Notes on Huawei's Introduction to Petroleum Engineering

WHAT IS PETROLEUM ENGINEERING?

An engineering discipline concerned with activities related to the production of hydrocarbons, which can be either crude oil or natural gas.
A hydrocarbon is an organic compound consisting entirely of hydrogen and carbon and other bonded compounds.
Petroleum is a naturally occurring, flammable liquid found in rock formations in the Earth, consisting of a complex mixture of hydrocarbons of various molecular weights, plus other organic compounds.
If petroleum comes straight out of the ground as a liquid, it is called crude oil if dark and viscous, and condensate if clear and white.
Note: “AASGARD” condensate (as listed in the slides) appears as a label; condensate is a key product from certain gas reservoirs.

WHAT IS PETROLEUM ENGINEER?

A petroleum engineer is involved in nearly all stages of oil and gas field evaluation, development, and production.
Petroleum engineers are divided into several groups:
- Petroleum geologists: find hydrocarbons by analyzing subsurface structures with geological and geophysical methods.
- Reservoir engineers: optimize production via well placement, production levels, and enhanced oil recovery techniques.
- Drilling engineers: manage the technical aspects of drilling exploratory, production, and injection wells; mud engineers manage the quality of drilling fluid.
- Production engineers (including subsurface engineers): manage the interface between the reservoir and the well, including perforations, sand control, downhole flow control, and downhole monitoring equipment; evaluate artificial lift methods; select surface equipment that separates produced fluids (oil, gas, water).

WHERE DOES PETROLEUM ENGINEERS WORK?

Employers: Government, Oil Company, Service Company, Supporting Company, Academic, Others.
Locations: Office, Onland Oil Rig, Offshore Oil Rig, Offshore Production Platform.

HISTORY

Etymology: petroleum derived from Latin Petra (rock) + oleum (oil).
Early uses: Babylonians used oil tar for mortar; Egyptians used oil products for embalming; Romans used crude oil in lamps; Arab scientists advanced distillation to produce kerosene.
Timeline highlights:
- 1821: First Natural Gas Well dug in Fredonia, NY (William Hart).
- 1852: Abraham Gesner (Canadian geologist) rediscovered kerogen/oil concepts.
- 1854: Invention of kerosene lamp leads to the formation of the first American Oil Company.
- 1858: First oil drilled in Canada.
- 1859: Romania becomes a center of oil mining (36,000 bbl/year from seeps); Edwin Drake drills first U.S. oil well in Titusville, PA.

CLASSIFICATION/PRODUCTION CONTEXT (OVERVIEW)

Crude oil and natural gas form from organic sediments; natural gas exists in several forms and can be associated with oil or found in non-associated gas reservoirs.
Fossil fuels are categorized as hydrocarbon resources (in place) vs hydrocarbon producing resources.
Fuels also include coal and oil shale; heavy oil and tar sands/bitumen are more viscous, requiring special processing.
Basic hydrocarbon resources include heavy oil, tar sand/bitumen, oil shale; coal types increase in carbon content and differ in maturity.

NATURAL GAS

Composition: natural gas is a mixture typically 50–90% methane (CH₄) by volume, with smaller amounts of ethane, propane, butane, and hydrogen sulfide.
Gas categories:
- Conventional natural gas vs unconventional gas.
- Conventional gas often lies above oil reservoirs and flows naturally; unconventional gas is found in relatively impermeable rocks (tight sands, coal beds) and often requires fracturing or enhanced extraction.
Unconventional resources technologies: horizontal drilling and hydraulic fracturing; higher well counts are usually required.
Gas types by association:
- Associated gas: gas found with oil (gas cap or dissolved in oil).
- Non-associated (dry) gas: gas produced with little or no condensates.
Gas and condensate relationships:
- Condensate is often produced with gas from condensate wells; condensate is a natural gas liquid (NGL).
- Plant condensate refers to condensates recovered at gas processing plants from dry gas.

1.1) Natural Gas: Dry vs. Wet

Dry natural gas:
- Very high methane content (≈99–100%).
- Remains dry after processing; used for heating, cooling, power generation; compressed dry gas can be used as vehicle fuel.
Wet natural gas:
- Contains liquid natural gases (LNGs) such as ethane or butane; methane content is typically <85%; contains condensates.
- LNGs can be separated and sold as individual compounds.
- Wet gas is common in shale formations discovered by hydraulic fracturing.

1.2) Types of Natural Gas

Raw natural gas comes from:
- Oil wells (associated gas)
- Gas wells
- Condensate wells (wet gas; associated or non-associated depending on oil presence)
Associated gas:
- Gas dissolved in oil; sometimes present in gas cap; often separated at surface.
Non-associated gas:
- Gas wells that primarily produce gas with little or no oil.
- Condensate from non-associated gas is called plant condensate.
Wet gas vs dry gas distinctions:
- Condensate wells produce raw natural gas with natural gas liquids.
- Dry gas wells produce mostly methane-rich gas with no hydrocarbon liquids.

Types of Natural Gas Liquids (NGLs)

Commercial Propane (C3) or Propylene (C3) blend: at least 95% purity; vapor pressure < 215 psig at 100 °F.
Commercial Butane (C4) and Butanes: at least 95% purity; vapor pressure < 70 psig at 100 °F; at least 95% should evaporate at 34 °F or lower in standard test.
Liquefied Petroleum Gas (LPG): mixture of Commercial Propane and Commercial Butane; max vapor pressure < 215 psig at 100 °F; at least 95% must evaporate at 34 °F or lower.
Natural Gasoline: extracted from natural gas; specifications include vapor pressure 10–34 psi, % evaporated at 140 °F: 24–85%, % evaporated at 275 °F: ≥ 90%.

HYDROCARBONS IN CRUDE OIL

Four hydrocarbon types commonly present in crude oil:
- Aliphatic hydrocarbons (paraffins): unsaturated? Actually saturated straight or branched-chain hydrocarbons; typically 15–60% of crude; C:H ≈ 1:2. The shorter the paraffins, the lighter the crude.
- Cycloalkanes (naphthenes): saturated hydrocarbons with one or more carbon rings; typically 30–60% of crude; C:H ≈ 1:2.
- Aromatic hydrocarbons: unsaturated, benzene-like rings; 3–30% of crude.
- Asphaltenes: complex molecules containing C, H, N, O, S, traces of V and Ni; saturated; C:H ≈ 1:1; source-dependent.

HYDROCARBON PRODUCTION SYSTEM

Reservoir rock pore space contains oil, gas, and water; accumulating hydrocarbons form a reservoir.
Reservoir fluids include original reservoir fluids plus fluids introduced during reservoir management.
Wells are drilled and completed to enable fluid flow from reservoir to surface.
Surface facilities, drilling, completion, and operation of wells are essential.
Transportation of produced fluids occurs via pipelines, trucks, tankers, LNG ships.
Refined hydrocarbons serve utilities (natural gas), transportation fuels (gasoline, diesel), and paving (asphalt).

CONVERSION OF KEROGEN TO OIL & GAS

Kerogen (non-hydrocarbon organic matter) is produced when lipids (fat, oil, waxes) are converted by anaerobic bacteria into a waxy substance; major source of oil and gas.
Burial and heating transform kerogen through maturation stages:
- Diagenesis: oxygen content decreases, carbon content increases; CO₂, H₂O, and some N, S, O compounds are released; source rocks are immature.
- Catagenesis: significant decrease in hydrogen content and H/C ratio due to hydrocarbon generation and cracking; main oil generation zone; wet gas with increasing methane.
- Metagenesis: higher temperatures lead to aromatic rearrangements; primarily dry gas generated at this stage; kerogen morphology changes visually (color shifts: yellow → orange → brown → black).

DIAGENESIS, CATAGENESIS, METAGENESIS (Maturity Diagram)

Kerogen evolves from immature to mature to oil and gas generation with increasing depth/temperature.
Van Krevelen diagram is used to present kerogen evolution (C/H and O/C ratios).
Important milestone: dry gas generation begins at ~175 °C.

FRACTIONAL DISTILLATION

Fractional distillation splits crude oil into fractions with different boiling ranges.
Process: crude oil is heated to about 370 °C and fed to a distillation tower (still).
In the tower, rising hot vapors cool as they ascend; heavier fractions condense at lower levels (lower in the tower) and lighter fractions condense higher up.
The tower acts as a heat exchanger, removing heat from vapors as they rise; top products condense near the top; heavier products condense near the bottom.
Result: a spectrum of fractions, each with a characteristic boiling-point range.

WHERE DO PRODUCTS COME OUT OF A STILL?

Distillation tower outputs a set of fractions, each a mix of hydrocarbons with a characteristic boiling range.
Example boiling ranges and products (typical refinery cuts):
- LPG: < 40 °C
- Napthas: 25–175 °C
- Kerosines: 150–260 °C
- Light gas oils: 235–360 °C
- Heavy gas oils: 330–380 °C
- Lubricants: 340–575 °C
- Fuel oil: > 490 °C
- Bitumen: > 580 °C

DISTILLATION FRACTION TABLE (USES AND BP RANGES)

LPG (BP < 40 °C): Bottled and sold as LPG; feedstock for petrochemical processes.
Napthas (BP 25–175 °C): Feedstock for further processing; chemical feedstock.
Kerosines (BP 150–260 °C): Aviation fuel.
Light gas oils (BP 235–360 °C): Feedstock for catalytic crackers.
Heavy gas oils (BP 330–380 °C): Feedstock for catalytic crackers; base for lubricants.
Lubricants (BP 340–575 °C): Base oils for lubrication and other products.
Fuel oil (>490 °C): Fuel for power stations and ships; also used as feedstock for refining processes.
Bitumen (>580 °C): Road and roof surfaces; paving.

THE FIRST OIL WELL

Modern oil industry dates to about 150 years ago.
Drake Well (Titusville, Pennsylvania) drilled in 1859; struck oil at 21 meters; produced about 3,000 liters per day.
Drake’s success spurred an international search for petroleum and reshaped modern life.

HOW LONG WILL THE WORLD’S OIL LAST?

Oil formed over millions of years; current known reserves are large but finite.
Discovered reserves are over 1,000,000 million barrels (1 trillion barrels).
Reserves numbers rise each year due to new discoveries and improved extraction technologies.

WORLD OIL RESERVES BY REGION (KEY REGIONS & SHARES)

Asia & Oceana: ~3%
Africa: ~9%
North America: ~16%
Middle East: ~56%
Central & South America: ~8%
Europe: ~1%
Eurasia: ~7%
Note: These are regional shares of world proven oil reserves as listed in the notes.

WORLD PROVEN OIL RESERVES – COUNTRIES (EXAMPLES)

Saudi Arabia: reserves ~688,860,600,000 bbl; date 2011.
Canada: ~264,600,000,000 bbl; date 2011.
Iran: ~175,200,000,000 bbl; date 2011.
Iraq: ~137,600,000,000 bbl; date 2011.
Kuwait: ~115,000,000,000 bbl; date 2010.
United Arab Emirates: ~104,000,000,000 bbl; date 2010.
Venezuela: ~97,770,000,000 bbl; date 2010.
Russia: ~74,200,000,000 bbl; date 2009.
Libya: ~47,000,000,000 bbl; date 2010.
Nigeria: ~37,500,000,000 bbl; date 2007.

WORLD OIL PRODUCERS (EXAMPLES WITH SHARES)

Top producers (as of 2011 data in the notes):
- Arab League: share ~29.71% of world production; production around 87,500,000 bbl/day.
- Russia: share ~12.01%; production around 10–11 million bbl/day in the cited data.
- Saudi Arabia: share ~11.59%; production around ~8.8–9.0 million bbl/day in the cited data.
- United States: share ~10.75%; production around ~7.8 million bbl/day in the cited data.
Note: The exact numbers in the notes are presented with formatting inconsistencies; the key takeaway is the relative ranking and the approximate world production level (~87.5 million bbl/day in the referenced period).

WORLD OIL EXPORTERS

Major exporters include countries such as Saudi Arabia, Russia, United Arab Emirates, Canada, Nigeria, Kuwait, Iran, Iraq, Venezuela, etc., with export volumes reported in the notes for various years.
The notes list specific export values (in bbl/day) tied to particular years (e.g., 2004–2010 estimates). Use those as reference points for historical context.

WORLD OIL CONSUMERS

Major consuming regions include United States, European Union, China, Japan, India, and others.
The notes provide consumption figures (bbl/day) and corresponding dates (years like 2004, 2007, 2008, etc.).

WORLD PROVEN NATURAL GAS RESERVES

Global perspective: natural gas reserves are extensive and distributed unevenly by region.
World natural gas producer (examples from the notes):
- United States: ≈3,127,000,000,000 m³ per year (2009 est.).
- Russia: ≈583,600,000,000 m³ (2009 est.).
- Iran: ≈200,000,000,000 m³ (2009 est.).
- Canada: ≈161,300,000,000 m³ (2009 est.).
- Norway: ≈103,500,000,000 m³ (2009 est.).
Note: The figures reflect regional and national production more than reserves, and dates are provided (2008–2009 estimates).

WORLD NATURAL GAS EXPORTERS

Major exporters include Saudi Arabia, Russia, Canada, United Arab Emirates, Algeria, Netherlands, Qatar, Turkmenistan, Nigeria, Indonesia, Malaysia, United States, etc., with export volumes in cubic meters and dates around 2007–2010.

OIL AND GAS UNITS

Two main unit systems appear in petroleum literature:
- Oil Field Units
- SI (Metric) Units
Common conversions (examples from the table):
- Length: ft (oil field) vs m (SI)
- Time: hr (oil field) vs sec (SI)
- Pressure: psia (oil field) vs Pa (SI)
- Volumetric flow rate: bbl/day (oil field) vs m³/s (SI)
- Viscosity: cp (centipoise) vs Pa·s (SI)
- Surface energy units (lbf/ft²) and volumetric flow terms (ft³/s) are used in oil-field contexts.

PRODUCTION PERFORMANCE RATIOS

Purpose: quantify the relationship between produced fluid phases to understand reservoir dynamics.
Define production rates: qo (oil), qw (water), q_g (gas).
Ratios:
- Gas-Oil Ratio (GOR): GOR = rac{qg}{qo}
- Gas-Water Ratio (GWR): typically GWR = rac{qg}{qw} (gas per unit water)
- Water-Oil Ratio (WOR): WOR = rac{qw}{qo}
- Water-Cut (WCT): fraction of water in produced fluids; commonly WCT = rac{qw}{qo + qw + qg} or, in some contexts, WCT = rac{qw}{qo + q_w} depending on whether gas is counted in the total stream.
Separator: equipment used to separate produced fluids into oil, water, and gas streams.
Example 1 (GOR): If a well produces 500 MSCF/day gas and 400 STB/day oil, then
- GOR = rac{500}{400} = 1.25 ext{ MSCF/STBO}
Note: The notes express GOR in MSCFG/STBO (thousand standard cubic feet of gas per stock tank barrel of oil).

EXAMPLE 1: GAS-OIL RATIO

Given: 500 MSCF gas/day and 400 STB oil/day.
Calculation: GOR = rac{qg}{qo} = rac{500}{400} = 1.25 ext{ MSCFG/STBO}

CLASSIFICATION OF OIL AND GAS

Surface conditions: surface temperature and pressure are usually lower than reservoir conditions.
Hydrocarbon fluids may exist as a single phase at reservoir conditions and transition to two phases at surface (due to pressure drop and temperature change).
Natural gas is gaseous at surface; crude oil is liquid at surface; heavy oils have limited gas in solution at reservoir conditions.

API GRAVITY

API gravity is defined in terms of oil specific gravity Y (relative to water):
Formula: API ext{ gravity} = rac{141.5}{Y} - 131.5
Where: Y = rac{
hoo}{ how} (oil density over water density).
Example 2: If oil SG is 0.85, then
- API = rac{141.5}{0.85} - 131.5
= 166.47 - 131.5
≈ 35^ ext{o}

CLASSIFICATION OF OIL AND GAS (API/Viscosity/Density Context)

Liquid hydrocarbon properties often summarized by API gravity and viscosity (cp).
A table indicates:
- Light oil: API > 31.1
- Medium oil: API 22.3–31.1
- Heavy oil: API 10–22.3
- Extra heavy oil: API 4–10
- Bitumen: API 4–10; viscosity typically > 10000 cp
Viscosity and density relationships: water has viscosity ≈ 1 cp and density ≈ 1 g/cm³ at 60°F; hydrocarbons have higher or lower viscosities depending on type; tar/asphaltic materials have very high viscosities.

LIFE CYCLE OF A RESERVOIR

Production can begin immediately after discovery or after appraisal and delineation wells.
Appraisal wells provide information about reservoir properties and fluid flow.
Delineation wells better define reservoir boundaries.
Production profile phases:
- Buildup (pre-production rise in oil rate)
- Plateau (production rate stabilizes)
- Decline (production falls)
- Abandonment when economic limit is reached
Key drivers: facility capacity (e.g., pipeline capacity) often defines plateau; ongoing economics drive end-of-field decisions.

RECOVERY EFFICIENCY

Recovery efficiency (RE) is the ratio of fluid volume remaining in the reservoir after production to the fluid volume originally in place.
Two contributing factors:
- Displacement efficiency (ED): fraction of original oil that can be mobilized by displacement processes.
- Volumetric sweep efficiency (Evol): product of areal sweep efficiency (EA) and vertical sweep efficiency (EV).
Definitions:
- Oil Saturation (Soi): initial oil saturation; (Soa): oil saturation at abandonment.
- Formation Volume Factor (FVF): volume occupied by a fluid at reservoir conditions divided by the volume occupied at standard surface conditions.
Formulas:
- Displacement efficiency: ED = rac{S{oi} - S{oa}}{S{oi}} imes rac{(B{oi})}{(B_{oa})}
 (Note: the slides show a ROUGH form; the standard definition is often ED = (Soi - Soa)/Soi. The Bo terms relate to formation volume factors at initial and abandonment states.)
- Areal sweep efficiency: E_A = rac{ ext{swept area}}{ ext{total area}}
- Vertical sweep efficiency: E_V = rac{ ext{swept net thickness}}{ ext{total net thickness}}
- Volumetric sweep efficiency: $E{vol} = EA imes E_V$
- Recovery efficiency: $RE = ED imes E{vol} = ED imes EA imes E_V$
All efficiencies range from 0 to 1 and can combine to yield overall recovery.

EXAMPLE 3: FORMATION VOLUME FACTOR (FVF)

Given: Oil occupies 1 bbl at stock tank (surface) conditions and 1.4 bbl at reservoir conditions.
Calculation:FVF = rac{ ext{Volume at reservoir}}{ ext{Volume at surface}} = rac{1.4}{1.0} = 1.4 ext{ RB/STB}

EXAMPLE 4: RECOVERY EFFICIENCY

Problem data (as in the notes):
- Area swept: 750 acres, Total area: 1000 acres.
- Thickness swept and other area/thickness data provided (not all numbers shown in the excerpt).
Answers provided in the notes:
- Displacement efficiency: $E_D = 0.6$
- Areal sweep efficiency: $E_A = 0.75$
- Vertical sweep efficiency: $E_V = 0.667$
- Volumetric sweep efficiency: $E{vol} = EV imes E_A = 0.5$
- Recovery efficiency: $RE = ED imes E{vol} = 0.3$

ACTIVITY #1 (EXERCISES)

Problem 1: Density-based properties
- Given oil density: 48 lb/ft³; water density: 62.4 lb/ft³. Compute the oil’s specific gravity (SG) and API gravity.
Problem 2: Recovery efficiency estimate
- Given displacement efficiency = 30%, areal sweep efficiency = 65%, vertical sweep efficiency = 70%.
- Compute Evol and RE if needed.
Problem 3: Water cut and WOR
- A well produces 1000 STB oil/day with water cut = 25%. A) Compute water production rate (STB water/day). B) Compute WOR.

SUMMARY OF KEY FORMULAS (RELEVANT TO EXAM)

API gravity from SG: $API = \frac{141.5}{Y} - 131.5$ where Y = rac{\rhoo}{\rhow}
SG from density: $Y = \frac{\rhoo}{\rhow}$ (oil density over water density)
GOR: $GOR = \frac{qg}{qo}$
GWR: $GWR = \frac{qg}{qw}$
WOR: $WOR = \frac{qw}{qo}$
WCT: $WCT = \frac{qw}{qo + qw + qg}$ (or alternative definitions as noted)
Areal sweep efficiency: $E_A = \frac{\text{swept area}}{\text{total area}}$
Vertical sweep efficiency: $E_V = \frac{\text{swept net thickness}}{\text{total net thickness}}$
Volumetric sweep efficiency: $E{vol} = EA \times E_V$
Recovery efficiency: $RE = ED \times E_{vol}$
Displacement efficiency (typical form): $ED = \frac{S{oi} - S{oa}}{S_{oi}}$ (with formation-factor considerations as appropriate)
Formation volume factor (FVF): $FVF = \frac{V{ ext{reservoir}}}{V{ ext{surface}}}$
Fractional distillation concept: heavier fractions condense lower in the still; lighter fractions rise higher and exit at the top.
Distillation tower operating summary: feed heated to ~370°C; products condensed in order of boiling point as vapors rise and cool.
Common refinery cuts and approximate BP ranges: LPG (

CONNECTIONS AND CONTEXT

Links to foundational principles:
- Thermodynamics of phase behavior (single-phase to two-phase transitions at the surface).
- Maturation of kerogen connects to geological time scales and maturation diagrams like Van Krevelen.
- Reservoir engineering concepts: permeability, porosity, saturation, capillary pressure relate to how recovery efficiency is defined and improved.
Real-world relevance:
- Understanding of GOR, WOR, and GWR informs production strategies and well completion designs.
- Fractional distillation is the basis for refining crude oil into useful fractions.
- API gravity is used to grade crude quality and affects pricing and processing routes.
Ethical and practical implications:
- Resource management and environmental considerations in production profiles.
- Technological advancement (e.g., hydraulic fracturing) has social, economic, and regulatory implications.