One of the basic problems that a directional driller faces is to accurately set a specific toolface orientation. After a connection, the driller must rotate the pipe at the surface and experiment with the weight-on-bit and top drive quill position to orient the toolface. The driller has to work with throttles, clutches, brakes, and a forward or reverse control to orient the drillpipe to the correct position. The challenge is to properly orientate the downhole tool to steer the well bore in a desired direction. This can only be done manually by feel, timing, experience, and estimation due to the fact that a certain amount of rotation at the surface may not necessarily result in equal rotation at the downhole tool. This obviously takes time.

The Canrig ROCKIT directional steering control system removes guesswork and eliminates the need for precise timing and the right amount of throttle. It has demonstrated its ability to save rig time by increasing the rate of penetration (ROP) while sliding, orienting the toolface setting more rapidly and improving the toolface control. By identifying particular areas of concern, engineers were able to design a system that solves directional drilling challenges and contributes to safer and more efficient drilling operations. Integrated with the standard Canrig top drive, the program controls the amount of rotation.

The system allows the driller to enter the quill position using a touchscreen so the top drive rotates the pipe to the desired orientation. The quill can be adjusted forward and reversed to achieve the desired toolface. The pipe no longer has to be marked manually by the rig crew or directional driller, and the entire process improves safety by keeping the crew away from the drillpipe.

Once the toolface is set, controlling and accurately maintaining its orientation becomes the next challenge. During slide drilling operations, orientation is altered by formation changes, variations in drilling parameters, or reactive torque causing unwanted deviations from the planned wellbore path. Directional drillers struggle to get the toolface back on track, frequently creating nonproductive flat time.

Expensive downhole agitators frequently are used to help reduce friction, but they create other problems that can only be fixed by a trip out of the hole. ROCKIT has a built-in bearing offset control that provides fine control of the toolface orientation allowing the operator to nudge the toolface left or right while drilling. These adjustments can be made while drillstring oscillation is in progress.

The system’s directional drilling automation platform integrates critical details onto one monitor, eliminating the need for a driller to view multiple screens while making drilling control decisions. (Images courtesy of Canrig)

Reduces friction, improves ROP

Wellbore friction reduces the amount of weight that can be put on the drill bit, which results in a lower ROP. Can-rig’s directional steering control system can oscillate the drillstring from the surface to dramatically decrease friction. The amount of oscillation left and right is adjusted by the operator and can be programmed from a slight fraction to several revolutions to provide maximum drill-string rocking without affecting toolface orientation.

The system was designed to give the driller the data needed for directional control. Historically, a driller has had to check a number of screens to gather information needed to make a drilling control decision. This system integrates critical details on one screen, including MWD toolface data, MWD inclination and azimuth, tool-face advisory, resultant toolface, pump pressure, and Delta pressure. Having all of this information in one place makes it easier to steer while sliding and makes the entire process more efficient. It also allows drilling personnel to react faster to changing downhole conditions and reduces the chance for costly errors.

The system consists of the programmable logic controller (PLC), a position feedback signal, a torque sensor, the man-machine interface (MMI), and the downhole tool information feedback unit. These five components operate together to accomplish tasks that, in the past, required repeated manual interventions and a trial-and-error process to obtain the proper results.

The Toolface Advisory on the ROCKIT screen is used to guide the driller into the directional target or back to the planned well path.

Success in the Barnett shale

A recent study analyzed six wells in the Barnett shale in the Fort Worth area of Texas. These wells were all medium radius horizontal wells with a pay zone around 1,676 m to 1,829 m (5,500 ft to 6,000 ft) true vertical depth. Each had lateral sections of between 457 m and 610 m (1,500 ft and 2,000 ft) with total measured depths of approximately 2,896 m to 3,048 m (9,500 ft to 10,000 ft). In the first three wells, slide drilling and toolface control were carried out in a conventional manner for the curve and lateral sections. In the following three wells, the ROCKIT technology was used to drill the curve and lateral section. The study showed significant improvements in ROP and drilling efficiency when the system was deployed.

Drilling performance also showed a marked improvement in ROP numbers from the previous three wells drilled in the same area and formations. The operator analyzed the performance data in house and arrived at the conclusion that ROCKIT technology significantly reduced drilling time by saving up to a day of rig time in drilling the curve and another day in the lateral sections of these wells.

The value proposition offered by the system has been widely accepted by operators and their directional drilling contractors, and it currently is in use in the Pinedale area, Eagle Ford shale, and Gulf Coast region. The directional steering control system is available on all new Canrig AC top drives and can be retrofitted to existing AC top drives.

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