Lec 4

Question 1

Are filamentous bacteria that conduct electricity across
distances over | cm In sediment and groundwater
aquifers.

Answer 1

Cable bacteria

Question 2

Economical and environmental aspects of using nitrate

Answer 2

1. Nitrate treatment is ecofriendly. No harm is done
2. storage area is free from the irritating
3. cost of nitrate 1s cheaper than conventional biocide treatment.
4. existing biocide injection pumps can handle the required nitrate volumes.

Question 3

Nitrate injection led to:
عددي

Answer 3

—Increase in NRB in the biofilm
—Decrease in SRB numbers and H2S.
— Corrosion 1s reduced.

Question 4

Prior to nitrate injection:
عددي

Answer 4

— SRB population dominated the biofilm.
— Gradual increase in sulfate reduction activity.
— Increased corrosion
—NRB and SOB were at low numbers.

Question 5

• chemolithotrophic bacteria
• produces biogas

Answer 5

Nitrate reducing-Sulfide-oxidizing bacteria (NR-SOB)

Question 6

Why Water injection into the oil reservoirs radically change the conditions for the microbes especially in the region close to the injection well?
عددي

Answer 6

because
1. stagnant reservoir fluids become diluted with the injection water.
2. Reservoir temperature
3. Introduction of oxygen and aerobic bacteria.
4. Introduction of sulfate and its derivates.
5. Introduction of indigenous SRB of sea water.
6. Introduction of nitrogen and phosphorus sources.

Question 7

Reservoir souring is the presence of an ………..
concentration of hydrogen sulfide (H2S)

Answer 7

increasing

Question 8

Reservoir souring can occur as a result of …………… into hydrocarbon reservoirs and exposing fluids to foreign microbes over an extended period of time.

Answer 8

injecting water

Question 9

Oil and gas export lines have a minimum allowable
concentration of H2S.
T/F?

Answer 9

F, maximum

Question 10

Limitation of applying the sour service metallurgy in control the H2S?

Answer 10

it costs 2% of the total project cost.

Question 11

Limitation of Chemical scavenger treatments in control of H2S?

Answer 11

• Cost implications
• Logistical implications due to the introduction of contaminating chemicals.

Question 12

How many species of SRB isolated from oil fields?

Answer 12

14 species , from 4-85° C

Question 13

SRB are also nutritionally diverse and are able to use?

Answer 13

different electron donors and carbon sources present

Question 14

abundant in the formation water at concentrations as high as 1,500 mg/liter.

Answer 14

Acetate

Question 15

• Less abundant in the formation water than acetate.
• oxidized to acetate by SRB.

Answer 15

Propionate

Question 16

—Is a short-chain HC.
—Is a constituent of residual oil.
—Is completely oxidized by SRB

Answer 16

Hexadecane

Question 17

techniques that are used to prevent H2S from being formed

Answer 17

Prophylaxis

Question 18

techniques thats the HS after it has been generated from the reservoir.

Answer 18

Masking the symptoms

Question 19

techniques that are used to reduce the amount of H2S that is generated.

Answer 19

Partial cures

Question 20

most common chemical used to discourage the SRB?

Answer 20

Addition of ammonium bisulfate (NH4HSO4)

Question 21

functions of Addition of ammonium bisulfate (NH4HSO4)

Answer 21

○ easily available nitrogen source for growth of beneficial bacteria (SOB+ NRB), Decrease H2S
○ used as oxygen scavenger prevent:
1. Oil biodegradation by aerobic bacteria
2. Chemical corrosion of pipelines

Question 22

water flooding step is essential for what?

Answer 22

1. Maintaining reservoir pressure.
2. Sweeping oil towards the production wells.

Question 23

needs to be applied in order to maximise recovery?

Answer 23

water injection