A water-gas dual-purpose drilling rig is a type of equipment that can use both water and gas simultaneously for drilling. It combines the advantages

 of both water and gas, typically used for the following purposes:

1. Improved Drilling Efficiency: The combination of water and gas can increase drilling speed, reduce friction, and help the drill bit penetrate

 geological formations more smoothly.

2. Cooling and Lubrication: Water can cool the drill bit to prevent overheating, while gas can help clear drill cuttings and keep the borehole clean.

3. Strong Adaptability: This type of rig can operate under various geological conditions, whether in soft soil or hard rock, demonstrating good adaptability.

4. Versatility: Water-gas dual-purpose drilling rigs can be used for various projects, such as water well drilling, geological exploration, and foundation engineering.

This equipment is commonly found in construction, mining, and environmental engineering fields, providing efficient and flexible drilling solutions.