The application of laser confocal method in microscopic oil analysis

The normal optical microscope image of fluorescence analysis is used as the traditional method to analyze remaining oil distribution, but it has limitations such as poor clarity, low resolution, unobvious color distinction between oil and water, unclear oil–water interface and cannot make quantitative research about the types and content of the remaining oil. With the improved fluorescence microscope and frozen slice of cores, the laser scanning confocal microscopy method (LSCM) for remaining oil analysis has the ability to determine clearer images, so it can clearly distinguish the oil–water interface, intuitively display the mineral form and microscopic remaining oil distribution. Based on this, the self-developed software can quantify the remaining oil content and total amount of oil and water. When the sample is representative and there are enough slices, the result can reflect remaining oil distribution of the selected oilfield area. With the help of fluorescence detecting technology and stratified scanning, LSCM can give the ratio of light and heavy oil in remaining oil, and quantitatively describe the distribution of light and heavy oil, and give the 2D and 3D distribution maps of oil and mineral and provide the feature of oil and water in rock pore to a more clear extent. Through 3D image reconstruction of scanned real sample, the porous media and oil distribution can reappear. In this paper, we introduce a new method, the LSCM, for analyzing remaining oil distribution. The comparison of this new method and the traditional method shows that the new method has advantages like clear image, consecutive scanning, image reconstruction, multiple labeling technique and quantitative analysis. This method was applied to an oilfield to study microscopic remaining distribution in different layers of the reservoir. By analyzing the experiment data, we discuss the remaining oil distribution after using different displacing agents, and the effects of different displacing agents on light and heavy components of oil. The reconstructed 3D image can provide useful guidelines and suggestions for the remaining oil production.