Patent ID: 9598906
Date: 2017-03-21
CPC Classifications: E21B

Claim:
1. An apparatus for use in a horizontal section of a drill string comprising: a motor, wherein the motor is connected to the horizontal section of the drill string; and a mandrel, the mandrel being a hollow shaft, the mandrel having a longitudinal axis, the mandrel having an imbalance, the imbalance including two eccentric masses attached to the mandrel, wherein the two eccentric masses are attached such that one eccentric mass is lower along the mandrel than the other eccentric mass, wherein the masses are about 180° apart on opposite sides of the mandrel with respect to the longitudinal axis, wherein the motor rotates the mandrel to impart lateral vibrations in the horizontal section of the drill string and wherein the vibrations are at about a lateral resonant frequency of the horizontal section of the drill string.