Salt: ESCO – Frisia well BAS-3 workover

With a successful technical complicated workover and cementing operation carried out on well BAS-3 for Frisia Zout BV, part of ESCO, the planned sidetrack for this well can be performed. Only with an integer seal of the old wellbore, this sidetrack is possible.

As part of abandonment operations and as preparation for the sidetrack a remaining string of cemented drill pipe had to be removed. Removal of this pipe was necessary to be able to secure the well with an additional column of cement on top of the balanced cement plug present. The balanced plug on itself is not an integer seal.

An HWU was selected to be able to gain access to the drill pipe with coiled tubing, work under well pressure and to be able to provide pulling/pushing force. A coiled tubing unit had to be rigged up on top of the HWU for milling. A crane supported the weight of the coiled tubing equipment.

To be able to get an integer and sealing cementation in another way, “gravitational” cementation was carried out around the “fish”; between the casing wall and the “sticking out” cemented drill pipe.

This workover can be considered high flying because:

• Milling out a cemented drill pipe sticking out at 3350 m AH depth with coiled tubing at very small clearances, very poor hole cleaning, in a deviated section, and under pressure.
• Gravitational cementing of the annular space between a cemented drill pipe fish (5”) and casing (11 ¾”) in this deviated part of the well.
• Latching with workstring to fish without any problems/ releasing from fish without any problems.
• Rig up of coil on top of a “snubbing” unit.