Well Completions and Stimulation Flashcards

What is the purpose of an acid pre-flush stage in a matrix acidizing job?

Answer: To dissolve carbonate minerals and prepare the formation for main acid

An acid pre-flush removes carbonate minerals and cleans the near-wellbore area before the main acid system is injected.

Which completion method is most commonly used in deepwater subsea wells?

Answer: Subsea tree with wet completion

Deepwater subsea wells use subsea trees (horizontal or vertical) installed on the wellhead at the seafloor, enabling wet completions.

What is 'proppant embedment' in hydraulic fracturing?

Answer: Proppant grains being pressed into soft formation rock, reducing fracture width

Embedment occurs when proppant grains press into soft or weak formation rock under closure stress, reducing the effective propped fracture width.

What diagnostic test uses the pressure decline after a small-volume injection to determine fracture closure pressure?

Answer: Mini-frac (or DFIT — Diagnostic Fracture Injection Test)

A DFIT (or mini-frac) analyzes the pressure decline after a small injection to determine closure pressure, permeability, and reservoir pressure.

What does a negative skin value indicate about a well?

Answer: The well has been stimulated beyond its natural productivity

Negative skin indicates enhanced near-wellbore flow, such as that created by hydraulic fracturing or acid stimulation.

In coiled tubing operations, what limits the maximum depth of coiled tubing deployment?

Answer: Coiled tubing weight, friction, and helical buckling

Helical buckling of coiled tubing under compressive load, combined with friction forces, limits how deep coiled tubing can be pushed in a well.

Which parameter is used to describe the efficiency of a hydraulic fracture treatment?

Answer: Fluid efficiency (ratio of fracture volume to total fluid injected)

Fluid efficiency is the ratio of the final fracture volume to total fluid pumped, accounting for fluid lost to leak-off.