Horizontal Directional Drilling
Horizontal directional drilling is a type of directional drilling, or slant drilling, used to reach natural resources such as oil and natural gas. It’s an important method to help people exploit the natural resources beneath the ground.
Horizontal directional drilling, in fact directional drilling, wasn’t possible until people realized that wells aren’t only vertical. It took a long time for this to come to people’s attention. In 1920 lawsuits over drilling reaching over property lines brought this to oil industry’s attention. Many well surveys were conducted. In fact new tools for surveying had to be designed to survey while a well was being drilled.
It’s easy to measure how much a well is shifted from straight vertical. This is an important step in horizontal directional drilling. It’s accomplished with a pendulum. But another measurement is needed. That is the direction of the well (or oil reservoir) from the vertical shaft. This was first done by measuring magnetic fields, but the metal drilling equipment could influence the fields. Later gyroscopic compasses were used. These were originally designed for aeronautical navigation.
Horizontal directional drilling required a number of other advances in drilling as well. Vertical drilling had provided experience of techniques that would drill crooked, away from the vertical. This was avoided in traditional drilling, but was used for this new type of drilling. Directional drillers eventually learned techniques to bring drilling back towards the vertical. These were both important for steering in directional drilling.
In the 1970’s a major advance made horizontal directional drilling more of a reality. Drills were designed that were mostly stationary, but had rotating drill bits driven by circulating mud down the drill shaft (or drill string.) Now direction could be changed on the fly simply by adding bent pipes at the top.
Horizontal directional drilling needed another thing. Some information about which way the drill was headed. This was MWD, or measurement while drilling. This refers to information about the direction of the drill bit.
Today there are tools to steer the bit in three dimensions for horizontal directional drilling. They cost a great deal so aren’t in wide use. But they make it possible to automate the drilling process. The price of these will rapidly decrease because larger companies have taken up the research of making cheaper versions that can actually be implemented.
So the quest for oil continues. Now, more and more, oil companies can get the oil wherever it is. That’s the whole point of horizontal directional drilling.
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