All Issue

2020 Vol.30, Issue 1 Preview Page

Research Article

A Quality-control Experiment Involving an Optical Televiewer Using a Fractured Borehole Model

균열모형시추공을 이용한 광학영상화검층 품질관리 시험

Seungho Jeong1
,
Jehyun Shin2*
,
Seho Hwang3
,
Ji-Soo Kim4
정 승호1
,
신 제현2*
,
황 세호3
,
김 지수4
1MsC. Student, Department of Earth and Environmental Sciences, Chungbuk National University
2Senior Researcher, Geologic Environment Division, Korea Institute of Geoscience and Mineral Resources
3Principal Researcher, Geologic Environment Division, Korea Institute of Geoscience and Mineral Resources
4Professor, Department of Earth and Environmental Sciences, Chungbuk National University
1충북대학교 지구환경과학과 석사과정
2한국지질자원연구원 지질환경연구본부 선임연구원
3한국지질자원연구원 지질환경연구본부 책임연구원
4충북대학교 지구환경과학과 교수
*Corresponding Author
31 March 2020. pp. 17-30
PDF XML Citation
Abstract

An optical televiewer is a geophysical logging device that produces continuous high-resolution full-azimuth images of a borehole wall using a light-emitting-diode and a complementary metal-oxide semiconductor image sensor to provide valuable information on subsurface discontinuities. Recently, borehole imaging logging has been applied in many fields, including ground subsidence monitoring, rock mass integrity evaluation, stress-induced fracture detection, and glacial annual-layer measurements in polar regions. Widely used commercial borehole imaging logging systems typically have limitations depending on equipment specifications, meaning that it is necessary to clearly verify the scope of applications while maintaining appropriate quality control for various borehole conditions. However, it is difficult to directly check the accuracy, implementation, and reliability for outcomes, as images derived from an optical televiewer constitute in situ data. In this study, we designed and constructed a modular fractured borehole model having similar conditions to a borehole environment to report unprecedented results regarding reliable data acquisition and processing. We investigate sonde magnetometer accuracy, color realization, and fracture resolution, and suggest data processing methods to obtain accurate aperture measurements. The experiment involving the fractured borehole model should enhance not only measurement quality but also interpretations of high-resolution and reliable optical imaging logs.

Keywords
optical televiewer
discontinuity
quality control
fractured borehole model

광학영상화검층은 광원과 CMOS 영상 센서를 이용하여 시추공벽을 이미지로 구현하는 물리검층 기술로 지하의 불연속면에 대한 여러 가지 원위치 정보를 고분해능으로 제공한다. 최근 시추공영상화검층은 지반침하 모니터링, 암반 무결성 평가, 응력으로 인한 단열 변화 탐지, 극지에서의 빙하 연대측정 등 그 활용범위가 매우 다양해졌다. 현재 국 내외로 많이 이용되고 있는 시추공영상화검층 시스템은 장비 사양에 따라 한계점을 가지고 있어 적용 범위에 대한 검증과 여러 가지 시추공 환경에 대한 적절한 품질관리가 필요하다. 그러나 광학영상화검층의 자료로 도출되는 이미지는 원위치 정보로 정확도, 구현도, 신뢰성에 대한 검증에 직접적인 비교 확인이 어렵다. 본 논문에서는 신뢰성 있는 고품질 자료 취득 방법과 자료 처리 방법을 확인하기 위해 시추공 환경과 유사한 모듈화 된 균열모형시추공을 설계 ‧ 제작하여 현재까지 보고되지 않은 실험에 대한 결과를 얻고자 하였다. 검출기 자기계 방향 확인의 정확성을 검증하고, 노출시간에 따른 색상의 구현도 및 균열의 분해능 관계, 정확한 간극 측정을 위한 자료 처리 방법 등을 제시하였다. 다양한 시추공 환경을 모사한 균열모형시추공 실험을 통해 고분해능의 신뢰성 높은 광학영상화검층의 자료 취득 및 해석이 가능할 것으로 기대된다.

키워드
광학영상화검층
불연속면
품질관리
균열모형시추공
References
1
Ashmore, D.W., Hubbard, B., Luckman, A., Kulessa, B., Bevan, S., Booth, A., Munneke, P.K., O'Leary, M., Sevestre, H., Holland, P.R., 2017, Ice and firn heterogeneity within Larsen C ice shelf from borehole optical televiewing, Journal of Geophysical Research: Earth Surface, 122(5), 1139-1153.
10.1002/2016JF004047
2
Ask, M., Ask, D., 2017, Analysis of acoustic and optical televiewer data from the Olkiluoto site: drillholes OL-KR10, OL-KR19, OL-KR40, OL-KR46 and OL-KR46B, 2010-2013, Working Report, POSIVA.
3
Bae, S.H., Jeon, S., Kim, J., Park, K., 2016, Study on the current horizontal stress characteristics of the Tertiary rock formations in the Pohang basin by integrated analysis with in-situ rock stress measurement and borehole scanning data set, Tunnel and Underground Space, 26(4), 304-315 (in Korean with English abstract).
10.7474/TUS.2016.26.4.304
4
Cheong, J.Y., Hamm, S.Y., Ok, S.I., Cho, H., Kim, S.G., Yun, S.M., 2019, Characterizing fracture system change at boreholes in a coastal area in Korea for monitoring earthquake, The Journal of Engineering Geology, 29(1), 1-12 (in Korean with English abstract).
5
Cho, H., Cheong, J.Y., Lim, D.H., Hamm, S.Y., 2017, Quantification of heterogenous background fractures in bedrocks of Gyeongju LILW disposal site, The Journal of Engineering Geology, 27(4), 463-474 (in Korean with English abstract).
6
Choi, J.R., Kim, S.S., Park, S.K., Shin, K.S., Kang, B.C., 2013, A case study of electrical resistivity and borehole imaging methods for detecting underground cavities and monitoring ground subsidence at abandoned underground mines, Journal of The Korean Earth Science Society, 34(3), 195-208 (in Korean with English abstract).
10.5467/JKESS.2013.34.3.195
7
Georgi, D.T., 1985, Geometrical aspects of borehole televiewer images, SPWLA 26th Annual Logging Symposium, Society of Petrophysicists and Well-Log Analysts, Dallas, SPWLA-1985-O.
8
Hawley, R.L., Waddington, E.D., Alley, R.B., Taylor, K.C., 2003, Annual layers in polar firn detected by borehole optical stratigraphy, Geophysical Research Letters, 30(15), 1788-1790.
10.1029/2003GL017675
9
Hwang, S., Shin, J., Jeong, S., 2019, Aperture width estimation from acoustic televiewer log using 3 inches physical fractured borehole model, Conference Proceedings 10th Congress of the Balkan Geophysical Society, 1-5.
10.3997/2214-4609.201902639
10
Koh, C.S., Yoon, S.H., Hong, J.G., Jeong, J.O., Kim, J.J., 2019, Stratigraphic analysis of the drilling core in Woljong-ri coastal area, Jeju Island, Journal of the Geological Society of Korea, 55(1), 1-20.
10.14770/jgsk.2019.55.1.1
11
Lee, J.H., Hamm, S.Y., Han, S.J., Ok, S.I., Cha, E.J., Cho, H.N., Choo, C.O., Kim, M.J., 2011, Verifying rehabilitation and evaluation of bedrock wells using air-brush surging and explosive methods, The Journal of Engineering Geology, 21(4), 369-379 (in Korean with English abstract).
10.9720/kseg.2011.21.4.369
12
Li, S.J., Feng, X.T., Wang, C.Y., Hudson, J.A., 2013, ISRM suggested method for rock fractures observations using a borehole digital optical televiewer, Rock Mechanics and Rock Engineering, 46, 635-644.
10.1007/s00603-012-0344-9
13
Massiot, C., McNamara, D.D., Lewis, B., 2015, Processing and analysis of high temperature geothermal acoustic borehole image logs in the Taupo volcanic zone, New Zealand, Geothermics, 53, 190-201.
10.1016/j.geothermics.2014.05.010
14
Park, S., Chung, I.M., 2016, Correlation between the distribution of discontinuities and groundwater flow in fractured rock, The Journal of Engineering Geology, 26(4), 505-513 (in Korean with English abstract).
10.9720/kseg.2016.4.505
15
Schepers, R., Rafat, G., Gelbke, C., Lehmann, B., 2001, Application of borehole logging, core imaging and tomography to geotechnical exploration, International Journal of Rock Mechanics and Mining Sciences, 38(6), 867-876.
10.1016/S1365-1609(01)00052-1
16
Williams, J.H., Johnson, C.D., 2004, Acoustic and optical borehole-wall imaging for fractured-rock aquifer studies, Journal of Applied Geophysics, 55, 151-159.
10.1016/j.jappgeo.2003.06.009
Information
  • Publisher :Korean Society of Engineering Geology
  • Publisher(Ko) :대한지질공학회
  • Journal Title :The Journal of Engineering Geology
  • Journal Title(Ko) :지질공학
  • Volume : 30
  • No :1
  • Pages :17-30
  • Received Date : 2020-02-18
  • Revised Date : 2020-03-03
  • Accepted Date : 2020-03-04
  • DOI :https://doi.org/10.9720/kseg.2020.1.017
Journal Informaiton The Journal of Engineering Geology The Journal of Engineering Geology
Online Submission
  • NRF
  • KOFST
  • KISTI Current Status
  • KISTI Cited-by
  • crosscheck
  • orcid
  • open access
  • ccl
Journal Informaiton Journal Informaiton - close