Improvements in drilling performance in key applications around the world continue to focus on reducing vibrations of the system consisting of the drill bit, bottomhole assembly (BHA) and drillstring. These vibrations can take the form of whirl, stick-slip, bit bounce or combinations of these, leading to drilling inefficiencies. Many efforts are under way to control and manage these vibrations and develop tools that can withstand the higher vibrations seen in today's drilling environment.Introduction of the most-recent design of a hybrid drill bit took place in 2009 with the presentation of IADC/SPE paper 128741. It was shown to be a viable drilling tool for potentially difficult or problem-prone applications. This paper covers the ongoing development work on the hybrid bit technology which combines elements of polycrystalline diamond compact (PDC) and tungsten carbide insert (TCI) bits. Testing is now taking place on a large scale and the results confirm the potential benefits revealed in the early prototype testing.Early tests of the hybrid bits were designed to show that it is sufficiently robust to drill and hold up under normal drilling. The next 100+ runs were targeted at areas where both traditional PDC and TCI drill bits struggle and the hybrid bit proved to be both faster and more durable than the conventional bits. This was achieved through the synergy of the smooth running action of the rolling cutters with the sharp cutting elements on the fixed PDC bit blades. This paper details the knowledge gained in drilling over 167,000 feet just over 10,100 hours that has led to further design improvements and a better definition of the applications in which a hybrid bit can deliver superior performance. These applications are generally in the harder and hard-interbedded formations. The targeting of the hybrid technology is enabling problem wells to be finished sooner and at lower cost while still avoiding dynamic dysfunctions commonly seen. Results of all hybrid runs in a wide range of applications will be compared and recommendations will be made on where this technology can provide the most significant improvements.

In Kuwait's largest reservoir, the Burgan Field, exploration wells have large potential for drilling optimization and savings; specifically a 22 inch hole, that is drilled conventionally using multiple roller cone bits in multiple trips through challenging inter-bedded formations. Hybrid drill bit technology, roller cone combined with Polycrystalline Diamond Compact, was introduced in search for an economically viable solution to deliver wells faster and achieve yearly operator targets. This paper analyzes the breakthrough drilling performance achieved by a 22 inch hybrid bit in comparison to conventional roller cones offsets and provides conclusions on economic viability. The main challenges drilling the 22 inch section are drill bit durability and drilling vibrations through inter-bedded formation layers of limestone, shale and sandstone. In addition to curing fluid losses in certain porous formations that negatively affect Rate Of Penetration (ROP). Typically two roller cone bits are used on rotary drive to drill this section at 15 feet per hour, consuming seven drilling days. Using Polycrystalline Diamond Compact (PDC) bit with a performance motor to increase ROP performance is not an economically viable solution. Using hybrid drill bit on rotary drive combines the benefits of PDC blades' durability and higher cutting efficiency with the cones' stability by grinding and gouging into the formation. The deployment of the hybrid technology was a collaboration project between a national oil company and a major oil services company. The teams focused on optimizing the complete drilling system including the bottom hole assembly, hydraulics, drilling parameters and geological factors to match the hybrid drill bit mechanism. The hybrid design selection and drilling optimization resulted in a 142-percent ROP improvement from offsets average performance. The hybrid designs consistently drilled the 22 inch hole after casing shoe to section total depth at 31 feet per hour, using one bit, in three drilling days in comparison to seven days average performance. The total operator savings from e section was approximately USD 175,000 in the first deployment. The second and third deployments established performance consistency. Such remarkable economical savings and technical optimization proved that the hybrid technology is the viable solution for two prolific exploration applications.

Technology Update It is inspiring to look back to 1909 when Howard Hughes Sr. and Walter Sharp introduced the roller-cone bit. The invention was the foundation for the discovery of vast amounts of oil in medium-and hard-rock formations, oil that many drillers suspected was there but was nearly impossible to reach with the bits of that day. The roller-cone bit changed the industry, but we may forget why its immediate predecessor, the fish-tail bit, was such a burden on drillers as they strived to probe deeper targets. Often 24 hours would not go by without a twist-off occurring, and rig hands were constantly changing bits and “fishing” parts out of the hole. For drilling anything other than loose formations near the surface, it had proved impractical. In a century’s time, the industry has made tremendous progress. But the limitations of physics continue to challenge the dynamic performance of the bit and bottomhole assembly (BHA) in the demanding downhole environments of today’s wells. Tools come equipped with features such as torque reducers, depth-of-cut controls, and more flexible assemblies, to mention a few. The inherent problem of controlling the reactive torque between the bit and formation, while achieving optimal performance to reduce the number of drilling days, has remained a challenge. The introduction of the hybrid drill bit in 2011, which combined roller cones and fixed cutters, was a catalyst to revisit these basic principles and better understand the benefits and efficacy of smooth drilling. The bit excelled in controlling torque fluctuations and exceeded the durability of fixed-cutter bits and the penetration rates of roller-cone bits. The hybrid bit soon became the standard bit for drilling in hard and interbedded formations, such as those in certain Oklahoma and Canadian plays, because it enabled drillers to reduce the number of curve runs needed. The use of the bit expanded globally, helping to improve drilling results in interbedded applications that historically have met with mixed success when medium-set roller cone or fixed-cutter bits have been used. As results continued to improve, interest in stretching the capability of the technology increased.

In Kuwait's largest reservoir, the Burgan Field, exploration wells have large potential for drilling optimization and savings; specifically a 22 inch hole, that is drilled conventionally using multiple roller cone bits in multiple trips through challenging inter-bedded formations. Hybrid drill bit technology, roller cone combined with Polycrystalline Diamond Compact, was introduced in search for an economically viable solution to deliver wells faster and achieve yearly operator targets. This paper analyzes the breakthrough drilling performance achieved by a 22 inch hybrid bit in comparison to conventional roller cones offsets and provides conclusions on economic viability. The main challenges drilling the 22 inch section are drill bit durability and drilling vibrations through 2,000 ft. of inter-bedded limestone, shale and sandstone. In addition to curing fluid losses in certain porous formation layers that negatively affect Rate Of Penetration (ROP). Typically two roller cone bits are used on rotary drive to drill this section at 15 feet per hour, consuming seven drilling days. Using Polycrystalline Diamond Compact (PDC) bit with a performance motor to increase ROP performance is not an economically viable solution. Using hybrid drill bit on rotary drive combines the benefits of PDC blades’ durability and higher cutting efficiency with the cones’ stability by grinding and gouging into the formation. The deployment of the hybrid technology was a collaboration project between a national oil company and a major oil services company. The teams focused on optimizing the complete drilling system including the bottom hole assembly, hydraulics, drilling parameters and geological factors to match the hybrid drill bit mechanism. The hybrid design selection and drilling optimization resulted in a 142-percent ROP improvement from offsets average performance. The hybrid design drilled the 22 inch hole after casing shoe to section total depth at 31 feet per hour, using one bit, in three drilling days in comparison to seven days average performance. The total operator savings from this section was approximately USD 175,000 in the first deployment. Such remarkable economical savings and technical optimization proved that the hybrid technology is the viable solution for Burgan 22 inch application.