Drill rigs, as key equipment for oil and gas extraction and the exploration of other subsurface resources, come in various types designed to meet different operational needs and geological conditions. Primarily, they can be categorized into three major classes:

　　1. Portable Drilling Machine: This is a handheld tool used for small-scale operations. It is commonly used for drilling small holes in various materials such as metal, wood, and plastic. Portable drilling machines are versatile and can be easily carried and operated in different locations.

　　2. Sensitive Drilling Machine: These machines are precision tools used for small to medium-sized drilling tasks. They are designed to handle small holes with high accuracy and are typically used in light, intricate drilling operations. Sensitive drilling machines are often used in industries like electronics or small component manufacturing.

　　3. Radial Drilling Machine: This type of drilling machine features a rotating arm that can move horizontally, allowing it to drill at various angles and positions. It is used for larger workpieces and allows for greater flexibility and precision in drilling holes. Radial drilling machines are often used in heavy industries like construction and automotive manufacturing.

　　Each type of drill rig has its specific applications and advantages, Each type of drilling machine serves different needs based on the complexity, scale, and precision required for the drilling task， and choosing the right one is crucial for ensuring successful drilling operations.