In this paper, the differential equation for the frictional resistance on the drill string in branch horizontal Wells was established and the total drill string friction during tripping was got.

本文建立了在水平分支井眼中的钻柱摩擦阻力微分方程，并得到了在起、下钻过程中钻柱的总摩阻。

youdao

Drillers also use sensors to detect particularly promising rock intervals within the formation, and are able to move the drill string up or down, left or right as they drill through the horizontal section to target those intervals.

FORBES: Horizontal Drilling: A Technological Marvel Ignored