Unit 3 reservoir rock properties

Lead - in

What are the typical rocks in the Earth’s crust?

What rocks show there is oil underground?

What are the most common reservoir rocks?

What properties of reservoir rock do you know?

What is a trap?

Terms and Vocabulary

closure	купол \ замыкание
crest	антиклинальный перегиб
gas cap	газовая шапка
gas-oil contact	газонефтяной контакт
oil-water contact	водонефтяной контакт
producible oil	нефтеотдача
transition zone	переходная зона
oil saturation	нефтенасыщенность
bottom water	подошвенная вода
edge water	краевая \контурная вода
porous	пористый
permeable	проницаемый
diatrophism	тектоническое воздействие
impermeable	непроницаемый
reservoir rock	коллекторская порода, пористая порода пласта коллектора
property cross-section existencу adjacent to planar be tilted be enclosed	свойство, характеристика профиль, поперечное сечение наличие граничащий; прилегающий; примыкающий; смежный плоский наклоненный окружённый

1. Pronounce the following words. Pay special attention to the underlined stress in the following words.

illustrate impermeable surround contain relationship existence permit laterally adjacent hydrodynamic producible unequal opposite temperature saturation

2. Read the text “Hydrocarbon traps” and fulfill the exercises.

Hydrocarbon traps may be illustrated by considering a porous, permeable formation that hаs been folded into an anticlinal trap by diatrophism and is enclosed between impermeable rocks [Fig. 1].

Hydrocarbon Traps

Fig.1. Idealized cross-section through an anticlinal trap formed by a porous, permeable formation surrounded by impermeable rocks. Oil and gas are trapped at the top of the anticline.

The closure of the trap is the distance between the crest and the spill point (lowest point of the trap that can contain hydrocarbons). In most cases, the hydrocarbon trap is not filled to the spill point. It may contain a gas cap if the oil contains light hydrocarbons and the pressure-temperature relationship of the zone permits the existence of a gas zone at the top of the reservoir.

If a gas cap exists, the gas-oil contact is the deepest level of producible gas. Likewise, the oil-water contact is the lowest level of producible oil. Transition zones between various zones grading from high oil saturation to hydrocarbon-free water. For example, the water zone immediately below the oil-water contact is the bottom water, whereas the edge water is laterally adjacent to the oil zone.

The gas-oil and water-oil contacts are generally planar, but they may be tilted due to hydrodynamic flow of fluids, a large permeability contrast between opposite sides of the reservoir, or unequal production of the reservoir.