To ensure safe drilling with narrow pressure margins in deepwater, a new deepwater dual-gradient drilling method based on downhole separation was designed. A laboratory experiment was conducted to verify the effective...To ensure safe drilling with narrow pressure margins in deepwater, a new deepwater dual-gradient drilling method based on downhole separation was designed. A laboratory experiment was conducted to verify the effectiveness of downhole separation and the feasibility of realizing dual-gradient in wellbore. The calculation of dynamic wellbore pressure during drilling was conducted. Then, an optimization model for drilling parameters was established for this drilling method, including separator position, separation efficiency, injection volume fraction, density of drilling fluid, wellhead back pressure and displacement. The optimization of drilling parameters under different control parameters and different narrow safe pressure margins is analyzed by case study. The optimization results indicate that the wellbore pressure profile can be optimized to adapt to the narrow pressure margins and achieve greater drilling depth. By using the optimization model, a smaller bottom-hole pressure difference can be obtained, which can increase the rate of penetration(ROP) and protect reservoirs. The dynamic wellbore pressure has been kept within safe pressure margins during optimization process, effectively avoiding the complicated underground situations caused by improper wellbore pressure.展开更多
文章通过匹配的2000~2006年间工业企业数据库和海关数据库,参考Bernard et al.(2011,2014)对多产品进口企业的贸易二元边际分解方法,考察了融资约束对企业进口行为的影响,同时考察了金融发展对于融资约束与进口二元边际相互关系的影响...文章通过匹配的2000~2006年间工业企业数据库和海关数据库,参考Bernard et al.(2011,2014)对多产品进口企业的贸易二元边际分解方法,考察了融资约束对企业进口行为的影响,同时考察了金融发展对于融资约束与进口二元边际相互关系的影响效应。研究发现:(1)融资约束显著制约了我国企业进口总额增加、扩展边际扩张和集约边际深化;(2)融资约束的抑制作用对于私营企业最为强烈,其次是外资企业,而对国有企业无显著性影响;(3)研究期间的金融发展并没有发挥既定的效果。展开更多
基金Supported by the Key Program of National Natural Science Foundation of China(51734010)
文摘To ensure safe drilling with narrow pressure margins in deepwater, a new deepwater dual-gradient drilling method based on downhole separation was designed. A laboratory experiment was conducted to verify the effectiveness of downhole separation and the feasibility of realizing dual-gradient in wellbore. The calculation of dynamic wellbore pressure during drilling was conducted. Then, an optimization model for drilling parameters was established for this drilling method, including separator position, separation efficiency, injection volume fraction, density of drilling fluid, wellhead back pressure and displacement. The optimization of drilling parameters under different control parameters and different narrow safe pressure margins is analyzed by case study. The optimization results indicate that the wellbore pressure profile can be optimized to adapt to the narrow pressure margins and achieve greater drilling depth. By using the optimization model, a smaller bottom-hole pressure difference can be obtained, which can increase the rate of penetration(ROP) and protect reservoirs. The dynamic wellbore pressure has been kept within safe pressure margins during optimization process, effectively avoiding the complicated underground situations caused by improper wellbore pressure.
文摘文章通过匹配的2000~2006年间工业企业数据库和海关数据库,参考Bernard et al.(2011,2014)对多产品进口企业的贸易二元边际分解方法,考察了融资约束对企业进口行为的影响,同时考察了金融发展对于融资约束与进口二元边际相互关系的影响效应。研究发现:(1)融资约束显著制约了我国企业进口总额增加、扩展边际扩张和集约边际深化;(2)融资约束的抑制作用对于私营企业最为强烈,其次是外资企业,而对国有企业无显著性影响;(3)研究期间的金融发展并没有发挥既定的效果。
