Kvitebjørn is a HPHT gas/condensate field under development in block 34/11, located in the south-eastern part of the Tampen Spur area in the North Sea. The field, which is east of Gullfaks and north of Huldra in block 30/2, is in 190 metres of water. The reservoir lies at approximately 4,000 metres depth and is classified as high temperature (155°C/311°F) and high pressure (81 MPa/11,700 psi).
By 2006, nine production wells were drilled and seven completed, with inclinations varying from 20–45°. All drilling took place from the Kvitebjørn platform’s fixed rig.
Of the seven completed wells, five were completed with openhole sand screens and two with cemented liners. Production started after drilling the first two wells, and the remaining part of the well construction programme took place in an environment of progressive reservoir pressure depletion. During drilling of the last well, 140–170 bar of depletion was encountered and losses were experienced. The remaining wells were drilled using managed pressure drilling (see separate case). In all these wells, the cesium formate brine system once again demonstrated clear performance benefits, such as very low equivalent circulating densities (ECDs), moderate to high rate of penetration (ROP), good hole cleaning, and excellent wellbore stability while drilling and logging. Quick, trouble-free, safe and robust completion operations were also accomplished. Furthermore, the wells that have been put on production show high production rates with low skin.
Full openhole formation evaluation of the Kvitebjørn reservoir has been carried out with logging-while-drilling (LWD) tools. The evaluation has been aided by the development of an innovative logging interpretation solution for a LWD density tool, where the extremely high photoelectric effect of cesium-rich filtrate plays a vital role.
This case history and all others are downloadable here.
Berg, P. C., Pedersen, E. S., Lauritsen, Behjat, N., Hagerup-Jenssen, S., Howard, S., Olsvik, G., Downs, J. D., Harris, M. and Turner, J. (2007, February 20–22). Drilling, Completion, and Openhole Formation Evaluation of High-Angle Wells in High-Density Cesium Formate Brine: The Kvitebjørn Experience, 2004–2006. Proc., SPE/IADC Drilling Conference, Amsterdam, The Netherlands. SPE-105733-MS. doi.org/10.2118/105733-MS.
Pedersen, B. K., Pedersen, E. S., Morriss, S., Constable, M. V., Vissapragada, B., Sibbit, A., Stoller, C., Almaguer, J., Evans, M., Shray, F., Grau, E., Fordham, E., Minh, C. C., Scott, H. and McKeon, D. (2006, September 24). Understanding the Effects of Cesium/Potassium Formate Fluid on Well Log Response – A Case Study of the Kristin and Kvitebjørn Fields, Offshore Norway. Proc., SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA. SPE-103067-MS. doi.org/10.2118/103067-MS.