of CSEM surveys is significantly less than drilling, exploration companies are able to investigate many more prospects than would have been the case if drilling was their only recourse".

The data acquisition programme is being conducted over a number of prospects in water depths of approximately 150 to 500 meters, using one of OHM's specialised survey crews and incorporating OHM's proprietary EM source and receiver systems.

Although this is the first survey of its kind in the Falkland Islands, feasibility modeling has indicated that the anticipated reservoir scenarios should give a significant EM response.

Before mobilizing for a CSEM survey, the prospect's electromagnetic response is calculated and used to assess the influence of local structure, for example salt or volcanic bodies, on the outcome of a survey. The sensitivity to target parameters such as reservoir thickness, resistivity and lateral extent is examined and the resolution with which these parameters can be determined is quantified. In cases where there are competing geological interpretations of existing data, modeling is used to ascertain to what extent these can be distinguished using CSEM surveying.

Finally, acquisition parameters are optimized for the defined survey objective. The model results are used to determine the source tow and receiver array geometries and source transmission frequencies that will provide the best resolution of target structures and properties.

Only when the modeling process has been completed, can OHM confirm that the technique will provide conclusive indication of the presence of resistive layers consistent with hydrocarbon reservoirs in the prospects modeled.

Once the data is gathered and processed, there are a range of 1D, 2D and 3D inversion algorithms that can be applied to the data along with OHM's innovative diffusive E-field focusing (DEFF) imaging technique, which allows resistivity volumes of the earth to be created.

The GSI Pacific will tow a six thousand metre seismic production cable. The total offset from the rear of the vessel to the floating tail buoy, indicated by a flashing light will be six thousand five hundred metres.

The vessel may manoeuvre outside the limits set for specific survey areas and all vessels which intend to move in the proximity of the survey areas are kindly requested to give the GSI Pacific a wide berth at all times. Also fishing vessels in the vicinity should maintain a good listening watch on VHF radio channel at all times.