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Abstract
From conceptual development to laboratory data this paper will describe the
need, development, testing, and results of ultra-high pressure Jet Cutters and
Severing Tools for use in environments up to 30ksi for today’s deepwater,
ultradeep well market. Designing and building of a new, first of its kind test
vessel allowed for actual separation of drill string components, at bottom hole
pressures, with zero tension applied.
Efficient separation of stuck drill strings with proven results is a must for
deepwater wells where depths can reach 35,000 ft and daily rates often exceed
USD
1,000,000. Operators want proven results instead of theoretical calculations or
critical path experimentation during a stuck pipe hazard event. Historical pipe
cutting or severing has been hindered by high bottom hole pressures and
internal diameter restrictions for decades. Chemical cutters and Radial Cutting
Torches being foremost affected by the effect of hydrostatic pressure on their
method of pipe separation, while jet cutters and severing tools explosive
charges could overcome more bottom hole pressure. After leaping the 20ksi
hurdle we were still limited to 25ksi or less and had unproven products, until
now.
Improvements in the initiation timing of explosive cutters and severing tools
along with adequate quantities of components in conjunction with laboratory
testing proved that jet cutting and severing drill string tubular components,
including drill pipe and heavyweight drill pipe, is achievable at pressures up
to 30ksi.
Substantial cost and critical path time savings for deep well and deepwater
operators can be realized during stuck pipe incidents by utilizing tested
technology proven to separate drill string components at bottom hole pressures
up to 30ksi. Improved safety features provides for more confident field
assembly with reduced risk involved.
Introduction
Stuck pipe incidents are unplanned events requiring drilling companies,
workover companies, and operators to analyze changing wellbore conditions and
make quick decisions in an effort to minimize or alleviate the sticking
condition. Multiple conditions cause stuck pipe events including mechanical
sticking, junk sticking, underguage and sloughing hole sticking, lost
circulation sticking, blowout sticking, and more. The most prevalent open hole
sticking condition is differential sticking or “wall sticking”. Although each
stuck pipe event is a unique set of circumstances involving a combination of
the well geometry, geology, depth, condition and sticking mechanism, there are
some similarities to the events as well. Utilizing a planned method of attack
(Fig. 1), recognizing the stuck pipe responses to manual
manipulations and applied stresses by monitoring at the surface, and using
downhole tool measurements, such as Free Point Tools, can often narrow down the
cause and help determine the stuck point of the string.
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