Advanced Slip-Crushing Considerations for Deepwater Drilling
| Autor: | U.B. Sathuvalli, P.V. Suryanarayana, J. Shepard, Mike Payne |
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| Rok vydání: | 2002 |
| Předmět: | |
| Zdroj: | SPE Drilling & Completion. 17:210-223 |
| ISSN: | 1930-0204 1064-6671 |
| DOI: | 10.2118/80169-pa |
| Popis: | Summary This paper addresses a problem pertinent to the design of landing strings and drillstrings for deepwater operations. These landing strings are designed to run long and heavy casings, tiebacks, or liners (typically deep intermediate and production tubulars), and the total weight may approach or exceed 1,000 kilo lbf (klbf) at the mudline. Adding the weight of the landing string to the rotary results in a serious design problem regarding both the landing string itself and the handling equipment. Slip-based handling systems work well in most instances but lead to biaxial loading from the tensile and radial loads exerted by slip inserts. As a result of biaxial loads, the axial load rating of the landing string is reduced. The current understanding of slip-crushing phenomena is based on testing and modeling work dating to 1959 by Reinhold and Spiri1 and Vreeland.2 This paper assembles all available data regarding slip crushing and places it in the perspective of current understanding. A secondary aim is to describe the physics of the slip-drillpipe interaction in some detail (i.e., extend the Reinhold-Spiri analysis1 to the next level). The analysis presented in this paper shows variations between the historical Reinhold-Spiri model and test results, and it indicates an unconservative margin of ~20%. These trends can be accounted for with a more accurate model of slip-crushing mechanics. The improved model supports a nonlinear stress distribution in the pipe, and its prediction of peak stresses is consistent with general test observations. With better quantification of the friction factors between the slip and the bowl, load uniformity, and equipment tolerancing and fits, this new model and its underlying approach provide an appropriate framework for a more accurate tubular rating for slip-crushing performance. Until such time as these refinements are made and available, drilling personnel should consider and implement appropriate safety factors when dealing with marginal designs for slip-crushing scenarios. |
| Databáze: | OpenAIRE |
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