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Directions: Present your perspective on one of the issues below, using relevant reasons and/or examples to support your views. “The function of science is to reassure; the purpose of art is to upset. Therein lies the value of each.”
文章词汇表达丰富，高级词汇积累做的也很棒；作者句法基本功不错，可适当增加从句的使用；全文结构较为严谨。
ARMA 17-284 A Study on Casing Stress During Multi-stage Hydro-fracturing Operation for Horizontal Shale Wells ABSTRACT: Multi-stage hydro-fracturing technique has become a very effective means to develop shale gas reservoirs. In the meantime , for poor cementing quality, variations of temperature and pressure during the hydro-fracturing operation are likely to induce casing failure that threaten the set well integrity. Based on the completion and fracturing operation data, this paper established a finite element model of CCF (casing-cement-formation) considering poor cementing quality, fracturing pressure and downhole temperature change, in contributing to the occurrence of casing failure mechanisms. The research results indicate: 1) For the poor cementing quality, the maximum Mises stress of casing increases and later decreases with the increase of the cement channel angle. 2) With the addition to the temperature, if the angle of cement channel is less than 30°，the maximum stress of the casing increases with the increase of the temperature change, while the stress decreasing when the angle is more than 30°. 3) For the different fracturing pressures, when the angle of cement channel and the temperature difference are small, the maximum Mises stress of the casing firstly decreases and then increases with the increase of the fracturing pressure. In addition, when the angle is small and the temperature change is large, or the angle is large, the maximum Mises stress increases with the increase of pressure. The results above can provide theoretical support for shale gas fracturing and improve the development of shale gas reservoirs.
