Imagine you're trying to clean up a big mess on your bedroom floor with a broom and dustpan. You sweep all the dirt and dust into a pile, but when you go to pick it up with the dustpan, some of it escapes and goes back onto the floor.
When oil and gas companies drill for oil or gas, they use a special type of drill called a drilling rig. Just like how you use a broom and dustpan to clean up a mess, drilling rigs sweep up rocks, dirt, and other stuff from the ground. But if they use too much force, some of the dirt and rock can escape and go back into the hole they're drilling.
To prevent this from happening, some drilling rigs use underbalanced drilling. Think of it like using a smaller broom and dustpan to clean up a smaller mess. The drill doesn't use as much force, so there's less chance for the dirt and rock to escape.
Underbalanced drilling means drilling with less pressure than the earth's natural pressure. This can help prevent damage to the rocks and soil underground, and can also make it easier to extract oil or gas. It's like how you might gently brush your hair instead of pulling on it to get rid of knots.
Overall, underbalanced drilling is a way for oil and gas companies to be more careful when drilling, and to make sure they get as much oil or gas as possible without damaging the ground or wasting resources.