Energy and the Environment

What are the major contributors to hydrocarbon “spills” in marine environments?

47% Natural Seeps, 3% Extraction of Petroleum, 12% Transportation of Petroleum, 38% Consumption of Petroleum.

What is the fate of light, medium-weight, and heavy hydrocarbons once they seep into marine environments?

1. Low Density HC evaporate or dissolve into seawater within 24 hours

2. Medium density HC metabolized by microbes or oxidized abiotically within weeks

3. High Density HC settles & incorporated into sea floor sediment

How are macro-organisms affected by ingesting or being covered in hydrocarbons?

1. Ingestion/ respiration: Inflammation of tissues & organs, and Damage organ systems

2. Light/med HC (including PAH) are lipid soluble - long residence time in tissues

3. Polycyclic Aromatic Hydrocarbons (PAH) are carcinogenic, enzyme disruptors, and immune suppressors 

4. Covers integument (outer surface, skin, fur, respirators, feathers, locomotion)

5. Limits photosynthesis
   

What is a well blowout?

loss of fluid pressure control & uncontrolled releases of HC in environments hundreds of thousands to millions of gallons/day

What is a relief well?

Relief wells intercept the blown well at depth
Relief wells intercept the blown well at depth. Typically, mud, cement, steel balls, etc. is pumped down relief wells to stop the flow.

How do dispersants and “fertilizers” enhance microbial activity during a hydrocarbon spill?

Dispersants help disperse the HC over a larger area and this allows more microbes to have access to metabolizing the HC. Fertilizers help microbes grow and gives nutrients to them to help them multiply and thrive to eat more HC.

What were some of the technical and human errors that led to the DWH blowout and
explosion?

1. Errors in well development of pressure test

2. Fewer centralizers than recommended 6 out of 21 

3. No final cement bond log —> test that measures how well the cement adheres to the casing & rock

4. Use unstable cement slurry

5. Incorrect interpretation of pressure tests

6. Failure of the blowout preventer (BOP)

What is the estimated final fate of the released DWH hydrocarbons?

5% - evaporated into atmosphere,

2-15% - moved or flowed to the surface then redeposited on the sea floor as “marine snow”,

17-25% - gathered by humans,

43-61% of oil continued to distribute via deep sea currents (100% natural gas).

Under what circumstances is the Corexit dispersant toxic to marine macro-organisms?

1. Dispersant only —> slightly toxic to nontoxic

2. Disp. + Oil —> moderately toxic

What do experimental results indicate regarding the effectiveness of Corexit?

Lab experiments indicate more “marine snow” was produced by Corexit i.e. greater incorporation of HC in sediment & deep currents

Corexit increased the abundance of dispersant eating microbes. Not all HC eating microbes. Oil only> any Corexit treatment

What components of a conventional hydrocarbon system are missing from a shale play?

Shale plays typically lack a distinct migration pathway and trap/seal because the hydrocarbons are extracted directly from the source rock

What is the goal of hydraulic fracturing?

Extract HC from source rock or reservoir rocks with low permeability

What are common chemicals/additives in frac fluid and what are their purposes?

Acids - Helps dissolve minerals and intiate fissures in rock (prefecture)

Breaker - Allows a delayed breakdown of the gel polymer chains

Friction Reducer - Minimizes the friction between fluid and pipe

Scale inhibitor Prevents scale deposits in the pipe

Borate Salts - Maintains fluid viscosity as temps. increase

Sodium/Potassium Carbonate - Maintains effectiveness of other components, such as crosslinkers

Biocide - Eliminates bacteria in the water

Guar Gum - Thickens the water to suspend the sand

Iron Control - Prevents precipitation of metal oxides

Isopropanol - Used to increase the viscosity of the fracture fluid.

What is the definition of a “water stressed area”?

Human activities consume a significant amount of the naturally available water, ≥10%

What is water flooding and enhanced oil recovery in the context of conventional oil?

Water Flooding: Inject water into reservoir to attain original pore pressure and increase production and prevent anthropogenic subsidence caused by reduction of pore pressure.

Enhanced Oil Recovery: Carbon dioxide (60% EOR operations in US), steam (40% in US), or surfactants (< 1 % in US) pumped into reservoir to lower viscosity and surface tension of hydrocarbons

How does water use compare between conventional oil and HF oil?

Conv. NG<HF NG < Conv. Oil (without EOR) < HF Oil < Conv. with EOR

Conventional oil recovery has a higher water demand due to the EOR methods involved

How do abandoned wells pose a risk for groundwater contamination?

Gas or Oil can move into the abandoned well from active wells displacing HC. Gas can then travel to surface and leak into aquifers or faults in the ground.

Generally speaking, how likely is the fracture system produced by HF to intersect potable aquifers?

Not Uncommon

How was the Ohio River watershed affected by “treated” wastewater released into local rivers and streams?

Effluent salt conc 600x river levels
→ Increased salt content of rivers
→ Increased concentration of naturally occurring radioactive materials (NORM) in river sediment

How does pore pressure affect stick-slip behavior?

More normal force (confining pressure) at fault = greater friction = more stress required to produce an earthquake

More pore pressure = less normal force = less friction = less stress required to produce an earthquake

What is the evidence that wastewater injections caused the 2011 Wilzetta Oil Field earthquakes?

20% of earthquakes occurred in injected
sedimentary layers

Why did it take 18 years of pore pressure change to induce an earthquake?

Earthquakes occur when stress at the fault plane exceeds friction at the fault plane. Expect pressure to dissipate on short timescales when injecting fluids into
disposal wells. Pore pressure built up over 18 years until reaching the critical pressure in 2011.

What makes oil sands an unconventional hydrocarbon system?

The composition of Oil sands is a mixture of Bitumen, sand, clay, and water. Usually, shallow deposits cannot naturally flow up a well. Uses Mined open pit or SAGD for deeper reserves.

What is steam assisted gravity drainage (SAGD)?

Drilling two directional wells an upper and lower well. the Upper well pumps steam and surfactants into the reservoir to decrease viscosity of Oil sand. Then the Oil sand drains downward from gravity into the lower well where it is then pumped to surface.

Why is the EROI of oil sand hydrocarbons so low?

High water uses for both in-situ and ex-situ. Upgrading Bitumen to Synthetic Oil cost money. Bitumen needs to be diluted into Dilbit to be pumped, lower energy density overall.

How does the water-oil ratio (WOR) of oil sand extraction compare with the WOR of
conventional oil?

1. Ex Situ: 2.5- 9 WOR (80% recycled)

2. In-Situ: 0.21 - 3 WOR (90% recycled)

3. HF: 0.2 - 1.4 WOR. Conv. oil: 0.1 - 5 WOR

What are the characteristics of mature fine tailings (MFT; the waste material from oil sand extraction)?

Very fine particles that stay suspended in the water, takes a long time to settle. Fine clay particles

What is reclamation debt?

the financial and environmental obligations associated with restoring land and ecosystems disturbed

Are carbon dioxide emissions estimated to be greater for ex situ or in situ extraction methods?

In-Situ has higher emissions

Are the carbon dioxide emissions from oil sand operations four times greater than those of conventional oil?

Yes

What is the benefit of mixing diluent with bitumen when transporting bitumen via pipeline?

Dilbit flows relatively well in pipelines. Companies don’t need to build upgrading facilities for Syncrude production.

Why was the clean-up of spilled dilbit at Kalamazoo more difficult than the clean-up of a conventional oil spill?

Bitumen went into a tributary.

Dilutants evaporated quickly leaving the highly viscous bitumen.

Made it harder to remove from riverbed. Stuck to riverbed.