What does wellhead clearance mean?

There are the following answers about wellhead sentences:

1, the bottle was damaged by the spring, and the waterwheel broke down at the wellhead.

2. Black crude oil gushed from the wellhead.

3. The light hits the high wellhead and spreads into huge light and shadow.

4, but he knows best that a general is bound to die in the battlefield and a crock will never leave the wellhead.

5. I am a frog. I'm tired of the constant and comfortable life in the well, and I'm determined to go out and break into the world. I jumped out of the well when it rained.

6. Wellhead pressure-mounted BOP is used to throw out tubing plugs during wellhead fracturing to block tubing and prevent blowout.

7. In the oilfield developed by water injection, with the increase of water content of crude oil, the wellhead oil temperature will also increase.

8. This situation is a bit like being in a dry well and hitting a wall on all sides. When the situation is worse, the wellhead will even be sealed.

Idioms related to wellhead:

1. Frogs at the bottom of the well (j ǐ ng d ǐ zh and w ā): Frogs at the bottom of the well can only see a day as big as the wellhead. Metaphor is a narrow-minded person.

2. The crock will not leave the wellhead (w m: guà n b ù lí j ǐ ng k ǒ u p ò): the crock that draws water will inevitably break at the wellhead. An adventurous officer is bound to miss.

3. The crock will not leave the well (w m: guà n bù lí j ǐ ng shà ng pò): The crock that draws water will inevitably break at the wellhead. An adventurous officer is bound to miss.