China is drilling a 10,000-meter (32,808 feet) hole into the Earth's crust in the oil-rich Xinjiang region.

The project, known as the China Deep Underground Science and 

Engineering Laboratory (CDUSL), is expected to take 10 years to complete. 

The CDUSL will be used to study the Earth's crust and mantle, and 

to test new technologies for deep drilling and exploration. 

The project is also expected to help China to develop new sources of energy and resources. 

Here are some of the reasons why China is drilling 10 km underground in oil-rich Xinjiang: 

1. To explore new sources of oil and gas. 

2. To study the Earth's crust and mantle. 

3. To collect samples of rock and fluids. 

4. To improve China's energy security. 

5. To advance scientific research.