| For reservoir development processes that do not require real-time data reading or frequent adjustment to downhole flow,cableless electronic tools can be used to measure formation parameters,which improve system safety and reduce oil production costs.However,cableless electronic tools need to be replenished after working for a period of time in the downhole.Contactless power transfer technology is a possible technical method.Due to the special environment of high temperature,high pressure and oil-water medium in oil and gas wells,the model of downhole contactless power transfer system is established to study the influence of metal protection cylinders and oil-water medium on contactless power transfer,which is the key technical problem to the study of downhole contactless power transfer technology.The research contents and main research work of this paper are as follows:1.For the characteristics of the contactless power transfer system for downhole electronic tools,a scheme of downhole contactless power transfer system with mutual spiral structure is proposed by comparing and analyzing the commonly methods of contactless power transfer.2.Considering the electromagnetic characteristics of the downhole oil-water medium,the transmitting coil protection cylinder and the receiving coil protection cylinder,an improved solenoid model,improved mutual inductance model and loss model for the downhole contactless power transfer system are established,and a series-series resonance compensation network is proposed to improve the efficiency of power transfer.3.Based on the established model of downhole contactless power transfer system,a simulation platform is built to study the influence of main structural parameters on the transfer performance of the system.The optimal mechanical structure parameters are proposed.A protype of downhole contactless power trarnsfer is designed and fabricated,which is tested and verified experimentally.The experiment results verify the correctness of the improved solenoid model,the improved mutual inductance model and the loss model,as well as the rationality of working parameters and structural parameters.The research work and the results obtained in this paper are of guiding significance for designing the engineering prototype and optimizing the working parameters of the downhole contactless power transfer system.The established model can also be referenced in contactless power transfer system with similar working environment,such as underwater vehicles and offshore drilling tools. |
