英和和英

出典:『Wikipedia』 (2011/02/20 23:21 UTC 版)

英語による解説

引用

A Deviation survey[1], more generally known in the oil industry as simply a 'survey', is the measurement of a borehole's departure from the vertical, measured in degrees (°).

• When a well plan dictates the drilling of a straight borehole, surveys are periodically taken to ensure that it will hit its target and also to ensure that it does not trespass underneath different property lines. These surveys can be taken fairly simply with a mechanical drift recorder more commonly known as a Totco or Totco barrel (named after the company that perfected the device). This device is run inside the drill string attached to a wire on a wireline unit, down to the bottom of the drill pipe where the device (which is simply an inverted pendulum with a timer that punches a pin-hole onto a round paper tab delineated with concentric circles indicating increments of degrees) measures the angle of the hole and then is pulled back out to visually inspect to determine the angle. There are versions of this device that actually take a picture on film and are often used in situations where the azimuth (direction) needs to be determined also.