西南石油大学学报(自然科学版)

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Study on the Erosion Law of Gas with Cuttings Against Tool Joint

Ming Xin1, Lian Zhanghua1, Lin Tiejun1, Chen Xinhai1, Zheng Jianxiang1,2   

  1. 1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu,Sichuan 610500,China
    2. Cementing Bureau,East China Company,SINOPEC,Yangzhou,Jiangsu 225101,China
  • Online:2014-06-01 Published:2014-06-01

Abstract:

Abstract:Severe erosion against the tool joint always leads to rapid failure of the drill pipe in gas drilling. In order to understand
the mechanism of this problem,we established the CFD model of the erosion of gas with cuttings against the drill pipe with
18° slope based on two phase fluid theory. According to this model,systematical studies have been made about the effects of
different eccentricity,injection volume of gas,and drill rate on the erosion rate against the tool joint,and on the trajectory and
distribution of cuttings and gas velocity. The results show that:at the first,when the drill pipe is in the cylindrical center of
borehole,the distribution of erosion rate is symmetrical,the erosion against tool joint is more severe than against the drill pipes’
body and the maximum erosion rate is near the windward slope top. Meanwhile,the quantitative relationship between cuttings’
mass flow rate,gas velocity and the maximum erosion rate has been worked out. And then,the maximum erosion rate against
the drill pipe and the erosion rate against the tool joint on one side of the wide flowpath are more severe when the drill pipe is
eccentric. The maximum erosion is transferred from the joint to the drill pipes’ body when the drill pipe eccentricity from 30%
to 70%. The maximum erosion rate against the tool joint increased with the increase of gas velocity when drill pipe eccentricity
was at 0~30%,50%~70% and 80%~90%,respectively. But the maximum erosion rate against the tool joint decreased with the
decrease of cutting concentration in wide flowpath when drill pipe eccentricity was at 30%~50% and 70%~80%,respectively.
All the results from these studies provide the theoretical support for preventing failure of the tool joint and were applied in some
oilfields.

Key words: Key words:cuttings, two-phase flow, erosion, tool joint, eccentricity