| For the purpose of enhancing oil recovery from reservoirs under primary depletion, this thesis proposes a new borehole sound source based on an external-driven flextensional radiator, which utilizes both the low-frequency high-power characteristic of giant magnetostrictive actuator and advantages of flextensional transducer in terms of compactness and ability of radiating sound of high power and low frequency. The main contribution includes:1. Based on the seepage model of multi-phase medium, the propagation of sound in reservoirs medium is studied, the system requirement and main design parameters of the sound source is determined;2. To fulfill the requirement of installation space and operation strength on size and prestrain of the active material and/or device, the structure of the external-driven flextensional radiator is designed, whose vibration characteristics further determines the performance specification of vibration source;3. The giant magnetostrictive material (GMM) is selected to construct giant magnetostrictive actuator (GMA) based on detailed analysis of active material characteristics; Furthermore, after the determination of optimum parameters set and structure of the GMM rod, related study is conducted on prestrain setup, electrical/magnetic design, cooling method and mechanical transfer;4. Using the electric-mechanic-acoustic model of the system constructed based on appropriate simplification and boundary condition, the key parameters to the system's dynamic performance is analyzed and simulated;5. Utilizing the experimental platform constructed and Labview? virtual machine software, the performance of the sound generator prototype system is studied against the simulation results.6. These work lays the foundations for the further research of new low-frequency high-power borehole sound generator, and serves as an important reference for both the industrial application of GMM and development of low-frequency high-power soundgenerator.
|
PDF Full Text Request