In Drilling Fluid: Lifeblood of the Well you can find out about the many functions of drilling fluid - the liquid that fills the borehole of a well as it is being drilled. One of these is buoyancy, the ability of a liquid to partially support the weigh of an object, in this case, the steel drill pipe. Here's a demonstration of how this works.

Tools & Materials

You will need:

• Tall glass or graduated cylinder
• Large bolt or screw
• Piece of thread about 30 centimeters (12 inches) long
• Water and at least one other liquid. Corn syrup is a good choice.
• Spring scale.

The Experiment

Here's what to do:

1. Tie one end of the thread around the screw. Make a loop at the other end to hang on the hook of the spring scale.
2. Weigh the screw and record your result.
3. Submerge the screw in water and weigh it again, making sure it is fully submerged but not resting on the bottom of the container or against the sides.

• How does the weight of the screw in air compare to its weight in water?
• How do these two weights compare to the weight in corn syrup and any other liquids you used?
• Can you calculate the volume of the screw?
• Can you calculate the density of the corn syrup and the other liquids?

Take a look at our results.

To find out about drilling fluids read Drilling Fluid: Lifeblood of the Well