PEH Volume I Chapter 9: Asphaltenes and Waxes

The 18 chapters in the Petroleum Engineering Handbook (PEH) Volume I are as follows.
This post will review Chapter 9:

C1-3: Math
C4: Fluid Sampling
C5: Gas Properties
C6: Oil Correlations
C7: Thermo/Phase
C8: Phase Diagrams
C9: Asphaltene/Wax
C10: Produced Water
C11: Phase Behavior
C12: Emulsions
C13: Rock Properties
C14: Permeability
C15: Relative Permeability
C16: Economics
C17: International Law
C18: 21st Century Law

C9 Review:

PNA: Paraffinic, Naphthenic, Aromatic (includes resins & asphaltenes) fractions. (I-400)
SARA: Saturates, Aromatics, Resins, and Asphaltenes. SARA Analysis: weight fraction method.

Asphaltenes and Waxes (I-397-400)
Deposited solids: asphaltenes, waxes, or a mixture (with resins, crude oil, fines, scale, water) Characteristics: Light C6 fraction (with N2, CO2, H2S), heavy end C6

Asphaltenes 
Asphaltenes precipitation in reservoir: by decreasing pressure or mixing oil with injected solvent. Asphaltenes precipitation near wellbore: by drilling, completion, acid, fracs, etc.
Heavier crudes have less asphaltenes-precipitation problems than lighter crudes.
Primary production has maximum asphaltenes around the saturation pressure.
Asphaltene precipitation/deposition envelope (APE) has dependence on both P & T.
APE: the region which asphaltenes precipitation occurs.

Waxes 
Wax precipitation envelope vertical P/T curve; strong dependence on T but weak on pressure.
Wax crystals tend to fluid disperse (deposit on a surface more likely among fines, asphaltenes, clays). Temperature drop is most common cause of wax deposition; oil/gas expansion (sandface, orifices).