CPG Case Analysis & Practical Application 3

Question 1

A stratigraphic trap is identified in a deltaic sequence where reservoir pinches out up-dip into tight shale. Which seal risk element is most important to evaluate?

Accepted Answer

Lateral seal integrity along the updip pinch-out and absence of faults cutting the shale

Answer

The updip shale seal must be laterally continuous and unfaulted for the stratigraphic trap to hold hydrocarbons.

Question 2

A field's primary recovery factor from a water-drive reservoir is estimated at 35%. The operator is evaluating waterflooding to increase recovery. The most important reservoir property to assess first is:

Accepted Answer

Permeability distribution and vertical communication between layers

Answer

Waterflood efficiency depends critically on reservoir heterogeneity and vertical permeability communication, which control sweep efficiency.

Question 3

A geologist observes that two adjacent fault blocks have different reservoir pressures measured at the same datum. This most directly implies:

Accepted Answer

The fault between the blocks is sealing and prevents pressure communication

Answer

Pressure differences across a fault at the same datum confirm that the fault is acting as a barrier to fluid flow and pressure communication.

Question 4

When constructing a prospect's resource distribution for probabilistic volumetrics, which parameter typically contributes the greatest uncertainty range?

Accepted Answer

Recovery factor, because it integrates reservoir quality, drive mechanism, and development design

Answer

Recovery factor spans the widest range because it depends on multiple interacting subsurface and engineering uncertainties.

Question 5

A CPG is tasked with risking a deepwater prospect and assigns a 15% POS. This means:

Accepted Answer

There is a 15% probability that all required elements (trap, reservoir, seal, charge, timing) are simultaneously satisfied

Answer

Probability of Success (POS) is the geologic chance that all risk elements are present and functional, yielding a commercial accumulation.

(CPG) Certified Petroleum Geologist Practice Test

(CPG) Certified Petroleum Geologist Practice Test

CPG Case Analysis & Practical Application 3