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Colleagues,

We are considering a deep HPHT sour gas exploration well offshore using a jack-up. One camp wants to drill the well as a possible “keeper” so after drilling and testing we could suspend, install a platform and tie-it back as the first producer, thus paying for the exploration well. There are plenty of good reasons to do this and also not to do it.

The focus of my attention is the later tie-back of the 9-7/8” mud line hanger. We go to great lengths to select production casing connections that have been fully ISO 13679 tested under just about every load and temperature case possible and pass the test all the way around the von Mises equivalent stress envelope (VME). The mud line system only conforms with API 17D requirements which just requires end caps and a pressure test. So, the final production casing has a very obvious weak point that may not stay the course for 20 years of cyclic loading.

My question is, what do other Operators do at this point ? Are production string MLS tie-backs on HPHT wells accepted or rejected outright, are there any alternatives, are there any MLS vendors with a system that overcomes this weakness.

Your feedback would be appreciated.

Keith