Gas Condensate Reserver Engineering

Program Objectives

This 5-day training course deals with “gas condensate reservoir management” with special emphasis on the use of compositional reservoir simulation for well and reservoir management. It begins with a brief introduction to the course objectives followed by basic gas condensate reservoir engineering including reservoir classification, fluid phase modeling, reservoir rock characterization, and multi-phase fluid flow in reservoir. It is then followed by how to determine quantitatively hydrocarbon asset value based on fluid-in-place, recovery factor, and production rate profile. For well and reservoir performance calculation, both simple and complex reservoir simulation methods are introduced. The importance of phase modeling and reservoir description in reservoir simulations are discussed in detail with several field examples. After reviewing general recovery mechanisms in a gas condensate reservoir, specific well and reservoir management issues are considered in detail. They include gas blow-down, pressure maintenance and gas recycling, well deliverability reduction due to condensate build-up, oil production from thin oil-rim, etc. In doing so, two reservoir simulation examples are used for class illustration and for the students’ hand-on experience using a compositional simulator. Well testing, field surveillance and facilities/operations are presented thereafter. Finally the course wraps up with considering how to plan for gas condensate field projects under various uncertainties and a brief course review.
Course Outline
Day 1
  • Types of hydrocarbon reservoirs 
    • Based on phase behavior of reservoir fluid 
    • Based on reservoir structure 
  • Reservoir-type classification criteria
  • Issues in gas condensate reservoir management 
    • Hydrocarbon asset valuation 
    • Production operation issues 
  • Fluid phase behaviors 
    • Black oil model 
    • EOS model 
    • PVT lab experiments for phase modeling 
  • Formation characterization
    • General core analysis 
    • Special core analysis 
    • Determination of Fluid-Initially-In-Place (FIIP) 
Day 2
  • Multiphase fluid flow 
    • Pc-curves and the reservoir initialization 
    • Relativity permeability curves with the end-point scaling due to trapping number changes 
    • Non-Darcy flow effect 
  • Recovery mechanisms
  • Production Operations
    • Natural depletion 
    • Water drive supported by aquifer 
    • Gas recycling 
    • Oil production from Oil rim 
  • Well deliverability reduction due to condensate buildup, non-Darcy flow, etc. 
    • Coning, or high perm streaks, or production problems with thin oil leg, etc. 
    • Well type (horizontal vs. vertical), well spacing, flow rate, etc.

Day 3
  • Simple methods 
    • Tank-model analysis (black-oil-based material balance with Rvo)
    • Simple well deliverability calculation 
  • Effective total skin, non-Darcy flow effect, etc. 
  • General compositional reservoir simulation 
  • Single-well model 
  • Mechanistic model 
  • General field scale model 
Day 4
  • Preparation for Simulator-Based Class Projects 
    • Overview on compositional reservoir simulation 
    • Input Data Preparation 
    • Simulation quality control 
    • Prediction runs 
  • Class Project 1: Single-well model example (grid-size effect, etc.)
  • Class Project 2: Gas recycling case example 
Day 5
  • Production-related issues (sand production, hi-perm streaks, remediation of condensate build-up, etc.) 
  • Well testing and single-well simulation 
  • Field surveillance, fluid sampling, etc. 
  • Uncertainties in gas condensate field management (from exploration to abandonment)