Petroleum Exploration and Production Test 1

Mesozoic era

Age of reptiles. This era includes the Jurassic period, in which mammals appeared. At the end of this period, all the dinosaurs and 60% of plants and animals died out- great killing. This was caused by an asteroid, which caused a ton of dust to be thrown up into the air and caused the world to be in darkness for several decades. The collision created greenhouse gases, which warmed the earth.

Cenozoic

Age of the mammals. Ice age

°API Gravity

American Petroleum Institute measurement of density for hydrocarbons. Formula= (141.5 / specific gravity at 60 °F) - 131.5 It standardizes petroleum industry equipment and procedures. Freshwater has an °API gravity of 10. The average density of crude oils are 25 to 35. Light oils are 35 to 45. They are very fluid, often transparent, rich and gasoline, and the most valuable. Heavy oils are below 25. They are very viscous and dark colored, contain considerable asphalt, and are less valuable.

Shield

Area in the earth in which there are no or very few sedimentary rocks, and the basement rock is on or near the surface.

Subduction zones, 3 different kinds, how they interact

Areas where seafloors from two different mid-ocean ridges collide. 1. oceanic and oceanic. One oceanic plate goes under another and creates a series of volcanoes along the oceanic trench. 2. oceanic and continental. The oceanic crust goes under the continental. This forms an ocean trench off the coast of the continent. The edge of the continent is compressed to form a coastal mountain range. Molten rock from the subducted seafloor under the edge of the continent rises to form volcanoes in the coastal mountains. 3. When 2 continentals meet. Neither continent is subducted into the interior because both are composed of relatively light granite. The colliding continents compress to form mountain ranges.

Which kind of rock can be all three of the functions?

Shale

Condensate

Shorter-chain liquid hydrocarbon that is gas subsurface but condenses into a hydrocarbon when its temperature lowers at the surface. This liquid is almost pure gasoline, clear to yellowish to bluish in color, and has 45 to 62 °API gravities. It is commonly called casing head gasoline, drip gasoline, white gas or natural gasoline. It is often added to crude oil in the field in a process called spiking to decrease the °API gravity and increase the volume and value of the oil.

graben

a valley formed by the downward displacement of a fault-bounded block.

seafloor spreading

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5 major parts of a rotary drilling rig

1. Drillstring- Steel drillpipe with a bit at the end that is suspended in the well and can be thousands of feet long. 2. Drillpipe- Pipe that is part of the drillstring. Every 30 ft in depth, another section of drillpipe is screwed on the drill string to make it longer. 3. Drill bit- Bit that is at the lowest part of the drill string, attached to the drill pipe 4. Engines- Diesel engine that supplies power to the rig. 5. Derrick or Mast- A steel tower above the well. Along with a hoisting line and pulley system, this is used to raise and lower equipment in the well.

3 basic types of rock

1. Igneous- Plutonic (Granite is most common)or volcanic (Basault is most common) 2. Sedimentary (Shale is most common) 3. Metamorphic (example is marble)

Important periods in Paleozoic era

1. Pennsylvanian- Swamps covered large areas of the land. Deposits from these swamps formed many of the world's coal deposits. 2. Permian- Egg-laying reptiles appeared and at the end, the greatest extinction of plants and animal species in the history of the earth occurred- called the great dying, which was caused by poisonous gases released by volcanic eruptions in Siberia.

3 Geologic Conditions Necessary for Commercial Geologic Deposits

1. Source Rock in the subsurface of that area that generated the gas or oil at some time in the geological past 2. There must be a separate, subsurface reservoir rock that holds the gas or oil. 3. Caprock

What types of rock compose each of the three necessary conditions?

1. Source: Must have organic matter that will turn into hydrocarbons. The most common is organic-rich sedimentary rock. Most common is black shale, which was deposited as organic-rich mud on ancient ocean bottoms. 2. Reservoir: Porous rock. Most common is sandstone. Limestone, which is deposited as shell beds or reefs, is also common. 3. Caprock: Impervious rock that lies above the reservoir rock in the trap. Most common caprocks are shale and salt.

Refining Process

1. Various components of crude oil are separated by their boiling points at the refinery in a furnace until most of the crude oil is vaporized. 2. The hot vapor is then sprayed into the bottom of a distilling column, where gases rise and any remaining liquid falls. The liquid that comes out the bottom of the distilling column is called residuum, or bottom of the barrel. It is the least valuable. 3. In the distilling column are bubble trays filled with liquid. The rising vapors bubble up through the trays and are cooled. The cooling vapors condense into liquid on the trays where they are removed by side draws. Each Liquid removed by cooling is called a cut. Heavy cuts come out at high temperatures, whereas light cuts come out at low temperatures. In order of cooling temperatures, the cuts are heavy gas oil, light gas oil, kerosene, naphtha, and straight run gasoline. 4. A process called cracking is used to make more gasoline from the longer, less valuable cuts. These longe-moleculed cuts are used as cracking stock. The Cracking stock is put in cracking towers at the refinery, where high temperatures and pressures and caustic chemicals split the longer molecules to form gasoline. Refineries also produce feedstocks, which are used to make plastics and many other petroleum products.

Natural gas has a carbon chain with __ carbon atoms

4 or less

Gasoline has a carbon chain with __ carbon atoms.

5 to ten

The amount of BTUs in one barrel of oil is equal to the BTUs in __ cubic feet of average natural gas and is called ___.

6,040; BOE

Basin formation: 5 ways

A basin is a large area with relatively thick sedimentary rocks, where most oil and gas is found. 1. Subsidence of the basement rock. 2. Half-graben basins are formed by subsidence along one side of a normal fault. 3. Intermontane basins form when mountain ranges are created, and the basin is located between the mountain peaks and is often occupied by a lake. Basins also form along the edges of mountains. 4. Basins also form by grabens 5. Coastal plains are basins that form by thick sediments being deposited adjacent to an ocean.

Basin

A large area with relatively thick sedimentary rocks, where most oil and gas can be found.

Circulating System

Drilling mud, usually made of clay and water, is pumped down the inside of the drill pipe where it jets out of nozzles on the bit and returns up the outside of the drillpipe to the surface. The drilling mud removes the rock chips made by the bit, called well cuttings, from the bottom of the hole and prevents them from clogging up the bottom of the well. The well is always kept filled to the top with the heavy drilling mud as it is being drilled because the pressure of the drilling mud prevents any fluids such as water, gas and oil from flowing out of the subsurface rocks into the well. If gas or oil flowed up onto the floor of the drilling rig, the could catch fire, causing a blowout. Even if only water flowed out of the surrounding rock into the well, the sides of the well could cave in, and the well could be lost.

Absolute Age dating

Exact dates for the formation of rocks are made by radioactive analysis, which analyzes the decaying of radioactive elements in the rock. Radioactivity is the spontaneous decay of radioactive atoms that occur naturally in rocks. The rate of radioactive decay, measured in half-lives. It is used on igneous and metamorphic rock and cannot be used to age sedimentary rock.

Oblique fault

Has roughly equal dip-slip and strike-slip displacements.

Heat content of oil/gas

Measured in BTU; one of which is about the amount of heat given off by burning one wooden match.

Quantity of oil/gas

Measured per barrel (bbl), which holds 42 US gallons, and by Mcf, which is an abbreviation for 1,000 cubic feet.

Strike-slip fault

Moves primarily horizontally

dip-slip fault

Moves primarily up and down. The side goes down is called the downthrown side, and the side that goes up is the upthrown side. 2 types: normal (hanging wall moves down) and reverse (hanging wall moves up).

Relative Age Dating

Technique of determining a sequence of geological events based on the structural elements of rocks, used to date the age of sedimentary rocks.

Permeability

The ability of a rock or sediment to let fluids pass through its open spaces, or pores.

Pour point

The lowest temperature at which the oil will still pour before it solidifies. It indicates the amount of wax in crude oil. Crude oil pour points range from +125° to -75°F. Higher pour points reflect higher wax content. The cloud point is the temperature at which the oil first appears cloudy as wax forms when the temperature is lowered.

Continental crust

The older, thicker, and less dense part of Earth's crust; the bulk of Earth's land masses. Mostly granite

Porosity

The percent of reservoir rock that is pore space.

Oceanic crust

The portion of Earth's crust that is usually below the oceans, thinner and higher in density than continental crust and made of basalt, which is an igneous rock.

Footwall

The side of a fault that extends under the fault plain.

Hanging wall

The side that protrudes above the fault plane

Lithosphere

The solid rock layer that floats atop the mantle and composes tectonic plates.

Plate tectonics

The theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle