Well Completions and Stimulation Flashcards

What is 'gel damage' in hydraulic fracturing and how is it mitigated?

Answer: Residual polymer from fracturing fluid that reduces proppant pack permeability; mitigated with breaker additives

Gel damage occurs when unbroken polymer residues reduce proppant pack conductivity; breaker chemicals degrade the gel to restore permeability.

Which well integrity test is performed to verify the cement bond between casing and formation after cementing?

Answer: Cement bond log (CBL) or ultrasonic cement evaluation tool

A CBL (or ultrasonic cement evaluation tool) measures acoustic attenuation to assess the quality of the cement bond behind casing.

What is the primary mechanism by which matrix acidizing increases productivity in a sandstone formation?

Answer: Dissolving formation damage (clays, scales, drilling mud) to restore natural permeability

Matrix acidizing in sandstones uses HF-based systems to dissolve clay minerals, silica, and damage solids, restoring near-wellbore permeability.

In a well with multiple pay zones, what completion technique allows selective production or injection from individual zones without killing the well?

Answer: Dual packer system with sliding sleeves for zonal isolation and selective flow control

Dual (or multiple) packer systems with sliding sleeves allow individual zones to be opened or closed without killing the well or performing workovers.

What is 'wellbore breathing' observed during leak-off tests, and what does it indicate?

Answer: Elastic opening and closing of near-wellbore fractures during pressurization and bleed-off

Wellbore breathing is caused by near-wellbore fractures opening when pressurized and closing when bled off, indicating natural fractures or a low fracture gradient.

What is the Nolte-Smith plot used for in hydraulic fracturing analysis?

Answer: To diagnose fracture behavior (height growth, screenout, or tip extension) from treating pressure vs. time log-log plot

The Nolte-Smith plot of net pressure vs. pumping time on a log-log scale identifies fracture behavior patterns including confined height growth, T-shaped fractures, or imminent screenout.

Which type of artificial lift method is most commonly used in deepwater subsea well completions?

Answer: Electric submersible pump (ESP) deployed on production tubing

ESPs are the dominant artificial lift choice for deepwater wells due to their ability to handle high flow rates and compatibility with subsea tubing-deployed systems.