Влияние места установки амортизатора на показатели ударного импульса аварийной компоновки бурильной колонны

У статті на основі розробленої нелінійної математичної та комп’ютерної моделі роботи бурильної колони з ударним механізмом, котрий застосовують для ліквідації прихоплень бурильного інструменту, проведено дослідження місця установки амортизатора на ударний імпульс в місці нанесення удару й місці прихоплення. Проведено чисельний розрахунок тривалості удару, ударних сил та імпульсів, накопиченої пружної деформації й втраченої внаслідок удару енергії. Проаналізовано вплив місця установки амортизатора при різних значеннях ходу ударного механізму на ефективність його роботи.The article, based on the developed nonlinear mathematical and computer models of the work of the drill string with the hammer mechanism, which is used to eliminate sticking drilling tool, conducted research on the location of the shock absorber shock pulse in the place of strike and place of sticking. Produced by numerical calculations of the duration of impact, impact forces and impulses accumulated elastic strain and lost as a result of the impact energy. For different values of the impact mechanism stroke analyzed the influence of the installation site on the performance of the shock absorber.В статье, на основании разработанной нелинейной математической и компьютерной модели работы бурильной колонны с ударным механизмом, который используют для ликвидации прихватов бурильного инструмента, проведены исследования места установки амортизатора на ударный импульс в месте нанесения удара и месте прихвата. Произведен численный расчёт длительности удара, ударных сил и импульсов, накопленной упругой деформации и потерянной в результате удара энергии. Проанализировано влияние места установки амортизатора при различных значениях хода ударного механизма на эффективность его работы

Влияние утяжеленных бурильных труб на спектр продольных колебаний бурильного инструмента

При бурінні свердловин у процесі експлуатації породоруйнівний інструмент і бурильна колона руйнуються внаслідок пружних вібрацій, а також статичних й зовнішніх навантажень. Тому актуальною є проблема дослідження спектру власних коливань бурильної колони в залежності від її компоновки (кількості секцій), загальної довжини секцій, площі поперечного перерізу бурильних труб. Розроблення методики визначення частотного діапазону для кожної комплектації бурильної колони дозволить прогнозувати появу резонансних зон. Застосування бурильного інструменту на цих частотах небажане, однак у випадку ліквідації аварій (прихоплення бурильної колони) за допомогою вібраторів варто налаштовуватись саме на резонансні частоти.When drilling holes in the operation breed destructive tool and drill string are destroyed as a result of elastic vibrations and static and external loads. Therefore, the actual problem is the study of the spectrum of natural vibrations of the drill string, depending on its layout (number of sections), the total length of the sections, the cross-section of drill pipe. The development of methods for determining the frequency range for each configuration of the drill string will predict the emergence of high-profile areas. The development of methods for determining the frequency range for each configuration of the drill string will predict the emergence of high-profile areas. The use of the boring tool for these unwanted frequencies, but in case of accidents (stuck drill string) vibration method should be adjusted exactly to the resonance frequency.При бурении скважин в процессе эксплуатации породоразрушающий инструмент и бурильная колонна разрушаются вследствии упругих вибраций, а также статических и внешних нагрузок. Поэтому актуальной является проблема исследования спектра собственных колебаний бурильной колонны в зависимости от её компоновки (количества секций), общей длины секций, площади поперечного сечения бурильных труб. Разработка методики определения частотного диапазона для каждой комплектации бурильной колонны позволит прогнозировать возникновение резонансных зон. Применение бурильного инструмента на этих частотах нежелательно, вместе с тем в случае аварий (прихватов бурильной колонны) при помощи вибраторов следует настраиваться на резонансные частоты

Neutron polarizabilities investigated by quasi-free Compton scattering from the deuteron

Measuring Compton scattered photons and recoil neutrons in coincidence, quasi-free Compton scattering by the neutron has been investigated at MAMI (Mainz) at $theta^{lab}_\gamma=136^o$ in an energy range from 200 to 400 MeV. From the data a polarizability difference of $\alpha_n - \beta_n = 9.8 \pm 3.6(stat)^{+2.1}_{-1.1}(syst)\pm 2.2(model)$ in units of $10^{-4}fm^3$ has been determined. In combination with the polarizability sum $\alpha_n+\beta_n= 15.2\pm 0.5$ deduced from photo absorption data, the neutron electric and magnetic polarizabilities, $\alpha_n=12.5\pm 1.8(stat)^{+1.1}_{-0.6}(syst)\pm 1.1(model)$ and $\beta_n = 2.7\mp 1.8(stat)^{+0.6}_{-1.1}(syst)\mp 1.1(model)$, are obtained

Quasi-free π0\pi^0 Photoproduction from the Bound Nucleon

Differential cross-sections for quasi-free $\pi^0$ photoproduction from the proton and neutron bound in the deuteron have been measured for $E_\gamma= 200 - 400$ MeV at $\theta^{\rm lab}_\gamma = 136.2^\circ$ usind the Glasgow photon tagger at MAMI, the Mainz 48 cm $\varnothing$ $\times$ 64 cm NaI(Tl) photon detector and the G\"ottingen SENECA recoil detector. For the proton measurements made with both liquid deuterium and liquid hydrogen targets allow direct comparison of "free" $\pi^0$ photoproduction cross-sections as extracted from the bound proton data with experimental free cross sections which are found to be in reasonable agreement below 320 MeV. At higher energies the "free" cross sections extracted from quasifree data are significantly smaller than the experimental free cross sections and theoretical predictions based on multipole analysis. For the first time, "free" neutron cross sections have been extracted in the $\Delta$-region. They are also in agreement with the predictions from multipole analysis up to 320 MeV and significantly smaller at higher photon energies

Low-Energy Compton Scattering of Polarized Photons on Polarized Nucleons

The general structure of the cross section of $\gamma N$ scattering with polarized photon and/or nucleon in initial and/or final state is systematically described and exposed through invariant amplitudes. A low-energy expansion of the cross section up to and including terms of order $\omega^4$ is given which involves ten structure parameters of the nucleon (dipole, quadrupole, dispersion, and spin polarizabilities). Their physical meaning is discussed in detail. Using fixed-t dispersion relations, predictions for these parameters are obtained and compared with results of chiral perturbation theory. It is emphasized that Compton scattering experiments at large angles can fix the most uncertain of these structure parameters. Predictions for the cross section and double-polarization asymmetries are given and the convergence of the expansion is investigated. The feasibility of the experimental determination of some of the struture parameters is discussed.Comment: 41 pages of text, 9 figures; minor revisions prior to publication in Phys. Rev.

Quasi-free Compton Scattering and the Polarizabilities of the Neutron

Differential cross sections for quasi-free Compton scattering from the proton and neutron bound in the deuteron have been measured using the Glasgow/Mainz tagging spectrometer at the Mainz MAMI accelerator together with the Mainz 48 cm $\oslash$ $\times$ 64 cm NaI(Tl) photon detector and the G\"ottingen SENECA recoil detector. The data cover photon energies ranging from 200 MeV to 400 MeV at $\theta^{LAB}_\gamma=136.2^\circ$. Liquid deuterium and hydrogen targets allowed direct comparison of free and quasi-free scattering from the proton. The neutron detection efficiency of the SENECA detector was measured via the reaction $p(\gamma,\pi^+ n)$. The "free" proton Compton scattering cross sections extracted from the bound proton data are in reasonable agreement with those for the free proton which gives confidence in the method to extract the differential cross section for free scattering from quasi-free data. Differential cross sections on the free neutron have been extracted and the difference of the electromagnetic polarizabilities of the neutron have been obtained to be $\alpha-\beta= 9.8\pm 3.6(stat){}^{2.1}_1.1(syst)\pm 2.2(model)$ in units $10^{-4}fm^3$. In combination with the polarizability sum $\alpha +\beta=15.2\pm 0.5$ deduced from photoabsorption data, the neutron electric and magnetic polarizabilities, $\alpha_n=12.5\pm 1.8(stat){}^{+1.1}_{-0.6}\pm 1.1(model)$ and $\beta_n=2.7\mp 1.8(stat){}^{+0.6}_{-1.1}(syst)\mp 1.1(model)$ are obtained. The backward spin polarizability of the neutron was determined to be $\gamma^{(n)}_\pi=(58.6\pm 4.0)\times 10^{-4}fm^4$

Nucleon Spin-Polarisabilities from Polarisation Observables in Low-Energy Deuteron Compton Scattering

We investigate the dependence of polarisation observables in elastic deuteron Compton scattering below the pion production threshold on the spin-independent and spin-dependent iso-scalar dipole polarisabilities of the nucleon. The calculation uses Chiral Effective Field Theory with dynamical Delta(1232) degrees of freedom in the Small Scale Expansion at next-to-leading order. Resummation of the NN intermediate rescattering states and including the Delta induces sizeable effects. The analysis considers cross-sections and the analysing power of linearly polarised photons on an unpolarised target, and cross-section differences and asymmetries of linearly and circularly polarised beams on a vector-polarised deuteron. An intuitive argument helps one to identify kinematics in which one or several polarisabilities do not contribute. Some double-polarised observables are only sensitive to linear combinations of two of the spin-polarisabilities, simplifying a multipole-analysis of the data. Spin-polarisabilities can be extracted at photon energies \gtrsim 100 MeV, after measurements at lower energies of \lesssim 70 MeV provide high-accuracy determinations of the spin-independent ones. An interactive Mathematica 7.0 notebook of our findings is available from [email protected]: 30 pages LaTeX2e, including 22 figures as 66 .eps file embedded with includegraphicx; three errors in initial submission corrected. This submission includes ot the erratum to be published in EPJA (2012) and the corrections in the tex

Dirac-Foldy term and the electromagnetic polarizability of the neutron

We reconsider the Dirac-Foldy contribution $\mu^2/m$ to the neutron electric polarizability. Using a Dirac equation approach to neutron-nucleus scattering, we review the definitions of Compton continuum ($\bar{\alpha}$), classical static ($\alpha^n_E$), and Schr\"{o}dinger ($\alpha_{Sch}$) polarizabilities and discuss in some detail their relationship. The latter $\alpha_{Sch}$ is the value of the neutron electric polarizability as obtained from an analysis using the Schr\"{o}dinger equation. We find in particular $\alpha_{Sch} = \bar{\alpha} - \mu^2/m$ , where $\mu$ is the magnitude of the magnetic moment of a neutron of mass $m$. However, we argue that the static polarizability $\alpha^n_E$ is correctly defined in the rest frame of the particle, leading to the conclusion that twice the Dirac-Foldy contribution should be added to $\alpha_{Sch}$ to obtain the static polarizability $\alpha^n_E$.Comment: 11 pages, RevTeX, to appear in Physical Review

Quasi-free Compton Scattering from the Deuteron and Nucleon Polarizabilities

Cross sections for quasi-free Compton scattering from the deuteron were measured for incident energies of 236--260 MeV at the laboratory angle -135 degrees. The recoil nucleons were detected in a liquid-scintillator array situated at 20 degrees. The measured differential cross sections were used, with the calculations of Levchuk et al., to determine the polarizabilities of the bound nucleons. For the bound proton, the extracted values were consistent with the accepted value for the free proton. Combining our results for the bound neutron with those from Rose et al., we obtain one-sigma constraints of alpha_n = 7.6-14.0 and beta_n = 1.2-7.6.Comment: 4 pages, 3 figures, accepted in PR

Polarization degrees of freedom in photoinduced two-nucleon knockout from finite nuclei

The polarization degrees of freedom in photoinduced two-nucleon knockout from finite nuclei are studied. It is pointed out that they open good perspectives to study the dynamics of dinucleons in the medium in detail. The ($\gamma,pp$) and ($\gamma,pn$) angular cross sections, photon asymmetries and outgoing nucleon polarizations are calculated for the target nuclei $^{16}$O and $^{12}$C and photonenergies ranging from 100 up to 500 MeV. It is investigated to which degree the two-nucleon emission reaction is dominated by photoabsorption on $^3S_1(T=0)$ proton-neutron and $^1S_0(T=1)$ proton-proton pairs in the nuclear medium. The calculations demonstrate that dominance of $S$ wave photoabsorption in the ($\gamma,pn$) channel does not necessarily imply that the reaction mechanism is similar to what is observed in deuteron photodisintegration.Comment: 27 pages, REVTeX 3.0 with epsf.sty, 11 figures in EPS forma