Petroleum Engineering Fundamentals

Flashcards covering key terms and definitions from the lecture notes on Petroleum Engineering roles, oil price variables, geology, rock properties, origin of petroleum, reservoir rocks, hydrocarbon traps, reservoir drives, crude oil properties, natural gas, reservoir water, and OOIP.

Drilling Engineers

Manage the drilling of exploratory, production, and injection wells.

Well Log Analysts (Petro-physicists)

Evaluate boreholes for petroleum potential.

Production Engineers

Manage the reservoir–well interface, artificial lift, and surface separation equipment.

Reservoir Engineers

Optimize production via well placement, rates, and recovery methods.

Oil Price Variables

Consumption (demand), Production (supply), Inventories (storage), Spare Capacity (unused wells), Geopolitical Risks, and Market Variables (investment, exchange rates, equity, futures).

Porosity

The ratio of pore space to bulk rock volume (Vp/Vb).

Inter-granular Porosity

Pore space located between grains in a rock.

Intra-granular Porosity

Pore space located within grains in a rock.

Cementation

The process where crystals (like calcite, silica, iron oxides, clays) bind grains together.

Permeability

The ability of fluids to flow through connected pores in a rock.

Effective Porosity

The interconnected pores that allow fluid flow (less than total porosity).

Inorganic Theory of Petroleum Origin

Petroleum formed deep in Earth from hydrogen + carbon, or was leftover from the solar system, resulting in similar chemistry across regions.

Organic Theory of Petroleum Origin

Petroleum formed from plankton & algae in ancient seas, buried in sediment, preserved in anaerobic conditions, and transformed by heat + pressure over millions of years.

Sedimentary Rocks

Rocks such as sandstone, limestone, dolomite, and shale that can act as reservoir rocks.

Sandstone

A porous and permeable sedimentary rock, often a good reservoir rock.

Limestone

A calcium carbonate rock that sometimes stores petroleum.

Dolomite

A sedimentary rock similar to limestone but containing more than 50% magnesium carbonate.

Shale

A fine-grained clay/mud rock, and the most common type of sedimentary rock.

Structural Traps

Hydrocarbon traps formed by the deformation of rock layers.

Anticline Trap

A structural trap where rock layers are folded upward into an arch, trapping hydrocarbons.

Fault Trap

A structural trap where a rock break and movement creates a barrier for hydrocarbons.

Salt Dome Trap

A structural trap where an upward-moving salt mass pushes and deforms rock layers, trapping hydrocarbons.

Stratigraphic Traps

Hydrocarbon traps formed by changes in porosity or permeability, or sealed by a cap-rock.

Unconformity Trap

A stratigraphic trap where an eroded porous layer is sealed by an impermeable rock layer.

Permeability Change Trap

A stratigraphic trap where a permeable rock body is surrounded by impermeable rock.

Bubble Point

The pressure and temperature at which dissolved gas begins to escape from oil.

Gas-cap Drive

A reservoir drive mechanism where an expanding gas cap pushes oil upward into production wells.

Solution Gas Drive

A reservoir drive mechanism where gas dissolved in the oil expands as pressure drops, pushing oil to the well.

Water Drive

A reservoir drive mechanism where the expansion of underground water forces oil into the well.

Wetting Water

A thin film of water that coats rock grains and cannot be displaced by oil.

Sweet Crude

Crude oil with a sulfur content of less than 0.7%.

Sour Crude

Crude oil with a sulfur content greater than 0.7%.

API Gravity Formula

(141.5 / (Specific Gravity @ Standard Temperature and Pressure)) – 131.5.

Light Crude

Crude oil with an API gravity greater than 31.1.

Medium Crude

Crude oil with an API gravity between 22.3 and 31.1.

Heavy Crude

Crude oil with an API gravity less than 22.3.

Extra Heavy Crude

Crude oil with an API gravity less than 10.

Viscosity of Crude Oil

Decreases with increasing temperature and increases with increasing pressure.

Natural Gas Composition

Primarily 90–98% methane, with smaller amounts of ethane, propane, and butanes.

Gas Gravity

The ratio of gas density to air density at standard conditions.

Ethane

A component of natural gas used to make ethylene, which is a precursor for plastics.

Barrel (bbl)

A standard unit of measurement for oil, equal to 42 gallons.

Standard Conditions

Defined as 60°F and 14.7 psia for gas measurements.

Connate Water

Water that was 'born with' the rock and remains trapped in its pores.

Swi (Irreducible Water Saturation)

The portion of pore space in a reservoir rock that always holds immovable water.

OOIP (Original Oil in Place)

The total amount of crude oil that existed in a reservoir before any production began. Formula: (Area × Thickness × Porosity × Oil Saturation) ÷ 5.614.