Study On Theoretical Analysis And Technology Of Workover Sticking Hydraulic Lift

Sticking accidents caused by increasing casing damage and interpay segmentationoccurred frequently at the late development stage of oilfield. Sticking leads to degressivedownhole operation rate, incremental cost, sustained single-well downtime and even wellabandoned. Sticking hydrodynamic lift theory and technology was studied for minimizingthe.economic losses and fast processing of sticking lift.Following achievements were obtained:(1) By analyzing stuck freeing data of Shengtuoblock, best window in stuck freeing and technical abandon window were establishedaccording to time period of successful stuck freeing. Conclusions have vast importance to theprocess methods selection and rapid stuck freeing.(2) Methods for stuck freeing schemedesign were established by analyzing quantization parameters of production and operation.Workover sticking types are analyzed by combination of reservoir characteristics, actual wellconditions, well structure and string structure. The results has guide to optimize schemedesigning.(3) Based on sticking mechanics analysis, models for highly deviated well werebuilt. Models considered the dynamic effect of friction and axial force caused by lateralpressure during string uplifting. It supplies new methods for calculation of three-dimensionalaxial force and free point. In contrast with conventional theory, models in the paper has highercalculating precision and supply reliable assurance for scheme designing.(4) Hydraulic stuckfreeing processes such as hydraulic force amplifier, reversing stuck freeing and internaltubing-cutting were developed by combination of hydraulic principle and mechanical design.The principle of driving piston were used for designing hydraulic force amplifier device. Thedevice integrates two-stage anchoring, hydraulic force amplifier and anchor releasingfunctions. Comparing with conventional process, effective power of the device can work atfree point directly. It improves the success rate and reliability significantly. Based onhydraulic motors increasing torsion principles, hydraulic reversing stuck freeing string wasdesigned. The device integrated flap anchoring, dropping buckle compensation and increasingtorque by slowdown. It amplifies torque of hydraulic motors using specific tool and reversed sticking with right lateral thread tube or drill pipe. The usage of reversing tube or drill pipe isreduced. Internal tubing-cutting device derives torque from small diameter hydraulic motorand integrates hydraulic anchor, hydraulic upending and automatic reposition. The device cancut tube from within. It is environmental and safe compared with collecting energy cuttingand chemical cutting.The good effectiveness of hydraulic sticking lift window design and technology had beendemonstrated in field application. It had the advantage of operability and safety. Higherefficiency, success rate, lower labor intensity and green construction are all achieved, which issignificant for improving construction efficiency and economic benefits.