Cairn gears up for fourth well offshore Senegal

Cairn Energy is preparing to start drilling the fourth exploration well in the ongoing evaluation programme offshore Senegal, after completing its latest, third well with ‘positive results’. 

Operations on the third well, BEL-1, have been completed following drilling, coring and logging and the well is now being plugged and abandoned before the drillship Ocean Rig Athena moves to a fourth well, SNE-4.

According to Cairn, the operator, the BEL-1 well was targeting the Bellatrix exploration prospect and appraising the northern extent of the SNE field discovered in 2014.

Cairn said on Monday that, based on the positive campaign results to date, the Joint Venture (JV) has agreed a fourth well location, SNE-4, which will start operations shortly.

BEL-1 Exploration Target:

– The main exploration objective zones are tight gas-bearing sandstones that are not of productive reservoir quality;

– Two good quality gas-bearing sand reservoirs (combined net thickness of 8 metres (m)) were encountered between the Bellatrix main objective and deeper SNE appraisal objective.

BEL-1 Appraisal Target:

– Confirms the extension of reservoirs in the northern area of the SNE field;

– Good quality reservoir sands encountered within the Upper Reservoirs;

– Good correlation and presence of the principal reservoir units between SNE-1, SNE-2, SNE-3 and BEL-1 over a distance of more than 9 kilometres (km);

– Gas-Oil and Oil-Water depths indicate an oil column of ~100m gross at BEL-1 similar to  SNE-1, SNE-1 and SNE-3;

– 144m of continuous core taken across the entire oil reservoir interval with 100% recovery;

– Multiple samples of gas, oil and water recovered to the surface;

– Initial measurements show similar oil quality as seen in SNE-1, SNE-2 and SNE-3, with higher oil density towards the base of the column.

The BEL-1 well targeted a shallower ‘buried hill” exploration play which is one of multiple exploration play types that have been identified across the block. The BEL-1 well exploration results confirm the presence of shallower regionally extensive reservoirs also encountered in the SNE-3 well more than 9 km away.

These well results, along with the latest 3D seismic acquired in 4Q 2015, will be incorporated into block wide remapping to look at possible new plays and down-dip oil potentially associated with the shallower reservoirs.

Cairn informed that the JV has agreed that the Ocean Rig Athena will now drill SNE-4, located 5km south-east of the SNE-1 discovery well, to appraise the eastern extent of the field and aiming to confirm the nature of the upper reservoirs in the oil zone.

Cairn Energy PLC Chief Executive Simon Thomson said: “The drilling programme in Senegal continues to provide positive evidence of the scale and extent of the SNE field.

“The BEL-1 appraisal results have provided definitive information confirming the northern extent of the high quality reservoirs seen in the other wells and demonstrated an increased oil column in this area of the field.

“Operations have been safely and successfully completed and significant data gathered to help the joint venture partners establish the ultimate size of the significant resource base. The evaluation programme continues with the SNE-4 well.”

Cairn has a 40% working interest in three blocks offshore Senegal (Sangomar Deep, Sangomar Offshore and Rufisque), ConocoPhillips has 35%, FAR Ltd 15% and PETROSEN, the national oil company of Senegal 10% working interest.