Abstract

Drilling Industry is exploring various ways of reducing costs through multitude of initiatives. One of the major area where there is potential for cost reduction is downtime due to drill string failures. Losing a bottom hole assembly (BHA) is one of the most costly unplanned drilling events that can occur for an operator. Time spent on fishing for the lost assembly, the rig time wasted waiting on the mobilization of equipment and people, as well as the additional costs of whip stocks, cement, and directional tools significantly increase the cost of a well and often results in exceeding the approval for expenditure. Even though this is an old problem, with new drilling technology, especially related to the use of drill collars (larger OD), which is one of the main component of the drill string which in 60% of cases get stuck, therefore there is a need to redesign the drill collar which can be able to drill ahead even in case of stuck pipe situations. In this paper, a new solution to prevent stuck pipe problems and to retrieve stuck BHA is proposed. A drill collar is designed in such a way that during stuck situations, it can be released and we can continue drilling ahead and/or retrieve drill string easily. This is achieved by use of expandable techniques on drill collar. This proposed technique will allow us for continuous and easier drilling, thus saving rig time and ultimately economics of the entire operation at a fraction of increased cost in new drill collar. This paper explains the causes and solution for stuck pipe problems and then presents a new designed drill collar with its design and operating concept. Finally conclude that use of this drill collar can be a viable tool for Drilling industry.

Introduction:

An interruption in planned operations as excessive drag forces prevents pulling the drill string out of the hole. Industries statistics gathered since 1989 show the relative cost of non-productive time. Stuck pipe is still the drilling industry's most costly unscheduled event.

There are numerous causes of stuck pipe; some occur regularly, some may be peculiar to a particular area and some may be unique. A string may become stuck because of any one or combination of these, although historically in drilling industry's operation stuck pipe due to packing-off and differential sticking mechanisms has accounted for approximately 72% of incidences. Industry categories these cause as either differential or mechanical sticking.

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