GRE写作Issue模拟题:The Importance of Science and Art

作者词汇基础扎实，拼写也很棒；文中从句的使用的有点少了；文中基本没有过渡词和衔接词，建议增加衔接词汇的积累。

By using the finite element method to build a three dimension simulation model considering the cement channeling (Yuan Z. et al. 2012), the casing had highest von Mises stress at the hole angle of 90°, and the cement tended to fail in tension. The casing eccentricity tended to reduce cement shear stress and tensile stress, but increase cement compressive stress. The cement had the highest compressive failure probability in casing eccentricity condition. Recently, some author pointed out (King, G.E. and Valencia, R.L., 2016) that almost all of the failures of fracture and re-fracture treatments and separated into a few major categories: 1) Design, 2) Drilling issues, 3) Mechanical failures, 4) Application failures, 5) Cement sheath failure, 6) Production or Completion damage, 7) Geologic forces, 8) Unknowns. Even though, the author considered that no one-size-fits-all check list of damage potential or risk could be offered to accurately address all damage mechanical. Therefore, specific type of collapse must be discussed. In this paper, the actual casing damage of shale gas plays in Sichuan is investigated, and the cementing quality of fracturing section is statistically analyzed. The results show that there is a great correlation between poor cementing quality and casing damage. This is the same with other scholars' conclusions (De Andrade, J. et al, 2014, Peng, Q. et al, 2015, Yu H. et al. 2015, Fan, M. et al. 2016). The main manifestation of poor quality of wells is the cement ring channeling.