SPE Well Testing and Pressure Transient Analysis 2

Question 1

A pressure buildup test is shut in after a production time 'tp'. The Horner approximation works best when which condition is met?

Accepted Answer

Production time (tp) greatly exceeds shut-in time (Δt)

Answer

The Horner approximation (using superposition with a single producing time tp) is most accurate when tp >> Δt, ensuring that the transient is still within the early buildup response.

Question 2

Which reservoir boundary condition produces a doubling of the semi-log straight line slope in a buildup or drawdown pressure transient test?

Accepted Answer

A sealing fault (no-flow boundary) at some distance from the well

Answer

When a sealing fault is encountered, flow transitions from radial to hemi-radial, effectively halving the drainage area and doubling the slope on the semi-log plot.

Question 3

In a drill stem test (DST), the 'Initial Shut-In Pressure' (ISIP) measured at the start of the test is most useful for estimating which parameter?

Accepted Answer

Static reservoir pressure or pore pressure

Answer

The ISIP in a DST approaches static reservoir pressure as equilibration occurs, making it the primary indicator of pore pressure or original reservoir pressure.

Question 4

What does the term 'pseudosteady-state flow' (PSS) describe in reservoir engineering and well testing?

Accepted Answer

Flow regime where reservoir pressure declines uniformly at a constant rate throughout the drainage area

Answer

Pseudosteady-state (PSS) occurs after transients reach all boundaries; the reservoir then depletes uniformly, with pressure declining at the same constant rate everywhere in the drainage volume.

Question 5

In a pressure falloff test performed on an injection well, which parameter can be derived using the same analytical methods as a standard buildup test?

Accepted Answer

Formation permeability and skin factor

Answer

A pressure falloff test (shut-in after injection) is the injection-well analog to a buildup test; the same semi-log and derivative analysis yields formation permeability (k) and skin (S).

(SPE) Society of Petroleum Engineers Certification Practice Test

(SPE) Society of Petroleum Engineers Certification Practice Test

SPE Well Testing and Pressure Transient Analysis 2