How the Top Drive System works

This video shows detailed about top drive from Varco with a lot of operation aspect and it will help you learn a lot of details about Top Drive. We already add full the video transcript in order to help people understand all details.

Full VDO Transcript


The Varco Top Drive drilling system is more than a concept. It is a proven, practical drilling system that has been setting drilling records and producing profits for operators since the early spring of 1982. Time savings have averaged over 25% on the wells drilled with this system. In addition to reaching TD ahead of schedule, the operators feel that the ability to drill down 90 foot stands, produces a cleaner borehole and fewer subsequent sticking problems. By rotating the string from a drilling motor and gear train, mounted on rails and a derrick, the rig is able to function with the measure of speed, efficiency and safety; never before possible with conventional drilling methods.

The Top Drive’s flexibility to simultaneously rotate and hoist pipe at any time, whether drilling or tripping, can provide many previously unavailable options to drilling personnel. Development of this drilling system began several years ago, when after considerable investigation, Varco determined that the key to a successful derrick mounted drilling system would be found in the method of making and breaking connections overhead in the derrick. At that time, the technology did not exist to reliably handle this operation, but several years later with Varco’s hydraulic pipe handling tools proven successful, a second look was given the problem of breaking connections in the derrick. Initial designs utilized a railway traction motor, mounted in the derrick, rotating the string through a locomotive reduction gear and a hollow shaft, replacing the axel and flanged wheels.

The success of this design proved the concept and development continued to progress. Improvements were made to provide more torque and enabled a new drilling system to be used in the standard 142 foot derrick and on floaters with motion compensators. To increase the available torque, the railway traction motor was replaced with a square frame oilfield motor with special thrust bearings to enable it to run in a vertical position. And air break was fitted to the upper end of the double-ended armature shaft, and a new higher ratio reduction gear was designed. This change improved the available torque from the system, while short coupling the swivel to the drilling shaft and eliminating the hook, reduced the length sufficiently to allow it to be used in a 142 foot derrick.

The hook’s function was taken over by a series of features on the unit. First, the hook spring was replaced by springs located in the torque arresters to cushion the system, when the string was hoisted and allow the pin to jump the box, when connections were broken. Orientation of the elevators was accomplished by a positioning system located below the gearbox. Hoisting capacity of this system is a full, 500 tons, using standard links and a drill pipe elevator or casing tools. If a hook is desired in the system, a 147 foot derrick should be considered the minimum for adequate headroom. A hydraulic torque wrench is mounted beneath the drilling motor to break out connections at any point in the derrick. This tool is an adaptation of Varco’s proven successful TW60 torque wrench, hundreds of which are in use all over the world.

The Top Drive drilling system is mounted in a dolly, running on rails in the derrick structure. These rails may be incorporated into most existing derricks or mast with little or no additional reinforcement of the structure. The controls are built into the driller’s panel and are designed to be familiar to the driller, and ammeter and the tachometer, the only additional instruments, while the controls are usually integrated into the existing electrical distribution system; switches for breaks, link tilled inside BOP and torque limiter override, are placed for the convenience of the driller. In operation, the system allows drilling with 90 foot stands, which produces several distinct advantages over conventional drilling. By eliminating two of every three connections, a greater proportion of time is spent drilling ahead. When connections are made, they may be accomplished quickly, so as to maximize rotating time.

When a stand has been drilled down, the driller stops rotation and sets the slip. He then initiates the hydraulic pipe handler’s breakout sequence. The torque wrench elevates to engage the spline on the drilling shaft, the lower jaw clamps the box and the connection is rotated 30° to break. Next, the driller reverses the drilling motor to spin out of the string and hoists the system back to the monkey board, where the derrick man drops in the next stand. The new stand is hoisted and stabbed into the string, and the driller slacks off to stab the drilling shaft into the upper box. Both connections are spun up and torqued by the drilling motor, where the single tong holding back up at the floor. When the driller pulls the slips and starts the pumps and begins rotation, the system is making hole again.

Singles may be made up from the mouse hole just as easily. When the stand is drilled down, the slip set and the connection broken, the driller activates the link tilt feature to extend the elevators to the mouse hole, where they’re easily latched and the new joint is hoisted and stabbed into the string. The single is made up in the same way as the stand, and the system is drilling ahead in about a minute and a half from the time the slips were set.

Tripping is accomplished in the normal manner. With the drilling system in the string, the elevators simply handle the pipe in a conventional manner, except for the added advantage of the link tilt feature, which can be set to hand the stands to the derrick man. Should a tight spot be encountered, coming out or going in the hole, the driller stabs the drilling shaft back into the connection in the elevators, to rotate and circulate through the key seat or bridge. When tripping this ability to get back on the hole, is particularly important should a kick occur. Before the trip, a second inside BOP is made up on the drilling shaft. And should the driller notice a flow increase, or pit game during the trip, he simply sets the slips and stabs the drilling shaft back into the string, and makes up that connection as he would during routine drilling. At this point, he can close the pipe rams and readjust pressures on casing and drill pipe and begin the circulation of heavier mud. If necessary, he can close the remote operated kelly cog and lower the string to the floor, close the inside BOP and breakoff the drilling shaft to install this valve and steel hose. This operation does not require the presence of the floor crew to shut-in the well.

When running casing, the drilling system is left in place, and longer links and standard casing tools are suspended from the link adapter. As each joint is added, the driller can open the remote kelly cog and pump mud into the string through the short length of hose between the drilling shaft and the top of a casing. Should a tight spot be encountered, the spider slips are set and the elevator released, and the casing is stabbed into the casing swedge and made up. Now, the spider slips can be released and the casing rotated and reciprocated through the problem area.

The Top Drive drilling system provides the advantages of speed, efficiency, and safety, to the operator on practically any rig. The ability to drill with stands eliminates two thirds of the drilling connections, while providing a cleaner hole. Connections are made more quickly, since both upper and lower connections are spun up and torqued simultaneously. The link tilt features speeds latching the elevators on mouse holes connections, as well as extending stands of collars towards the derrick men on the monkey board.

Drilling with stands also facilitates directional drilling, coring, and fishing operations. Finally, additional efficiency is gained by the ability to rotate both drill pipe and casing through tight spots in the borehole. This system also provides considerable operating economy, simplicity of design, the use of common oilfield equipment, and the availability of parts, all contribute to the long-term economy of this system. The precise torque, applied to the drill string connections, contributes to their expected service life and the use of the remote kelly cog is a much safer valve during connections, preserves expensive drilling fluids.

Safety of men and equipment is the last advantage of this system, although it is probably the most important. By reducing the number of connections and eliminating several rotating members from the floor, while placing the entire operation in the hands of the driller, makes a significant contribution to the safety of the rig crew. Rapid and precise response to a kick situation enables the drilling system to contribute to the overall safety of the operation, giving the driller the ability to shut in the well and begin his control procedures without critical delay.

The Top Drive drilling system has proven itself to be not just an advanced concept, but a practical, reliable tool that is setting footage records wherever it is put to work. If you drill a well from the top down, why not drill it right? Drill it from the top with the Varco Top Drive drilling system.

This is the Varco power-sub drilling system, designed to rotate the drill string by means of an electric motor and gear drive, suspended in the derrick, the power-sub drilling system permits the driller to rotate the pipe while pulling out of the hole; and gives him the ability to drill down whole 90 foot stands. When drilling in a high angle hold, it’s occasionally necessary to rotate the string while pulling out to prevent the pipe from becoming stuck in the angled portion of the borehole. Drilling with 90 foot stands eliminates two kelly connections every 90 feet, thus saving some considerable time in the drilling operation.

The power-sub consists of a railway traction motor and gearbox, with a shaft replacing the axel and flanged wheel assembly. This widely available unit is mounted on end on a carriage to drive the drill string. The motor is offset from the string, thus no drilling fluid passes through it. The power-sub is placed in the overhead string, just below the standard swivel. Below the sub extends the pipe handler assembly. A hydraulic torque wrench used to break out connections from the power-sub either at the floor or in the derrick. Hanging beneath the pipe handler is a pair of standard Varco links and a drill pipe elevator. The links may be tilted out to reach the mouse hole with a built-in air system to assist the floor crew when picking up or laying down joints in the mouse hole.

The power-sub drilling system is designed to be compatible with any standard drilling system. The power-sub carriage assembly is mounted on a pair of rails in the derrick, similar to block guides. The drilling motor and the rest of the power-sub drilling system may be swung aside when not in use, and drilling with a kelly may proceed normally. To change from conventional drilling to power-sub drilling, the sub is swung from its stowed position and secured in the carriage. Meanwhile, the conventional kelly and swivel is set back in the rat hole. At this point, the hook picks up the power-sub by the swivel bail and the rig is ready to drill ahead or remount.

In practice, the rigs currently using the power-sub are leaving it in the string. Since the conventional elevators hanging below it, allow normal tripping. Here are Varco SSW30 hydraulic spinning wrenches being used to spin out the stand after breaking it with the tongs. In the same way, the trip in the hole can be made conventionally. Making connections while drilling is faster than conventional kelly connections. When the stand is drilled down, the slips are set. The torque wrench and the pipe handler begins its automatic cycle to break out the power-sub.

First, the wrench body elevates to engage the spline sub on the driveshaft. As the torque wrench clamps on the box connection, the torque cylinder rotate the connection 30° to break it out. Once this is done, the driller reverses the drilling motor to back the power-sub out of the box. Meanwhile, the crew has opened the elevators and they can be hoisted back to the monkey board, where the derrick man drops in the next stand and latches them. Now the driller hoists the stand and the crew stabs it into the box in the rotor. As the driller slacks off to stab the power-sub into the stand, he cracks the SER control, to rotate the drilling motor and spin up both connections. When the connections have shouldered, he dials up the prescribed current to properly torque the connections.

At this point, the string is hoisted, the slips pulled, circulation reestablished and the driller is ready to make another 90 feet of hole. When a turbo drill or a mud motor is used in a high angle hole, conventional drilling methods make it difficult to maintain a consistent weight on the bit. The power-sub drilling system allows the driller to rotate the string, while drilling with a mud motor to prevent wall sticking and maintain more accurate weight on the bit, for more consistent penetration.

A break on the drilling motor allows directional drilling with a mud motor and a bent set, and the ability to drill down 90 foot stands means fewer interruptions and loos of two-face orientation for fewer surveys, thus a considerable savings and drilling time. If single joints must be added too or removed from the string, a link tilt assembly lifts the elevators to the mouse hole to pick up or lay down the single. Drilling with stands is normally accomplished by picking up single joints in the mouse hole and assembling the needed stands prior to drilling. However, if additional footage is required, stands may be assembled while out of the hole; testing BOPs for example.

Finally, the ability to have what would normally be the kelly connection immediately available during trips, is likely to prove one of the most valuable features in the power-sub drilling system. Should the driller experience a kick while tripping, statistically one about half of all kicks occur, he needs only to stab the power-sub back into the string by slacking off, rotating and torqueing in the normal manner. That quickly he’s back on the kelly and able to pump into the well to reestablish reservoir dominants. Since connections are made quickly, stripping back in whole stands at a time needed, requires minimal interruption in pumping.

The first two power-subs delivered to Sedneth 201 and 202 proved the power-sub drilling system’s value to the contractor. The first unit set a drilling record on its first well, which was beaten on its second. The second power-sub on Sedneth 202 has performed just as well. Of the three wells, completed by the two power-subs, Sedneth 201’s first well required about 10 hours of downtime, due to some problems in the sub. Once the solution was found to these, the second well required less than two hours of downtime. And Sedneth 202’s first well required minimal interruption of drilling due to the power-sub. This is rather impressive, since these power-subs were still effectively prototype units, having never been previously exposed to actual drilling conditions. In this directional wells, torque was quite high and the physical stresses imposed on the system, particularly while drilling the surface hole, were extreme. The Setco drilling proved, drillers and rig superintendent and like, preferred the power-sub to the more conventional drilling methods with the kelly and rotary table for all kinds of drilling. They sighted the improved rate of penetration and time savings over the conventional drilling technique as the reasons for their preference.

This kind of performance, plus the support of Varco’s engineering and service departments, as well as the simple design and common oil field components, have produced the power-sub drilling system’s first satisfied customer. And we’re proud of that.

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