Study On Electrochemical Potential Theories And Experiments

At the present, the study and settling how to compute the formation water salinity and Qv are the important research topic of well logging technology. There is a quantitative relation between electrochemical potential (natural potential and induced polarization potential) and the formation water salinity, Qv . As a self-developing and characteristic well logging method, polarity logging method combines with characteristics as continental deposit, using flood development for oil fields and reservoirs containing high water in our country. This method is powerful tool for reservoirs evaluation in freshwater areas. So it is necessary to do experimental study on the electrochemical character for rocks.In order to expand the application of the polarity log, based on the electrochemical potential experimental, this article mainly study on the spectrum inversion of induced polarization relaxation time and the frequency-domain induced polarization method.Electrochemical potential mainly includes spontaneous potential and induced polarization potential. It has quantitative relationship with formation water saturation and formation cation exchange capacity. So how to calculate formation water saturation and formation cation exchange capacity Qv is the important research topics of well logging technology. At the same time, it is necessary to study on the induced polarization effect property of rocks.This study is from the experimental point, and study on membrane potential and induced polarization characteristics of rocks under different mineralization saturation. Analyse various influencing factors of polarization potential and polarizability of the core. Firstly, we inverse the NMR data with the conventional simultaneous iterative reconstruction algorism and the damped least square method, and compare the results with the measured T2 spectrum. We obtain that the damped least square method has the better inversion. Secondly, we analyse the relationship between the number, the saturation of solution and oil saturation of cores and the induced polarization relaxation time spectrum. We compare the T2 spectrum with the polarization spectrum of the same rock, and obtain different distribution history on reflecting pore throats. This lays the foundation for the application of polarization spectrum.We compare the advantages and disadvantages of the time-domain induced polarization log with those of the frequency-domain induced polarization log. We transform the induced polarization potential curves in time domain into that in frequency domain. We obtain the amplitude and phase curves of the rock in frequency domain, and the amplitude curve and the phase curve has good correlation. Analyze the relationships between step, solution salinity, core oil saturation, the cation exchange capacity, and so on, and them in frequency domain. According to these relationships, we can draw that the frequency-domain induced polarization method overcomes the disadvantages of the time-domain induced polarization method, and it can also reflect the electrochemical characteristics of rocks. Furthermore, this experiment can also provide the criterion of the frequency selected for the frequency domain study of formation rocks. So the frequency-domain induced polarization has a broader space for development.By these study, We enhance understanding of the electrochemical potential witch is rich of more logging information, provide powerful technical support for electrochemical log.