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Analysis of the Difficulties in Drilling Wells in Clay Layers
Difficulties Analysis of Drilling in Clay Layers
Drilling in clay layers presents unique challenges due to specific geological characteristics. Clay has fine particles and a compact structure, leading to extremely poor water permeability. Compared with soils like sand, water seeps through clay layers very slowly, which usually results in lower water yield from wells.
During drilling operations, the stickiness of clay causes many troubles. With high viscosity, clay easily adheres to the drill bit during boring, causing the “bit sticking” phenomenon. This significantly affects drilling efficiency and reduces the drilling speed substantially. Moreover, when clay meets water—especially after rain—it becomes wet and soft. Combined with its high expansibility, this further increases the operational difficulty for equipment. If the drilling depth is too large, it is highly likely to cause slurry retention in the wellbore, severely affecting normal pumping operations.
The expansibility of clay also threatens the stability of the wellbore. Over time and with changes in the groundwater level, clay may expand or shrink, which can lead to cracks or even collapse of the wellbore. Once the wellbore is damaged, it not only affects the normal use of the water well but also brings potential safety hazards, requiring a lot of manpower and material resources for repair. Therefore, when drilling in clay layers, these difficulties must be fully considered, and targeted measures should be taken to ensure the smooth progress of the drilling project and the long-term stable use of the water well.