The need for accelerated economic growth sets the task of increasing efficiency and improving the quality of drilling for the oil industry. This task includes both quantitative growth, i.e. an increase in the speed of drilling, and improvement of the quality of drilling operations themselves. One of the most important factors of quality improvement is the drilling of directional and, particularly, horizontal wells strictly according to the project. This paper provides a brief analysis of the operation of horizontal wells at the Zhanazhol deposit. It also presents studies on the statistics of the effective length of horizontal well sections.