Several Important Aspects to Consider During Drilling Operations

Several Important Aspects to Consider During Drilling Operations

Drilling is a continuous process with interconnected stages, and any oversight in any stage can affect well quality, construction safety, and ultimately, the lifespan of the well. To ensure the smooth progress of the project, several crucial aspects require the joint attention of both the construction personnel and the client. These aspects constitute the main technical and quality control line from drilling to well completion.

The first important aspect is the identification of geological formations and observation of rock cuttings during the drilling process. This is not simply a mechanical operation, but a skilled task requiring experience and meticulous attention. As the drill bit descends, operators must closely observe the rock cuttings (crushed rock fragments) carried by the returning drilling fluid (or clean water). By observing the composition, color, particle size, and quantity changes of these cuttings, the geological formation encountered—whether clay, sand, gravel, or bedrock—can be accurately determined. Simultaneously, the depth at which each formation appears must be meticulously recorded; this is called "logging." This record is the only scientific basis for deciding when to install casing and how to position the screen pipe (perforated pipe), directly determining whether the well can successfully "find" and utilize the aquifer.

The second crucial aspect is the installation of the well casing and backfilling with filter material. This is the transformative step that converts the "borehole" into a "water well." Before casing installation, the borehole must be clean and properly shaped. During casing installation, it is essential to ensure that the well casing (especially the perforated screen pipe section) is securely connected, vertically centered in the borehole, and accurately positioned at the target aquifer. Subsequently, the annular space between the well casing and the borehole wall is uniformly and continuously filled with screened gravel of appropriate particle size (called "filter material" or "pea gravel"). This step is crucial: the filter material forms a natural, highly efficient filter that allows groundwater to flow smoothly into the well while effectively preventing fine sand from entering the well from the aquifer, thus preventing well clogging. Uneven or interrupted filling can lead to "sand surging," severely shortening the well's lifespan.

The third indispensable aspect is thorough well cleaning and pumping tests. After casing installation and gravel backfilling, the well is filled with drilling mud and fine particles, resulting in low water yield and turbid water. At this point, a powerful and thorough well cleaning operation is necessary, usually involving repeated flushing with pistons, air compressors, or high-flow water pumps until the returned water is clear and transparent with very low sand content. The purpose of well cleaning is to clear the aquifer channels and remove mud and fine silt from the filter pack and well walls, thereby fully activating the well's potential water production capacity. After well cleaning, a formal pumping test must be conducted: continuous pumping for several hours, measuring the stable water yield and water level drawdown, and taking water samples for quality analysis. Only when the pumping test data is satisfactory can the well construction be considered successful. These three stages are interconnected and progressively ensure that the final delivered well is a qualified well with sufficient water volume, good water quality, and a long lifespan.