This paper describes a novel polycrystalline-diamond-compact (PDC) -bit concept based on insights into PDC-bit cutting mechanism and rock behavior during drilling. The design comprises a hydraulic layout that optimizes bit cleaning and cuttings removal in soft and sticky formations. Significant improvements in performance have been achieved in Cretaceous and Triassic formations drilled with water-based muds.

The drilling industry has substantially improved performance based on knowledge from physics-based, statistical, and empirical models of components and systems. However, most models and source code have been recreated multiple times, which requires significant effort and energy with little additional benefit or step-wise improvements. The authors propose that it is time to form a coalition of industry and academic leaders to support an open source effort for drilling, to encourage the reuse of continuously improving models and coding efforts. The vision for this guiding coalition is to 1) set up a repository for source code, data, benchmarks, and documentation, 2) encourage good coding practices, 3) review and comment on the models and data submitted, 4) test, use and improve the code, 5) propose and collect anonymized real data, 6) attract talent and support to the effort, and 7) mentor those getting started. Those interested to add their time and talent to the cause may publish their results through peer-reviewed literature. Several online meetings are planned to create this coalition, establish a charter, and layout the guiding principles. Multiple support avenues are proposed to sustain the effort such as: annual user group meetings, create a SPE Technical Section, and initiating a Joint Industry Program (JIP). The Open Porous Media Initiative is just one example of how this could be organized and maintained. As a starting point, this paper reviews existing published drilling models and highlights the similarities and differences for commonly used drillstring hydraulics, dynamics, directional, and bit-rock interaction models. The key requirements for re-usability of the models and code are: 1) The model itself must be available as open source, well documented with the objective and expected outcomes, include commented code, and shared in a publicly available repository which can be updated, 2) A user's guide must include how to run the core software, how to extend software capabilities, i.e., plug in new features or elements, 3) Include a "theory" manual to explain the fundamental principles, the base equations, any assumptions, and the known limitations, 4) Data examples and formatting requirements to cover a diversity of drilling operations, and 5) Test cases to benchmark the performance and output of different proposed models. In May 2018 at "The 4th International Colloquium on Non-linear dynamics and control of deep drilling systems," the keynote question was, "Is it time to start using open source models?" The answer is "yes". Modeling the drilling process is done to help drill a round, ledge free hole, without patterns, with minimum vibration, minimum unplanned dog legs, that reaches all geological targets, in one run per section, and in the least time possible. An open source repository for drilling will speed up the rate of learning and automation efforts to achieve this goal throughout the entire well execution workflow, including planning, BHA design, real-time operations, and post well analysis.

This paper describes the progress in upgrading the IADC dull code system. The IADC code is a compact, text-based way to describe the bit condition. The current PDC code was created in 1987 (Clark et.al. 1987) and revised in 1992 (Brandon et. al. 1992) along with roller cone bits (McGehee et. al. 1992) and more recently proposed for other cutting tools (Ulvedal et. al. 2011). It has held up well, however with the introduction of automated systems, machine learning, evolving products, and requirement for more detailed analysis, there is a substantial need to improve the system. The key objectives are to: rework the IADC dull grading system to better support continuous improvement workflow, root cause analysis, reduce the subjectivity inherent in the current system, support human and emerging automated bit dull grading systems, and create a best practice for a digital storage format including searchable metadata. Over 160 volunteer subject matter experts have been divided into four workgroups to focus on: 1) a qualitative classification scheme for PDC cutters, drill bits, and tools, 2) BHAs, motors, RSS tools, and stabilizers, 3) case studies, and 4) data definition, storage, retrieval, and exchange. The bit and BHA sub groups are defining a standard set of examples and descriptions for each damage classification. They are gathering and labeling a set of photo examples for human training and machine learning. Once complete, the proposed codes will be sent out for an end user trial of the new system. Updated codes and best practices instructions will be created based on this feedback and submitted to the IADC for publication. The Case Study group is collecting and documenting case studies for continuous improvement and forensics analysis to provide examples for the industry based on the input of a large group of industry and academic experts. Much of this work is presented in a companion paper. (Watson et. al. 2022) Last, the required metadata needed to support this effort has been documented and examples of best practice storage methods for image and metadata are offered to the industry for voluntary adoption. This is the scope of workgroup 4. This is the first major revision of the IADC dull code system in 35 years. It is taking into account changes in the data needed and available for continuous improvement, with a plan for future developments in photometrics, AI classification, and storage technologies. It is also the first joint industry attempt to document case studies and forensics workflow best practices.

This paper describes the design and application of a new bit/steerable system combination. The design of the new bit, featuring a block set type of segment arrangement, will be discussed. The performance of the bit/steerable system combination will be presented and analyzed. Traditionally, impregnated diamond bits were reserved for the harder and more abrasive formations, which normally cause severe damage to conventional PDC bits. In the North Sea, instantaneous penetration rates as high as 150 ft/hr have been recorded with this bit design on turbine drive. Generally, the shallower and softer formations encountered in directional work have been drilled quite satisfactorily with soft formation roller cone and PDC bits used in conjunction with bent housing positive displacement motors. However, this technology has exhibited serious limitations in the harder and/or abrasive sequences, particularly when poor homogeneity is present. Addressing these problems focused on creating full-system compatibility of all the components involved. A new IADC Class M84 1 impregnated diamond bit and a 6 5/8" turbodrill dressed with a 0.75 bent housing successfully completed the build-up phase from 45 to 90 and the 521-meter horizontal section in a well drilled offshore The Netherlands. The section, which historically required as many as 12 bits, was completed with only two IADC Type M84 1 impregnated diamond bits at an average penetration rate of 5 m/hr, as opposed to an average penetration rate of 1.7 m/hr for the best available offset. The latest well was drilled 20 days faster than the best available offset, resulting in savings of approximately $2 million US. The new system not only resulted in faster drilling and fewer trips, but also provided more tangible benefits associated with a higher quality wellbore. Introduction Two wells were drilled horizontally offshore The Netherlands with completion in the Lower Graben sandstones that are normally encountered around 3000 m (TVD). Fig. 1 illustrates the lithological characteristics of a representative well in the block. The Lower Graben is preceded by soft clays that exhibit sonic log values from 100 sec/ft to as high as 135 sec/ft. These clays are interrupted by hard and abrasive sandstones (around 60 sec/ft). As detailed in Fig. 2, the calculated unconfined compressive strength ranges between 9000 psi to 22000 psi. The first well drilled (designated as Well A) represents the offset. On that well, the operator used a combination of roller cone, TSP and PDC bits on positive displacement motors (PDM) to drill the 8 1/2" production interval. On Well A, a total of 12 bits were used to drill the section. In nine of those runs, the bits had to be pulled prematurely, because of problems in meeting the wellpath directional requirements. Besides the directional control problems, the performance of the PDC bits, in terms of life and rate of penetration (ROP), was equally discouraging. Heretofore, it was widely accepted that steerability was primarily a function of the bit. However, an optimum steerable system must be considered as a single unit with the bit as an integral component. P. 571