Question

A drilling mud with high gel strength is undesirable because it

• A. retards the separation of cuttings and entrained gas at the surface.
• B. leads to the lost circulation.
• C. creates swabbing action beneath the bit while pulling the string.
• D. leads to the hole ballooning.

Hint:

Excessive gel strength traps solids and gas—maintain recommended gel values for efficient surface separation.

Answer 1

The Correct Option is A

High gel strength means that mud forms a strong internal structure when flow stops.
Although beneficial for suspending cuttings during connections, excessive gel strength creates problems.
The primary issue is poor surface separation: thick, highly structured mud prevents cuttings from settling and restricts degassing at the shale shaker and mud tanks.
Entrained gas cannot escape easily, leading to gas-cut mud and density fluctuations.
Option B is incorrect: lost circulation is mainly caused by fractures or weak formations, not gel strength.
Option C is incorrect: swabbing is related to improper tripping speed and mud column effects, not gel strength.
Option D is incorrect: hole ballooning is caused by wellbore breathing and fracture elasticity, not gel strength.
Thus, the correct reason is retarded solids and gas separation at the surface.