scholarly journals Research on borehole stability of shale based on seepage-stress-damage coupling model

2013 ◽  
Vol 8 (27) ◽  
pp. 74-82 ◽  
Author(s):  
Xiaofeng Ran ◽  
Yuezhi Wang ◽  
Shanpo Jia
Keyword(s):  
Coupling Model ◽  
Borehole Stability ◽  
Stress Damage

scholarly journals A chemo-mechanical coupling model of deviated borehole stability in hard brittle shale

2014 ◽  
Vol 41 (6) ◽  
pp. 817-823 ◽  
Author(s):  
Hang WEN ◽  
Mian CHEN ◽  
Yan JIN ◽  
Kai WANG ◽  
Yang XIA ◽  
...  
Keyword(s):  
Coupling Model ◽  
Borehole Stability ◽  
Mechanical Coupling

scholarly journals Electromechanical-Mode Coupling Model and Failure Prediction of CFRP under Three-Point Bending

Electronics ◽  
2021 ◽  
Vol 10 (16) ◽  
pp. 2007
Author(s):  
Ronghua Zhang ◽  
Lifu Zhang ◽  
Hongying Fang ◽  
Wuliang Yin
Keyword(s):  
Carbon Fiber ◽  
Electromechanical Coupling ◽  
Three Dimensional ◽  
Failure Prediction ◽  
Coupling Model ◽  
Polymer Materials ◽  
Three Point Bending ◽  
Conductivity Change ◽  
Electromagnetic Methods ◽  
Stress Damage

Carbon fiber reinforced polymer materials (CFRP) cause CFRP to bend or fail when subjected to external loads or impacts. In the case of static three-point bending, using the conductive properties of the carbon fiber inside the CFRP, the overall damage detection and failure prediction can be carried out by electromagnetic methods. The eddy current coil is used to realize real-time monitoring of damage, and the measured voltage value can be mapped to obtain the load of the sample. This paper conducts theoretical analysis and experimental verification, and obtains the relationship between CFRP stress damage and spatial conductivity change, and proposes a CFRP electromechanical coupling model under quasistatic three-point bending. Combined with the theory of electrically ineffective length, the CFRP three-point bending electromechanical coupling model was revised. Experimental results prove that the revised model can describe the load-conductivity change trend of three-dimensional braided CFRP more accurately, which provides a theoretical basis for monitoring the structural health of CFRP through electromagnetic methods.

scholarly journals Borehole enlargement rate as a measure of borehole instability in hydrate reservoir and its relationship with drilling mud density

2021 ◽  
Vol 11 (3) ◽  
pp. 1185-1198
Author(s):  
Qingchao Li ◽  
Lingling Liu ◽  
Baohai Yu ◽  
Linian Guo ◽  
Sheng Shi ◽  
...  
Keyword(s):  
Natural Gas ◽  
Drilling Fluid ◽  
Coupling Model ◽  
Fluid Density ◽  
Drilling Mud ◽  
Borehole Stability ◽  
Hydrate Dissociation ◽  
Hydrate Reservoir ◽  
Fluid Seepage ◽  
Model Fluid

AbstractBorehole collapse will pose a threat to the safety of equipment and personnel during drilling operation. In this paper, a finite element multi-field coupling model for investigating borehole collapse in hydrate reservoir was developed. In this model, fluid seepage, heat transfer, hydrate dissociation and borehole deformation are all considered. Based on which, effects of drilling fluid density on both of hydrate dissociation and borehole collapse are investigated. The investigation results show that disturbance of drilling fluid invasion to hydrate reservoir will lead to hydrate dissociation around wellbore, and dissociation range narrows obviously with the increase in drilling fluid density. When the relative fluid density is 0.98, natural gas hydrates in reservoir with a width of about 16.65 cm around wellbore dissociate completely. However, dissociation range of natural gas hydrate has decreased to 12.08 cm when the relative fluid density is 1.10. Moreover, hydrate dissociation around wellbore caused by drilling fluid invasion may lead to borehole collapse, and borehole collapse can be significantly restrained with the increase in relative fluid density. Borehole enlargement rate is 33.67% when the relative fluid density is 0.98, but nearly no collapse area displays around wellbore when the relative fluid density increases to 1.12. In addition, investigation herein can provide an idea for designing drilling fluid density in hydrate reservoir when different allowable borehole enlargement rate is considered. The minimum fluid density designed for avoiding disastrous borehole collapse increases nonlinearly when higher requirements for borehole stability are proposed.

Stress–damage–flow coupling model and its application to pressure relief coal bed methane in deep coal seam

2011 ◽  
Vol 86 (4) ◽  
pp. 357-366 ◽  
Author(s):  
T.H. Yang ◽  
T. Xu ◽  
H.Y. Liu ◽  
C.A. Tang ◽  
B.M. Shi ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coupling Model ◽  
Coal Bed ◽  
Coal Bed Methane ◽  
Pressure Relief ◽  
Flow Coupling ◽  
Stress Damage

Physical exercise protects dynamic balance and motor coordination of rats treated with vincristine

2020 ◽  
Vol 19 (5) ◽  
pp. 336
Author(s):  
Luiza Minato Sagrillo ◽  
Viviane Nogueira De Zorzi ◽  
Luiz Fernando Freire Royes ◽  
Michele Rechia Fighera ◽  
Beatriz Da Silva Rosa Bonadiman ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Locomotor Activity ◽  
Physical Exercise ◽  
Motor Coordination ◽  
Dynamic Balance ◽  
Exercise Group ◽  
Adult Rats ◽  
The Central Nervous System ◽  
Stress Damage ◽  
Training Protocol

Physical exercise has been shown to be an important modulator of the antioxidant system and neuroprotective in several diseases and treatments that affect the central nervous system. In this sense, the present study aimed to evaluate the effect of physical exercise in dynamic balance, motor coordination, exploratory locomotor activity and in the oxidative and immunological balance of rats treated with vincristine (VCR). For that, 40 adult rats were divided into two groups: exercise group (6 weeks of swimming, 1h/day, 5 days/week, with overload of 5% of body weight) and sedentary group. After training, rats were treated with 0.5 mg/kg of vincristine sulfate for two weeks or with the same dose of 0.9% NaCl. The behavioral tests were conducted 1 and 7 days after each dose of VCR. On day 15 we carried out the biochemical analyzes of the cerebellum. The physical exercise was able to protect against the loss of dynamic balance and motor coordination and, had effect per se in the exploratory locomotor activity, and neutralize oxidative stress, damage DNA and immune damage caused by VCR up to 15 days after the end of the training protocol. In conclusion, we observed that previous physical training protects of the damage motor induced by vincristine.Key-words: exercise, oxidative stress, neuroprotection, cerebellum.

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