During the turn of the year to 2003 the sidetrack A-19 A was drilled from the motherwell A-19 as a Through Tubing Rotary Drilling (TTRD) well, on the Veslefrikk Field in the Norwegian sector of the North Sea.

A whipstock with holes to produce the motherwell through was set in the 5 in. liner. 4 1/8 in. polycrystalline diamond compact (PDC) bit and 2 7/8 in. high torque motor with adjustable kick off (AKO) setting of 3.8° were run on 2 7/8 in. drill pipe through 5 ½ in. tubing.

The sidetrack started with 25° inclination and the wellpath was horizontal after 24 m true vertical depth (TVD) drilled. An average dogleg severity (DLS) of 42° /30 m was achieved in the build up section. An 80 m horizontal section was drilled and geo-steered using gamma ray (GR) and multi propagation resistivity (MPR) measurements. The same bottom hole assembly (BHA) was used for the horizontal section as for the build up section of the sidetrack.

A pre-perforated 2 7/8 in. liner was installed in the 4 1/8 in. open hole.

The operations were performed using a Rig Assist Snubbing (RAS) unit in cooperation with the rig system. The pre and past-drilling operations were performed in underbalance while the drilling operation was in overbalance through the snubbing BOPs.

The motherbore and the sidetrack were set in production immediately after the liner was run.

In the future Statoil are looking at performing a similar drilling operation in underbalance. It should then be possible to make a sidetrack in approximately 10 days.

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