Tractor-based conveyance and intervention systems for horizontal and high angle well operations have been in use for nearly 20 years. The first open hole (OH) application of a tractor was introduced to the industry in 1999. Since then, there have been many attempts to tractor in open holes with mixed results.
This paper will share the lessons learned and best practices derived from 15 years of OH tractoring operations. It will examine the track record of OH conveyance in several countries, including operations in the Middle East and in unconventional wells in the USA, describe the success factors, review rock strength issues and compare the risks of tractor-based conveyance to drill pipe conveyance.
Building on experience, success factor analyses and best practice guidelines, the success rate of OH tractoring has steadily improved over the years. One of the traditional limiting factors is the diameter of the OH, which can be beyond the reach of the tractor arms or wheels, either due to large bit sizes or enlarged boreholes caused by washouts. A new generation tractor was introduced in 2010 to address this issue. With an outer diameter of 4 1/2” and an operational OH diameter from 4.8” – 18” this tractor has made another step improvement in the success rate of OH tractoring.
This paper will also review the tractor-based OH conveyance logging services including triple combos, production logging tools, formation imaging logs as well as formation testing.