Introduction
Bimonthly, started in 1957
Administrator
Shanxi Provincial Education Department
Sponsor
Taiyuan University of Technology
Publisher
Ed. Office of Journal of TYUT
Editor-in-Chief
SUN Hongbin
ISSN: 1007-9432
CN: 14-1220/N
Administrator
Shanxi Provincial Education Department
Sponsor
Taiyuan University of Technology
Publisher
Ed. Office of Journal of TYUT
Editor-in-Chief
SUN Hongbin
ISSN: 1007-9432
CN: 14-1220/N
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Study on Borehole Deformation and Damage in Hot Dry Rock Based on Viscoelastic Theory
DOI:
10.16355/j.cnki.issn1007-9432tyut.2019.06.017
Received:
Accepted:
abstract:
The instability of wellbore surrounding rock is a universal technical problem during the deep drilling in hot dry rock geothermal. Aiming at the geological structure that geothermal geology exploration hole revealed in Gonghe Basin, Qinghai province, we derived the discriminant formula of damage and failure of wellbore surrounding rock under three-dimensional stress on the basis of viscoelastic theory. Using finite element software COMSOL to carry out numerical experiments, we investigated the deformation and damage of wellbore with structural layers under different influencing factors, such as the temperature, maximum horizontal stress, and wellbore diameter. The results show that, structural surface is the key to the failure and instability of the surrounding rock of dry hot rock wellbore, and it is also the key to the stability control of the surrounding rock of dry hot rock wellbore; temperature is the main factor causing wellbore deformation in hot dry rock, and it has a significant impact on the damage and destruction of the surrounding rock of the wellbore containing structural plane, of which 300 ℃ is a temperature threshold; temperature and wellbore diameter are the main factors that cause damage and destruction of the surrounding rock of dry hot rock wellbore, and the surrounding rock of the wellbore in structure surface is more likely to be damaged than that in granite layer.
Keywords:
hot dry rock;wellbore deformation;wellbore damage;viscoelastic theory;numerical experimentation;stability of surrounding rock