Exploration & Production Processes Flashcards

What distinguishes unconventional reservoirs (e.g., shale gas, tight oil) from conventional reservoirs?

Answer: They have very low permeability requiring stimulation to produce economically

Unconventional reservoirs have nano-darcy to micro-darcy permeability and require horizontal drilling and hydraulic fracturing to achieve commercial flow rates.

Which pressure regime is said to exist when formation pressure exceeds normal hydrostatic gradient and can cause well control challenges?

Answer: Overpressure (geopressure)

Overpressured (geopressured) zones have pore pressures above normal hydrostatic, increasing blowout risk if mud weight is insufficient.

In a gas reservoir using material balance, what is the primary data required to estimate original gas in place (OGIP) using the p/z method?

Answer: Reservoir pressure and cumulative gas production over time

The p/z method plots p/z versus cumulative gas production; extrapolation to p/z = 0 gives OGIP for a volumetric gas reservoir.

Which completion method involves isolating production zones using inflatable or swellable packers to selectively fracture multiple intervals in a horizontal well?

Answer: Multistage hydraulic fracturing completion

Multistage fracturing uses packers to isolate clusters or stages along the lateral, enabling sequential hydraulic fracturing of each interval.

What is the function of a subsurface safety valve (SSSV) in a production well?

Answer: To automatically shut in the well downhole if surface conditions indicate a loss of control

The SSSV is a fail-safe device set below the wellhead that closes automatically if surface pressure or control line pressure is lost.

Which drilling hazard is characterized by the drill string becoming stuck due to differential pressure pinning it against a permeable formation?

Answer: Differential sticking

Differential sticking occurs when the pressure difference between the wellbore and a permeable formation pushes the drill string against the filter cake, embedding it.

What is the purpose of an extended well test (EWT) conducted before full field development?

Answer: To evaluate reservoir performance, fluid properties, and flow rates over an extended period

An EWT provides long-duration dynamic reservoir data including pressure behavior, fluid characterization, and productivity before committing to full development.