Work suspended at Tullow Uganda well
As of midnight last Saturday, Tullow Oil’s Ugandan Mputa-2 has been cased and suspended as a potential future oil producer. This follows the completion of extended wireline logging activities after some equipment malfunctions.
The results of Mputa-2 confirm that the upper reservoir sands intersected in Mputa-1 and Waraga-1 are laterally extensive, but at this location are water-wet.
Pressure data indicates that the hydrocarbon column height in the upper zone of the Mputa field is potentially of the order of 100 metres, although at this upper level, the Mputa and Waraga structures do not have a common oil leg.
The implications of this pressure data and the fact that the target sands came in over 100 metres shallow to prognosis are both positive to the interpretation of the Mputa Field.
The new data is being integrated with existing models in order to provide estimates of oil in place for these upper sands shortly.
The extent to which these sands will flow commercial volumes of oil will be determined when flow-testing operations begin on Waraga-1, expected to commence mid-June.
Oil samples have been recovered from the lower reservoir zone in Mputa-2, which can be correlated to similar oil-bearing zones in both Mputa-1 and Waraga-1.
The presence of oil-saturated sands in these basal units in all wells drilled to date implies an extensive stratigraphic trapping mechanism at this level.
The gross interval of these units is variable and there does not appear to be pressure communication between them.
But contained within the sequence are obvious oil-bearing zones of around five metres’ thickness that will be flowed in Tullow’s testing programme at Waraga-1 to determine whether they are capable of sustaining commercial flow rates.
The information derived will then determine whether Mputa-1 or Mputa-2, or both, will be subsequently tested.
Assessing where the thicker sand units and more extensive net pay exists in these sequences will be key to their commercial potential and the need for 3D seismic acquisition is being evaluated.
The results from the three discovery wells and the testing programme will be integrated to define the reserve estimates, commerciality and potential development scenarios for the onshore area.
Planning for additional exploration/appraisal wells onshore and a test of a prospect just offshore has commenced, with onshore drilling scheduled for Q4 2006.
Plans for the acquisition of further 2D seismic in the north of the block are also well advanced.
