PETROLEUM GEOLOGY

Question 1

A general term for all naturally occurring hydrocarbons (hydrogen + carbon)

Answer 1

petroleum

Question 2

Solid hydrocarbons: Asphalt
Liquid hydrocarbons: _____

Answer 2

crude oil

Question 3

most oil and gas starts out as __________ and ____ that live in the ocean

Answer 3

microscopic plants and animals

Question 4

. One of the most important group of plankton involved in the formation of oil and gas are single-celled marine ‘plants’ called _____

Answer 4

dinoflagellates

Question 5

Where sediment contains
more than 5% organic matter, it eventually forms a rock known as a ___ which makes oil and gas

Answer 5

black Shale

Question 6

A rock that has produced oil and gas in
this way is known as a ____

Answer 6

source Rock

Question 7

The organic fragments in sedimentary rocks are called _____

Answer 7

kerogen

Question 8

3 types of kerogen

Answer 8

type I: algal kerogen - best oil source and lipi-rich
type II - berbaceous kerogen - good oil source, includes zooplankton sapropelic
type III - woody kerogen (coaly) good gas source

Question 9

TOC content is
a measure of the source rock potential and is measured with
total pyrolysis

Answer 9

Total Organic Carbon (TOC)

Question 10

true or false: Oil and gas migrate downward through the rock in much the same way that the air bubbles of an underwater diver rise to the surface

Answer 10

upwards- false

Question 11

The rising oil and gas eventually gets trapped in pockets in the rock called ___

Answer 11

reservoirs

Question 12

difference of primary migration and secondary migration

Answer 12

A. Primary migration - passage of petroleum out of the source rock in which it was generated.

B. Secondary migration - passage of petroleum through porous and
permeable media, driven by buoyancy contrast between petroleum
and water that otherwise fills porosity

Question 13

Generation, migration and trapping of hydrocarbons

Answer 13

Several conditions must be satisfied for an economic hydrocarbon accumulation to exist. First, there must be sedimentary rocks that have good source rock characteristics and have reached thermal maturity. Second, the hydrocarbons must have migrated from the source rock to a potential reservoir, which must have adequate porosity and permeability. Finally, there must be a trap to arrest the hydrocarbon migration and hold sufficient quantities to make the prospect economic. Hydrocarbon traps usually consist of an impervious layer (seal), such as shale, above the reservoir and barrier such as a fault or facies pinch that terminates the reservoir.

Question 14

most common examples of reservoir rocks are __ and ___

Answer 14

sandstone and carbonates (limestone and dolomite)

Question 15

a good reservoir rock must be

Answer 15

porous and permeable

Question 16

is the capability of a rock to hold fluids in pores

Answer 16

porosity

Question 17

is the capability of a rock to transmit a fluid

Answer 17

permeability

Question 18

major factors affecting permeability

Answer 18

grain size, grain sorting and grain roundness

Question 19

is the post-depositional chemicall and mechanical changes that occur in sedimentary rocks

Answer 19

diagenesis

Question 20

diagenesis may ____ porosity

Answer 20

enhance

Question 21

These large-scale dissolution features are called karst and are caused by _____ water

Answer 21

meteoric

Question 22

____are essential in creating permeable paths in tight carbonate rocks limestone. They can create high permeabilities but low porosities

Answer 22

fractures

Question 23

___can be rocks that do not allow fluids to pass through them, or folds and faults in the rock can trap petroleum

Answer 23

traps

Question 24

______ is an impermeable rock which don’t allow the hydrocarbons to escape from the reservoir rock (chalks, shales, clays etc)

Answer 24

seal or cap

Question 25

Resources vs Reserves

Answer 25

Resources - the total amount of a valuable geologic material in all deposits, discovered and undiscovered

Reserves - discovered deposits of geologic resources that can be extracted economically and legally under present conditions

Question 26

What do we get from oi?>

Answer 26

1 barrel = 42 gallons of crude oil
83% becomes fuel
Gasoline, diesel, jet fuel, heating oil, and liquefied petroleum gas (propane and butane)
17% other
Solvents, fertilizers, pesticides, plastics

Question 27

How to find oil?

Answer 27

• subsurface explo
• surface explo

Question 28

is natural gas produced from shale rocks which are formed by compaction and because of this, they tend to have low porosity and extremely low permeability

Answer 28

shale gas

Question 29

is used to provide greater access to the gas trapped deep in the producing formation. First, a vertical well is drilled to the targeted rock formation. At the desired depth, the drill bit is turned to bore a well that stretches through the reservoir horizontally, exposing the well to more of the producing shale.

Answer 29

horizontal drilling

Question 30

there are three primary techniques of enhanced oil recovery

Answer 30

(1) gas injection
(2) thermal injection
(3) chemical injection