Comparing Polycrystalline Diamond Compact Cutter Stress to its Structural Integrity when Drilling Interbedded Formations
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2025-02-25 |
| Journal | SPE/IADC International Drilling Conference and Exhibition |
| Authors | Mason M. Cherry, Paul Pastusek, Gregory S. Payette, Rahul R. Bijai, Ole Gjertsen |
| Institutions | ExxonMobil (United States) |
Abstract
Section titled âAbstractâAbstract Measurement of the strength of materials and calculation of applied and residual stress are fundamental to mechanical engineering design and the continuous improvement of mechanical systems and processes. This paper uses these fundamental principles to establish an enhanced engineering framework and workflow for drill bit design, application, and drilling process improvements. It also highlights improvements in modeling and experimental data collection that are needed to continue to improve the drilling process. Transient rock-cutting models are used to calculate the contact stress on the face of polycrystalline diamond compact (PDC) cutters on drill bits. This is applied to finite element models (FEM) of the cutters to calculate the maximum principal stresses. This process can be used to study the effects of bit profile, blade count, and cutter density on the maximum principal stress while drilling at different penetration per revolution (PPR) in various formation hardnesses. These stresses are compared with a forensics study to find instances of tangential overload-induced fractures to determine the maximum PPR a given PDC bit design can withstand for a given rock strength and application. When drilling homogeneous or interbedded formations, it is necessary to control the PDC cutter stress below its structural limit. One method to do this is to create roadmaps of the acceptable parameters (particularly PPR) to reduce unwanted tool failures and trips. Roadmap creation is often experimental and fine-tuned with field development. With the outlined workflow, digital data from offset wells and forensics observations can be used to calculate stress for specific designs and applications. Along with estimations of a particular cutterâs tangentially loaded structural integrity, this can be used to create much more accurate roadmaps of the drilling systemâs capabilities. Computation of the dynamic stress required to fail cutters is a major improvement for the industry. It makes the design process and parameter recommendations based on well-established engineering principles. This process is continuously improved as the experimental and modeling capabilities are upgraded. Specific guidance on maximum allowable PPR as a function of confined compressive rock strength can now be given to reduce uncertainties in roadmap creation. Bit designers can study the effects of bit profile, blade count, cutter density, and depth of cut (DOC) elements on the peak cutter stress while drilling interbedded formations, and bit selection of existing designs is now put on a firm engineering basis. This is a significant improvement over the maximum weight on bit (WOB) recommendations used today.
Tech Support
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Section titled âOriginal SourceâReferences
Section titled âReferencesâ- 2023 - Direct Linear Equation Solver