A New Developed Method Based On Crude Oil Synchronous Fluorescence Spectrum Analysis For Oil Logging

Fluorescence techniques, either based on emission spectrum, synchronous fluorescence spectrum (SFS) or three-dimensional (3D) fluorescence spectrum have been widely used in medical, biological and chemical analysis. Fluorescence techniques are also among the most important analytic methods in petroleum logging, but still some drawbacks such as the limited concentration range and the lower accuracy. In this thesis, some experimental investigations have been made, with various crude oil samples, in the purpose of establishing a new suitable method for oil logging.Firstly, as variable-angle synchronous fluorescence spectroscopy (VASFS) is a newly developed method of fluorescence analysis, the simulation of variable-angle synchronous fluorescence spectrum of crude oil samples has been done by a series of program, which is described in chapter 4. Based on three-dimensional fluorescence spectroscopy and synchronous fluorescence spectroscopy, VASFS could be an efficient tool for the analysis of mixtures of fluorescent compounds in solution that have overlapping fluorescence bands. The VASF spectra can be obtained either from special-designed synchronous spectrometry or by intercepting from the excitation-emission matrix. Based on two-dimensional cubic convolution interpolation, this thesis compiles a serial of programs on MATLAB which can emulated synchronous fluorescence spectra visually and expediently by executing this program, a variable-angle synchronous scanning path can be chosen at the will of the investigator and the spectrum can be acquired promptly and automatically using interpolation. This program provides an emulation method in obtaining and analyzingvariable-angle synchronous fluorescence spectrum and also provides conveniences to the fluorescence investigators to choose an optimum path to get synchronous spectra.In chapter 5, 31 crude oil samples from 20 different bore-fields in concentration range from 10-4 g/L to 10g/L have been investigated with different spectral approaches. It was shown that, compared with conventional emission spectrum based technique used in oil logging, the 3D fluorescence technique can provide much more information in fluorescence analysis of crude oil samples but at the price of time consuming. While the SFS spectrum of a crude oil sample, taken under the emission and exciting wavelength synchronous scan with AX = 40 nm, can represent the main characteristic of the 3D spectrum provided, with even better spectral qualities. All the results suggest that SFS technique is a more suitable approach in crude oil sample analysis than the other two and has great potential to be developed as a new quantitative analysis method in petroleum logging.Based on the SFS spectral analysis of crude oil samples, in chapter 6, a new method for concentration determination of crude oil sample has been established. The SFS spectra of the crude oil sample show that the shapes of the spectra change a lot in company with the change of the sample concentration. Concerning the change of the peak height and position, a new method for concentration determination of crude oil sample using three-dimensional synchronous fluorescence is introduced in this chapter. It has been shown from experiments that, in concentration range from 10-4g/L to1.0g/L, these methods have lower relative deviation under 3% compared with the traditional fluorescence techniques. All the results suggest that the newly developed methods may become a useful means in petroleum logging.In the last part of the thesis, a general discussion of the work and some suggests of possible future developments have been given in Chapter 7.