Ulterra Discusses Drill Bit Design in Oilfield Technology Magazine
Oilfield Technology invited experts from BHGE, ULTERRA, and VAREL to share their knowledge on a variety of drill bit design topics. Ulterra weighed in to share their expertise on a variety of topics.
Topic 1: Cutter Configuration & Design
Ulterra: The company’s team of design engineers analyse individual cutter work load to reduce cutter imbalance and to ensure that the work is being distributed evenly amongst the cutters. Based on the drilling application, the cutter layout is adjusted to optimise drilling efficiency. Critical to the success of the cutter layout is the quality of the cutters used. Ulterra’s Omega™ cutter engineering team works with field sales, sales engineers, and design engineers to ensure the latest cutter technology is at work in the field. By maintaining a lean cutter inventory, customers are able to apply the latest cutter technology to their drilling operation. Operating at a fast pace that leaves little room for individual naming, Omega cutter technology is at the front of a constantly moving frontier of improvement. To get the most from each cutter, every aspect of the target application is analysed to identify and address specific problems. Using proprietary tools built within Ulterra to seamlessly integrate cutter configurations with cutter and bit design technologies, specific operator challenges such as stick slip in shale formations are addressed with improved drilling mechanics.
These tools take into account a broad range of information from simulation results and manufacturing considerations, but most important is the evaluation of past and current real-world performance. Actual iteration in order to learn and continually evolve is still at the core of all successful bit designs. Results from field testing verify that the cutters, blades, and nozzles are all working together as a system to achieve the best performance
“Ulterra’s Omega™ cutter engineering team works with field sales, sales engineers, and design engineers to ensure the latest cutter technology is at work in the field.”
Topic 2: Directional Drilling Challenges
Ulterra: One of the most significant trends in directional drilling is the effort to combine directional and lateral sections, using the same drill bit, in order to reduce time, save trips, and cut costs. In addition, rotary steerable system (RSS) usage is on an upward trend throughout most basins with more than 1100 RSS runs this year in the Permian Basin alone. With the increase in RSS usage, as tool pricing has improved, operators are looking to go farther into the lateral sections of their wellbores, in order to make the most of future completions. Improved bit stability, durability, and steerability are critical factors in addressing these objectives, allowing the bit to drill effectively in all sections of the well, and to hit the extended depth targets. In lateral sections, improved control and stability allows operators to end up with a cleaner bore hole, resulting in higher-outputting completions. Ulterra’s SplitBlade™ PDC bit technology has seen success in combining directional and lateral sections, achieving record ROP and total footage on both RSS and traditional motors. This performance has been realised in the Permian basin on an AutoTrak RSS, drilling a record curve and lateral performance that increased ROP by 23% over the competition at 140 ft/hr. Also, recently, in a Woodford lateral in Oklahoma, an 8.5 in. SPL616 set a lateral RSS ROP record, drilling 178 ft/hr. One of the unique challenges of directional drilling with various BHAs involves what happens to the primary cutters and gauge layout when drilling in the bend. Because the bit is drilling on a bias moving forward, lateral vibrations can be amplified. Considered one of the leading causes of RSS tool failure, the combination of SplitBlade and CounterForce® technology has proven a notable increase in bit life, resulting in more consistent section completions without a tradeoff in speed or directional control. Ulterra currently has the leading average dull grades from RSS runs in the Permian, Delaware, Eagle Ford, Anadarko, Marcellus, and Niobrara basins, supporting customers and operators to further push the boundaries of what is possible
“Ulterra’s SplitBlade™ PDC bit technology has seen success in combining directional and lateral sections, achieving record ROP and total footage on both RSS and traditional motors.”
Topic 3: Abrasion/Wear Resistance
Ulterra: In difficult drilling environments – featuring hard rock, transition zones, and highly interbedded lithologies – abrasion can be a factor that limits drill bit performance. Reaching increasingly difficult drilling targets in these challenging environments requires the drill bit to withstand higher drilling forces, particularly increased weight-on-bit (WOB). The bit must also incorporate an overall level of durability, ensuring that it can accommodate the vibration and wear factors associated with the drilling process. Ulterra’s XP™ bits are designed and manufactured for these demanding drilling environments, to ensure that the bit is never the performance limiter. The focus of XP technology is on making the bit as durable as possible, to maximize its structural integrity and stability. Along with a bit body designed to ensure structural integrity, Ulterra XP bits are force-balanced to enhance stability. Through the application of specific, premium, abrasion resistant PDC cutters – and the positioning of the cutters to reduce tangential overload – XP bits deliver improved durability, allowing operators to increase drilling performance while pushing operational parameters. The design of XP allows the use of greater WOB in even the most challenging drilling environments. These bits are capable of achieving high ROP rates through the toughest hard rock sections, with less wear on the bit. Additionally, TuffCast™ materials enhancement technology can be added in order to combat abrasion without sacrificing junk slot areas or blade strength.
“The focus of XP technology is on making the bit as durable as possible, to maximize its structural integrity and stability.”
Topic 4: Boosting ROP
Ulterra: Achieving high ROP targets is the result of the entire drilling system functioning properly. The drill bit, drill pipe, bottom hole assembly, drilling fluid, and steering mechanism all must work together. Equipment, overall setup, and people factors are all relevant to getting the best performance. In the case of the drill bit, speed is always a priority, yet the speed of drilling must be balanced with the bit’s ability to reach its desired interval depth. Minimizing the overall time required to reach TD is the key. It is about saving rig time, helping operators work efficiently, and getting the well into production as quickly as possible. It is a fact that ‘sharp bits drill faster’, but there are other factors at play. If a bit is smooth and stable – drilling in an efficient manner – it will drill fast, be more resistant to damage, and be able to deliver maximum performance. The first step is to choose a bit that is suitable for the application, given all the technical challenges and performance limitations. Cutter counts and placements are analysed to be sure the depth of cut will be as good as it can be, all based on the bit’s ability to make the distance. In any application, there will be some parameters or factors that define the upper limit of ROP performance. These factors can include available pump pressure, torque and drag, and available weight at the drill bit. While selecting the right technology, it is important to analyse the limits present and apply the correct technology to help mitigate any limiters to performance. The smooth and stable drilling of Ulterra’s CounterForce® bit technology results in higher ROP. This technology is focused on harnessing the forces that cause vibration and using them to increase drilling efficiency. Following its introduction in 2013, CounterForce bits have successfully drilled more than 100 million ft, and 80% of the bits in the Permian today are backed by CounterForce technology. In addition, Ulterra’s SplitBlade™ helps to eliminate lateral vibration at the bit through better hydraulics and improved steerability. This bit design is also setting new ROP records in a wide variety of formations. With these recent advances, fewer compromises are needed in order to hit ROP targets.
“Following its introduction in 2013, CounterForce bits have successfully drilled more than 100 million ft, and 80% of the bits in the Permian today are backed by CounterForce technology.”
This was originally posted in Oilfield Technology‘s Drill Bit Design Q&A.
To view other responses, please view the complete Drill Bit Design Q&A