Questions
6 questions in major PSU papers
Difficulty
Medium
Importance
High yield for ON/OFF campus PSU hiring
Overview
Surface facilities and gas processing focus on the midstream operations required to condition oil and gas for transport and commercial sale. This topic is essential for PSU exams as it tests practical knowledge of separation, purification, and flow assurance technologies used in the petroleum industry.
Oil-Water-Gas Separation
Separation processes utilize the difference in densities between oil, gas, and water to achieve phase segregation. Gravity-based vessels are the industry standard for initial treatment to remove free water and prevent emulsion formation.
- Stokes' Law governs the settling velocity of droplets
- Separator types: Two-phase (gas/liquid) and Three-phase (oil/water/gas)
- Key internal components: Inlet diverter, mist extractor, and weir plates
- Retention time is the critical design parameter for efficient separation
Gas Sweetening & Dehydration
Raw gas contains impurities like H2S and CO2 that must be removed via sweetening to prevent corrosion. Dehydration processes, primarily using Triethylene Glycol (TEG), remove water vapor to prevent the formation of hydrates.
- Amine process (MEA, DEA, MDEA) uses chemical absorption for acid gas removal
- Gas hydrates form at high pressure and low temperature conditions
- TEG dehydration relies on absorption in a contactor tower
- Regeneration of TEG occurs in a reboiler at approximately 200°C
Pipeline Hydraulics
This subtopic deals with the energy losses associated with fluid flow through pipes. Understanding the relationship between pressure drop, friction factors, and velocity is crucial for designing transport systems.
- Darcy-Weisbach equation for head loss calculation
- Reynolds number determines flow regime: Laminar (Re < 2100) vs Turbulent
- Moody chart relates friction factor, Reynolds number, and relative roughness
- Bernoulli’s principle serves as the fundamental energy conservation basis
Metering & Custody Transfer
Custody transfer involves the high-precision measurement of fluid volumes as they change ownership. Meters must be calibrated to strict standards to minimize financial risk during bulk transfer.
- Orifice meters are common for flow measurement due to simple construction
- Turbine meters offer high accuracy for clean, low-viscosity fluids
- Coriolis meters directly measure mass flow rate
- AGA (American Gas Association) standards dictate custody transfer protocols
Formula Sheet
Stokes Law: v = g(dp - df)D^2 / 18μ
Darcy-Weisbach: ΔP = f * (L/D) * (ρv^2 / 2)
Reynolds Number: Re = ρvD / μ
Exam Tip
Memorize the application-specific use of different flow meters—Coriolis for mass, Orifice for pressure differential, and Turbine for volumetric flow—as these are frequently tested.
Common Mistakes
- Confusing the operating principles of chemical absorption (amines) with physical adsorption (molecular sieves)
- Neglecting to apply the correct flow regime equation when calculating pressure drop for gas versus liquid pipelines
- Assuming separation efficiency is independent of residence time in gravity separators
More Revision Notes
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