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Structural Engineering and Mechanics   Volume 69, Number 5, March10 2019, pages 537-545
DOI: https://doi.org/10.12989/sem.2019.69.5.537
 
Numerical modelling of bottom-hole rock in underbalanced drilling using thermo-poroelastoplasticity model
Weiji Liu, Yunlai Zhou, Xiaohua Zhu, Xiannan Meng, Mei Liu and Magd Abdel Wahab

 
Abstract     [Buy Article]
    Stress analysis of bottom-hole rock has to be considered with much care to further understand rock fragmentation mechanism and high penetration rate. This original study establishes a fully coupled simulation model and explores the effects of overburden pressure, horizontal in-situ stresses, drilling mud pressure, pore pressure and temperature on the stress distribution in bottom-hole rock. The research finds that in air drilling, as the well depth increases, the more easily the bottom-hole rock is to be broken. Moreover, the mud pressure has a great effect on the bottom-hole rock. The bigger the mud pressure is, the more difficult to break the bottom-hole rock is. Furthermore, the maximum principal stress of the bottom-hole increases as the mud pressure, well depth and temperature difference increase. The bottom-hole rock can be divided into three main regions according to the stress state, namely a) three directions tensile area, b) two directions compression areas and c) three directions compression area, which are classified as a) easy, b) normal and c) hard, respectively, for the corresponding fragmentation degree of difficulty. The main contribution of this paper is that it presents for the first time a thorough study of the effect of related factors, including stress distribution and temperature, on the bottom-hole rock fracture rather than the well wall, using a thermo-poroelastoplasticity model.
 
Key Words
    thermo-poroelastoplasticity; bottom-hole rock stress; fully coupled analysis; finite element analysis; fragmentation mechanism
 
Address
Weiji Liu:
1) School of Mechatronic Engineering, Southwest Petroleum University, 610500, Chengdu, China
2) Department of Civil and Environmental Engineering, National University of Singapore, 117576, Singapore
Yunlai Zhou and Xiannan Meng: Department of Civil and Environmental Engineering, National University of Singapore, 117576, Singapore
Xiaohua Zhu: School of Mechatronic Engineering, Southwest Petroleum University, 610500, Chengdu, China
Mei Liu: Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, Shenzhen University, Shenzhen 518060, China
Magd Abdel Wahab:
1) Division of Computational Mechanics, Ton Duc Thang University, Ho Chi Minh City, Vietnam
2) Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam
3) Soete Laboratory, Faculty of Engineering and Architecture, Ghent University, Technologiepark Zwijnaarde 903, Zwijnaarde B-9052, Belgium
 

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