1. Match the proportions of chemical elements:

Carbon	0.5-6%
Hydrogen	0.1-1.5%
Nitrogen	10-14%
Oxygen	0.1-2%
Sulfur	83-87%
Metals	<1000 ppm

2. Tell about the chemical composition of crude oil and its usage. History of petroleum industry

Read and translate the text:

Historical references trace oil use in ancient Egypt, Mesopotamia, and Persia through various reports and sacred documents. Oil in general has been used since early human history to keep fires ablaze, and also for warfare. Its importance in the world economy evolved slowly. Wood and coal were used for heating and cooking, while whale oil was used for lighting. Whale oil however, burned to produce a black, smelly, thick residue known as tar or rock oil. The earliest known oil wells were drilled in China in 347 CE or earlier. They had depths of up to about 800 feet (244 m) and were drilled using bits attached to bamboo poles. The oil was burned to evaporate brine and produce salt. By the 10th century, extensive bamboo pipelines connected oil wells with salt springs. The ancient records of China and Japan are said to contain many allusions to the use of natural gas for lighting and heating. Petroleum was known as burning water in Japan in the 7th century.

The petroleum industry was established in the 8th century, when the streets of Baghdad were paved with tar, derived from petroleum through destructive distillation. In the 9th century, oil fields were exploited in the area around modern Baku, Azerbaijan, to produce naphtha. These fields were described by al-Masudi in the 10th century, and by Marco Polo in the 13th century, who described the output of those oil wells as hundreds of shiploads. Petroleum was distilled by Persian chemist al-Razi in the 9th century, producing chemicals such as kerosene in the alembic, which he used to invent kerosene lamps for use in the oil lamp industry.

oil field in California, 1938.

The Industrial Revolution generated an increasing need for energy which was fuelled mainly by coal. However, it was discovered that kerosene could be extracted from crude oil and used as a light and heating fuel. Petroleum was in great demand and by the twentieth century had become the most valuable commodity traded on the world market. Even until the mid-1950s, coal was still the world's foremost fuel, but oil quickly took over as the introduction of the internal combustion engine provided a demand that has largely sustained the industry to this day.

Today petroleum's worth as a portable, dense energy source powering the vast majority of vehicles and as the base of many industrial chemicals makes it one of the world's most important commodities. The top three oil producing countries are Saudi Arabia, Russia, and the United States. OPEC nations still account for two-thirds of the world's oil reserves as about 80% of the world's readily accessible reserves are located in the Middle East with 62.5% coming from the Arab 5: Saudi Arabia, UAE, Iraq, Qatar and Kuwait. The world at large consumes 30 billion barrels (4.8 km³) of oil per year, and the top oil consumers largely consist of developed nations.

The production, distribution, refining, and retailing of petroleum taken as a whole represent the single largest industry in terms of dollar value on earth. The petroleum industry can be divided into two broad groups: "upstream" producers (exploration, development and production of crude oil or natural gas) and "downstream" transporters (tanker, Pipeline transport, refiners, retailers, and consumers). Oil companies are generally categorized as "supermajors" (BP, Chevron, ExxonMobil, ConocoPhillips, Shell and Total S.A.), "majors," and "independents" or "jobbers." Most upstream work in the oil field or on an oil well is contracted out to drilling contractors and oil field service companies.