Crude oil contains wax and has been a headache for the petroleum industry since humans began extracting oil. Accumulation of wax in oil pipelines is a major problem. According to incomplete statistics in the late 1980s, the cost of removing wax from oil wells in the US alone was as high as 6 million dollars per year. Therefore, wax has been a long-term topic of discussion for petroleum technology workers.

Before oil fields are developed, crude oil is buried underground and exists mainly as a single-phase liquid under high-temperature and high-pressure conditions. Wax is completely dissolved in the crude oil. During the development of oil fields, when crude oil flows from the oil reservoir to the bottom of the well and is lifted to the surface along the wellbore, the wax separates from the crude oil due to a reduction in pressure and temperature, and forms crystal particles, which accumulate and adhere to the wall of the pipeline under certain conditions, known as wax deposition.

Scientists have investigated the world’s discovered oil fields and found an interesting phenomenon. High-wax crude oil is rarely produced in the world’s richest oil-producing areas, such as the Middle East, the Gulf of Mexico, Mexico, and Texas in the United States. However, specific regions of all continents on earth, including the third series of oil fields in China, have a high wax content in their crude oil.