geologyИзвестия высших учебных заведений. Геология и разведкаProceedings of higher educational establishments. Geology and Exploration0016-77622618-8708Sergo Ordzhonikidze Russian State University for Geological Prospecting10.32454/0016-7762-2015-5-52-59geology-73Research ArticleГЕОФИЗИЧЕСКИЕ МЕТОДЫ ПОИСКОВ И РАЗВЕДКИGEOPHYSICAL METHODS OF PROSPECTING AND EXPLORATIONАнализ поляризации дипольных волн в скважинах некругового сечения в анизотропной породеAnalysis of polarization of dipole modes in non-circular boreholes in anisotropic formationШеликГ. С.ShchelikG. S.german.schelik@phystech.eduМосковский физико-технический институт; Московский научный центр ШлюмбержеРоссияMoscow Institute of Physics and Technology; Schlumberger Moscow ResearchRussian Federation201528102015055259Copyright © Шелик Г.С., 20152015Шелик Г.С.Shchelik G.S.Данная работа распространяется под лицензией Creative Commons Attribution 4.0.This work is licensed under a Creative Commons Attribution 4.0 License.https://www.geology-mgri.ru/jour/article/view/73

Исследован вопрос определения главных направлений анизотропной породы в скважинах с нарушением цилиндрической геометрии с помощью численного моделирования измерений акустического каротажа. Модель используемых на практике алгоритмов обработки предполагает распространение вдоль скважины двух ортогонально поляризованных волн, которые в рассматриваемых задачах соответствуют дипольным модам. На примере эллиптических скважин показано, что направления колебаний мод могут быть существенно неортогональными и зависеть от частотного спектра сигнала источника, что приводит к некорректному определению главных направлений трансверсально-изотропной породы. Полученные после обработки направления сопоставлены с независимым расчётом собственных векторов дипольных мод полуаналитическим методом конечных элементов (SAFE). Результаты сравнения свидетельствуют об эффективности применения частотных фильтров и «неортогональных» алгоритмов для проверки корректности найденных направлений и повышения точности значений углов.

The problem of determination of principle axes in anisotropic formation in non-circular boreholes is studied with numerical simulation of acoustic logging measurements. The processing algorithms for acoustic logging data used in practice involve propagation of two orthogonally polarized waves along borehole axis that correspond to dipole modes. However, the oscillation directions of dipole modes in elliptical boreholes are shown to be substantially non-orthogonal and depend on frequency spectrum of the source signal. This leads to incorrect determination of principle directions in the considered transversely-isotropic media. The results for principle directions obtained after processing are compared with eigenvectors for dipole modes calculated independently with semi-analytical finite element method (SAFE). The application of frequency filters and «non-orthogonal» processing algorithms is proved to be effective for validation and accuracy improvement of the obtained directions.

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The authors declare that there are no conflicts of interest present.