BEL-1 well off Senegal confirms northern extension of SNE field

The Cairn Energy PLC BEL-1 well offshore Senegal confirmed the extension of reservoirs in the northern area of SNE field.

The well encountered good quality reservoir sands within the upper reservoirs, and showed 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 km, the firm says.

Gas-oil and oil-water depths indicate an oil column of 100 m gross at BEL-1 similar to SNE-1; SNE-2 (OGJ Online, Dec. 10, 2015); and SNE-3 (OGJ Online, Mar. 9, 2016). About 144 m of continuous core was taken across the entire oil reservoir interval with 100% recovery.

Multiple samples of gas, oil, and water were 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.

SNE field was discovered in 2014 (OGJ Online, Nov. 10, 2014).

BEL-1 was drilled in 1,032 m of water, 90 km offshore in the Sangomar Deep offshore block. It reached the planned TD of 2,742 m below sea level. 

Bellatrix prospect

In addition to appraising the northern extent of SNE, the BEL-1 well targeted the Bellatrix exploration prospect. The main exploration objective zones are tight gas-bearing sandstones that are not of productive reservoir quality.

Cairn says two good quality gas-bearing sand reservoirs with combined net thickness of 8 m were encountered between the Bellatrix main objective and deeper SNE appraisal objective.

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

The results, along with the latest 3D seismic acquired in fourth-quarter 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 says.

SNE-4 to be drilled

Due to the recent results, the joint venture has agreed that the Ocean Rig Athena will now drill SNE-4, 5 km southeast 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 (OGJ Online, Oct. 14, 2015).

“The drilling program in Senegal continues to provide positive evidence of the scale and extent of the SNE field,” commented Simon Thomson, Cairn chief executive officer. “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.”

Cairn as operator has 40% working interest in the Sangomar Deep, Sangomar Offshore, and Rufisque blocks offshore Senegal. Partners are ConocoPhillips with 35%; FAR Ltd. 15%; and Petrosen, the national oil company of Senegal, 10%.


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