CPG Drilling Operations & Well Logging

Question 1

What is the primary purpose of drilling mud in well operations?

Accepted Answer

To lubricate the drill bit and maintain pressure

Answer

The primary purpose of drilling mud in well operations is to lubricate and cool the drill bit, carry rock cuttings to the surface, and crucially, maintain hydrostatic pressure in the wellbore. This pressure prevents formation fluids from flowing uncontrollably into the well, which is known as a 'kick,' thus ensuring drilling safety and wellbore stability.

Question 2

What does the term 'kick' refer to in drilling?

Accepted Answer

An influx of formation fluids into the wellbore

Answer

In drilling, a 'kick' refers to an influx of formation fluids (oil, gas, or water) into the wellbore. This occurs when the pressure exerted by the drilling mud column is insufficient to counteract the pressure of fluids within the rock formation. If not quickly controlled, a kick can escalate into a dangerous blowout, posing significant safety and environmental risks.

Question 3

What is the function of well logging?

Accepted Answer

To record geological data about the subsurface

Answer

The function of well logging is to record geological and petrophysical data about the subsurface formations encountered during drilling. Specialized tools are lowered into the wellbore to measure various properties, such as resistivity, radioactivity, and acoustic velocity. This data is crucial for identifying hydrocarbon zones, evaluating reservoir quality, and making informed decisions for well completion and production.

Question 4

Which tool is used to measure formation resistivity?

Accepted Answer

Resistivity log

Answer

A resistivity log is the tool used to measure formation resistivity, which is the ability of a material to oppose the flow of electric current. Hydrocarbons and gas are highly resistive, while saline formation water is conductive. By analyzing resistivity measurements, geologists can identify hydrocarbon-bearing zones and determine water saturation within the reservoir.

Question 5

Why is casing used in a well?

Accepted Answer

To prevent formation collapse and fluid migration

Answer

Casing is used in a well to prevent formation collapse and fluid migration, providing structural integrity to the wellbore. Steel pipes are inserted and cemented in place, isolating different geological formations and preventing unwanted fluids from moving between zones or into the wellbore. This ensures well stability, safety, and environmental protection.

(CPG) Certified Petroleum Geologist Practice Test

(CPG) Certified Petroleum Geologist Practice Test

CPG Drilling Operations & Well Logging