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An Analysis of The Flow Resistance in Coiled Tubing Wound Around A Reel, In Microhole Drilling

Xuejun Hou1,2, Deli Gao1, Zhonghou Shen1
State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum, Beijing 102249, China. Corresponding author: Deli GAO, E-mail:
College of Petrol Engineering, Chongqing University of Science and Technology, Chongqing 401331, China.

Computer Modeling in Engineering & Sciences 2012, 89(2), 97-110.


Microhole drilling (MHD) is a new frontier drilling technology in which the diameter of wellbore is less than 88.9mm and coiled tubing (CT) is used as drill string. The CT wound around reel for MHD has small bending radius and large length to result in large circulating flow resistance and affect normal MHD circulation. The calculation model for curvature radius and length of CT wound around reel are established by analyzing the relationships among the various geometrical parameters of the reel system. The calculation model is combined with Dean number and power-law fluid state equation to put forward the calculation model for the flow resistance in CT wound around reel (CTFR), which takes into changes of the parameters such as flow rate & density of drilling fluid, inner diameter & length of CT and the reel diameter. The calculation result shows that CTFR is considerably affected by the diameter & length of CT and drilling fluid flow rate. CTFR increases rapidly with reducing of the CT diameter and increasing of the CT length and drilling fluid flow rate. Simultaneously, it is significantly affected by the circulation drilling fluid density in CT. With increasing of circulating drilling fluid density, CTFR increases significantly. The higher the flow rate is, the larger the CTFR increment is. The research results may be useful for MHD parameter selections related to CTFR.


microhole drilling, coiled tubing, reel system, flow resistance, power-law fluid

Cite This Article

Hou, X., Gao, D., Shen, Z. (2012). An Analysis of The Flow Resistance in Coiled Tubing Wound Around A Reel, In Microhole Drilling. CMES-Computer Modeling in Engineering & Sciences, 89(2), 97–110.

This work is licensed under a Creative Commons Attribution 4.0 International License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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