Calculation and Analysis of Drag of Spoon-Shaped Well Strings

Abstract

In order to improve recovery ratio in “Well Factory” development model, spoon-shaped wells are introduced. Spoon-shaped wells need a reverse hole extension with deviate and azimuth change before forward drilling. The complicated well trajectory leads to larger drag on the working string during the string slacking off and pulling up. In order to analyze the friction characteristics of downhole string, software is developed. Case study shows that spoon-shaped hole section makes it more difficult for the working string to slack off and pull up than an ordinary horizontal well. The software calculates the axial force, and the in-depth analysis concludes that the contact force between string and borehole wall in the forward deviation-built section is very large, especially in the section that deviation and azimuth change; large target section deviation increases the contact force.