Design And Analysis Electrical Logging Models Using Finite Element Method

Human beings have made a higher request for detectivity of the well logging instrument with the rapid development of geophysical exploration and the well logging technology. Now the well logging instrument development mainly suffer from the following several difficulties: firstly, the structure of the instrument is more complex and the fore-end of which have more fine structures. Secondly, the stratum environments become more complicated with the emergence of the directional wells, inclined wells, horizontal wells, and the large displacement wells. Finally, with the secondary development and a shortage of oil resources, we have a higher demand for the detecting precision and detectivity of the instruments. In order to make up above several deficiencies, in this paper, some complex models were constructed using the finite element method(FEM) and domain decomposition method(DDM), meanwhile, multi-size physical models were constructed and then were solved out using domain decomposition method.A sensor probe based on cylinder capacitance was put forward, and it is used for measuring the electrical parameters of oil-base mud while drilling. To cover the measurement range of resistivity ? ?1000 ~ 1000000??m and permittivity 1 ~ 80r? ?, the operating frequency of the sensor probe was tested and the structure was optimizated. To obtain ideal test results, the experiental prototypes were processed and measured finally.In view of the problems of the core electric parameter measurement, a feasible design scheme is proposed by us in this thesis. The current will get together and flow across the rock through increasing shielding electrode around the traditional plate, so that it will break through underground complex environments. The working principles and modes of above models were given finally after a series of investigations and analyses.Dielectric logging technology is a vital complement of the electromagnetic wave logging, which is mainly used to determine the water saturation, and judge the information of oil and water flooded layer and so on. The development of dielectric scanner logging instruments provides reliable date sources for dielectric logging. In this paper, the principles of dielectric logging were expounded, and then the response characteristic curves were gave after investigating in more detail for the dielectric logging instrument. In this paper, the vertical resolution, investigation depth of this instrument, and other important parameters were analysed. This provides a foundation for instrument design.