Report on Extended Leak-Off Test Conducted During Drilling Large Diameter Borehole

Yeonguk Jo; Yoonho Song; Sehyeok Park; Myung Sun Kim; In-Hwa Park; Changhyun Lee

doi:10.7474/TUS.2022.32.5.285

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2022 Vol.32, Issue 5 Next Page

Technical Note

Report on Extended Leak-Off Test Conducted During Drilling Large Diameter Borehole 국내 대구경 시추공 굴진 중 Extended Leak-Off Test 수행 사례 보고

31 October 2022. pp. 285-297

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Abstract

We report results of Extended Leak-Off Test (XLOT) conducted in a large diameter borehole, which is drilled for installation of deep borehole geophysical monitoring system to monitor micro-earthquakes and fault behavior of major fault zones in the southeastern Korean Peninsula. The borehole was planned to secure a final diameter of 200 mm (or more) at a depth of ~1 km, with 12" diameter wellbore to intermediate depths, and 7-7/8" (~200 mm) to the bottom hole depth. We drilled first the 12" borehole to approximately 504 m deep and installed American Petroleum Institute standard 8-5/8" casing, then annulus between the casing and bedrock was fully cemented. XLOT was carried out for several purposes such as confirming casing and cementing integrity, measuring rock stress states. To that end, we drilled additional 4 m long open hole interval to directly inject water and pressurize into the rock mass using the upper API casings. During the XLOT, flow rates and interval pressures were recorded in real time. Based on the logs we tried to analyze hydraulic conductivity of the test interval.

Keywords

Borehole

Extended Leak-Off Test (XLOT)

Flow rate

Interval pressure

Rock mass permeability

본 고에서는 한반도 동남권에 분포하는 주요 단층대에 대한 장기 거동 및 미소진동 관찰을 목적으로 하는 시추공 기반 심부 복합지구물리 모니터링 시스템 구축의 일환으로 수행된 대구경 시추공 굴착 현장에서 이루어진 Extended Leak-Off Test (XLOT)에 대한 내용 및 결과를 보고한다. 다양한 시추공 센서 설치를 위한 모니터링공의 굴착은 ~1 km 깊이에서 최종 구경 200 mm 이상을 확보하는 것을 목표로 하여, 중간 깊이까지 12" 구경의 시추공 굴진 및 케이싱 설치, 이후 최종 심도까지 7-7/8" 구경의 시추공을 굴진하는 것으로 설계되었다. 현장 여건에 맞추어 약 504 m 깊이까지 12" 구경의 시추공이 굴착되었으며, API 규격의 8-5/8" 케이싱을 설치하고 배면과 암반 간의 틈새(annulus)에 대한 세멘팅 작업을 수행하였다. 이후 하부 구간 굴진(7-7/8")에 앞서 세멘팅 건정성 확인 및 암반 응력 측정 등을 목적으로 XLOT를 수행하였다. 약 4 m 길이의 나공 구간(open hole)을 확보하고, 상부에 설치된 케이싱을 이용해 물을 주입하여 시험 심도의 암반을 가압하였다. XLOT 수행 과정에서 주입 유량에 따른 시험 구간 내 압력 변화 양상을 실시간 모니터링 하였으며, 이 자료들을 일부 활용하여 현장 시추공 조건에서의 암반 투수율을 해석하였다.

키워드

대구경 시추공

Extended Leak-Off Test (XLOT)

유량

압력

암반 투수율

References

Aadnoy, B.S. and Larsen, K., 1989, Method for Fracture-Gradient Prediction for Vertical and Inclined Boreholes, SPE Drill. Eng., 4, 99-103. 10.2118/16695-PA

Addis, M.A., Hanssen, T.H., Yassir, N., Willoughby, D.R., and Enever, J., 1998, Comparison of leak-off test and extended leak-off test data for stress estimation, Proc. SPE/ISRM Rock Mech. in Petrol. Eng. Conf., 1, 131-140. 10.2118/47235-MS

Bae, S., Kim, H., Kim, J., Park, E. S., Jo, Y., Ji, T., and Won, K., 2021, Hydraulic Characteristics of Deep and Low Permeable Rock Masses in Gyeongju Area by High Precision Constant Pressure Injection Test, Tunnel and Underground Space, 31(4), 243-269.

Blanton, T.L., 1982, An experimental study of interaction between hydraulically induced and pre-existing fractures, In SPE unconventional gas recovery symposium, SPE-10847-MS, 10.2118/10847-MS

Chang, C., Jo, Y., Quach, N., Shinn, Y. J., Song, I., and Kwon, Y. K., 2016, Geomechanical characterization for the CO₂ injection test site, offshore Pohang Basin, SE Korea, Proceedings of 50th US Rock Mechanics/Geomechanics Symposium, 1064-1069.

Cheng, W., Yan, J., Mian, C., Tong, X.U., Zhang, Y., and Ce, D., 2014, A criterion for identifying hydraulic fractures crossing natural fractures in 3D space, Pet. Explor. Dev., 41(3), 371-376. 10.1016/S1876-3804(14)60042-2

Choi, S.-J., Park, K.G., Park, C., and Lee, C., 2021, Protection and Installation of FBG Strain Sensor in Deep Boreholes for Subsurface Faults Behavior Monitoring, Sensors, 21, 5170. 10.3390/s2115517034372406PMC8348588

Cooper, H.H. and Jacob, C.E., 1946, A generalized graphical method for evaluating formation constants and summarizing well-field history, Trans., Am. Geophys. Union, 27(4), 526. 10.1029/TR027i004p00526

Janiszewski, M., Shen, B., and Rinne, M., 2019, Simulation of the interactions between hydraulic and natural fractures using a fracture mechanics approach, J. Rock Mech. Geotech. Eng., 11(6), 1138-1150. 10.1016/j.jrmge.2019.07.004

KIGAM, 2021, Development of integrated geophysical monitoring system at depth for assessing earthquake and fault activities at south-eastern Korea, KR-2021-Basic-005-2021, KIGAM, Daejeon, South Korea

Kim, S.-K., Chang, C., Shinn, Y.J., and Kwon, Y.K., 2018, Characteristics of Pohang CO₂ Geological Sequestration Test Site, J. Eng. Geol., 28(2), 175-182.

Kunze, K.R. and Steiger, R.P., 1991, Extended Leakoff Tests to Measure In Situ Stress During Drilling, 32nd US Symp. Rock Mech., Norman, Oklahoma, ARMA-91-035.

Lavrov, A., Larsen, I., and Bauer, A., 2016, Numerical modelling of extended leak-off test with a pre-existing fracture, Rock Mech Rock Eng, 49(4), 1359-1368. 10.1007/s00603-015-0807-x

Lin, W., Yamamoto, K., Ito, H., Masago, H., and Kawamura, Y., 2008, Estimation of Minimum Principal Stress from an Extended Leak-off Test Onboard the Chikyu Drilling Vessel and Suggestions for Future Test Procedures. Scientific Drilling, 6, 43-47. 10.5194/sd-6-43-2008

Postler, D.P., 1997, Pressure Integrity Test Interpretation, SPE/IADC Drill. Conf., SPE-37589-MS. 10.2118/37589-MS

Quach, N.Q., Jo, Y., and Chang, C., 2018, Rock Permeability Estimation from Hydraulic Injection Tests in a Sealed Borehole Interval. J. Eng. Geol., 28(1), 1-9.

Raaen, A.M., Horsrud, P., Kjørholt, H., and Økland, D., 2006, Improved routine estimation of the minimum horizontal stress component from extended leak-off tests, Int. J. Rock Mech. Min. Sci., 43(1), 37-48. 10.1016/j.ijrmms.2005.04.005

Renard, P., 2017, Hytool: an open source matlab toolbox for the interpretation of hydraulic tests using analytical solutions, The Journal of Open Source Software, 2(19), 441. 10.21105/joss.00441

Sarmadivaleh, M., Rasouli, V, 2014, Modified Reinshaw and Pollard criteria for a non-orthogonal cohesive natural interface intersected by an induced fracture, Rock Mech. Rock Eng., 47(6), 2107-2115. 10.1007/s00603-013-0509-1

Theis, C.V., 1935, The relation between the lowering of the piezometric surface and the rate and duration of discharge of a well using groundwater storage, Trans., Am. Geophys. Union, 16(2), 519-524. 10.1029/TR016i002p00519

White, A. J., Traugott, M. O., and Swarbrick, R. E., 2002, The use of leak-off tests as means of predicting minimum in-situ stress, Petroleum Geoscience, 8(2), 189-193. 10.1144/petgeo.8.2.189

Zang, A., Zimmermann, G., Hofmann, H., Niemz, P., Kim, K.Y., Diaz, M., Zhuang, L., Yoon, J.S., 2021, Relaxation damage control via fatigue-hydraulic fracturing in granitic rock as inferred from laboratory-, mine-, and field-scale experiments, Scientific reports, 11(1), 1-16. 10.1038/s41598-021-86094-533762643PMC7991663

Zhang, J. and Yin, S.X., 2017, Fracture gradient prediction: an overview and an improved method, Petroleum Science, 14(4), 720-730. 10.1007/s12182-017-0182-1

Zhang, L., Zhou, J., Braun, A., and Han, Z, 2018, Sensitivity analysis on the interaction between hydraulic and natural fractures based on an explicitly coupled hydro-geomechanical model in PFC2, J. Pet. Sci. Eng., 167, 638-653. 10.1016/j.petrol.2018.04.046

Information

Publisher :Korean Society for Rock Mechanics and Rock Engineering
Publisher(Ko) :한국암반공학회
Journal Title :Tunnel and Underground Space
Journal Title(Ko) :터널과 지하공간
Volume : 32
No :5
Pages :285-297
Received Date : 2022-09-26
Revised Date : 2022-10-14
Accepted Date : 2022-10-17
DOI :https://doi.org/10.7474/TUS.2022.32.5.285

Tunnel and Underground SpaceISSN:1225-1275(Print) 2287-1748(Online)한국암반공학회

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