Petroleum Geology & Reservoir Characterization Flashcards

The Buckley-Leverett equation is used in reservoir engineering to describe:

Answer: Immiscible two-phase fluid displacement in porous media

The Buckley-Leverett equation describes the fractional flow and frontal advance of an immiscible displacing fluid (e.g., water) through a porous medium.

Which structural trap type is formed by the intersection of two normal fault systems creating a down-dropped central block?

Answer: Graben

A graben is a down-dropped crustal block bounded by normal faults on both sides, formed where two normal fault systems intersect or parallel each other.

In a type II kerogen, what is the primary hydrocarbon product generated during peak thermal maturation?

Answer: Oil-prone hydrocarbons

Type II kerogen is primarily marine-derived and oil-prone, generating liquid hydrocarbons at peak maturation within the oil window (Ro ~0.6–1.3%).

Permeability anisotropy in clastic reservoirs is MOST commonly caused by:

Answer: Preferential alignment of clay minerals and bedding lamination

Bedding-parallel lamination and aligned clay minerals create higher horizontal permeability than vertical permeability, making permeability anisotropy common in clastic reservoirs.

The depth to the gas-water contact in a reservoir is controlled by:

Answer: The spill point of the structural trap

The gas-water contact is ultimately constrained by the spill point of the structural or stratigraphic trap, below which hydrocarbons cannot be retained.

Which seismic attribute is MOST useful for detecting stratigraphic traps associated with channel sand bodies?

Answer: Coherence/similarity attribute

Coherence/similarity attributes highlight discontinuities in seismic reflectors, making them ideal for mapping channel edges, faults, and stratigraphic boundaries.

What is the significance of a 'bright spot' anomaly on a seismic section in a clastic reservoir?

Answer: It may indicate a gas sand with anomalously low acoustic impedance

A bright spot is a high-amplitude seismic anomaly often caused by gas-saturated sands, which have significantly lower acoustic impedance than brine-saturated sands or shales.