Have you ever poured a glass of water and noticed how it moves slowly through a straw? This is because the water molecules are moving through small spaces, and sometimes they get stuck. The Buckley-Leverett equation is a way to explain how liquids like water and oil move through rocks in the ground.
Imagine you have a rock with tiny spaces called pores. These pores are filled with a liquid (like water or oil) that you want to extract from the rock. The Buckley-Leverett equation helps you figure out how fast the liquid will move through the rock, and how much of it you can get out.
The equation says that as the liquid moves through the rock, it will create two different zones. In the front zone (also called the wetting front), the liquid moves quickly and fills up the pores. In the back zone, the liquid moves more slowly and leaves some of the pores empty.
When the front zone reaches the end of the rock, you can't get any more liquid out. This is called the breakthrough time. The Buckley-Leverett equation helps you predict how long it will take to reach breakthrough, and how much of the liquid you can extract.
So, it's like trying to suck a milkshake out of a straw. You have to work hard at first to fill the straw with milkshake, but once it's filled you can quickly suck the milkshake out. The Buckley-Leverett equation helps us understand how the milkshake (or any liquid) moves through tiny spaces like straws or rocks.