Drilling encompasses numerous specialisations, including large-diameter rotary drilling, small-diameter exploration drilling, ultra-deep scientific research drilling, underground tunnel drilling, shaft sinking, trenchless drilling, water-grinding pile drilling, and water well drilling.
Each type employs distinct equipment, construction methods, and operational requirements.
However, every drilling project begins with a drilling specification document. This outlines the project name, location, single-hole workload, total project volume, schedule, and per-borehole parameters including diameter, depth, core recovery rate, casing specifications, structural requirements, and hole sealing protocols.
The drilling brief serves as a crucial document for selecting drilling equipment and techniques, and formulating the construction plan. Based on this document, one assesses whether the project can be undertaken by comparing one’s own technical capabilities and equipment. If the construction capacity is deemed sufficient, a site survey may be conducted.
Today we shall begin by introducing the common drilling tools frequently used in water well drilling:
Drill pipes feature male and female couplings. Sub-surface drill pipes, commonly used for water well drilling, come in diameters of 76, 89, 102, and 114mm, with lengths varying between 3, 4, 5, and 6 metres. For depths below 300 metres, 76mm drill pipes are generally sufficient. Beyond 300 metres, considering the need to support heavier drill string and greater torque, drill pipes of 89mm diameter or larger are recommended. It should be noted that drill pipes of different diameters feature distinct thread specifications, necessitating compatibility with the rotary head threads of the drilling rig. Such details serve as a benchmark for evaluating drilling rig solution providers.
Additionally, down-the-hole drill pipes are categorised by wall thickness, with some construction tenders stipulating explicit wall thickness requirements. Standard wall thicknesses for conventional 76mm and 89mm drill pipes are 6.5mm, while 102mm pipes typically measure 8.38mm or 8.5mm. However, some manufacturers may falsely declare wall thicknesses; this can be verified by comparing weights of pipes of identical diameter and length.
Drill pipes also vary in manufacturing processes and materials, which we shall not elaborate upon here. A dedicated article will subsequently address drill pipe specifications in detail.
Pipe wrench/tooth wrench: Used for tightening drill pipes, available in 12-inch, 18-inch, 24-inch (commonly used), 36-inch, and 48-inch sizes.
Free-form tongs/triple-ring tongs: For assembling/disassembling drill string, casing or wireline drill pipes. Available in multiple sizes, each capable of handling two pipe sizes: 73/89, 108/127, 146/168. The 146/168 size is most commonly used; sizes above 168 are less frequent due to weight, typically requiring chain tongs for 168-diameter pipes.
Additional tongs include outer tongs for wireline coring and inner tongs.
Spacer: An essential tool for routine drilling operations. Two common sizes are available: the 42 spacer for handling 42mm drill pipes and the 50 spacer for 50mm drill pipes. These dimensions refer to the jaw opening width; all other dimensions are identical.
Wrench: Used for drill string disassembly during hoisting. Common sizes 42 and 50 correspond to 42mm and 50mm drill pipes respectively.
Hoist: Employed for winch hoisting or lowering operations. Common sizes 42 and 50 are available, with larger variants also produced.
Hoist basket: The upper component of the hoist is termed the basket. Above this sits a U-shaped ring, also known as a shackle, which connects the hoist to the main wire rope.
This is a safety ring. When attaching drill pipes, pull it upwards; once secured, pull it downwards to prevent the pipes from slipping out. During drilling operations, it prevents detachment and potential injury. Some specialised drilling tools feature unique hoists.
Small spanner: Serves the same purpose as the drill pipe wrench. Occasionally, after loosening with the wrench, if manual tightening proves difficult, this small spanner can be used to complete the task.
Casing clamp: Used for running casing. Geologic exploration casing sizes include 73, 89, 108, 127, 146, 168, 194 mm, etc. Sizes 108 and 127 mm are most common in geologic exploration, while larger diameters are preferred for water well construction, also for running and pulling casing.
