Increased Gas Recovery by High-Angle Subsea Wells in High-Pressure-High-Temperature (HPHT) Environment at Kristin Field

The Kristin Field is the most extreme high-pressure-high-temperature (HPHT) field in Norway, with a reservoir pressure of 911 bars and a temperature of 175°C. This has led to huge challenges in developing the Field.<br><br>The production wells were initially planned as medium inclined wells due to well control issues. Towards field development, strong indications showed that the permeability in the uppermost reservoir was less prosperous than predicted. This would imply only half of the production plateau period committed, reduced recovery from the Field and a substantial deficit in project net-present-value as a result. The need for longer reservoir sections became quite evident.<br><br>The scope was extended to near horizontal well designs. The ultimate Kristin well is 6580 m MD long with an 8½" HPHT section of 1083 m with 746 m above 80°. This is the world’s longest and most deviated HPHT subsea gas producer.<br><br>By production start 3 November 2005, Kristin has drilled 9 and completed 4 wells, most being high angle wells above 75°. The production simulations show that the plateau production is back up to the original commitments. <br>