Three-dimensional discrete element method simulation of core disking

Research Article - Solid Earth Sciences
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Abstract

The phenomenon of core disking is commonly seen in deep drilling of highly stressed regions in the Earth’s crust. Given its close relationship with the in situ stress state, the presence and features of core disking can be used to interpret the stresses when traditional in situ stress measuring techniques are not available. The core disking process was simulated in this paper using the three-dimensional discrete element method software PFC3D (particle flow code). In particular, PFC3D is used to examine the evolution of fracture initiation, propagation and coalescence associated with core disking under various stress states. In this paper, four unresolved problems concerning core disking are investigated with a series of numerical simulations. These simulations also provide some verification of existing results by other researchers: (1) Core disking occurs when the maximum principal stress is about 6.5 times the tensile strength. (2) For most stress situations, core disking occurs from the outer surface, except for the thrust faulting stress regime, where the fractures were found to initiate from the inner part. (3) The anisotropy of the two horizontal principal stresses has an effect on the core disking morphology. (4) The thickness of core disk has a positive relationship with radial stress and a negative relationship with axial stresses.

Keywords

Core disking Discrete element method Numerical simulation Axial stress Radial stress 

Notes

Acknowledgements

The support received from Key Program of Natural Science Foundation of China (51774020) and Beijing Training Project for the Leading Talent in S & T (Z151100000315014) is gratefully acknowledged.

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Copyright information

© Institute of Geophysics, Polish Academy of Sciences & Polish Academy of Sciences 2018

Authors and Affiliations

  1. 1.University of Science and Technology BeijingBeijingChina
  2. 2.Key Laboratory of Ministry for Efficient Mining and Safety of Metal MinesUniversity of Science and Technology BeijingBeijingChina
  3. 3.Kunming University of Science and TechnologyKunmingChina
  4. 4.University of ArizonaTucsonUSA

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