2014-08-202014-08-201993-08-17SILVA, Hamilton Pereira da. Aplicação de análise de séries temporais em perfis de poço. 1993. 102 f. Dissertação (Mestrado) - Universidade Federal do Pará, Centro de Geociências, Belém, 1993. Curso de Pós-Graduação em Geofísica.https://repositorio.ufpa.br/handle/2011/5444This thesis describes the application of time seris analysis to wireline logs. Through this technique it is possible to evaluate both their repeatability and vertical resolution, and determine the optimum sampling interval and acquisition speed for different logs. A comparison between three wells is also made, based on the same type of log. The sequence used, is to obtain data, in the same domain, for which the number of samples (N) does not exceed 2048. For these data the mean sample value and the algebraic polynomial are determined. The following were then applied, in order: cosine taper, high pass filter, Hanning window, the calculation of the coherence function, the phase spectra, and the signal to noise ratio of the power spectra for both the signal and the noise. For the coherence function, it was necessary to calculate the level of confidence for 50 necessary to determine the vertical resolution of some logs. The others were calculated to provide information concerning the position of the levels of coherence calculated. In relation to the phase spectra, its calculation suggests it is necessary to obtain additional information in respect of the processed logs, or in other words knowledge of any relative depth shifts made between the principal and repeat sections. The signal to noise ratio was calculated to investigate the possibility of evaluating the different types of logs by making a comparison with the coherence and the calculated power spectra. The power spectra of the signal and the noise were calculated to provide one additional parameter to evaluate the repeat section. In theory the power spectra of the signal and the noise of the repeat section should be equal to their respective spectra for the principal sections. The data used in this work were provided by PETROBRAS and originated in four boles of the Potiguar Basin. These are referred to as Holes A, B, C, and D. The evaluation of the repeatability between different types of logs indicates that, for Hole A, the microspherical log (MSFL) has better repeatability than the porosity log (CNL), and that this repeats better than the gamma ray log (GR). For the logs run in Hole D, a decrease in the speed at which the logs are run, from 550 m/hr to 275 m/hr, is advantageous only for the neutron porosity log. The velocity of 920 m/hr used in Hole C is totally inadequate for the resistivity logs (MSFL, ILD, and ILM). A decrease in the sampling interval from 0.2m to 0.0508m, for the gamma ray and neutron porosity logs, and to 0.0254m for the density log, gives good results when applied to Hole D. The calculation of vertical resolution indicates, that the neutron porosity is of superior quality when compared with the natural gamma ray in Hole A. In hole C the microspherical log (MSFL) has a vertical resolution of the same order as the natural gamma ray log (GR) in Hole B. This confirms the inappropriate speed for the logs acquired in Hole C. For Hole D, the calculation of vertical resolution indicates a superior quality for the high resolution density log when compared with the high resolution gamma ray log. The comparison between Holes A, B and D, uses the respective neutron porosity logs, confirming that the presence of noise, in general, is directly linked with the porosity of the formation - a higher porosity indicates more noise and consequently, a lower quality log is obtained. Analysis of phase spectra of each log indicates a depth shift exists between the principal and repeat sections for all the logs of Hole C. This could be confirmed through superposition of the sections.porAcesso AbertoPerfilagem geofísica de poçosAnálise de séries temporaisDissertaçãoCNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOFISICA::GEOFISICA APLICADA