The use of coiled tubing (CT) to drill horizontal re-entry wells has received considerable interest in the industry over the last two years. The benefit of being able to drill at balance, safely and in a controlled manner, with nitrogen to reduce downhole pressure while drilling highly depleted reservoirs, provides an advantage over conventional techniques, particularly in reducing formation damage. This paper describes such a horizontal re-entry drilled in the shallow depleted waterflooded reservoir Barenburg in northern Germany. The scope of work for this project included (1) cutting windows through 6 5 / S -and 9 5 / s -in. casing, (2) drilling a 5 7 / s -in.-medium-radius curve, (3) running a 5-in. liner and a 5Jf2-in. parasitic string for nitrogen injection, (4) drilling a 4 3 / s -in. horizontal with nitrogen to maintain a balanced condition, (5) running openhole logs, and (6) running 3Jf2-in. slotted liner. The entire program was executed with no intervention from a conventional rig or workover hoist. A special structure to be positioned over the well to support the CT injector head and to provide a work platform had to be constructed for this type of operation. A dedicated mast for lifting pipe and downhole tools was placed on the substructure. The development of a surfacecontrolled orienting tool and an adjustable motor provided excellent directional capabilities on a 23/ s -in. CT. This program represents a significant extension of the capabilities of drilling with CT.

The use of coiled tubing to drill horizontal reentry wells has received considerable interest in the industry over the last two years. The benefit of being able to drill at balance, safely and in a controlled manner, using nitrogen to reduce down hole pressure while drilling highly depleted reservoirs, provides an advantage over conventional techniques, particularly in reducing impairment to the formation. The paper describes such a horizontal re-entry drilled in the shallow depleted water flooded reservoir Barenburg in Northern Germany. The scope of work for this project included:Cutting a window through 6 5/8" and 9 5/8" casingDrilling a 5 7/8" medium radius curveRunning a 5" liner and a 5 1/2" parasitic string for nitrogen injectionDrilling a 4 3/8" horizontal using nitrogen to maintain a balanced conditionRun open hole logsRun 3 1 /2" slotted liner The entire program was executed with no intervention from a conventional rig or workover hoist. A special structure to be positioned over the well to support the coiled tubing injector head and to provide a work platform had to be constructed for this type of operation. A dedicated mast for lifting of pipe and down hole tools was placed on the substructure. The development of a surface controlled orienting tool and an adjustable motor provided excellent directional capabilities on a 2 3/8" coiled tubing. This program represents a significant extension of the capabilities of drilling with coiled tubing.