Well R101 was spudded by the N75 rig in October 2005 and suspended at a depth of 4,570m in January 2006 after encountering significantly higher than expected pressures in the lower section. It was decided to isolate the lower section and test the upper Visean and Tournasian formations only. The N75 rig returned to the well in May of this year to install a high strength casing string and prepare the well for testing. The underlying high pressure Devonian formations are planned to be investigated with a new deeper well to be drilled by a larger rig.
Two gas bearing intervals were identified from mud logs within the Tournasian sandstones. A gas bearing interval of 119m located between 4,330m and 4,449m has now been perforated using tubing conveyed guns. The well flowed at an initial rate of 1 million cubic feet of gas per day with a wellhead flowing pressure of 1,400 psi. This declined to a rate of 0.3 million cubic feet of gas per day with a wellhead flowing pressure of 300 psi over the 4-day test period. Pre sure data indicate that the reservoir permeability of this interval is low. The second 115m gas bearing interval between 4,095m and 4,210m is scheduled for testing in late August/September when the N75 rig completes the drilling of development Wells M155 and M153 in the northern part of the Molchanovskoye Field.
A number of further gas bearing intervals totalling up to 59m has been identified from mud logs in the Visean sandstones at depths between 3,443m and 4,082m. Scheduling of the investigation of these shallower intervals is dependent on results of the Tournasian sandstone test program. Fracture stimulation is also being considered as a supplement to the planned test programs.
Well R12 in the south of the Rudenkovskoye Field continues to be productive from Devonian sands between 3,400m and 3,500m.
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