Access to new reservoirs requires drilling at increasingly greater depths through more challenging environments with limited resources. Hard Rock bit cutting structure layout has been developed to extend bit life, drilling through hard, abrasive, and thick conglomerate and sandstone intervals while achieving significant rate of penetration (ROP) improvement. A case study is presented to demonstrate the liability and consistency of this new technology. In Oman, one of the most challenging formations is Amin. It's composed of hard conglomerates, abrasive sandstone, and layers of medium hard shale. The formation thickness is typically 1500 m. Roller cone bits have been used to drill it for years with low performance and high operational risks. Eight to eleven bits were usually required to drill the section at poor ROP. Polycrystalline diamond compact (PDC) bits were also tested previously with limited improvement at poor footage and ROP. An unconventional bit cutting structure layout referred to as multilevel force balancing was used to develop fit-for-purpose designs combined to a new generation of cutters. A comprehensive engineering analysis of bit performance in the area was carried out, including formation strength, bit design details, drive system, and an understanding of drilling parameters. Additionally, the introduction of new materials led to bit design adjustments based on hard rock drilling concepts. The combination of cutter technology and multilevel cutting structure layout was used to create a fixed cutter bit, setting records for drilling hard and abrasive lithology in Oman, delivering more intervals drilled with higher ROPs than the roller cone bits used previously. The bit consumption was reduced to an average of three bits, achieving 75% improvement in terms of footage drilled, and 100% ROP improvement. This new generation of fixed cutter bits has now become the standard for drilling in high interbedded formation as well as hard and abrasive rock formations in Oman. This paper discusses hard and heterogeneous rock drilling challenges and how the hard rock bit technology could help address the lacking conventional drill bit performance. The specialized implementation process and analysis of the technologies are highlighted. Detailed offset data and rock strength analysis are included to support the results achieved.

Access to develop new drill bit technologies are increasing the capabilities to improve performance in the most challenging directional applications, where the focus is to reduce any type of disfunctions that will be generated due to the interaction between the drill bit, drill string and formation compressive strength. A case study is presented to demonstrate the liability and consistency of this new technology. This paper discusses the sensing at the bit technology that has different capabilities that can be used to improve drilling performance, combining the new cutting structure in the drill bit that keeps in series the shearing and breaking actions generated by the new cutting elements, at the same time those actions are recorded by the drill bit sensor. The generated information is used to compare standard drill bits with modified designs where the advantages can be seen clearly, and at the same time new engineered technologies can be put in place to have further improvements in performance. In Kuwait, the 12 ¼" section is a challenging application in terms of directional requirements, rate of penetration and is mandatory to have the necessary stability to be able to increase the required drilling parameters that will end up with outstanding performances. A compressive engineering analysis of a customized drill bit and the implementation of the sensing at the bit data capture was used to understand the drilling parameters, drilling disfunctions and the interaction between the engineered cutting structure and the formations drilled. The data was correlated with available data from offset wells and helped to confirm the performances achieved. The detection of different disfunctions and the frequency generated for the added device was the key to understand the functionality of the tool. It showed that the new technology drill bit, in which a rolling crush-and-shear cone is incorporated to the center of a PDC bit, increases bit stability and mitigates lateral vibration while achieving outstanding performance.

A PDC design containing updated fracturing elements and utilizing in-bit sensing to optimize parameters can deliver improved ROP and drill a challenging heterogeneous section containing massive chert in one run compared to previously used PDC. The demonstration is supported by a real field case from an unconventional gas exploratory field project in Abu Dhabi. In this unconventional field, seven wells have been drilled using three bits on average to complete the 12 ¼″ section (tricone and PDC) where the presence of chert has resulted in additional trips due to bit life. The content of cherts are large, at approximately 2,000 ft thick, which is the reason why it was decided to think of a new customized PDC bit design and use it in well number seven. The plan is to prove that is possible to achieve one run to TD by fracturing cutter development and optimized drillers roadmap using in-bit sensing. The new unique PDC shaped cutter, with increased point surface area and thicker diamond table, makes the overall design more impact resistant and reduces vibrations while drilling. In bit sensing data is utilized to increase the efficiency in rock interaction through optimized parameters. It will be used in the ongoing exploratory project to demonstrate its advantage in terms of cost saving and rig time reduction. The study will compare the data with previously used bit and create a basement for the exploratory field in 12 ¼″ section. A strong hypothesis is that this bit will complete the well in this particular area and optimize drilling costs in development studies. Where such non-homogenous formations containing massive cherts can be crossed and have detrimental impact on the bit life, the novelty is to bring to the stage an enhanced combined PDC and parameter solution, which will be able to offer a different alternative by reducing torque, having healthier wells, and optimizing drilling cost in this unconventional field where drilling CAPEX reduction are paramount.

A new PDC Bit design containing fracturing and shearing elements which can deliver improved ROP in a single trip to drill a challenging heterogeneous section containing massive chert compared to previously used conventional hybrid or roller cone bit designs. The demonstration is supported by a real field case from an unconventional gas exploratory field project in Abu Dhabi. In this unconventional field, 6 wells have been drilled using 4 Bits on average to complete the 12 ¼″ section (Tricone and PDC) where the presence of chert has resulted in additional trips due to Bit life. The massive content of abrasive cherts is approximately 2,000 ft thick, reason why it was decided to think of a new customized PDC Bit design and use it in well # 7. Plan is to prove that is possible to introduce an alternative option to complete the section in one trip and stablish a comparison with previous wells where Hybrid Bits were used. The new unique PDC design features dual row cutters, new shaped cutters, advance elements to reduce vibration and sensing at the bit technology to increase the efficiency in rock interaction. It will be used in the ongoing exploratory project to demonstrate its advantage in terms of cost saving and rig time reduction. Reduction target at least 15% is anticipated while increasing the ROP and eliminating a trip across the chert formation. The study will compare the data with previously used Hybrid Bit and create a basement for the exploratory field in 12 ¼″ section. A strong hypothesis is that this bit will complete the well in this particular area and optimizing drilling cost in development studies. All the analysis, studies and design have been done and completed during Q2 and Q3 Where such non-homogenous formations containing massive abrasive cherts can be crossed and have detrimental impact on the bit life, the novelty is to bring to the stage a new PDC bit, which will be able to offer a different alternative by reducing torque, having healthier wells, and optimizing drilling cost in this unconventional field where drilling CAPEX reduction are paramount.