Oil and Gas

Oil and Gas | Reservoir Engineering


Course Code: N934
Instructors:  Bahman Tohidi
Course Outline:  Download
Format and Duration
3 days


The course covers reservoir fluid composition, phase behaviour and reservoir fluids classification; PVT tests and correlations/modelling; the evaluation and application of PVT reports; Equation of State tuning, PVT analysis by compositional methods using a compositional behaviour model; applications in reservoir simulation. There will be a discussion of potential causes of errors and several case studies.


A well presented and thorough course on a very theoretical subject.

Duration and Training Method

Three day, classroom course with theory, case studies, exercises, and discussion.

Course Overview

Participants will learn to:

  1. Assess the fundamentals of reservoir fluid composition, phase behaviour, correlations and classification.
  2. Construct PVT testing requirements.
  3. Appraise PVT analysis by compositional methods.
  4. Prepare the results of PVT analysis for use in reservoir modelling and reservoir engineering studies.
  5. Characterise sources of error and evaluate case studies.

The course aims to address a number of key topics in this area, but there is some flexibility in the formal itinerary depending on the groups preferences. The key topics that are covered include:

  • Fundamentals - reservoir fluid composition; basic concepts of phase behaviour; classification of reservoir fluids.
  • PVT tests and correlations - compositional analysis by gas chromatography and distillation; conventional PVT tests.
  • PVT report - its evaluation, quality control, data processing and application of test results.
  • Applications in reservoir simulation - pseudo components and grouping; optimum fluid characterisation; tuning equation of state data; generating black oil tables for reservoir simulation.
  • Causes of errors in PVT modelling, case studies.
  • Specialised topics and current research topics, based on the wealth of knowledge available to the tutor via his links to Heriot-Watt.

Day 1: PVT in hydrocarbon reservoirs

  • Pressure-Temperature diagram for pure compounds
  • Critical point
  • Ideal and real gases
  • Corresponding state
  • Acentric factor
  • Phase behaviour of binary and multicomponent systems
  • Phase envelope
  • Classifications of hydrocarbon reservoirs
  • Retrograde condensation, cricondenbar and cricondentherm
  • Effect of composition on phase envelope
  • Behaviour of dry/wet gas, volatile/black oil at reservoir and separator conditions
  • PVT tests for dry/wet gas, black/volatile oil and gas condensate
  • Determining molecular weight of liquid hydrocarbons
  • Constant Composition Expansion (CCE) test
  • Differential Liberation (DL) test
  • Separator test
  • Constant Volume Depletion (CVD) test

Day 2: Fundamentals of phase equilibria and Fluid Characterisation

  • Equation of state (EoS)
  • Van der Waals EoS
  • SRK EoS
  • PR EoS
  • Mixing rules
  • Binary Interaction Parameters
  • Algorithm for computer calculations
  • Distillation
  • Gas chromatography
  • Single carbon number (SCN)
  • Semi-continuous fluid description
  • Calculating physical properties of SCN

Day 3: Using data in EoS tuning and reservoir simulation

  • Application to reservoir simulation
  • PVT reports
  • Grouping
  • Group Selection, Group Properties
  • Tuning of EoS
  • Tuning of EoS for an oil using a commercial software
  • Tuning of EoS for a gas condensate a commercial software
  • Generating black oil tables for exporting to reservoir simulators

This course is also available as a 5-day course with the following additional content:

  • Fluid Sampling - well stabilisation and optimum production rate; multi-phase sampling; oil-based mud filtrate contamination sample evaluation.
  • PVT tests and correlations - compositional analysis by gas chromatography and distillation; conventional PVT tests; well inflow, pressure build-up and gas recycling; gas injection tests; reservoir fluids properties measurement and predictions.
  • PVT analysis by compositional methods - equilibrium ratio correlations and their application; equation of state modelling; simulation of PVT data using fluid composition; evaluation of PVT data using compositional models, fluid characterisation.
  • Applications in reservoir simulation - pseudo components and grouping; optimum fluid characterisation; tuning equation of state data; generating black oil tables for reservoir simulation, measurement and prediction of interfacial tension; viscosity correlations and prediction by compositional methods; gas injection and multi-contact miscibility.

PVT in hydrocarbon reservoirs and fluid sampling

  • An introduction to reservoir fluid sampling and its importance
  • Well preparation for sampling for different reservoir fluids
  • Downhole, wellhead and separator sampling

Fluid sampling and PVT tests

  • Effect of contamination
  • Retrieving the original fluid composition from contaminated samples
  • How to use test results on contaminated samples to calculate EOS parameters for uncontaminated fluid
  • Application of tracers for retrieving composition of the original fluids in gas condensate reservoirs
  • IFT measurement and prediction
  • Viscosity measurement and prediction
  • Some useful correlations in Petroleum Industry
  • Introduction to gas hydrates

Fundamentals of phase equilibria

  • K-value calculations
  • Raoult’s law
  • Henry’s law
  • Flash, bubble point, dew point calculations

Miscible gas injection

  • Gas injection
  • Ternary diagram
  • First contact miscible
  • Vaporizing gas drive
  • Condensing gas drive
  • Limitations of ternary diagram
  • Slim tube
  • Rising bubble
  • Minimum Miscibility Pressure and Minimum Miscibility Enrichment
  • Solvent injection

Using data in EoS tuning and reservoir simulation comparison of EoS

  • Phase Composition
  • Saturation Pressure
  • Density
  • Gas and Liquid Volumes
  • Robustness
  • Fluid Characterisation
  • Selection of EOS
  • Experimental Data
  • Selection of Regression Variables
  • Limits of Tuned Parameters
  • Methodology

The course is designed for Petroleum and Production Engineers as well as Geoscientists who need to understand what types of fluid are available and how the results can be used.

Bahman Tohidi

After graduation Tohidi joined National Iranian Oil Company (NIOC) in 1984 where he worked as production engineer as well as university lecturer for seven years.  Bahman Tohidi joined Heriot-Watt University in 1991 and graduated with a PhD in Petroleum Engineering in 1995 with his doctoral work on the phase behaviour of water-hydrocarbon systems and gas hydrates. He started his employment in January 1994 working in both Hydrate and Reservoir Fluids research projects.

His research interests include gas hydrates, flow assurance, phase behaviour and properties of reservoir fluids, and reducing the emission of greenhouse gases.  Currently, he leads both Hydrate and Reservoir Fluids Research Groups at Institute of Petroleum Engineering, Heriot-Watt University.  He is the Director of Centre for Gas Hydrate Research and the newly formed Centre for Flow Assurance Research (C-FAR) at Institute of Petroleum Engineering, Heriot-Watt University with several projects on various aspects of gas hydrates and flow assurance, and phase behaviour and properties of reservoir fluids.  His is a consultant to major oil and service companies.  Bahman is Managing Director of “HYDRAFACT LIMITED” a Heriot-Watt spin-out company with Flow Assurance and PVT as its main area of activity.

His teaching responsibilities include Petroleum Engineering and Production Technology, as well as offering several short courses to the industry (including; Advanced Flow Assurance and Gas Hydrates, PVT and Phase Behaviour of Reservoir Fluids, and Petroleum Engineering for other Disciplines).  He has published more than 160 papers and holds 8 patents mainly in gas hydrates and PVT.

Affiliations and Accreditation
PhD Petroleum Engineering
BSc Abadan Institute of Technology, Iran - Chemical Engineering
SPE Distinguished Lecturer in (2005-2006)
SPE- Member
EPSRC - Peer Review College (2006-2009)
Journal of Chemical Engineering Research and Design (2010-2013)

Courses Taught
N934: PVT


CEU: 2.4 Continuing Education Units
PDH: 24 Professional Development Hours
Certificate: Certificate Issued Upon Completion
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We issue a Certificate of Attendance which verifies the number of training hours attended. Our courses are generally accepted by most professional licensing boards/associations towards continuing education credits. Please check with your licensing board to determine if the courses and certificate of attendance meet their specific criteria.