9/2-6 S

General The deviated well 9/2-6 S is located on the Yme Gamma South East structure, and was drilled from slot 6 of the Yme template. The well was planned as an exploration well, being the first well drilled on the South East structure, but would be completed as an oil production well if commercial oil reserves were proven, or sidetracked to the Yme Gamma Vest structure if the oil column was less than 25 m. The well objective was also to evaluate whether the Bryne Formation in this well could be used as an Yme gas injection well.

Operations and results Wildcat well 9/2-6 S was spudded with the jack-up installation Mærsk Giant on 19 August 1996 and drilled to a total depth of 5205.0 m (3600.8 m TVD SS) in the Middle Jurassic Bryne Formation. The 9/2-6 S well was planned with a "S" shaped profile, in order to drill vertically through the Sandnes Formation in the crestal area of the Gamma South East structure, to the east of the graben separating the South East segment from the Yme Gamma Vest Field. However, due to difficulties dropping angle, a deviation to the plan was made so that the angle would be dropped to 30 deg. The well was drilled with seawater and gelled bentonite pills through the 37 &" hole and with seawater and PAC pills through the 26" hole down to 842 m. KCl/Aquadrill (with glycols) mud was used from 842 m to 2481 m, and with ester-based Petrofree mud from 2481 to TD. From 4845 m and to TD the well was drilled with Neyfor Turbine and diamond bit. The top of the Sandnes Formation reservoir was encountered al 4783 m (3228.7 m TVD SS), and the oil/water-contact was found at 3277.0 m TVD SS, giving an oil column of 48 m. The Sandnes S12 target was penetrated approximately 3085.5 m South East of the platform, at an inclination of 20.4 deg. 12 February 1997. Two cores were cut in the interval 4793 - 4845 m across the OWC in the Sandnes Formation. Core 2 (4808 - 4845 m) retrieved 40.8 m. The extra 3.8 m retrieved in this core is believed to be the lower