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How should different soil layers encountered by water well drilling rigs be handled?

Release time:

2023-12-14

Theoretical analysis results were found to align well with practical drilling outcomes.

The concepts of the drill bit lateral cutting index, anisotropy index, and comprehensive cutting directional anisotropy index were introduced, leading to general and simplified formulas for the natural inclination force of strata suitable for actual drill bits of drilling machines under conditions of volume and surface fragmentation. Using the drilling machine's cone pressure method, formulas for the inclination change force and azimuth change force of strata during directional drilling were derived, providing a basis for stratigraphic force analysis in directional well trajectory control. Theoretical analysis results were found to align well with practical drilling outcomes.

During the drilling process, when encountering different geological layers, such as sand layers and gypsum layers, different methods should be adopted to achieve optimal results. In case of gypsum intrusion during drilling, calcium ions can be removed by adding soda ash, decalcification, and viscosity reduction methods. Additionally, strong calcium-resistant viscosity reducers can be used to control viscosity, compensating for deficiencies in loss reduction agents and anti-collapse agents.

1. Gypsum Layer: Before drilling into the gypsum layer, pre-treat the drilling fluid on the drilling platform to reduce solid content and viscosity, and add anti-gypsum treatment agents (such as soda ash, decalcification agents, and viscosity reducers). Prepare treatment agents for the gypsum layer based on materials used in adjacent wells. Increase the pH value of the water well drilling fluid to enhance the small water well drilling machine's mechanical resistance to gypsum contamination.

2. Sand Layer: During drilling in sandy layers, it is necessary to increase the viscosity of the drilling fluid and the bentonite content in the water well drilling fluid, generally requiring more than 10%. To improve the wellbore formation properties of the water well drilling fluid, appropriately reduce the flow rate during the project to minimize erosion in the sandy layer. Before pulling out the drill string, it is essential to seal this section with mud slurry of viscosity greater than 80 to ensure smooth operations such as pulling out and running the drill string, electrical logging, and casing."