Statoil now considers Stavanger-based Petec’s Dynaflodrill (DfD) as mission-critical for its under balanced drilling program on the Gullfaks field. DfD, part of Petec’s Drillbench suite, is used for the design of under balanced operations and enables engineers to investigate static and dynamic problems related to under balanced drilling operations (UBD).
Statoil UBD operations manager Johan Eck-Olsen said, ‘Following a successful qualification period, where the accuracy of the model was tested by comparing simulated results with actual UBD well data, Dynaflodrill has been a very valuable tool in planning and training for the UBD drilling campaign on Gullfaks.’
UBD helps reduce lost circulation, minimizing the risk of differential sticking, increases bit life and penetration rates. UBD also can avoid formation damage, increase well productivity and may eliminate the need for stimulation.
Statoil is going to perform the Norway’s first UBD on the Gullfaks C-5 well later this year. UBD was selected to overcome frequent well control problems faced in previous Gullfaks wells due to low margins between pore and fracture pressures.
Planning and preparing for an offshore UBD operation is more complicated than a traditional overbalanced well. Statoil has a strong focus on HSE, and being the first UBD drilling operation in Norway, it has also been necessary to convince the Norwegian Petroleum Directorate that the operations can be performed with an acceptable safety level.
Several Drillbench applications have been used in the project. Steadyflodrill and Dynaflodrill were used to design the UBD program and to train team members. The dynamic surge and swab module in Presmod was used to design the tripping procedures to avoid exceeding the operational pressure window during tripping.
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