Exploration And Production Test 1

Front 1

3 geological conditions for commercial deposits of oil and gas

Back 1

1- source rock that generated oil or gas
2- separate subsurface reservoir rock to hold oil & gas
3- trap to concentrate oil & gas into commercial quantities

Front 2

Source Rock Type

Back 2

sandstone, mudstone, organic matter

Front 3

Reservoir Rock Type

Back 3

sandstone, limestone, and shale (if fractured)

Front 4

Trap Rock Type

Back 4

- slate, salt, limestone, igneous/metamorphic
- if there is no caprock, oil will puddle at surface and gas will evaporate into the air

Front 5

Porosity

Back 5

The percent of reservoir rock that is pore space, commonly 10 to 30%. the gas an oil flow into the pores of the reservoir rock layer. because the reservoir rock also contains water, the gas and oil will continue to rise by flowing from pore to pore up the angle of the reservoir rock toward the surface (migration).

Front 6

Permeability

Back 6

The ease with which the gas and oil can flow through the rock due to the tunnels and connections between the pores.

Front 7

5 Parts of a Rotary Drilling Rig

Back 7

1) Derrick or mast - tower above the well with a hoisting line and pulley system that's used to raise and lower equipment in the well
2) Engines - supplies power to the rig
3) Drillstring - The assembled collection of the drill pipe, drill collars, tools and drill bit.
4) Drillpipe - Transmits drilling mud and torque to the drill bit
5) Drillbit - cuts the hole
5)

Front 8

Why is it called a "Rotary" drilling rig?

Back 8

the drill pipe rotates along with the bit

Front 9

Circulating Mud System

Back 9

Drilling mud, usually made of clay and water, is pumped down inside of the drillpipe 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 from the bottom of the hole and keeps the them from clogging the bottom of the well. the pressure of the drilling mud prevents any fluid such as water, gas, and oil from flowing out of the subsurface rocks and into the well, which can cause a blowout.

Front 10

API Gravity

Back 10

- Stands for the American Petroleum Institute
- compares and describes crude oils by density
- API gravity is (141.5/specific gravity at 60°F) - 131.5
- Freshwater has an API gravity of 10
- The Degree API gravity of crude oils vary from 5 to 55
- Average density of crude oils are 25 to 35
- average density of light oils are 35 to 45 (less viscous)
- average density of dark oils are below 25 (more viscous)
- the higher the api gravity, the better the oil

Front 11

Pour Point

Back 11

- the lowest temperature at which the oil will still pour before it solidifies
- higher pour points reflect higher wax content

Front 12

Cloud Point

Back 12

- related to pour point
- it is the temperatu7re at which the oil first appears cloudy as wax forms when the temperature is lowered
- 2° to 5° above the pour point
- yellow if very waxy
- green if slightly waxy
- black if low or no wax

Front 13

Measurement

Back 13

- crude oil measures by barrel (bbl) that holds 42 gallons
- oil well production is measured in barrels of oil per day (bopd or b/d)
- natural gas is measured by cubic foot (cf)
- heat content of fuel is measured by Btu (one Btu is about the amount of heat given off by burning one wooden match)

Front 14

Refining

Back 14

1) components of crude oil are separated by their boiling points
2) crude oil is heated in a furnace until most of it is vaporized (the longer the hydrocarbon molecule, the higher its boiling temperature)
3) the hot vapor is sprayed into the bottom of a distilling column, where gas rises and any remaining liquid falls
4) the liquid that comes from the bottom of the column is residuum and is least valuable
5) the rising vapors bubble up and are cooled
6) the cooling vapors condense into liquid and are removed by sidedraws
7) each liquid removed is called a cut

Front 15

Condensate

Back 15

- when gas is produced, the temperature decreases and the liquid hydrocarbons condense out of the gas on the surface
- almost pure gasoline

Front 16

Types of Rocks

Back 16

1) igneous
2) sedimentary
3) metamorphic

Front 17

Igneous Rocks

Back 17

- form when molten melt is cooled
- two types are plutonic and volcanic
- plutonic crystallizes below the surface
- volcanic crystallizes on the earth as lava
- harder to drill than sedimentary
- impenetrable, best cap rock

Front 18

plutonic igneous

Back 18

-solidifies below surface
- take thousands of years to solidify
- large mineral crystals form
- large mineral grains
- formed as hot liquids that were injected into and displaced preexisting rocks in subsurface to form instrusions

Front 19

volcanic igneous

Back 19

- crystallize on surface as lava
- rapidly solidifies
- forms very small crystals
-

Front 20

sedimentary rocks

Back 20

- clastic
- organic
- crystalline
- as sediments are buried in the subsurface, they become solid
- source and reservoir rocks
- only sedimentary rocks below the water table contain oil and gas

Front 21

Clastic sedimentary

Back 21

- consist of sedimented grains, natural cements, and pores
- pores are filled with water in the subsurface
- boulder; cobble; pebble; granule; and silt

Front 22

Metamorphic rocks

Back 22

- any rocks that have been altered by high heat and pressure
- since temperatures and pressures become greater with depth, a rock often becomes metamorphosed when buried very deep in the earth

Front 23

Earth's crust

Back 23

- average thickness is about 5,000' of well layered sedimentary rocks underlain by very old metamorphic or igneous rock
- about 100 layers of sedimentary rocks

Front 24

sandstone formed by

Back 24

sands

Front 25

shale formed by

Back 25

mud

Front 26

limestone formed by

Back 26

seashells

Front 27

basement rocks

Back 27

- unproductive rocks for gas and oil, usually igneous and metamorphic rocks underlying the sedimentary rocks
- when drilling encounters basement rock, the drilling stops

Front 28

shields

Back 28

- areas of the earth where there are no, or very few, sedimentary rocks, and the basement rock is on or near the surface
- no gas or oil
- every continent has at least one shield area
- tends to be a large, low-lying area

Front 29

basins

Back 29

- sedimentary rocks are very thick
- basins have been filled with sedimentary rocks and are dry land today
- 20,000 to 40,000 ft of sedimentary rock is typical of many basins
- most of the oil and gas is produced in the sedimentary rock
- most basins have source rocks that have been buried deep enough in the past to generate oil and gas

Front 30

kitchen

Back 30

- the deep part of the basin where the organic matter is cooked to form oil and gas

Front 31

amorphous

Back 31

minerals with no crystal form

Front 32

cleavage

Back 32

the tendency for some minerals to break along smooth surfaces

Front 33

Moh's Scale

Back 33

quantifies the hardness of a mineral on a scale of 1 to 10

Front 34

specific gravity

Back 34

the relative weight of a mineral compared to the weight of an equal volume of water

Front 35

mica

Back 35

- breaks along one perfect cleavage plain forming very thin, elastic flakes

Front 36

quartz

Back 36

- hardest common mineral
- tinted by impurities

Front 37

calcite

Back 37

- a common mineral that is either colorless or white
- breaks along three perfect cleavage plains that are not at right angles to form rhombs
- relatively soft
- composes most seashells

Front 38

halite

Back 38

- breaks along three perfect cleavage planes at right angles, forming rectangles and cubes
- forms from the evaporation of seawater

Front 39

gypsum

Back 39

- forms tabular crystals and has one perfect cleavage plane
- very soft

Front 40

pyrite

Back 40

- forms either cubes or an earthy mass and is relatively heavy
- fool's gold

Front 41

granite

Back 41

- igneous
- most common plutonic igneous rock

Front 42

basalt

Back 42

- igneous
- most common volcanic rock

Front 43

90% of rocks

Back 43

shale, sandstone, limestone

Front 44

absolute age dating

Back 44

- puts an exact time on the formation of a rock or an event
- must use same exact kind of rocks
- made by radioactive analysis
- measure the amount of parent atoms left and daughter atoms created to determine the age of the mineral grains in a rock
- used primarily on igneous and metamorphic rocks and cannot be used directly on sedimentary rocks because they are derived from the erosion of preexisting rocks
- as time goes on, the amount of radioactive parent atoms decreases, and the amount of daughter atoms increases

Front 45

relative age dating

Back 45

- arranges the rocks and events into a sequence of older to younger
- used to measure the age of sedimentary rock sequences in order from oldest to youngest

Front 46

radioactivity

Back 46

the spontaneous decay of radioactive atoms that occur naturally in rocks

Front 47

parent

Back 47

the original radioactive atom

Front 48

daughter

Back 48

- product of radioactive decay
- one daughter atom is formed by the decay of each parent atom

Front 49

half-lives

Back 49

the time in years that it takes one-half of the parent atoms to decay into daughter atoms

Front 50

fossils

Back 50

- an important tool in relative age dating
- the preserved remains of plants and animals

Front 51

trace fossils

Back 51

- indirect evidence of ancient life
- ex. burrows, tracks, or trails

Front 52

guide or index fossil

Back 52

a distinctive plant or animal that lived during a relatively short period of time and identifies the age of any sedimentary in which it occurs

Front 53

fossil assemblage

Back 53

a group of fossils found in the same sedimentary rocks that identifies the zone of rocks and the geologic time during which those rocks and fossils were deposited

Front 54

weathering

Back 54

breakdown of a solid rock

Front 55

erosional process

Back 55

transports and deposits sediments (ex. rivers, wind, waves, gravity (landslide), and glaciers)

Front 56

unconformities

Back 56

-buried, ancient erosional surfaces that were formed whenever sea level was lower, the land was exposed to erosion, and some of the sedimentary rocks were stripped off the surface of the land
- something other than the original horizontal layer

Front 57

2 types of unconformities

Back 57

disconformities and angular conformities

Front 58

disconformity

Back 58

- an erosional channel in which the sedimentary rock layers above and below the erosional surface are parallel
- it is an ancient river channel usually filled with sand that has become sandstone

Front 59

angular conformity

Back 59

- an ancient erosional surface in which the sedimentary rock layers below the unconformity are tilted at an angle to the layers above the unconformity
- represents a time of mountain building followed by erosion
- can form gas and oil traps if one of the sedimentary rock layers tilted at an angle sits on top of a reservoir rock
- ex. Prudhoe Bay in Alaska

Front 60

no. 3 daisy bradford well

Back 60

- first well to reach below the angular unconformity in the east texas oil field
- drilled by Dad Joiner

Front 61

anticline

Back 61

- a large, upward arch of sedimentary rocks
- form high areas in reservoir rocks and can be traps

Front 62

syncline

Back 62

a large, downward arch of rocks

Front 63

compressional forces

Back 63

-shorten the earth's crust by squeezing it
- compressed areas fold into anticlines and synclines
- form reverse dip-slip and thrust faults and folds (ex. anticlines and synclines)

Front 64

dome

Back 64

- a circular or elliptical uplift
- form traps
- forms a hill before it's eroded down

Front 65

first types of traps recognized

Back 65

anticlines and domes

Front 66

homoclines

Back 66

- sedimentary rocks that dip uniformly in one direction
- do not form traps

Front 67

2 types of natural fractures in rocks

Back 67

joints and faults

Front 68

joint

Back 68

- a fracture in the rocks with no movement of one side relative to the other
- common in sedimentary rocks
- improve the reservoir quality of the rock by slightly increasing porosity and greatly increasing permeability

Front 69

faults

Back 69

- breaks in the rocks along which one side has moved relative to the other
- can be active and produce shockwaves (earthquakes) or inactive

Front 70

dip-slip fault

Back 70

- move primarily up and down
- form faults by displacing the reservoir rock

Front 71

strike-slip faults

Back 71

- move primarily horizontally

Front 72

oblique-slip faults

Back 72

- have roughly equal dip-slip and strike-slip displacements

Front 73

footwall

Back 73

the side of a fault that extends under the fault plane

Front 74

hanging wall

Back 74

the side of a fault that protrudes above the fault plane

Front 75

throw

Back 75

the vertical displacement on a dip-slip fault

Front 76

downthrown side of a fault

Back 76

the side of the dip-slip fault that does down

Front 77

upthrown side of a fault

Back 77

the side of the dip-slip fault that goes up

Front 78

two types of dip-slip faults

Back 78

1) normal- when the hanging wall has moved down relative to the footwall after the beds have been separated and pulled apart by tensional forces
2) reverse- when the hanging wall has moved up relative to the footwall causing some beds to overlap due to compressional forces

Front 79

lost section

Back 79

a missing layer or layers of rocks when a well is drilled through the fault that identifies a normal dip-slip fault in the subsurface (drills a dry hole because you completely miss the reservoir rock)

Front 80

a series of parallel, normal dip-slip faults forms a structure called _________ and ________

Back 80

horst; graben

Front 81

graben

Back 81

the down-dropped block between two normal faults

Front 82

horst

Back 82

- the ridge left standing between two grabens
- can range in size from inches to miles

Front 83

double section

Back 83

- when you drill through a reverse-dip fault and encounter the same rock layers twice

Front 84

thrust fault

Back 84

- a reverse fault with a fault plane less than 45 degrees from horizontal (extremely slanted)
- the upper hanging wall has been thrust up and over the lower footwall

Front 85

tensional forces

Back 85

- causes normal dip-slip faults with horsts and grabens

Front 86

sealing fault

Back 86

- prevents fluid flow across or along the fault
- any gas and oil migrating up a reservoir rock will be trapped under the sealing fault
- fault itself is not a trap, but the result is

Front 87

right-lateral strike-slip fault

Back 87

- when the opposite side of a strike-slip fault as you face it moves to the right

Front 88

left-lateral strike-slip fault

Back 88

- when the opposite side of a strike-slip fault as you face it moves to the left

Front 89

continental shelf

Back 89

- a shallow, almost flat platform that surrounds all continents
- extends from the shoreline out with a slope of less than 1 degree to the shelf break
- width varies from 1/2 mile to more than 500 miles, with an average width of 50 miles
- sedimentary rocks that are encountered in drilling along the beach extend out under the continental shelf
- a very active petroleum exploration and production area
- the same source rocks, reservoir rocks, and traps that occur on land are found on the continental shelves

Front 90

shelf break

Back 90

- the ocean bottom sharply increases in slope
- located in an average water depth of 450'

Front 91

continental slope

Back 91

- seaward of the continental shelf and slope break
- extends down to the bottom of the ocean
- has a slope of about 3 degrees and is the geological edge of the continents

Front 92

ocean trenches

Back 92

- the deepest parts of the seafloor that are long, narrow depressions and are usually located along the margins of the oceans
- adjacent to many deep trenches are active volcanoes

Front 93

mid-ocean ridge

Back 93

- located almost in the very center of the Atlantic Ocean
- the world's longest mountain chain that can be traced for 40,000 miles

Front 94

continental crust

Back 94

- granite and 20-45 miles thick

Front 95

oceanic crust

Back 95

- basalt lava rock and about 3 miles thick

Front 96

continental crust elevation vs. oceanic crust elevation

Back 96

- continents are high in elevation because they are composed primarily of granite that is relatively light in density compared to basalt, and it floats higher on the rocks in the interior of the earth

Front 97

seafloor spreading

Back 97

- this theory provided the processes for the breakup of Pangea and the drifting of the continents
- theory that large, slow-moving convection currents occur in the interior of the earth where rocks act as viscous liquids
- the term comes from the seafloor being spread out at right angles from the crest of the mid-ocean ridge

Front 98

subduction zones

Back 98

- areas where seafloors from two different mid-ocean ridges collide

Front 99

3 types of subduction zones

Back 99

1) 2 seafloors from different mid-ocean ridges meet and one is thrust below the other to form an ocean trench. The subducted sea floor gets so hot it melts and the molten rock rises to form a series of volcanoes
2) One seafloor meets another seafloor with a continent riding on it and the seafloor without the continent on it thrust under the one with the continent to form a trench. The edge of the continent is compressed to form a coastal mountain range. Molten rock from the subducted seafloor rises to form volcanoes in the coastal mountains.
3) When two seafloors meet, both carrying continents, neither continent is subducted into the interior because both are composed of light granite. One seafloor is thrust under the other seafloor, and the colliding continents are compressed to form a mountain range between the continents.

Front 100

Plate Tectonics

Back 100

- combines the idea of seafloor spreading and continental drift
- postulates that the solid lithosphere of the earth is divided into large, moving plates

Front 101

triple junction

Back 101

- the form taken by the initial breakup of a continent by plate tectonics
- has 3 rifts (arms) that join in the center
- usually two of the arms unite and continue rifting to form an ocean

Front 102

failed arm

Back 102

- the one arm of a triple junction that stops spreading
- this is a graben that can be filled with sediments

Front 103

basin

Back 103

- a large area with relatively thick sedimentary rocks where most oil and gas are found

Front 104

5 ways to form a basin

Back 104

1) subsidence of the basement rock - the depression is originally filled with ocean water, and eventually sediments. Petroleum occurs in reefs that surrounded the basin during that time because of the dying animals.
2) grabens
3) half-graben
4) intermontane basins
5) coastal plains

Front 105

sedimentary rock facies

Back 105

- a single layer of sedimentary rock can be composed of two or more different rock types.
- each is a facies, a distinctive portion of the rock layer
- occur near oceans
- heavier grains (sand) stay on beach to form sandstone
- lighter grains (silt and clay) are carried into the water to become shale

Front 106

sedimentary rock facies change

Back 106

the change between rock types in a single layer of sedimentary rock

Front 107

interfinger or wedge out

Back 107

- when the boundary between two facies is sharp and the boundary is gradational
-

Front 108

updip pinch-out

Back 108

- in a reservoir rock in a shale or salt layer can form a petroleum trap