Upstream by Levonne Louie

Author:Levonne Louie
Language: eng
Format: epub
ISBN: 978-0-9938037-3-4
Publisher: Citrine Press
Published: 2015-05-28T16:00:00+00:00

It is always hoped that things go smoothly when drilling, but that is not always the case. Sometimes a foreign object is found in the hole; this is called a fish. A fish could be a chunk of metal (perhaps the result of a lost tool dropped into the hole), a piece of drill bit that has broken off, or a piece of drill string that has separated. The company then has to start a “fishing” operation to try to remove the object so that drilling can continue. Remember that all of this activity, including the drilling, is done within a relatively small-diameter hole (much smaller than the hole you would drill for a fence post). Some of the fishing methods are a magnet to retrieve smaller pieces of iron; a spear, which tries to hold the fish by friction; milling, which grinds away on the pipe to get an effective contact point; and jars to loosen the fish. Many drilling budgets have been overshot due to the need for multiple fishing trips.

Sometimes a well needs to be directionally drilled or “whipstocked” in order for the bottomhole to reach the ultimate formation target. This can be built into the initial drilling program, particularly if the surface location above the target is inaccessible, such as when there is a large lake, river, or roadway. However, sometimes the well needs to be whipstocked while drilling if a large object is encountered that cannot be drilled out by the drill bit. A wedge-shaped device is placed in the hole at a predetermined depth, which causes the drill string to deviate in the desired direction. Directional survey tools are lowered into the hole to measure the deviation and determine its direction. Remember that this might all be done in a hole that has a diameter of ten to twenty-five centimetres (four to ten inches), potentially hundreds or thousands of metres below the surface of the land.

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