Intro to Petroleum Mid-Term Study Guide

1. Engineering Ethics

  • SPE Code of Conduct: The Society of Petroleum Engineers (SPE) Code of Conduct is a set of ethical guidelines that emphasize integrity, responsibility, and professionalism. Key points include respecting public safety, honesty in reporting and analysis, environmental stewardship, and a commitment to lifelong learning.

2. History of Oil and Gas

  • Initial Uses of Oil: Historically, oil was used for lighting, lubrication, and waterproofing materials. Its adoption for energy purposes grew with technological advancements.

  • Energy Density Concept: This refers to the amount of energy stored per unit volume or mass. A barrel of oil, for instance, contains the energy equivalent to approximately 10.5 years of human labor.

  • Biomass, Coal, and Oil and Gas: Energy density is highest in oil and gas, followed by coal and then biomass, which made oil and gas pivotal for industrial growth and population expansion.

  • Impact on Population Growth: High energy density fuels enabled significant advancements in industry and agriculture, leading to rapid population growth.

  • Usage Projections to 2050: Oil and gas usage is expected to decline as renewable energy sources increase, though they will remain significant sources of energy.

  • Energy Transition Areas Requiring Subsurface Skills: Carbon capture and storage (CCS), geothermal energy, and hydrogen storage are some areas in the energy transition needing subsurface engineering expertise.

3. Geology

  • Elements for Conventional Hydrocarbon Accumulation: Source rock, migration pathway, reservoir rock, trap, and seal.

  • Difference Between Conventional and Unconventional Reservoirs: Conventional reservoirs have permeable rock allowing easy oil/gas extraction, whereas unconventional reservoirs (like shale) require advanced techniques like hydraulic fracturing.

  • Source Rock Requirements: Must have significant organic material, kerogen type, sufficient thermal maturity, and migration capability.

  • Typical Reservoir Rocks: Sandstone, limestone, and dolomite.

  • Clastic vs. Carbonate Reservoirs: Clastic reservoirs are sedimentary, with fragmented rock grains, while carbonate reservoirs form primarily from marine organisms.

  • Typical Clastic Depositional Environments: Rivers, deltas, beaches, and deserts.

  • Laminations and Formation: Layers within sedimentary rocks, often formed by seasonal variations or changes in depositional environment.

  • Clastic Sedimentary Rock Description: Described by grain size, sorting, and composition to understand porosity and permeability.

  • Phi Grain Size Scale: A logarithmic scale that helps classify sediment grains; it assists in grain size distribution analysis.

  • Clastic Porosity Changes: Higher porosity with rounded, well-sorted, and smaller grain sizes.

  • Post-Depositional Factors Affecting Porosity and Permeability: Compaction, cementation, and dissolution. Compaction is often the most influential.

  • Sealing Lithology in Clastic Rocks: Shale and mudstone typically act as seals.

  • Typical Trapping Configurations: Structural (anticlines, faults) and stratigraphic traps.

4. The Crust and Geologic Time

  • Sedimentation Stages in Outcrops: Sedimentation, compaction, uplift, erosion, and burial stages.

  • Plate Tectonics: Theory explaining the movement of Earth’s lithospheric plates. In petroleum engineering, it is crucial for understanding basin formation and hydrocarbon traps.

  • Three Principal Subsurface Stresses: Vertical stress, maximum horizontal stress, and minimum horizontal stress.

  • Stress Regimes and Hydrocarbon Basins:

    • Extensional Regime: Rift basins (e.g., East Africa).

    • Compressional Regime: Foreland basins (e.g., Rocky Mountains).

    • Strike-Slip Regime: Transform boundaries (e.g., San Andreas Fault).

  • Importance of Subsurface Stresses: Understanding stresses aids in wellbore stability, fracture stimulation, and reservoir management.

  • Hydrostatic Pressure: Pressure due to the weight of fluid at a given depth. Overpressure is pressure exceeding hydrostatic pressure due to rapid burial or fluid migration.

5. Reservoir Fluids

  • Organic Components in Natural Gas and Crude Oil: Methane, ethane, propane, butane, and hydrocarbons with varying chains.

  • Valuable Components: Methane is highly valuable for its versatility as a fuel.

  • Physical Properties of Hydrocarbons:

    • Specific Gravity: Density of the hydrocarbon compared to water.

    • API Gravity: Measures the density of crude oil.

    • Viscosity: Measures resistance to flow.

  • Phase Diagram and Fluid Phase Changes: Shows temperature and pressure changes that affect fluid phases (liquid, gas).

  • Bubble Point and Dew Point: The bubble point is the pressure where liquid starts to vaporize, and the dew point is where vapor begins to condense.

  • PT Path Differences in Reservoir vs. Production: PT path in the reservoir is stable compared to the fluctuations seen during production due to pressure drops and cooling.