Crude Oil Properties and Characterization

Crude Oil Composition

• Detailed analysis of the hydrocarbon families present in crude oil: paraffins (alkanes), naphthenes (cycloalkanes), aromatics, and resins/asphaltenes. Understanding the chemical structure and properties of each family, including their impact on crude oil viscosity, density, and processability.
• Non-hydrocarbon components: sulfur compounds (hydrogen sulfide, mercaptans, disulfides), nitrogen compounds (pyridines, quinolines, porphyrins), oxygen compounds (carboxylic acids, phenols), and trace metals (vanadium, nickel). Studying their role in corrosion, catalyst poisoning, and environmental concerns.
• Detailed examination of SARA analysis (Saturates, Aromatics, Resins, Asphaltenes) and its use in characterizing crude oil fractions and predicting behavior during refining processes.

Crude Oil Physical Properties

• Viscosity: Newtonian and non-Newtonian behavior of crude oil; factors affecting viscosity (temperature, pressure, composition); measurement techniques (rotational viscometers, capillary viscometers); viscosity correlations (e.g., Beggs and Brill, Vasquez-Beggs) and their limitations.
• Density and Specific Gravity: Measurement methods (hydrometers, pycnometers, vibrating tube densitometers); density correlations and their use in estimating oil reserves and pipeline transportation. API gravity and its classification of crude oils.
• Pour Point and Cloud Point: Understanding the wax precipitation mechanism and its impact on crude oil flowability at low temperatures. Pour point depressants and their mechanism of action.
• Boiling Point Distribution: True Boiling Point (TBP) distillation and simulated distillation (Gas Chromatography) techniques. Analyzing TBP curves to determine the composition and potential yield of various refinery products.

Water Chemistry in Oil and Gas Production

Formation Water Composition and Properties

• Detailed analysis of major ions (Na+, Ca2+, Mg2+, Cl-, SO42-, HCO3-) and minor ions (Sr2+, Ba2+, Fe2+) in formation water. Understanding their sources and significance in terms of scale formation, corrosion, and reservoir souring.
• Salinity and Total Dissolved Solids (TDS): Measurement techniques and their impact on fluid properties, scale formation potential, and produced water treatment.
• pH and Alkalinity: Buffering capacity of formation water and its influence on corrosion rates. The role of dissolved CO2 and H2S in controlling pH.
• Redox Potential (Eh): Understanding the oxidation-reduction reactions in the reservoir and their impact on corrosion and microbial activity.

Scale Formation and Control

• Mechanisms of scale formation: solubility product, supersaturation, nucleation, crystal growth. Understanding the thermodynamics and kinetics of scale precipitation.
• Types of scales: calcium carbonate (CaCO3), calcium sulfate (CaSO4), barium sulfate (BaSO4), strontium sulfate (SrSO4), iron sulfide (FeS). Factors affecting the precipitation of each type of scale.
• Scale prediction: using software and thermodynamic models to predict the scaling potential of formation water. Stiff and Davis, Ryznar Stability Index, Puckorius Scaling Index.
• Scale inhibitors: classification of scale inhibitors (phosphonates, polyacrylates, polymers); mechanisms of action (threshold inhibition, crystal distortion, dispersion); application methods (squeeze treatment, continuous injection).

Corrosion Chemistry and Control

• Electrochemical nature of corrosion: anode, cathode, electrolyte, and electron flow. Understanding the principles of oxidation and reduction reactions.
• Types of corrosion: uniform corrosion, pitting corrosion, galvanic corrosion, erosion corrosion, stress corrosion cracking, microbiologically influenced corrosion (MIC).
• Factors affecting corrosion rates: temperature, pH, salinity, flow velocity, presence of dissolved gases (CO2, H2S, O2).
• Corrosion inhibitors: classification of corrosion inhibitors (filming amines, imidazoline derivatives, phosphate esters, quaternary ammonium compounds); mechanisms of action (adsorption, film formation, neutralization); application methods (batch treatment, continuous injection).
• Materials selection: understanding the corrosion resistance of different materials used in oil and gas production (carbon steel, stainless steel, duplex stainless steel, corrosion-resistant alloys).

Gas Hydrates

Hydrate Formation and Dissociation

• Understanding the structure of gas hydrates: clathrate hydrates, cage structures (structure I, structure II, structure H).
• Factors affecting hydrate formation: temperature, pressure, gas composition, water salinity, presence of hydrate inhibitors. Hydrate equilibrium curves.
• Hydrate dissociation mechanisms: depressurization, thermal stimulation, chemical inhibition.
• Kinetic hydrate inhibitors (KHIs) and thermodynamic hydrate inhibitors (THIs): Polymer based, alcohol-based, and salt-based inhibitors. Mechanisms of action and limitations.

Hydrate Prevention and Remediation

• Strategies for hydrate prevention: maintaining temperature above the hydrate formation temperature, reducing pressure below the hydrate formation pressure, injecting hydrate inhibitors.
• Hydrate remediation methods: depressurization, heating, chemical injection. Understanding the risks associated with each method.
• Hydrate monitoring and detection: using temperature and pressure sensors, flow meters, and acoustic monitoring to detect hydrate formation.

Asphaltenes and Paraffins

Asphaltene Precipitation and Deposition

• Chemical structure of asphaltenes: polycyclic aromatic hydrocarbons with alkyl side chains and heteroatoms (N, S, O).
• Factors affecting asphaltene precipitation: pressure, temperature, composition (alkane content, aromaticity), mixing with incompatible fluids.
• Asphaltene precipitation modeling: using thermodynamic models to predict asphaltene onset and deposition.
• Asphaltene inhibitors: dispersants, solvents, and polymeric inhibitors. Mechanisms of action and application methods.

Paraffin Wax Deposition

• Composition of paraffin waxes: long-chain n-alkanes (C18+).
• Factors affecting paraffin wax deposition: temperature, pressure, composition, flow rate, pipe surface roughness.
• Wax deposition modeling: using heat transfer models to predict wax deposition rates.
• Wax inhibitors: pour point depressants, wax crystal modifiers, dispersants. Mechanisms of action and application methods.
• Hot oiling, chemical solvents, and mechanical removal techniques for removing wax deposits.

Emulsion Chemistry

Emulsion Formation and Stability

• Types of emulsions: water-in-oil (W/O) and oil-in-water (O/W) emulsions.
• Factors affecting emulsion stability: interfacial tension, viscosity, droplet size distribution, presence of emulsifiers.
• Emulsifiers: surfactants, asphaltenes, resins, fine solids. Mechanisms of action and their role in stabilizing emulsions.
• Measurement of emulsion stability: bottle tests, electrical stability tests, interfacial tension measurements.

Emulsion Breaking and Treatment

• Demulsifiers: chemical demulsifiers (anionic, cationic, nonionic); mechanisms of action (interfacial tension reduction, flocculation, coalescence); application methods (batch treatment, continuous injection).
• Physical methods for emulsion breaking: heating, settling, centrifugation, electrostatic coalescence.
• Design and operation of emulsion treatment facilities: heater treaters, electrostatic treaters, separators.