4D Seismic and Through Tubing Drilling and Completion Wells Extend Life on theGullfaks Field

摘要

The Gullfaks Main Field is one of the largest oil fields in theNorwegian sector of the North Sea. Production started in 1986and reached a peak in 1994. Today approximately 90 % of thebase reserves have been produced from this mature field.Locating remaining oil reserves is therefore a challenging andimportant task for the future of Gullfaks. The reservoirs arecomprised of middle and early Jurassic sandstones, possessingoverall excellent reservoir properties. The structural setting ofthe field is complex, and represents one of the main factors ofuncertainty concerning the drainage of the field. The paperdescribes how multiple time-lapse seismic (4D) have provenvery accurate in identifying undrained oil pockets in the BrentGroup. The importance of 4D/4C in the wells drilled isestimated to represent a reserve oil volume of approximately 4Mill. Sm3 per 2004, (25 Mill. Sbbl). TTD&C (Through TubingDrilling and Completion), being a more flexible and lessexpensive technology, has also been crucial in reachingsmaller oil pockets on the Gullfaks Main Field. The potentialoffered by these technologies has been optimized bymultidisciplinary teamwork on Gullfaks, thus creating synergyand flexibility. These three key elements have contributed toreverse the oil production decline, establish a new plateau,reduce costs and increase profit.