Chapter 3 - Natural Gas Overview

Question 1

What is the simplest hydrocarbon molecule?

Answer 1

One carbon atom bonded to four hydrogen atoms (CH4) – Methane

Question 2

Raw natural gas may contain other hydrocarbons, as well as?

Answer 2

Water
Carbon Dioxide
Oxygen
Nitrogen
Hydrogen Sulfide
Helium

Question 3

Define inerts.

Answer 3

The nonydrocarbons that must be removed from raw natural gas

Question 4

What is added to natural gas to give it an identifiable smell?

Answer 4

Mercaptan

Question 5

Natural gas also may contain heavier hydrocarbons in the gaseous state, such as pentane, hexane, and heptane. At surface conditions, what happens?

Answer 5

These will condense out of the gas to form natural gas condensate, often shortened to condensate.

Question 6

Define Conventional Natural Gas.

Answer 6

The term conventional generally used to describe natural gas produced from well-understood geologic formations known through experience to hold natural gas.

Question 7

Where has the greatest U.S. natural gas reserves historically have been concentrated around?

Answer 7

Texas and the Gulf of Mexico, with substantial amounts also found in the Rocky Mountain West.

Question 8

Define associated gas.

Answer 8

Conventional gas that is produced during the extraction of crude oil

Question 9

Define nonassociated gas

Answer 9

A formation targeted specifically for extraction of natural gas

Question 10

Define unconventional natural gas.

Answer 10

Unconventional natural gas is a gas that cannot be economically produced unless one or more technologies are used to stimulate the gas-bearing formation and to expose more of the formation to the wellbore.

Question 11

What did the Natural Gas Policy Act of 1978 provide?

Answer 11

The act provided incentives for searching for and extracting unconventional natural gas and spurred investment into deep exploration and development drilling.

Question 12

What are the six main categories of unconventional natural gas?

Answer 12

Deep gas
Tight gas
Shale gas
Coal-bed methane
Gas in geopressurized zones
Methane hydrate

Question 13

Define Deep Gas.

Answer 13

Deep gas is typically found 15,000 feet or deeper underground, consider deeper than conventional gas. Therefore, deep gas is relatively expensive to find and produce.

Question 14

Define Tight gas.

Answer 14

Tight gas is trapped in unusually impermeable hard rock or in sandstone or limestone that is highly nonporous (tight sand). Extraction of gas from tight formations typically requires expensive techniques such as fracturing and acidizing.

Question 15

Define Shale gas.

Answer 15

Natural gas can also exist in deposits of shale, a fine-grained and soft sedimentary rock that breaks easily into thin, parallel layers. Gas is typically found in sections where two thick, black shale deposits “sandwich” a thinner area of shale.

Question 16

What are the major shale plays in the US?

Answer 16

Marcellus (Appalachia)
Haynesville (Louisiana/Texas)
Barnett (Texas)
Fayetteville (Arkansas
Woodford (Oklahoma)
Eagle Ford (Texas)
Antrim (Michigan)

Question 17

What are the major oil plays in Canada?

Answer 17

Horn River/Muskwa (northeast BC)
Colorado Group (west-central Saskatchewan/south-central Alberta)
Montney (Alberta)

Question 18

Touch on the productivity of shale gas wells

Answer 18

There is an emergy debate about how rapidly production from a typical shale well is likely to decline and whether that decline rate flattens out over time.

If the curve flattens out slowly, then shale wells will rpduce gas at a reasonably high rate and low cost over a long period of time. By Contrast, if the curve declines more sharply and rapidly, then the ultimately recovered gas reserves from a shale formation could be significantly lower and the production costs could be higher.

For this reason, some experts argue that better models are needed to guide the commitment of financial resources to the continued development of gas-bearing shales.

Question 19

Define Coal-bed Methane

Answer 19

Historically, methane was a nuisance and a safety hazard in the coal-mining industry. Today, however, coal-bed methane has become a popular form of unconventional natural gas, with many projects put in place around the world to extract and market it.

Question 20

Touch on the recoverable coal-bed methane. USA.

Answer 20

In April 2011, the Potential Gas Committee (PGC) estimated that about 158.6 trillian cubic feet of technically recoverable (probably, possible, and speculative) coal-bed methane existed in the United States at the end of 2010.

Question 21

Touch on recoverable coal-bed methane. Australia.

Answer 21

In eastern Australia, coal-bed gas reserves (proved plus probable) grew from about 6 tcf in 2006 to about 27 tcf in 2010, according to Resource and Land Management Services, a consultancy based in Brisbane.

Question 22

Define Geopressurized Gas.

Answer 22

Natural geologic formations in which the pressure is higher than would be expected for a given depth are said to be geopressurized. In these zones, layers of clay have been deposited and compacted quickly on top of sand or silt. The water and natural gas present in the clay have been squeezed out by the compression of the clay and have entered the more porous sand or silt deposits. Owing to this compression, the natural gas in the sand or silt is under very high pressure.

Question 23

Touch on recoverable geopressurized gas.

Answer 23

Geopressurized zones are typically quite deep, usually 10,000-25,000 geet below the surface of the Earth. In the United States, they are located chiefly in the Gulf Coast region. It has been estimated that U.S. geopressurized zones could hold anywhere from 5,000 to 49,000 tcf of natural gas.

Question 24

Define Methane Hydrate.

Answer 24

Another unconventional gas resource under evaluation for potential production in the longer term is methane hydrate. Hydrate is typically a cold, slushlike, crystalline structure consisting of methane molecules trapped in a lattice of water molecules. Such hydrates are abundant in the Arctic (where they were first discovered) and in the marine sediments, below the seabed.

Question 25

Touch on recoverable methane hydrate.

Answer 25

Estimates of the worldwide methane hydrate resource vary from 7,000 to more than 73,000 tcf; however, these numbers are far from certain. Sumstantial additional research is needed to assess how hydrates form, interact with surrounding materials, behave during extraction operations, and potentially affect the environment.

Question 26

Define Liquefied Natural Gas (LNG)

Answer 26

LNG is not a naturally occurring gas resource. Rather, it is created by deeply cooling natural gas (typically to 260F below zero)

Question 27

Define the LNG process.

Answer 27

The process transforms natural gas from gaseous to liquid form-increasing its energy density (Btu per cubic foot) by a factor of about 600-and makes possible the cost-effective shipment of the LNG in insulated tanker ships from gas production regions to major market regions.

Question 28

Touch on the LNG unloading process.

Answer 28

The LNG is then unloaded from the tankers and regasified (i.e. warmed to convert it back into the gaseous state), treated to bring its composition to compliance with market specifications, and then distributed to users through conventional pipeline networks.

Question 29

Touch on the projected trends in gas production

Answer 29

Looking to the future, gas resources from a variety of sources are expected to keep world markets well supplied at relatively low prices for the period from 2007 to 2035, according to EIA. The major increase in production is expected from the Middle East, Africa, and Russia. EIA projects that Iran and Qatar alone will increase production by a combined 12 tcf by 2035-nearly one-fourth of the total growth in global production.

Question 30

How are tight sands, gas-bearing shales and coal beds going to effect gas production?

Answer 30

Tight sands, gas-bearing shales, and coal beds are expected to make major contributions to growth in gas production-and not just in the United States. For example, these three resources are expected to account for 63% of total domestic production in Canada and 56% in China in 2035.

Question 31

What are the areas for projected U.S. Natural gas consumption (2009-2035)

Answer 31

Lease + Plant Fuel
Pipeline Fuel
Transportation
Electric Power
Industrial
Commercial
Residential