Almost all deep wells are now drilled by the turning pipe and bit, which are called a rotary rig. But sometimes you can see an old-fashioned cable rig at work. It makes hole with a bit that pounds its way down into earth and rock. A cable raises the bit, and then lets it fall down with a bang that chips away a hole. On both kinds of rig, the hole is cleaned out with water. The water turns the rock dust into mud, which is then pumped out.
The cable rig idea is about two thousand years old! That long ago Chinese drillers made water wells, salt wells and even oil wells. The picture shows what one of these ancient rigs was like.
Look first of all at the long board attached to the rope that goes up over a roller and down into the well. Then look at the platform behind the board. Men jumped from this platform down onto the board. That jerked on the rope and pulled the drilling bit up in the well hole. When a man jumped off the board, the bit fell down and chipped away some rock. Round and round a whole crew of men raced, jumping onto the board and climbing back onto the platform as fast as they could. Still it took a long time to drill a well—sometimes as long as ten years.
Now look at the big wheel turned by a bull at the right. This wheel lifted the pipe made of hollow bamboo that you see at the left. The pipe was actually a bailer. Every once in a while the men poured water into the hole, let the bailer down and hauled up mud. Then the bit could go on drilling. Oil workers today still call the wheel which winds up cable “the bull wheel.”
PIPELINE MACHINES
When a well brings in oil, a new group of men and machines go to work. They lay a pipeline, through which the oil can be pumped to factories called refineries. Some pipelines are hundreds of miles long.
After surveyors have decided just where the line should go, bulldozers clear away brush, push over trees, heave big boulders to one side, making a wide pathway across country. In many places, the pathway is good enough for trucks to follow. They bring in lengths of pipe and lay them down end to end. Where the going is rough, a caterpillar tractor carries the pipe, one length at a time, hanging from a side-boom.
Now welding crews go to work fastening the ends of the pipe-lengths together. When they have finished, the “hot-dope gang” comes along. They are men who cover the pipe with a wrapping and then with a hot asphalt mixture to protect the metal.
Meantime, a wonderful machine called a trencher has been at work. This is a cat attached to a rig which
