Wellbore Stability Analysis for Hydrate Bearing Sediments using a Bonded Particle Model

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2010 Vol.47, Issue 2 Preview Page Next Page

Wellbore Stability Analysis for Hydrate Bearing Sediments using a Bonded Particle Model 입자결합모델을 이용한 하이드레이트 함유지층의 공벽안정성 분석: 류정현 , 이경재 , 박장준 , 최종근
Jung Hyun Ryu, Kyung Jae Lee, Jang Jun Bahk and Jonggeun Choe

30 April 2010. pp. 191-198

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Abstract

Hydrate dissociation may cause many drilling related problems while drilling in hydrate bearing sediments (HBS). Therefore, it is necessary to analyze mechanical wellbore stability before drilling in HBS. In this study, PFC3D is used to simulate mechanical wellbore stability in HBS with a bonded particle model. Results of stability analyses are quantified by average displacement of formation particles, number of cracks, and the ratio of displacement to the hole diameter. The effects of dissociation range, in-situ stress, dissociation rate, and mudcake are analyzed. As a result, the increases of dissociation range of hydrate and in-situ stress cause formation instability by making more cracks and displacement of formation particles. On the other hand, hydrate dissociation rate and cohesion of mudcake are not critical factors in wellbore stability. Higher hydrate saturation accelerates wellbore instability.

Keywords

Gas hydrate

Wellbore stability

Bonded particle model

PFC3D

Hydrate dissociation

가스하이드레이트 함유지층의 시추 시 발생하는 하이드레이트의 해리는 입자간 점착력을 감소시키고변위를 유발하여 공벽안정성을 약화시키기 때문에 하이드레이트 층의 시추에 앞서 역학적 안정성에 대한 분석이 필수적이다. 본 연구에서는 시추공 안정성에 영향을 미치는 인자들을 파악하기 위해 입자결합모델인 PFC3D를 이용하여 시추공의 거동과 역학적 안정성을 분석하였다. 하이드레이트의 해리유무, 해리범위, 지하응력, 해리속도, 이벽(mudcake)의 존재유무와 강도 변화에 따른 각 인자들의 영향을 평균변위와 균열수, 시추공지름대비변위로 정량화하였다. 그 결과, 해리가 발생하는 경우 해리가 일어나지 않을 때에 비해 지층의 균열과 지층입자의 변위가 큰 폭으로 증가하여 공벽안정성이 약화되었다. 민감도분석 결과, 해리범위와 지하응력은 변위와 균열을 크게 증가시키며 안정성에 매우 큰 영향을 미치는 결과를 보였다. 해리속도와 이벽에 의한 지층강도의 증가는 지층안정성에 미미한 영향을 미쳤으며, 포화도의 증가는 공벽의 불안정성을 가속화시킴을 확인하였다.

키워드

공벽안정성

입자결합모델

PFC3D

하이드레이트 해리

References

박성식, 2008, “가스 GH의 해리로 인한 해저사면의 붕괴에 관한 연구,” 한국지구시스템공학회지, 제 45권 2호, pp. 164-173.
허대기, 2005, “가스GH 기술개발 현황,” 한국지구시스템공학회지, 제 42권 3호, pp. 206-213.
Birchwood, R., Noeth, S., Hooyman, P. and Winters, W., 2005, “Wellbore Stability Model for Marine Sediments Containing Gas Hydrates,” AADE National Technical Conference and Exhibition, Houston, AADE, Texas, April 5-7, Paper No. AADE-05-NTCE-13.
Durham, W.B., Kirby, S.H., Stern, L.A. and Zhang, W., 2003, “The Strength and Rheology of Methane Clathrate Hydrate,” Journal of Geophysical Research, Vol. 108, No. B4, pp. 2182-2193.
Freij-Ayoub, R., Tan, C., Clennell, B., Tohidi, B. and Yang, J., 2007, “A Wellbore Stability Model for Hydrate Bearing Sediments,” Journal of Petroleum Science and Engineering, Vol. 57, No. 1, pp. 209-220.
Kreiter, S. and Feeser, V., 2004, “Numerical Simulation of Gas Hydrate Behavior in Marine Sediments using PFC2D,” Numerical Modeling in Micromechanics via Particle Methods, Vol. 1, No. 7, pp. 191-198.
Salehabadi, M., Jin, M., Yang, J., Haghighi, H., Ahmed, R. and Tohidi, B., 2009, “Finite Element Modeling of Casing in Gas Hydrate Bearing Sediments,” SPE Drilling and Completion, Vol. 24, No. 4, pp. 545-552.
Tan, C., Freij-Ayoub, R., Clennell, M.B., Tohidi, B. and Yang, J., 2005, “Managing Wellbore Instability Risk in Gas-Hydrate-Bearing Sediments,” Asia Pacific Oil & Gas Conference and Exhibition, Jakarta, Indonesia, April 5-7, Paper No. 92960-MS.

Information

Publisher :The Korean Society of Mineral and Energy Resources Engineers
Publisher(Ko) :한국자원공학회
Journal Title :Journal of the Korean Society for Geosystem Engineering
Journal Title(Ko) :한국지구시스템공학회지
Volume : 47
No :2
Pages :191-198

[1] 박성식, 2008, “가스 GH의 해리로 인한 해저사면의 붕괴에 관한 연구,” 한국지구시스템공학회지, 제 45권 2호, pp. 164-173.

[2] 허대기, 2005, “가스GH 기술개발 현황,” 한국지구시스템공학회지, 제 42권 3호, pp. 206-213.

[3] Birchwood, R., Noeth, S., Hooyman, P. and Winters, W., 2005, “Wellbore Stability Model for Marine Sediments Containing Gas Hydrates,” AADE National Technical Conference and Exhibition, Houston, AADE, Texas, April 5-7, Paper No. AADE-05-NTCE-13.

[4] Durham, W.B., Kirby, S.H., Stern, L.A. and Zhang, W., 2003, “The Strength and Rheology of Methane Clathrate Hydrate,” Journal of Geophysical Research, Vol. 108, No. B4, pp. 2182-2193.

[5] Freij-Ayoub, R., Tan, C., Clennell, B., Tohidi, B. and Yang, J., 2007, “A Wellbore Stability Model for Hydrate Bearing Sediments,” Journal of Petroleum Science and Engineering, Vol. 57, No. 1, pp. 209-220.

[6] Kreiter, S. and Feeser, V., 2004, “Numerical Simulation of Gas Hydrate Behavior in Marine Sediments using PFC2D,” Numerical Modeling in Micromechanics via Particle Methods, Vol. 1, No. 7, pp. 191-198.

[7] Salehabadi, M., Jin, M., Yang, J., Haghighi, H., Ahmed, R. and Tohidi, B., 2009, “Finite Element Modeling of Casing in Gas Hydrate Bearing Sediments,” SPE Drilling and Completion, Vol. 24, No. 4, pp. 545-552.

[8] Tan, C., Freij-Ayoub, R., Clennell, M.B., Tohidi, B. and Yang, J., 2005, “Managing Wellbore Instability Risk in Gas-Hydrate-Bearing Sediments,” Asia Pacific Oil & Gas Conference and Exhibition, Jakarta, Indonesia, April 5-7, Paper No. 92960-MS.

Journal of the Korean Society of Mineral and Energy Resources Engineers ISSN:2288-0291(Print) 2288-2790(Online) 한국자원공학회지

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