When faced with challenging formations on the Goliat field in the Barents Sea, ENI Norge decided to take advantage of the expertise OWS is known for when it comes to drilling top holes.
When drilling a top hole, the main challenge is drilling the section as vertical as possible. There are very small margins and the deviation must not exceed 1,5 degrees. In the Barents Sea, and especially on the Goliat field, the formations make this task even more difficult. ENI Norge had used the Boulder Buster 26*36 for their exploration drilling and the experiences was so good that they wanted OWS to develop a hole opener specially designed to handle the difficult production drilling they were faced with. In collaboration with ENI Norge, OWS ended up with a design for a to step hole opener measuring 28*46. A Boulder Buster weighing eight tons, tailored for top hole drilling in extreme formations.
ENI Norway has so far drilled eight out of nine top holes on Goliat using the Boulder Buster 28*46. Its unique cutter design and heavy weight delivers excellent results and all the holes have been drilled to specifications. In February 2015 the Boulder Buster drilled five top holes with the same bottom hole assembly (BHA). Considering the difficult formations, this is a very good achievement.
ENI is very happy with the Boulder Buster and has never considered other tools for Goliat.
- I’m not sure if the Boulder Buster is faster than other hole openers, but given the fact that it drills that vertical, you don’t need to ream the top hole, says David Winterton, Senior Drilling Engineer at ENI Norge. The one-piece design reduces the need for people in red zone, and master bushings only needs to be removed once when the Boulder Buster is going through the rotary table. That means to-three hours saved, Winterton says.