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Shengli Oilfield:SEM analysis technology helps shale oil exploration and development

Zoom in… Zoom in… Zoom in again, and the object in front of the lens becomes clear.

This is not a large film made by a director, but a”large film” made by geological researchers of Sinopec Shengli Oilfield. Under the electron microscope lens of 100000 times, the internal structure of the originally flat rock sample is displayed at a glance. The white is carbonate rock and the black is mudstone. There are many pores and cracks in the middle, as fine as hair. The oil that geologists think about day and night is here.

Taking out a 1 cm square sample from the equipment, Wang Weiqing, manager of the stratigraphic paleontology Laboratory of Shengli Oilfield Exploration and Development Research Institute, began to uncover the secret:”although it is only as big as the tip of your little thumb, it is a vast ‘Universe’ after tens of thousands of times magnification by scanning electron microscope.”

The image just seen is only the area of dozens of square microns on this sample.

In 2021, the exploration and development of shale oil in Shengli Oilfield made a breakthrough, with 458 million tons of predicted oil geological reserves reported in the first batch, which first benefited from the breakthrough of geological researchers in basic research.

The diameter of a hair is generally about 0.03 mm. The shale oil of Shengli Oilfield is contained in this hairy or even small hole and fissure. Researchers found the”dwelling place” of shale oil from pores thinner than hair.

It’s easy to say, but it’s really not easy to do. Yu jiejie, the scanning electron microscope staff of the stratigraphic paleontology laboratory, said that this part seen in the sample is like looking for a table tennis ball in a football field. To find this”table tennis ball”, we must first make qualified samples.

Scanning electron microscope has very high requirements for rock samples. Shale coring is very difficult. There are many thin and fragile layers. It is necessary to master the strength and skills of manual processing of samples. The shale is made into small pieces of 1cm square by hand, and then polished repeatedly with sandpaper until the section is smooth under the ordinary microscope, and then polished with argon ion polishing instrument. This process may have to be repeated dozens of times until the mirror effect is achieved, and then it can be observed by scanning electron microscope.

Scanning electron microscope can focus on nano scale, which can directly reflect the reservoir space, composition characteristics and mineral structure of shale oil.

A typical picture, like a capillary diagram, shows the pores of shale oil, which usually needs to be selected from hundreds or even thousands of pictures. This requires researchers to quickly lock the target.

Through tackling key technical problems, optimizing the test parameter process, innovating the work flow, focusing on improving the quality of electron microscope analysis, the researchers in the formation Office of exploration and Development Research Institute have broken through the technical difficulties such as low vacuum observation of oil-bearing samples, argon ion polishing high-precision imaging and fine identification of backscatter sample composition, mastered the electron microscope analysis method of unconventional samples, and provided key information for the evaluation of unconventional reservoirs in the oilfield, Boosting the exploration breakthrough of shale oil and tight oil in the oilfield.

Nano scale electron microscope images become the”golden key” to open the micro world of unconventional reservoirs. With excellent analysis technology and analysis quality, the exploration and Development Research Institute has formulated the industry standard for electron microscope analysis of shale oil, becoming the industry benchmark and leader.

In addition to shale oil, SEM analysis technology also plays a”sharp tool” role in research work in the fields of how to identify good reservoirs in tight sandstone, how to avoid oil and gas reservoir damage and transform low-yield reservoirs.

It is reported that the exploration and Development Research Institute will develop a more accurate focused ion beam scanning electron microscope analysis technology to simulate and find the flow and path of shale oil. At that time, the glass marbles on the football field will no longer be difficult to find, and there will be new answers to the problems such as how the crude oil in the unconventional reservoir flows out of the formation.