Key Stages and Precautions in Drilling Operations

Key Stages and Precautions in Drilling Operations

Drilling is a continuous, highly technical process with interconnected stages. Mastering these key stages and paying attention to related precautions is crucial for ensuring well quality, construction safety, and project efficiency. These stages form the main line from ground preparation to final well completion; neglecting any one stage can lead to the failure of the entire project.

The first key stage is drilling and formation identification. This is not just mechanical drilling, but also a continuous geological reconnaissance process. Operators must closely monitor the drilling rig's pressure and rotation speed changes, as well as the rock cuttings (debris) carried by the drilling fluid (or water) returning from the well. By observing the composition, color, and particle size of these cuttings, it is possible to accurately determine whether the current formation is clay, sand, or rock, and record the depth at which each formation appears. This "formation log" is crucial; it is the only scientific basis for deciding where and how to install the well casing and filter section. Precautions: Drilling must be smooth, avoiding sudden lifting and lowering; mud circulation must be kept unobstructed to prevent drill string sticking or wellbore collapse; any abnormal signs (such as sudden large mud loss) must be dealt with immediately.

The second key stage is casing installation and filter packing. This is the transformative step that turns a "borehole" into a "water well." Based on the previous formation records, the pre-connected well casing (with filter screens aligned with the aquifer) is smoothly and vertically lowered into the borehole. Subsequently, screened gravel of appropriate particle size (called filter material) is evenly and continuously filled into the annular space between the well casing and the borehole wall. Precautions: The casing installation process must be careful, ensuring that the casing is centered and securely connected. Filter packing must be continuous and uniform, at a moderate speed, to prevent blockage or "bridging" that could lead to voids. The quality and specifications of the filter material directly affect whether the well produces sand and its service life.

The third key stage is thorough well cleaning and pumping tests. After casing installation and gravel packing, the well and the surrounding aquifer are still filled with drilling fluid and fine particles, which must be removed through powerful well cleaning. Typically, the well is repeatedly flushed and agitated using pistons, air compressors, or high-volume water pumps until the returned water is clear and contains very little sand. After the well cleaning is complete, a formal pumping test must be conducted: continuous, stable pumping for several hours to measure the well's maximum water output and the depth of the water level drop, and water samples must be taken for water quality analysis. Important considerations: Well cleaning must be thorough; this is crucial for maximizing the well's water output capacity and cannot be neglected. The data from the pumping test is a critical indicator for determining whether the well is acceptable and must be accurately recorded. Only when both the water output and water quality meet the standards is the well considered successful.

Throughout the entire process, safety and record-keeping are paramount. Personnel must stay away from the operating drilling rig and the removed drilling tools; electrical wiring must be properly installed to prevent electrical leakage; and the site must be kept clean to prevent slips and falls. At the same time, detailed and accurate construction records (including geological formation records, casing depth, material usage, test data, etc.) should be delivered along with the well; these are important documents for future maintenance, repair, or dispute resolution. By adhering to these procedures and considerations, a high-quality, long-lasting well can be successfully obtained.