The Structure Analysis And Safety Evaluation For Ownhole Operation Hoist Ystem

By statistic, the derrick and peg are the two weak parts in the safe work of downhole operation hoist system. The most frequently employed method in engineering is to determine the load resisting capacity of derrick by the method of the linearity extrapolation from the measured data about stress, displacement and dynamic characteristic arrived from tests for derrick in oil field. But because the measured points can only be set at the limited danger positions of derrick at loading test and the tested load is greatly lower than the design load, it is difficult to get the comprehensive and logical evaluation result. In the past people only blindly evaluate the ground anchor peg by the former experience without any scientific method, so that there are quite a few accidents happened in fieldwork.Combining structure and measure analysis for derrick, this thesis put forward an evaluation method based on the model modification theory, which was capable of truly reflecting the mechanical performance of any part under different load and then carrying out the safety evaluation for derrick scientifically. In the structure analysis for derrick, firstly Algor FEAS was developed. The author established the computer numerical model to analyze the relation of the load resisting capacity of derrick and the mechanical parameters about displacement, stress, mode and stability, hi the measure analysis for derrick, based on the DASP analysis platform, mass parallel real-time Acquisition Analysis System having 16 channels was developed for dynamic signal of derrick, which was capable of satisfying the demand of dynamic measure for derricks in oilfield. According the two researches above, the author presented an evaluation theory of numerical model modification by processing initial defects equivalently. The computer numerical model of the ideal derrick structure was modified on basis of the measured data, so as to approach to the real structure of derrick in use, and then through computer loading simulation test, the load resisting capacity of the derrick was determined. Then the derricks were evaluated comprehensively by the remaining resistance state evaluation theory.Using instantaneous impulsion and the method of frequency conversion to get the conductance curve of ground anchor peg, this thesis firstly expressed the measure research on ground anchor peg of downhole operation hoist system. By using the signal collection equipment INV303/306 to get the information and calculating out the transfer function with the software DASP, the author got the dynamic rigidity and the resistive pull finally. The outcome can be used as reference data for the workers in oil field.