Section 5 Well Drilling Methods（第五节钻井方法）.pdfVIP

WATER WELL DRILLING METHODS There are several different types of drilling methods used in Michigan. This section covers the most common methods used. Rotary Drilling Rotary drilling is the most popular well drilling method in Michigan. Mud rotary is widely used in the Lower Peninsula where substantial overburden exists, while air rotary rigs are found primarily in the Upper Peninsula and the few high bedrock areas of Lower Michigan. The principle of rotary drilling is based upon a rotating drill stem made of lengths of drill pipe about 15 feet long. A bit is attached to a heavy stabilizer or drill collar at the end of the column of drill pipe. The extra weight and larger outside diameter of the stabilizer just above the bit helps to maintain a straight drill hole. The drill stem is hollow and has a drilling fluid of either mud or air circulating down the drill stem out through the nozzles in the bit and up along the outside of the drill stem. The rotating action of the bit breaks up the material and the drilling fluid carries the cuttings to the surface where they settle out in a mud tank. Several types of bits are available to the rotary driller. The bit most generally used in Michigan is the tri-cone roller bit. The type and number of cutting teeth on the bit cones vary depending upon the type of formations to be penetrated. The upper end of the drill stem is attached to a kelly on a table drive rig and swivel which are mounted on a large mast. Hydraulic controls lower or raise the drill stem and operate the rotary motion. When a hole has been drilled the full length of the kelly, the drill stem is raised, the joint between the kelly and drill pipe is broken, and an additional length of drill pipe is added. The drive mechanism for the drilling ope