Less than a week after Kosmos reported the success of Mahogany 3, in appraising existing reservoir and coming up on new, deeper payzone, Tullow Oil put out the news that its Hyedua-2 well flowed at a stable rate of 16,750 BOPD. Both wells are located in the deepwater Jubilee field, offshore Ghana. In fact, the Mahogany field, discovered in the West Cape Points Three Points and the Heydua accumulation, located in Deepwater Tano License, are one and the same field ; they straddle and are being jointly developed (unitized) as a single (Jubilee) field.
In the ongoing appraisal activity the operators keep christening the wells with the original prospect names and this may be confusing to those who are trying to follow up the development of Jubilee field.
Kosmos reported that 33metres of net pay were encountered in Mahogany 3, “whose primary objective was to appraise the Jubilee field reservoir section away from the strong seismic amplitudes which have been the main targets to date”. The company said that the results of drilling, wireline logs and samples of reservoir fluid indicate that 16 metres of high quality stacked oil bearing sandstones have been encountered. “This confirms a significant extension of the Jubilee field to the southeast”. The company said that the secondary objective of the well was to drill Mahogany Deep, an exploration target which had been identified on 3D seismic but lies at a previously untested stratigraphic level. In this section, “the well encountered 17 metres of good quality oil bearing reservoir sandstones at levels significantly deeper than the oil water contacts previously intersected on the Jubilee field”. This success opens up further potential in the region and is the subject of ongoing evaluation.
Kosmos didn’t do any drill stem test on Mahogany 3, which reached a total depth of 4,028 metres in a water depth of 1,236 metres.
Tullow’s announcement of 16,75OBOPD as flow rates for Heydua 2 recalls the early days of deepwater discoveries in deepwater Angola. Heydua 2 reached a total depth of about 3,663 metres in a water depth of 1,246 metres and was tested via 88/64” choke with a tubing head pressure of 1,380psi( pounds per square inch). It intersected 55 metres of high quality oil bearing reservoir sandstones of which a 41 metre section was tested.
The flow rates, “at nearly 17,000 BOPD of high quality crude, from a well not even in the centre of the field, is an outstanding success and indicative of a world class reservoir”, said Aidan Heavey, Tullow’s Chief Executive. Hyedua-2 is located on the north-west flank of the field and Tullow says the excellent reservoir properties measured during the flow test are expected to be even better in the core area of the field. The company reports that stable oil and gas flow rates were maintained throughout the tests and the pressure data indicated that it is connected to a large pore volume. “Excellent reservoir continuity enhances our expectation of connectivity between the planned production and injection wells and we are currently assessing the positive impact on Phase 1 reserves”.