This term describes the movement of water upwards or gas downwards towards a decrease in pressure caused by producing hydrocarbons in a zone with no vertical permeability boundaries.

• A. Upward diffusion
• B. Channeling
• C. Coning
• D. Siphoning

Answer: (C)

Coning describes how a pressure drop near a producing well pulls the surrounding fluid into the well in a cone-shaped region, especially when there are no vertical barriers to flow. As oil is produced, the near-well pressure falls, and water from below can rise toward the well while gas from above can move downward toward it. Gravity and the density/viscosity differences cause this invading phase to form a roughly conical intrusion around the well, leading to early water or gas breakthrough. This phenomenon is a key production risk because it reduces oil recovery and changes the well’s flowing composition. Diffusion is too slow and lacks the characteristic cone shape; channeling means flow through a high-permeability path but not the menacing cone around the well; siphoning isn’t the mechanism involved here.