JV partner Pancontinental Oil and Gas has advised that the BG Group-operated Sunbird-1 well off the southern Kenyan coast has been completed and the well has intersected a hydrocarbon-bearing zone in the top of the Sunbird Miocene Pinnacle Reef.
Analysis of the zone itself and recovered hydrocarbon samples are continuing. Analysis of the wireline log data and the fluid samples recovered from the limestone reservoir is complex due to the large volume of drilling fluid, seawater and cement lost to highly porous and permeable zones in the Sunbird Reef, including into the hydrocarbon bearing zone.
Both gas and liquid samples have been recovered. In addition to the recovered gas, the nature of the liquid samples and whether or not these contain naturally occurring hydrocarbon liquids (oil or condensate) remains to be determined by further analysis.
The top of the Sunbird Miocene Pinnacle Reef was reached at 1,583.7m subsea. The water depth is 723m. The 43.6m gross hydrocarbon bearing zone is currently assessed to contain a net pay thickness of 27.8m.
In this case, net pay is defined as the cumulative thickness of zones having porosity of 10% or greater. Zones with porosity lower than 10% are not included in the net pay assessment. At this stage, due to its estimated size, the Sunbird discovery itself is considered unlikely to be commercial.
Pancontinental has an 18.75 percent interest in the well and Block L10A. The Operator of the Block L10A Petroleum Sharing Contract,BG Group, is continuing to assess the results for the L10A consortium and will recommend a follow-up program.
A further statement regarding the discovery will be made once the remaining analyses have been completed. Sunbird-1 has now been ‘plugged and abandoned’ in accordance with the planned drilling program, meaning that the well has been made safe in such a way that it can be left permanently without further intervention.
These measures are designed to ensure that there is no danger of leakage of oil or gas within the well or to the sea floor.
Pancontinental’s Chief Executive Officer Barry Rushworth said the implications for regional exploration were very positive.
“The drilling operation using the Deepsea Metro 1 drillship has been completed, with the well drilling into a hydrocarbon-bearing carbonate reef reservoir that was highly porous and permeable. We await the results of the continuing analysis of the data acquired from the well. We encountered a thick and effective seal over the top of the Sunbird Reef, which was an initial risk for us, and the regional follow-on implications are truly great. Porosity, permeability and seal for the reservoir were all better than Pancontinental expected. While the high quality of parts of the reservoir, in terms of porosity and permeability, resulted in the loss of quantities of drilling fluids and consequently the analysis of the
hydrocarbon column has been made difficult, we expect to have a conclusive result after further analysis’. He said.
‘We look forward to receiving the full and final Sunbird results and we believe that we are now in an excellent position to explore for larger volumes of gas and oil over our very extensive portfolio of prospects and leads offshore Kenya’.
The L10A joint venture is considering follow-up exploration activities after the Sunbird-1 discovery. The Sunbird discovery is expected to yield important details of the hydrocarbon system in the Lamu Basin, including the age of the source rock and the timing of generation. L10A covers a variety of play types, prospects and leads. Many of the prospects have been defined using the two 3D seismic surveys carried out by the joint venture. The Sunbird Prospect is one of an inboard cluster of Miocene reefs. Outboard prospects include Tertiary and Cretaceous channels, large anticlinal complexes and series of Cretaceous and Tertiary fault bounded prospects.
Other offshore Kenyan activity includes an exploration well to be drilled by Anadarko, as recently announced for later in 2014.