April 2, 2013
The Top Drive Drilling System is recognized as one of the most significant advancements in
drilling technology since the introduction of the rotary table. When comparing them to
regular drilling rigs, Top Drive Systems consistently drill faster and safer, with less
chance of drill pipes being stuck. Top Drives also allow operators to reach areas and
types of formations that would not be accessible with conventional rotary drilling.
Horizontal drilling and extended reach have brought about drastic increases in production
rates, and these wells can only be drilled with Top Drives. Along with improved well
control and better hole conditioning, these benefits contribute to the unquestionable
financial justification for the Top Drive.
In 1981, Duke Zinkgraf of Sedco (now Transocean) sought out a way to drill from the top
down from the drillstring and adding complete strand of pipe, which would end the need for
the kelly drilling process. He searched for a company that was willing to embrace and
develop his new concept. Duke found a partner with Varco (now National Oilwell Varco).
George Boyadjieff, Varco?s president, assembled a team of engineers and dedicated it
solely to this project. Their initial prototypes were first installed in the Middle East,
they then made their way to the U.S. At first, the road to acceptance was bumpy. Many
companies did not want the hassle of integrating the top drive drilling systems into the
existing drilling processes. Once alterations were made to the top drives to make them
easier to incorporate and more reliable, companies took notice. Once the industry began
to realize the practical drilling capabilities of the top drive methods, new and radical
well programs were being designed around them. More and more advances in top drive
equipment and operation are rapidly changing the way drilling is done. More than 60
percent of all drilling rigs are now incorporating top drives. The main reasons are
increased safety and efficiency.
A Top Drive is a motor that is suspended from the derrick, or mast, of the rig. This
motor can be either electrical or hydraulic. These motors produce at least 1,000
horsepower. It is connected to a short section of pipe called the quill. From there, the
quill is either screwed into a saver sub or the drillstring itself. Because the Top Drive
is suspended, it is free to move up and down the derrick. Top Drives average around 15
feet in length and about 4 feet in width, which make it convenient to transfer due to its
slender build. The average weight is somewhere around 10,000 lbs.
A Top Drive has many advantages. It is capable of drilling with three joints stands,
instead of just one pipe at a time. Top Drives typically decrease the frequency of stuck
pipe, which contributes to cost savings. They also allow for quicker pump engagement and
disengagement or the rotary while removing or restringing the pipe. Top Drives are also