Coiled Tubing Buckling Implication in Drilling and Completing Horizontal Wells
- Jiang Wu (Maurer Engineering Inc.) | H.C. Juvkam-Wold (Texas A and M U.)
- Document ID
- Society of Petroleum Engineers
- SPE Drilling & Completion
- Publication Date
- March 1995
- Document Type
- Journal Paper
- 16 - 21
- 1995. Society of Petroleum Engineers
- 1.6 Drilling Operations, 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 1.10 Drilling Equipment, 1.6.1 Drilling Operation Management, 5.6.1 Open hole/cased hole log analysis, 1.1 Well Planning, 2 Well Completion, 3 Production and Well Operations
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This paper discusses helical buckling and frictional drag of coiled tubing in drilling and completing horizontal wells. Analytical equations are presented to predict helical buckling of coiled tubing, actual bit weight or packer load, and maximum horizontal length that may be drilled if helical buckling occurs. These equations can also be used for other operations with coiled tubing in horizontal wells, such as coiled tubing wireline logging, coiled tubing well stimulation, and for conventional drilling using a joint-connected drill string. The results are compared with previous results in the literature.
Drilling and completing horizontal wells using coiled tubing are currently developing technologies in the oil industry. These technologies bring about significant saving, but they also raise new problems, such as buckling and "lockup" of coiled tubing in the wellbore. This paper will analyze, in detail, the nature of coiled tubing buckling and frictional drag in horizontal wells (including vertical, buildup, and horizontal sections), and presents the equations to predict bit weight/packer load, maximum horizontal section that can be drilled, and coiled tubing "lockup".
When coiled tubing is run into a horizontal section, it is subjected to compressive load due to frictional drag, The axial compressive load is highest at the end of the build section and lowest at the far end of the well. When the compressive load exceeds the critical buckling load, the coiled tubing will initiate a sinusoidal buckling. Further increase of the compressive load can result in a helical buckling of the coiled tubing. The helical buckling is developed simply because of the wellbore's confinement to the buckling deflection. For tubulars confined in the wellbore and under large axial compressive load in excess of the helical buckling load, the helix becomes the buckling shape with minimum potential energy.
Coiled tubing buckling can also occur in the vertical section of a horizontal well when "slacking-off" weight at the surface to apply bit weight or packer load and to push the coiled tubing into the horizontal section. With conventional drilling, heavy weight drill pipe or drill collars are often used above the "kickoff" point to prevent buckling. This is not possible with the continuous coiled tubing, so there is a high probability that the coiled tubing will buckle in the vertical wellbore section, and adversely affect the well plan.
Buckling of Coiled Tubing
Coiled tubing buckling may occur in any wellbore section (vertical, horizontal and buildup sections). However, the axial compressive load to initiate the buckling is different for different wellbore sections.
|File Size||311 KB||Number of Pages||6|