CPG Study Guide 2026
Everything you need to pass the CPG exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 CPG Exam Format at a Glance
📚 CPG Topics to Study (24)
✍️ Sample CPG Questions & Answers
1. Which log measurement is the primary direct indicator of formation fluid pressure in permeable zones while drilling?
The Repeat Formation Tester (RFT) or Modular Dynamic Tester (MDT) directly samples formation fluid and measures pore pressure at discrete depth intervals.
2. What is porosity in a reservoir rock?
Porosity in a reservoir rock refers to the percentage of the total rock volume that is made up of void spaces or pores. These interconnected pores are crucial because they are where hydrocarbons (oil and gas) and water are stored within the rock formation. High porosity is essential for a rock to be an effective reservoir, determining its storage capacity.
3. In NMR logging, what does the T2 distribution primarily represent?
The NMR T2 transverse relaxation time is inversely proportional to the surface-area-to-volume ratio of pores, making larger pores correspond to longer T2 times.
4. Which factor influences reservoir permeability?
Permeability is a measure of a rock's ability to allow fluids to flow through it. While porosity indicates the amount of space, pore throat size (the size of the connections between pores) dictates how easily fluids can move. Larger, well-connected pore throats result in higher permeability, which is vital for efficient hydrocarbon production from a reservoir.
5. Why is casing used in a well?
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.
6. Accommodation space in sequence stratigraphy is controlled primarily by the interplay of:
Accommodation is the space available for potential sediment fill, controlled by the sum of eustatic sea-level change and basin subsidence (or minus uplift), regardless of how much sediment is actually supplied.