Cairn completes SNE-4 well offshore Senegal, releases ‘Ocean Rig Athena’

Oil and gas company Cairn Energy has completed the SNE-4 appraisal well offshore Senegal. The well is now being plugged and abandoned and the rig will be released. 

Senegal PSC partners are Cairn Energy, the operator, with 40% interest, ConocoPhillips 35%, FAR 15%, and Petrosen 10% interest.

The SNE-4 well, spud in April, was appraising the eastern extent of the SNE field discovered in 2014 and aiming to confirm the nature of the upper reservoirs in the oil zone.

The SNE-4 well, located in 942m water depth and approximately 85km offshore in the Sangomar Offshore block, reached the planned total depth (TD) of 2,944m below sea level (TVDSS).

Cairn’s analysis of the dataset collected is continuing with initial results as follows:

– Confirms the extension of reservoirs in the eastern extent of the SNE field, more than 5 kilometres (km) to the east and down dip of SNE-3;

– Confirms oil bearing Upper Reservoir sands of similar quality to those encountered as gas bearing elsewhere in the field;

– The uppermost gas sands first encountered in SNE-3 and BEL-1 were also present and gas bearing in SNE-4;

– Confirms correlation and presence of the principal reservoir units between each of the wells across the whole field;

– A gross oil column of ~100 metres (m) encountered, similar to SNE-1, SNE-2, SNE-3 and

– 108m of continuous core taken across the oil bearing reservoir interval with 100% recovery;

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

– Initial indications confirm similar 32° API oil quality as seen across the field.

Cairn Energy Chief Executive Simon Thomson said: “We have now drilled four successful appraisal wells in Senegal and we are delighted with the results to date of the multi-well evaluation programme, which has confirmed the scale and potential of this world class asset. 

Thomson added: “We have gathered a very large volume of data from operations to date and we look forward to progressing our long-term, multi-field, multi-phase exploitation plan to maximise value in Senegal. We see clear potential to access additional cost savings from the current lower operating environment in respect of planned future activity.”

The SNE-4 well is the Joint Venture’s (JV) sixth well offshore Senegal and the fourth completed this year as part of a multi-well evaluation programme to help delineate the shape of the structure and establish deliverability and full potential of the field.

According to Cairn, the Ocean Rig Athena drillship will now be de-mobilised and the JV will continue integrating the significant amount of data collected from the four wells, including two drill stem tests and more than 600m of core. This will enable the JV to determine the most effective way to further the appraisal of this significant oil accumulation and evaluate development options, said the company.

FAR Managing Director Cath Norman said: “FAR is delighted with the result from the the SNE-4 well which has confirmed reservoir quality and oil in the upper reservoir section of the field. Our joint venture has now drilled 6 successful wells offshore Senegal with a 100% success rate.

“We are also very pleased with the overall Ocean Rig Athena drilling and evaluation operations which have come in significantly under planned schedule and budget. The Joint Venture is using the extensive data set acquired from the SNE appraisal wells to evaluate development options and determine the best approach for future appraisal drilling. The SNE-4 well will have gauges installed that, together with SNE-3 gauges, can be used to monitor oil field pressures.”

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