Development and Application of Casing Hydraulic Lifting Tool

In view of the shortcomings existed in traditional wellbore preparation,a casing hydraulic lifting tool was developed,and a casing recovery process was designed.By means of theoretical analysis,the lifting capacity of the tool was calculated,the strength of hydraulic booster cylinder,anchoring mechanism and piston rod under working conditions were checked; the stress effect of anchoring mechanism on the casing inwall was studied; the theoretical and technological research on different application scenarios of the tool were carried out; and simultaneously,field application was conducted for the tool in the Bohai Oilfield.The research and field application results show that the casing hydraulic lifting tool has lifting capacity of more than 3 000 kN,each component of the tool can withstand the stress load produced by lifting operation,and does not cause damage to the inner wall of the casing; the tool is applicable to various application scenarios such as inner casing recovery,riser recovery and multilayer casing recovery.At the time of recovering inner casing,the tool can recover the cemented casing with the length of 2.7～13.0 m(taking the commonly used ø244.48 mm casing for example); at the time of recovering multilayer casing below the mud line,the tool can recover different types of conductor/casing assembly with the length of more than 20.0 m.The combined drilling tool of cutter + casing trip spear + casing hydraulic lifting tool can save 2 trips of tripping,saving 71.3% construction period than the conventional milling recovery process.The conclusions provide technical support for the large-scale application of this tool offshore.