The Effects of Borehole Ovality on Bare Hole Horizontal Well Completion String Tripping in Friction

AI Chi, LIU Yu, LI Yuwei


Under the effect of non-uniform ground stress, the borehole becomes oval. The deformation regulations and friction calculation in oval borehole has great difference with which in circular borehole. Researching the effect of the ovality of borehole on string tripping in friction is of great significance. In this paper, the string deformation model in oval borehole was established; the maximum displacement changes with different ratios of the major and minor axis and inclination angles were analyzed. The deformation model between two contacting points was established, and the determining method of the new contacting point of multi-packer completion string was proposed. The friction calculating model was established finally.The Hongping 9 well was used as an example to calculate the effect of borehole ovality on the bare hole completion string tripping in friction. By calculating, the friction calculated using the model was in good agreement with the measured value. The friction of completion string is almost zero in vertical section, and in blending and horizontal section the friction is increasing gradually. With the increasing of ovality the friction is increasing. The ovality increases from 1.0 to 1.3, the increasing value of friction is 36.59 kN.
Key words: Borehole ovality; Completion string; Bare hole completion; Friction


Borehole ovality; Completion string; Bare hole completion; Friction

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