Tubular Mechanics in Oil-Gas Wells and Its Applications-PPT
 | |
| Author | Zifeng Li |
|---|---|
| Language | English |
| Subject | Petroleum engineering; mechanics of drill strings, casing, tubing and sucker rods |
| Published | 2012 |
Tubular Mechanics in Oil-Gas Wells and Its Applications is a survey of the mechanics of pipe strings in oil and gas wells by Zifeng Li, professor of petroleum engineering at Yanshan University. It is catalogued on this wiki in the form in which Li circulated it — a slide presentation distributed as a PDF, which is what the "PPT" in the page title records — rather than as a conventional book. It is the presentation version of Li's 2008 monograph Tubular Mechanics in Oil-Gas Wells and Its Applications (Petroleum Industry Publishing House, 256 pp.), which carries the same title and covers the same ground at length.
It is worth being clear about what this item is, because it sits oddly among Li's other entries here. Most of his material on this wiki belongs to his dissident physics: criticism of special relativity, of modern cosmology, and of what he regards as idealism in contemporary physics. This presentation is not that. It is a summary of his mainstream professional specialty, the field in which he holds a chair, edits journals and has published well over a hundred papers.
Subject
Tubular mechanics concerns the behaviour of the long, slender steel strings that make an oil or gas well work: the drill string that cuts the hole, the casing that lines it, the tubing through which fluids are produced, and the sucker rods that drive downhole pumps. These strings may run for thousands of metres in a hole only slightly wider than themselves, and they are simultaneously stretched, compressed, twisted, bent, heated and pressurized from within and without.
The engineering problems that follow are unforgiving and expensive. A drill string in compression buckles — first into a sinusoidal shape against the borehole wall, then into a helix — which increases friction, can lock the string in place, and in the worst case twists it off. Casing collapses under external pressure. Rods fatigue and part. Because a failure thousands of metres underground is difficult and costly to remedy, the mechanics has direct commercial consequence, and Li describes tubular mechanics as the most important applied fundamental science in petroleum and gas engineering.
Contents
The presentation surveys the mechanical behaviour of drill strings, pumping rods, tubing and casing, organized around three governing principles:
- Equilibrium
- Minimum potential energy
- Minimum power dissipation rate
From these it treats the standard problems of the field — static buckling, tension–torque models for strings in deviated and horizontal wells, and the vibration of drill strings — together with more specialized settings such as well testing and thermal recovery, where large temperature changes drive the loading.
Its closing move is the unexpected one. Li extends the same analysis beyond petroleum engineering to vascular interventional medicine — the mechanics of guidewires and catheters advanced through blood vessels, which is the same problem of pushing a slender elastic string along a narrow curved channel without buckling it — and to micro- and nano-scale systems. The generalization is a fair one: the governing mechanics does not care about the scale or the material, and the buckling of a catheter in an artery and of a drill string in a wellbore are the same problem in different clothes.
Context: a dissenter in his own field
The presentation is a summary of a research programme that has itself been contentious, and this is what makes the entry more than a curiosity on a wiki devoted to dissident science.
In "Research advances and debates on tubular mechanics in oil and gas wells" (Acta Petrolei Sinica, 2016, 37(4), 531–556), Li surveyed the field's open disputes and took positions in several of them. He has argued that using the fictitious force to judge the stability of a pipe string is incorrect; that the "unbending drill-collar" concept advanced by Gong Wei'an lacks theoretical basis; that recent work on drill-string bifurcation and chaos contains methodological problems; and he has been party to extended exchanges over casing strength design standards, including triaxial collapse resistance and wellhead load calculation.
These are ordinary scientific disagreements conducted in peer-reviewed journals, and Li conducts them from a position of recognized standing — technical editor for SPE Drilling & Completion and several Chinese petroleum journals, and winner of a First Class Monograph Award from the Government of Heilongjiang Province for Rod and Pipe String Mechanics in Oil and Gas Wells.
That is the useful context for the rest of his entries here. Li's relativity criticism is not the work of someone who quarrels with the mainstream only where he is an amateur: he disputes received results in his own discipline as well, where he is an expert and where his objections are published, refereed and answered. Readers may weigh that either way — as evidence of a genuinely independent cast of mind, or as a disposition to contradict — but it is the relevant fact about the author.
Publication
The material was circulated as a PDF slide deck, dated 2012 on this wiki. Li presented the same work under the title "Tubular mechanics in oil-gas wells and its applications" at the World Congress on Petroleum and Refinery in Brisbane, Australia, on 21–22 July 2016, with the abstract appearing in the Journal of Petroleum & Environmental Biotechnology.
His related books and papers on rod and pipe string mechanics, and his drilling-engineering course chapters, are catalogued separately on this wiki; see Zifeng Li for the full list.
See also
- Tubular Mechanics in Oil-Gas Wells and Its Applications — the 2008 book this presentation summarizes
- Zifeng Li
- Petroleum drilling engineering course material by the same author