A rapid evaluation method for oil saturation of shale oil wellsite

Abstract

The invention provides a quick evaluation method for the oil saturation of shale oil at the well site. The invention is aimed at the core just out of the barrel at the drilling site, but it is not limited to the site, and can also be realized in the laboratory. Firstly, the one-dimensional low-field high-frequency NMR measurement of samples in three states of massive ground original, massive self-absorbed saturated water, and frozen crushed manganese-saturated samples were sequentially carried out to obtain the total signal of original oil-water on the ground including the substrate (solid organic matter), saturated Water-state oil-water total signal and oil signal; quickly wash oil, wash salt, and dry the samples after three NMR measurements, and then perform one-dimensional NMR measurements one by one to obtain the base signal of each sample; The total porosity of the shale and the surface oil saturation can be obtained by combining the NMR measurement signals; finally, the shale oil saturation under the formation conditions can be obtained through the formation saturation recovery algorithm. Through four one-dimensional low-field high-frequency nuclear magnetic resonance measurements of the core on site, parameters such as shale oil properties and oiliness can be quickly and accurately obtained.

Description

technical field [0001] The invention relates to a method for quickly evaluating the oil saturation of shale oil at the well site. By performing four one-dimensional nuclear magnetic resonance measurements on the core just out of the barrel, the total porosity and oil saturation of shale oil can be obtained quickly and accurately, which belongs to rock Oil saturation testing field. Background technique [0002] In recent years, as fine-grained sedimentary continental shale oil wells have successively achieved high yields, shale oil has become a more realistic exploration breakthrough target and resource replacement field for major oil fields in China. The degree of exploration of shale oil is relatively low, and its heterogeneity and concealment are stronger. It requires a large number of drilling and coring, and carries out core analysis experiments such as geochemistry, lithology, physical properties, and oiliness to establish the "iron pillar" of shale oil. . Due to the ...

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Problems solved by technology

Due to the tight lithology and poor porosity and permeability of shale, laboratory experiments are costly and time-consuming, especially for oil-bearing analysis. From the core out of the barrel to the laboratory, the fluid loss is serious, and the experimental results are quite different from the real situation of the formation. Big

For sandstone, through three one-dimensional low-field high-frequency NMR measurements on massive cores, reservoir evaluation parameters such as rock porosity and saturation can be obtained quickly and non-destructively; but for organic-rich shale, its solid The NMR signal of organic matter cannot be ignored, and the permeability of shale is extremely poor. Generally, it is difficult for manganese chloride solution with a concentration of 15mg / L to penetrate into the core quickly, and the water signal cannot be completely eliminated. evaluation work

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