Geophysics and Geophysical Exploration (지구물리와물리탐사)

Korean Society of Earth and Exploration Geophysicists (한국지구물리·물리탐사학회)
권호 표지

Empirical Rock Strength Logging in Boreholes Penetrating Sedimentary Formations

퇴적암에 대한 경험적 암석강도 추정에 대한 고찰

  • Chang, Chan-Dong (Geology and Earth Environmental Sciences, Chungnam National University)
  • 장찬동 (충남대학교 지질환경과학과)
  • Published : 2004.08.01
Download PDF
⟨ Previous Next ⟩

Abstract

The knowledge of rock strength is important in assessing wellbore stability problems, effective sanding, and the estimation of in situ stress field. Numerous empirical equations that relate unconfined compressive strength of sedimentary rocks (sandstone, shale, and limestone, and dolomite) to physical properties (such as velocity, elastic modulus, and porosity) are collected and reviewed. These equations can be used to estimate rock strength from parameters measurable with geophysical well logs. Their ability to fit laboratory-measured strength and physical property data that were compiled from the literature is reviewed. While some equations work reasonably well (for example, some strength-porosity relationships for sandstone and shale), rock strength variations with individual physical property measurements scatter considerably, indicating that most of the empirical equations are not sufficiently generic to fit all the data published on rock strength and physical properties. This emphasizes the importance of local calibration before one utilizes any of the empirical relationships presented. Nonetheless, some reasonable correlations can be found between geophysical properties and rock strength that can be useful for applications related to wellhole stability where haying a lower bound estimate of in situ rock strength is especially useful.

퇴적암반에서의 암석 강도는 시추공 굴착 과정에서 동반될 수 있는 시추공 불안정이나 효율적인 모래 생산 평가, 또는 시추공 압축 파쇄대를 이용한 지반 응력장 추정 문제 등 다양한 범위의 지질 역학적 문제들에 있어서 선결적으로 규명되어야 할 요소 중 하나이다. 본 연구에서는 여러 종류의 퇴적암(사암, 셰일, 석회암, 방해석 등)에서의 일축 압축 강도와 기타 물성(속도, 탄성계수, 공극률)을 관계 짓는 경험식들을 수집하여 검토하였다. 이들 경험식들은 시추공 물리검층을 통해 측정 가능한 파라미터들로 암석 강도를 추정하는데 이용될 수 있다. 일부 관계식들(예를 들어 사암이나 셰일의 강도-공극률 관계식)은 일정정도 만족스러운 강도 추정 도구로 이용될 수도 있지만, 각각의 물성 측정치에 대한 암석 강도가 상당히 분산되어 있어 모든 자료를 만족스럽게 예측하기에는 충분히 일반화 시킬 수 없다는 문제점이 있다. 따라서 이들 경험식들을 이용하기 전에 해당 지역에 대한 강도-물성 관계 캘리브레이션의 중요성이 강조된다. 그럼에도 불구하고 현장 암석 강도의 최저 한계 정보를 제공할 수 있는 몇몇 경험식들은 시추공 불안정 분석과 관련하여 유용하게 이용될 수 있다.

Keywords

References

  1. Bell, J. S., and Gough, D. I., 1979, Northeast-southwest compressive stress in Alberta: Evidence from oil wells, Earth Planet. Sci. Lett., 45, 475-482
  2. Bradford, I. D. R., Fuller, J., Thompson, P. J., and Walsgrove, T. R., 1998, Benefits of assessing the solids production risk in a North Sea reservoir using elastoplastic modelling, SPEIISRM Eurock '98,261-269
  3. Brudy, M., Zoback, M. D., Fuchs, K., Rummel, E, and Baumgrtner,J., 1997, Estimation of the complete stress tensor to 8 kID depth in the KTB scientific drill holes: Implications for crustal strength, J. Geophys. Res., 102,453-18,475
  4. Carmichael, R. S., 1982, CRC Handbook ofPhysical Properties of Rocks, VolumeII, CRC Press, Inc., Boca Raton
  5. Colmenares, L. B., and Zoback, M. D., 2002, A statistical evaluation of intact rock failure criteria constrained by polyaxial test data for five different rocks, Int. J. Rock Mech. & Mining Sci., 39, 695-729
  6. Drucker, D. C., and Prager W., 1952, Soil mechanics and plastic analysis or limit design, Q. App!. Math., 10, 157-165
  7. Ewy, R. T., 1998, Wellbore stability predictions using a modified Lade criterion: Eurock 98, SPEIISRM Rock Mechanics in Petroleum Engineering, Vol. 1, SPEIlSRM paper no. 47251, 247-254
  8. Fairhurst, C, 1968, Methods of determining in-situ rock stresses at great depth, Tech. Report, 1-86, Missouri River Div., U.S. Army Corps of Engineers
  9. Fjaer, E., Holt, R. M., Horsrud, P., Raaen, A. M., and Risnes, R., 1992, Petroleum Related Rock Mechanics, Elsevier, Amsterdam
  10. Freyburg, E., 1972, Der Untere und mittlere Buntsandstein SWThuringen in seinen gesteinstechnischen Eigenschaften, Ber. Dte. Ges. Geo!. Wiss. A; Berlin, 176,911-919
  11. Golubev, A A and Rabinovich, G. Y, 1976, Resultaty primeneia appartury akusticeskogo karotasa dlja predeleina proconstych svoistv gomych porod na mestorosdeniaach tverdych isjopaemych, Prikladnaja GeofizikaMoskva, 73,109-116
  12. Haimson, B. C, and Herrick, C. G., 1986, Borehole breakoutsA new tool for estimating in situ stress?, International Symposium on Rock Stress and Rock Stress Measurements, Lulea Univ. of Technol., Stockholm, Sweden
  13. Haimson, B. C., and Song, I., 1995, A new borehole failure criterion for estimating in situ stress from breakout span, 8th International Congress of Rock Mechanics, 341-346, Tokyo, Japan, 341-346
  14. Horsrud, P., 2001, Estimating mechanical properties of shale from empirical correlations, SPE Drilling & Completion, 16, 68-73
  15. Jizba, D., 1991, Mechanical and Acoustical Properties of Sandstones and Shales, Ph.D. thesis, Stanford University
  16. Kwasniewski, M., 1989, Laws of brittle failure and of B-D transition in sandstones: Rock at Great Depth, edited by V. Maury and D. Fourmaintraux, AA Balkema, Brookfield, Vt., 45-58
  17. Lal, M., 1999, Shale stability: drilling fluid interaction and shale strength, SPE Latin American and Caribbean Petroleum Engineering Conference held in Caracas, Venezuela
  18. Lama, R. D., and Vutukuri, V. S., 1978, Handbook on Mechanical Properties of Rocks, Vol. II: Trans Tech Publications, Clausthal, Germany
  19. Lashkaripour, G. R., and Dusseault, M. B., 1993, A statistical study on shale properties; relationship among principal shale properties, Conference on Probabilistic Methods in Geotechnical Engineering, Canberra, Australia, 195-200
  20. Lund, B. and Zoback, M. D., 1999, State of stress to 7 km depth in the Siljan drill holes from observations of drilling-induced tensile wall fractures, Int. 1. Rock Mech., 36, 169-190
  21. McNally, G. H., 1987, Estimation of coal measures rock strength using sonic and neutron logs, Geoexploration, 24, 381-395
  22. Militzer and Stoll, 1973, Einige Beitrageder geophysics zur primadatenerfassung im Bergbau, Neue Bergbautechnik, Lipzig, 3, 21-25
  23. Moos, D., and Zoback, M. D., 1990, Utilization of observations of wellbore failure to constrain the orientation and magnitude of crustal stresses: Application to continental, Deep Sea Drilling Project and Ocean Drilling Program boreholes, J.Geophys. Res., 95, 9305-9325
  24. Moos, D., Zoback, M. D., and Bailey, L., 1999, Feasibility study of the stability of openhole multilaterals, Cook Inlet, Alaska, SPE Mid-Continent Operations Symposium held in Oklahoma City, Oklahoma
  25. Moos, D., Peska, P., Finkbeiner, T., and Zoback, M. D., 2003, Comprehensive wellbore stability analysis utilizing quantitative risk assessment, Journal of Petroleum Science and Engineering, Special Issue on Borehole Stability, B.S. Aadnoy and S. Ong, eds., 38, 97-110
  26. Plumb, R. A, and Hickman, S. H., 1985, Stress-induced borehole elongation: A comparison between the four-arm dipmeter and the borehole borehole televiewer in the Auburn geothermanl well, 1. Geophys. Res., 90, 5513-5522
  27. Rzhevsky, v., and Novick, G., 1971, The Physics ofRocks, MIR Publ
  28. Santarelli, F. J., Detienne, J. L., and Zundel, L. P., 1989, Determination of the mechanical properties of deep reservoir sandstones to assess the likelihoodof sand production, Rock at Great Depth, edited by Maury, V. and Fourmaintraux, D., AA Balkema, Brookfield, Vt., 779-787
  29. Stock, J. M., Healy, J. H., Hickman, S. H., and Zoback, M. D., 1985, Hydraulic fracturing stress measurements at Yucca Mountain, Nevada, and relationship to the regional stress field, J. Geophys. Res., 90, 8691-8706
  30. Vemik, L., Bruno, M., and Bovberg, C, 1993, Empirical relations between compressive strength and porosity of siliciclastic rocks, Int. J. Rock Mech. Min. Sci. & Geomech. Abstr., 30, 677-680
  31. Vernik, L., and Zoback, M. D., 1992, Estimation of maximum horizontal principal stress magnitude from stress-induced well bore breakouts in the Cajon Pass scientific research borehole, J. Geophys. Res., 97, 5109-5119
  32. Vernik, L., Zoback, M. D., and Brudy, M., 1992, Methodology and application of the wellbore breakout analysis in estimating the maximum horizontal stress magnitude in the KTB pilot hole, Sci. Drill., 3, 161-169
  33. Wong, T.-F., David, C., and Zhu, W., 1997, The transition from brittle faulting to cataclastic flow in porous sandstones: mechanical deformation, J. Geophys. Res., 102,3009-3025
  34. Zheng, Z., Kemeny, J., and Cook, N. G., 1989, Analysis of borehole breakouts, J. Geophys. Res., 94, 7171-7182
  35. Zoback, M. D., Moos, D., Mastin, L., and Anderson, R. N., 1985, Wellbore breakouts and in situ stress, J. Geophys. Res., 90, 5523-5530
  36. Zoback, M. D., Barton, C. A, Brudy, M., Castillo, D. A, Finkbeiner, T., Grollimund, B. R., Moos, D. B., Peska, P., Ward, C. D., and Wiprut, D. J., 2003, Determination of stress orientation and magnitude in deep wells, Int. 1. Rock Mech. Mining Sci., 40, 1049-1076