The use of coiled tubing 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, 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" casing

  • Drilling a 5 7/8" medium radius curve

  • Running a 5" liner and a 5 1/2" parasitic string for nitrogen injection

  • Drilling a 4 3/8" horizontal using nitrogen to maintain a balanced condition

  • Run open hole logs

  • Run 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.

You can access this article if you purchase or spend a download.