| The compensate device is an essential equipment necessary for exploration of oil and gas in deep-water,which could keep the weight on bit(WOB)by overcoming the heave movement caused by wind,waves,streams while running operations,avoiding equipment damage or even shutdown.Crown-Mounted Compensator(CMC)is one kind of drill string compensators,among which the Combined Active/Passive Crown-Mounted Compensator(CAPCMC)was wildly used in engineering practice due to its simple structure,automatic detection and intelligent control.Recent years,China's floating drilling platforms or ships have introduced the CAPCMC with highly cost,while researches carried out by domestic research institutes and universities were focus on gear rack type or compound cylinder type CMC.At present,the systematic design and analysis of CAPCMC is rarely reported,which was not conductive to master its core technology and was hindering the design of independent knowledge products and comprehensive development of deep-water oil or gas resources in China's south sea.Therefore,this thesis carried out researches about CAPCMC and the detailed contents and results are as follows:(1)Fuzzy comprehensive evaluation of CAPCMC was carried out.Based on the analysis of the product scheme and technical parameters of foreign CMC products,the evaluation index system of the system structure arrangement was established by using the analytic hierarchy process.Based on the theory of fuzzy mathematics,the fuzzy comprehensive evaluation of was carried out.The results show that the SAHC was better than PHC,and the CAPCMC was better than that compound cylinder type among SAHC;besides,the vertical arrangement of cylinder was better than inclined arrangement.(2)Structure of CAPCMC and its safety were analyzed.Through the force analysis and the establishment of the Simulink model,the alternating load of the key components such as the rocker mechanism and the water table under the compensation condition was solved.The finite element model of the compensator was established,and the safety analysis of the key components was carried out.The results show that the strength and stability of the key components meet the design requirements,and the key parts has no fatigue failure.(3)Vibration model of the drill string was studied.Based on structural characteristics of CAPCMC,the longitudinal vibration model of drill string under CAPCMC was established by using mechanical system dynamics theory.The stiffness and damping of each part in the model was calculated and the transfer function of the system was deduced.Then the control strategy was determined,which provides the basis for the calculation of the dynamic load in the drill string and intelligent control of the device.(4)Compensate efficiency of CAPCMC was analyzed.Combined with China's sea conditions,designed and calculated the rocker mechanism,hydraulic system.Established the AMEsim model of the CAPCMC and the theoretical compensation effect of the device was simulated.Results show that the maximum compensation error of the device was within 153mm,and the compensate efficiency was 95.98%.The variation of WOB reaches 10.47185kN,which has an error of 12.2 percent with theoretical value,ranging between ±7.13 percent.Under the two vibrate models,the dynamic trend of drill string vibration was basically the same,but the former fluctuates more violently.(5)Experimental study of CAPCMC was carried out.The similarity principle was used to design the proportional test device,and the test under the sine wave excitation was carried out.The results showed that under the compensation load 12.85kN,stroke 340mm and compensation period 12s,the max crown block displacement was 12.22mm and the compensation efficiency of the test device reached 92.81%;There was only 0.14 seconds lag between the compensator cylinder and the wave cylinder. |
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