Allowable non-verticality of deep well bores For a tube well of 200 m depth, what is the typical maximum permissible horizontal deviation from vertical (non-verticality) at the bottom?

Introduction / Context:
Verticality of well bores matters for proper screen placement, pump alignment, and longevity. Standards specify allowable deviation as a ratio (e.g., 1 in N) or as an equivalent lateral displacement at the bottom for a given depth.

Given Data / Assumptions:

• Well depth = 200 m.
• Typical verticality criterion is of the order of 1 in a few hundred (illustrative for design questions).
• We must choose from given discrete lateral deviations.

Concept / Approach:
If a commonly cited tolerance is about 1 in 200, the maximum lateral displacement allowed at the bottom equals depth / 200. For 200 m depth: displacement = 200 / 200 = 1 m = 100 cm. This value aligns practical drilling tolerances while safeguarding pump operations and screen integrity.

Step-by-Step Solution:

Verification / Alternative check:
Many specifications express verticality in percent or per-centimetre deviation per metre; for illustrative problems, 1:200 is a standard proxy.

Why Other Options Are Wrong:
25–75 cm are stricter than the typical illustrative limit; 150 cm would exceed the reasonable tolerance and risk equipment misalignment.

Common Pitfalls:
Confusing verticality (lateral offset) with bore drift angle; ignoring that small angular errors accumulate significantly over deep wells.

Final Answer:
100 cm