Unconventional Oil and Gas Production

Introduction to Unconventional Oil and Gas

• The 21st century has seen a shift from conventional oil and gas production to unconventional methods like fracking and deepwater drilling.

• Peak Oil Hypothesis: Predicts that conventional oil production will decline as easily accessible reserves are depleted.

Oil and Gas Geology

• Sedimentary Basins: Locations where oil and gas accumulate.

• Sedimentary Rocks in Oil and Gas Production:

  • Sandstone: Mainly quartz, good reservoir rock.

  • Carbonates (Limestone & Dolomite): Can contain oil and gas.

  • Shale: Source rock requiring fracking.

Fracking (Hydraulic Fracturing)

• Definition: The process of injecting high-pressure fluids to fracture shale rock and release oil and gas.

• Shale Oil vs. Conventional Wells:

  • Shale wells decline more rapidly in production than conventional wells.

• Environmental Effects of Fracking:

  • Air Pollution: Methane leakage contributes to greenhouse gas emissions.

  • Water Contamination:

    • Uses ~4 million gallons of water per well, generating ~2 million gallons of wastewater.

    • Concerns over faulty well casings and methane migration into drinking water.

  • Induced Seismicity: Wastewater injection can increase earthquakes, especially at injection volumes above 300,000 barrels/month.

Climate and Market Effects

• Methane Emissions:

  • The climate impact of natural gas depends on methane leakage rates.

  • If leakage is low, switching from coal to natural gas reduces greenhouse gas emissions.

• Market Effects of Fracking:

  • Increased supply → Lower oil and gas prices.

  • Greater energy independence for the U.S.

Enhanced Oil Recovery (EOR)

• Definition: Techniques used to extract remaining oil from reservoirs after conventional extraction.

• CO₂ Injection:

  • CO₂ is pumped into reservoirs to increase pressure and recover additional oil.

Deepwater Oil Production

• Offshore Drilling: Extracting oil from deep beneath the ocean floor.

• Types of Offshore Drilling Rigs:

  • Jackup Rigs: Cost $75,000 – $150,000 per day.

  • Drillships: Cost $300,000 – $600,000 per day.

• Example: Perdido offshore platform ($3 billion investment).

• Energy Return on Investment (EROI):

  • Unconventional oil has a lower EROI than conventional oil, meaning more energy input is required for extraction.

Summary of Key Takeaways

1. Fracking has revolutionized oil and gas production, increasing available reserves but with environmental concerns.

2. The U.S. has largely exhausted conventional oil and gas but has large unconventional reserves.

3. EOR and deepwater production are expanding but are more expensive and energy-intensive.

4. EROI of unconventional oil is lower than conventional oil, making it less efficient in terms of energy return.

Sample Quiz Questions

True or False

1. Shale oil wells decline in production more rapidly than conventional wells. (T)

2. Hydraulic fracturing does not require large amounts of water. (F, it requires millions of gallons per well).

3. CO₂ injection is a method used in enhanced oil recovery (EOR). (T)

4. The U.S. has abundant reserves of conventional oil and gas. (F, most conventional reserves are depleted).

5. Offshore drilling is generally cheaper than land-based fracking. (F, offshore drilling is more expensive).