Abstract
References
Information
Coiled tubing for use in directional drilling has a high risk of helical buckling than conventional drilling pipe. Helical buckling condition reduces drilling efficiency as a result of impediments for conveyed axial load all the way through penetration depth. It is important to discriminate helical buckling to reach the target depth. Calculated effective axial force is able to estimate axial load and predict helical buckling occurrence. Variations of effective axial force are influenced by coiled tubing diameter and wall thickness, borehole size and inclination angle, frictional coefficients (open or cased hole), kick off point. In this study, variations of axial load, helical buckling depth, and helical buckling force upon effective axial force changes could be numerically calculated by TFM (tubing force model). Analysis indicates that helical buckling could be avoided by increased annulars and deeper kick off point for reducing frictional effects. This study is useful to develop CTD system and predict helical buckling from coiled tubing directional drilling in curved well.
코일튜빙을 이용한 방향성 시추작업은 일반 시추관에 비해 헬리컬버클링 발생 위험도가 높다. 헬리컬버클링은 코일튜빙의 하중전달 및 시추공내 진입을 방해하여 시추효율을 감소시킨다. 코일튜빙에 발생하는 헬리컬버클링을 방지하여 목표심도에 도달하기 위해서는 헬리컬버클링 현상의 이해가 필요하다. 유효인장력은 분포하중을 계산할 수 있고, 헬리컬버클링 발생을 예측할 수 있다. 유효인장력은 코일튜빙 직경 및 두께, 시추공의 크기 및 경사, 마찰계수, 킥오프 지점 등의 매개변수들에 의해 영향을 받는다. 이 연구에서는 유효인장력에 영향을 주는 매개변수들을 변화시켜 분포하중 변화와 헬리컬버클링 발생 심도를 하중분포 모델식(TFM)에 의해 수치적으로 계산하였다. 분석결과 방향성 시추시 헬리컬버클링을 방지하기 위해서는 마찰계수 감소효과를 위해 애뉼러스를 증가시키고, 킥오프 지점을 깊은 심도에서 설계하는 것이 효과적임을 알 수 있었다. 이 같은 결과는 코일튜빙 시추시스템 구축과 헬리컬버클링 방지를 위한 코일튜빙 시추 설계시에 사용된다.
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- 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 : 46
- No :4
- Pages :409-423
Journal of the Korean Society of Mineral and Energy Resources Engineers
