Oil Wells — Pages of History

The earliest known oil wells were drilled in China in 347 BC. They had depths of up to about 800 feet (240 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.

Petroleum was distilled by the Persian alchemist Muham- mad ibn Zakaroya RBzi (Rhazes) in the 9th century, producing chemicals such as kerosene which was mainly used for kero- sene lamps, Arab and Persian chemists also distilled crude oil in order to produce flammable products for military purposes» Through Islamic Spain, distillation became available in Westem Europe by the 12th century.

Some sources claim that from the 9th century, oil fields were exploited in the area around modern Baku, Azerbaijan, to produce naphtha for the petroleum industry These fields were described by Marco Polo in the 13th century, who characterized the output of those oil wells as hundreds of shiploads. When Marco Polo in 1264 visited the Azerbaijani city of Baku, on the shores of the Caspian Sea, he saw oil being collected from seeps. He wrote that “on the confines toward Geirgine there is a fountain from which oil springs in great abundance, inasmuch as a hundred shiploads might be taken from it at one time”.

Shallow pits were dug at the Baku seeps in ancient times to facilitate collecting oil, and hand-dug holes up to 35 meters (115 ft) deep were in use by 1594. These holes were essentially oil wells. Apparently 116 of these wells in 1830 produced 3,840 metric tons (about 28,000 barrels) of oil. In 1849, Rus- sian engineer F.N.Semyenov used a cable tool to drill an oil well on the Apsheron Peninsula, ten years before Colonel Drake’s famous well in Pennsylvania. Also, offshore drilling started up at Baku at Bibi-Eibat field near the end of the 19th century, about the same time that the "first” offshore oil well was drilled in 1896 at Summerland field on the California Coast.

The earliest oil wells were drilled percussively by hamme- ring a cable tool into the earth. Soon after, cable tools were rep- laced with rotary drilling, which could drill boreholes to much greater depths and in less time. The recorddepth Kola Bore- hole used nonrotary mud motor drilling to achieve a depth of over 12,000 meters (38,000 ft). Until the 1970s, most oil wells were

vertical (although different lithology and mechanical imper- fections cause most wells to deviate at least slightly from true vertical). However, modern directional drilling technologies allow for strongly deviated wells which can, given sufficient depth and with the proper tools, actually become horizontal. This is of great value as the reservoir rocks which contain hyd- rocarbons are usually horizontal, or sub-horizontal; a hori- zontal wellbore placed in a production zone has more surface area in the production zone than a vertical well, resulting in a higher production rate. The use of deviated and horizontal drilling has also made it possible to reach reservoirs several ki- lometers or miles away from the drilling location (extended reach drilling), allowing for the production of hydrocarbons located below locations that are either difficult to place a drilling rig on, environmentally sensitive, or populated.