Mechanical Analysis And Optimization Design Of Y422-114 Retrievable Plug Slip Fluke

The unbalanced contradiction of storing and producing is obvious after DaQing oilfield has enteredthe especial high hydrous period. The poor-thin oil layer to be exploited has so low seepage rate that itreduces the recovery ratio. The fracturing reconstruction has undoubtedly turned out to be one of the mosteffective strimulation approaches for producing from low permeability reservoirs. Directed to problemslike oil layer being dispersive and interlayer span being too big in the course of poor-thin reservoirreconstruction, plug fracturing technique has become the very prevalent technique. It is applied in thecasing which dimension is greater than 5 and half an inch abroad and which dimension is equal to 5 andhalf an inch in Daqing Oilfield. The structure performance of bridge plug should be higer than the sameproduct abroad because many layers need to be fractured and there is limit space in casing. But inapplication, Daqing Oilfield have been confronted with problems like unstable plug setting, slip flukeliable to be damaged and casing badly injured and so on. The main reason for these problems is that thestructural design of slip fluke is not as reasonable, so with the producing depth being unceasinglyincreased, the property of bridge plug in withstanding pressure and temperature needs to be upgraded, andbetter performance of slip fluke is also in request. Consequently, mechanical analysis and optimizationdesign on the retrievable plug slip fluke is in urgent need for stress distribution law study on slip fluke andcasing, and for optimizing retrievable plug slip structure. This paper integrates basic theoretical study withexperimental study and applied technique study, thus a new method on optimizing retrievable bridge plughas taken shape, which is theoretically significant for perfecting retrievable bridge plug design andaccelerating allied discipline development.This paper involves multiple principles, for instance, production mechanics, solid mechanics,computational mechanics and so on, and it deals with multiple coupling problems of material nonlinearity,contact nonlinearity and transient dynamics. Mechanical model and finite element model of retrievablebridge plug are set up in this paper based on mechanical analysis. Conservation equation and transientdynamics balance equation of retrievable bridge plug are established by using momentum theorem anddynamics principle in the scope of finite distortion. And the relation between strain increment and stress onelastic-plasticity is established on the basis of strain increment. Meanwhile, non-embed measurementequation of contact interface is derived from the structural parameters and movement conditions ofretrievable bridge plug;and the weak form of equilibrium equation is also obtained according to variationprinciple and updated Lagrange format. All together, augmented Lagrange multiplier method is adopted toset up interfacial momentum equation of retrievable plug slip and casing. Finally, by applyingNewton-Raphson method, increment load procedure, augmented Lagrange multiplier method, andNewmark method on the basis of finite element method, the stress and deformation behavior of retrievablebridge plug is calculated under the condition of multiple coupling.By stress analysis and experimental research, the stress and snap-in force distribution rule of slipfluke and casing have been found out, and it serves as the basis for slip fluke optimization. In the course ofslip fluke optimization, we have determined in the first place the change law of target variables due to thechanging of each relative parameter on slip fluke. Afterwards, the corresponding results of each structuralparameter, for example, the equivalent friction coefficient, the maximum Von Mises stress, contact radialpressure and the like of slip and casing have been compared. In this way, the better structural parametershave been sorted out. In conclusion, the optimum structural parameter combination of the slip fluke hasbeen confirmed by combining the chosen structural parameters. This method provides new clue andmethod for optimizing retrievable bridge plug and similar equipments.Although the function of numerical calculation method grows to be stronger, and the computationprecision is also reliable for engineering solution, the numerical calculation is not enough for setting up themodel and defining the boundary condition, leading to the necessity of verification by experimental stressanalysis. In order to validate the correctness of results, photoelasticity experiment has been carried out tosimulate the bridge plug component model. The stress distribution law of slip and casing in computingmodel proves to be rather consistent with that in experimental model by comparing results from bothmodels. It shows that the numerical methods and the boundary conditions on finite element are correct.The optimization method put forward in this paper is dedicated to solve the new problems emergingpresently in Daqing Oilfield. The conclusion drawn lays a theoretical foundation for retrievable bridgeplug design, which guarantees normal operations, prolonged duty cycle, increased crude output andreduced production cost, and has realistic significance and practical value for improving oilfield economicbenefits.