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Regularity analysis applied to sonic logs data: a case study from KTB borehole site

تطبيق تحليل الانتظام على بيانات صوتية مسجلة في بئر: دراسة حالة من بئر KTB

Arabian Journal of Geosciences volume 4, pages 221–227 (2011)Cite this article

Abstract

Borehole logs provide in situ information about the fluctuations of petrophysical properties with depth and thus allow the characterization of the crustal heterogeneities. A detailed investigation of these measurements may lead to extract features of the geological media. In this study, we suggest a regularity analysis based on the continuous wavelet transform to examine sonic logs data. The description of the local behavior of the logs at each depth is carried out using the local Hurst exponent estimated by two (02) approaches: the local wavelet approach and the average–local wavelet approach. Firstly, a synthetic log, generated using the random midpoints displacement algorithm, is processed by the regularity analysis. The obtained Hurst curves allowed the discernment of the different layers composing the simulated geological model. Next, this analysis is extended to real sonic logs data recorded at the Kontinentales Tiefbohrprogramm (KTB) pilot borehole (Continental Deep Drilling Program, Germany). The results show a significant correlation between the estimated Hurst exponents and the lithological discontinuities crossed by the well. Hence, the Hurst exponent can be used as a tool to characterize underground heterogeneities.

خلاصة

البيانات المسجلة في بئر (Borehole logs) توفر معلومات حول تغيّرات الخصائص البتروفيزيائية مع العمق ، و بالتّالي تسمح بوصف التغاير في القشرة الأرضية. التحقيق المفصل في هذه التسجيلات يمكن أن يؤدي إلى استخلاص ميزات الوسط الجيولوجي. في هذا البحث ، نقترح دراسة انتظام مبنية على التحويلية المستمرﺓ للموﺠﺔ الصغيرة لفحص البيانات الصوتية المسجلة (sonic logs). ووصف السلوك المحلي للتسجيلات في كل عمق يتمّ باﺴﺘﻌﻤﺎﻝ داﻟﺔ أسّ هورست المحلية المقدّرة بطريقتين: طريقة الموجة الصغيرة المحلية وطريقة الموجة الصغيرة المحلية المتوسطة. في البداية، يتمّ إنشاء تسجيلات ﻧموذﺟﻴﺔ، باستخدام نظﺎم الحلول الحسابية ‘’ الانزیاح العشوائي للمنتصف’’ ، ثمّ تتمّ معالجتها ﻋن طرﻴﻕ تحليل الانتظام. وسمحت منحنيات هورست المتحصل عليها بتمييز الطبقات المختلفة المكونة للنموذج الجيولوجي. وفي الخطوة التالية، يوسّع مجال تطﺒﻴق منهجية التحليل ليشمل بيانات صوتية حقيقية مسجلة في البئر التجريبي KTB (برنامج الحفر العميق القاري، ألمانيا). وقد أظهرت النتائج وجود ارتباط كبير بين أسس هورست المقدّرة وعدم استمرارية الخصائص الصّخرية التي يجتازها البئر.وعلى ذلك، يمكن استخدام أسّ هورست كأداة لوصف التغاير في باطن الأرض. الكلمات الدالة : تحليل الانتظام ، تحويلية الموﺠﺔ الصغيرة ، تسجيلات في بئر ، فركتال ، علم الصخور.

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Authors and Affiliations

  1. Département Géophysique—FSTAT, Université des Sciences et de la Technologie Houari Boumediene (USTHB), BP 32 El Alia, 16111, Algiers, Algeria

    Said Gaci & Naima Zaourar

  2. Laboratoire Géosciences, Université Montpellier 2, Place E. Bataillon, 34095, Montpellier Cedex 05, France

    Louis Briqueu

  3. Institute for Mathematics, University of Potsdam, Am Neuen Palais 10, 14469, Potsdam, Germany

    Matthias Holschneider

Authors
  1. Said Gaci
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  2. Naima Zaourar
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  3. Louis Briqueu
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  4. Matthias Holschneider
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Correspondence to Said Gaci.

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Gaci, S., Zaourar, N., Briqueu, L. et al. Regularity analysis applied to sonic logs data: a case study from KTB borehole site. Arab J Geosci 4, 221–227 (2011). https://doi.org/10.1007/s12517-010-0129-y

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  • DOI: https://doi.org/10.1007/s12517-010-0129-y

Keywords

  • Regularity analysis
  • Wavelet transform
  • Well log
  • Fractal
  • Lithology