Special Oil & Gas Reservoirs ›› 2022, Vol. 29 ›› Issue (4): 149-155.DOI: 10.3969/j.issn.1006-6535.2022.04.021

• Drilling & Production Engineering • Previous Articles     Next Articles

Numerical Simulation of Rock Breaking by Triangular Prismatic Cutter in Conglomerate Formation Based on Discrete Element Method

Liu Xiaoao1, Zou Deyong1, Wang Qing2, Liu Hongshan3, Huang Yong1, Chen Yahui4   

  1. 1. China University of Petroleum (East China), Qingdao, Shandong 266580, China;
    2. CNPC Engineering Technology R&D Company Limited, Beijing 102206, China;
    3. PetroChina Qinghai Oilfield Company, Haixi, Qinghai 816499, China;
    4. Sinopec Chongqing Shale Gas Co., Ltd., Chongqing 408400, China
  • Received:2021-10-21 Revised:2022-06-30 Online:2022-08-25 Published:2023-01-09

Abstract: Due to its strong resistance to impact and wear, triangular prismatic cutter grants PDC bit with better rock-breaking efficiency and longer service life when it is used in conglomerate formation, but the rock-breaking mechanism and rock-breaking effect in conglomerate formation are not clear, resulting in a lack of theoretical support for the design of the PDC bit with triangular prismatic cutter which is used in the conglomerate formation. A numerical simulation model of conglomerate breaking by triangular prismatic cutter was established based on the discrete element method to study the conglomerate breaking mode and process under the condition of different bonding strength between conglomerate and cement matrix, and to analyze the effect of diameter and back rake angle of triangular prismatic cutter on the cutting force of triangular prismatic cutter and the propagation of rock cracks during conglomerate breaking. The results showed that the conglomerate was directly stripped at a bonding strength difference of more than 70 MPa, while it was directly broken at a bonding strength difference of less than 40 MPa; the conglomerate cutting and breaking efficiency was maximized at a triangular prismatic cutter diameter of 16 mm and a back rake angle of 15 ° for both bonding strength differences. The study is theoretically significant for the design of PDC bit with triangular prismatic cutter.

Key words: triangular prismatic cutter, PDC bit, conglomerate formation, rock breaking mechanism, cutter diameter, back rake angle, discrete element method

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