Going deep under water oil drilling- the basics Source: Expro
It’ s over six months now since the first oil was pumped from the Western Region’ s Jubilee Field and oil is constantly in the news. Oilcity magazine takes a closer look at this important resource.
Way back in 1859 Edwin Drake built the first oil rig in Pennsylvania, USA. By today’ s standards it was very shallow- a mere 21 metres( 69.5 feet)- and produced between eight and 10 barrels of crude oil per day.| Fig. 7 | Within a few short months oil fields were springing up across the northwestern Pennsylvania | Fig. 8 | countryside and the petroleum industry was born.
Going deep under water oil drilling- the basics Source: Expro
How Odoes petroleum form? ver millennia, as plants and animals die, they fall to the bottom of the sea or are washed by rivers, floods and run-off from the land into basins. Here they are covered in layers of sand and silt and, over a long period of time, these layers built up to thousands of metres, causing huge pressure and temperature. The residue left from the tiny plants and animals is subjected to a chemical reaction breaking them down into compounds made of hydrogen and carbon atoms commonly known as hydrocarbons which saturate the large areas of rock underneath. | Fig. 3 |
How Wdo we find oil? hile some oil is relatively easily accessible either on land or in shallow water other deposits lie deep under the ocean floor, as is the case in the Jubilee Field. Modern oil geologists employ a variety of methods to find oil. They examine surface rocks and terrain, with the additional help of satellite images. They can use sensitive gravity meters to measure tiny changes in the earth’ s gravitational field that could indicate flowing oil, as well as sensitive magnetometers to measure tiny changes in the earth’ s magnetic field caused by flowing oil. They can detect hydrocarbons using sensitive electronic noses called sniffers. Finally, and most commonly, they use seismology, creating shock waves that pass through hidden rock layers and interpreting the waves that are reflected back to the surface. The shock waves travel beneath the surface of the Earth and are reflected back by the various rock layers. The reflections travel at different speeds depending upon the type or density of rock layers through which they must pass. Sensitive microphones or vibration detectors detect the reflections of the shock waves- hydrophones over water, seismometers over land. Seismologists interpret the readings for signs of oil and gas traps. Once geologists find a prospective oil strike, they mark the location using GPS coordinates on land or by marker buoys on water. | Fig. 6 |
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