THE TROLL OIL DEVELOPMENT: ONE BILLION BARRELS OF OIL RESERVES CREATED THROUGH ADVANCED WELL TECHNOLOGY

摘要

The Troll field, at 340 m water depth offshore Norway, is primarily a huge gas field, but below this gas cap, 5 billion barrels (800 Mm~3) of oil are located in an oil layer varying from 4-27 m. Originally, effort was concentrated on developing only the gas, as the oil could not be economically exploited by conventional means.An extended test program in two horizontal wells in 1990-91 proved that economic oil production could be achieved. It was decided to develop the most productive part of the field and a minor part of a huge area containing a 13 m oil column. By this, the oil reserves increased from 0-440 million barrels (70 Mm~3).These reserves will be recovered by 24 horizontal subsea wells, located in five cluster areas, and are currently being drilled. These wells, originally planned with 800 m horizontal sections, through extensive improvements are realizing up to 2500 m horizontal sections, drilled with high vertical accuracy. To locate the wells optimally, advanced seismic methods are being applied.Production from the floating production platform Troll B started in September, 1995. The drilling and production performance so far have led to a decision to develop the remaining part of the area with the 13 m oil column, and the oil reserves have risen to 1100 million barrels (175 Mm~3). This new phase will consist of some 56 wells, several of them being multilateral wells.