TerrAdapt bit system is helping to reduce stick slip and increase drilling efficiency
March 29, 2017
Baker Hughes’ TerrAdapt bit system has variable and adaptable cutting elements, helping to reduce stick slip and increase drilling efficiency
Different drill bits and bit configurations are often used to tackle different formations, but the advantages of doing so may be outweighed by the time and cost of removing a drill string, replacing the bit, and re-tripping. As a consequence, drillers may opt to push through various formations to reach target depth, even when encountering difficult sections, or transitioning between layers of hard and soft rocks.
When a bit with fixed depth-of-cut (DOC) enters into a transition zone between formations, its bite can become too aggressive, causing vibrations and stick-slip. These stick-slip events dramatically increase drilling costs by reducing ROP, they result in poor directional control, and can seriously damage the bit and other expensive downhole tools such as (measurement-while-drilling) MWDs and motors. Even minor changes in the rock can cause impact loading, limiting the life of the bit.
Adjustments to rotations per minute (RPM) and weight-on-bit (WOB) from the surface can help, as well as blades with a variable DOC – but tend to be little more than informed guesswork. As with many other sub-sectors of the industry, automating some of these processes can hold immense value. It is with a view to solving this problem that Baker Hughes has unveiled its TerrAdapt Adaptive Drill Bit system. Movable control elements in the bit are self-adjusted to vary the DOC, according to the lithology of the environment. The system will also respond to events such as shocks and slips, preventing damage to the bottom hole assembly (BHA) and the bit itself.
For operators, Baker Hughes says, that means “faster, more consistent rates of penetration (ROP), longer bit/tool life and significantly reduced non-productive time.”
Adapt and thrive The TerrAdapt system uses a passive hydro-mechanical feedback mechanism built into cartridges installed inside the polycrystalline-diamond-compact (PDC) bit blades. Elements on top of these cartridges control the DOC, and can be retracted or extended. They respond to loads and vibration, preventing the bit from taking too large a bite in harder sections. When vibrations cease, or during normal drilling, the elements gradually adjust their exposure to keep drilling fast and efficient.
A Baker Hughes spokesperson explained more about the innovation’s history: “The TerrAdapt concept was developed as part of an internal Baker Hughes innovation contest called the Wildcat Challenge. The first one was kicked off at the end of 2013, challenging participants to think of a solution to a common industry problem that is not being addressed with current research and development projects. The idea of a bit that could be self-adjusting won the inaugural Challenge.”
Having then developed the bit over 12 months, the company launched a formal product development effort in 2015. “It has been exciting to take such a novel idea from concept to commercial offering in less than three years,” the development team told InnovOil.
The future of drilling? Reported results for one operator have been impressive. According to a Baker Hughes case study, one driller in the Delaware Basin, Texas was experiencing erratic drilling during intermediate sections running through interbedded shale, limestone and salt. These slowed drilling progress and were damaging equipment, increasing time and costs.
The TerrAdapt bit completed the 3,355-ft (1023-m) section in a single run, increasing ROP by 27% compared with ROP on offset wells drilled with standard PDC bits. Surface torque generated by the TerrAdapt bit was also 45% lower on average and 90% more consistent.
Given these results, drillers are likely to see more adaptive bits reaching their rigs. According to Baker Hughes, TerrAdapt is the first release in “a line of adaptive bits.” While the initial release of TerrAdapt focuses on 8.5 inches (216 mm) to 12.25 inches (311 mm), over the next year or two Baker Hughes confirmed that “we will be scoping/developing the next TerrAdapt/adaptive bit that can adjust other components on the bit to solve other downhole issues.”