Reservoir Engineering

Rock and Fluid Properties

Fundamental Petrophysical Characteristics

• Porosity measurement and calculation, distinguishing between total porosity and effective (interconnected) porosity within sandstone and carbonate reservoirs.
• Permeability characterization, including absolute, effective, and relative permeability, and how they define the flow capacity of porous media.
• Fluid saturation distribution, applying Archie’s Law and its variations to determine water and hydrocarbon saturation in situ.

Reservoir Fluid Behavior

• Phase behavior of hydrocarbons, using equation-of-state modeling to analyze gas-oil ratios, formation volume factors, and fluid densities.
• Understanding the thermodynamic properties of black oil, volatile oil, retrograde gas, and wet gas reservoirs through pressure-volume-temperature (PVT) analysis.
• The impact of surface tension and capillary pressure on fluid migration and trapping mechanisms within the pore network.

Material Balance and Estimation

Volumetric and Material Balance Calculations

• Calculating Original Oil in Place (OOIP) and Original Gas in Place (OGIP) by integrating reservoir geometry, porosity, and net pay thickness.
• Utilizing the general material balance equation to track reservoir depletion, identify drive mechanisms, and predict pressure performance over time.
• Distinguishing between active water drive, gas cap expansion, solution gas drive, and gravity drainage mechanisms to forecast recovery factors.

Pressure Maintenance and Secondary Recovery

• Evaluating waterflooding efficiency, including the calculation of sweep efficiency and displacement efficiency in multi-well patterns.
• Determining the timing for pressure maintenance projects to optimize the transition from primary to secondary production phases.

Well Performance and Fluid Flow

Inflow and Outflow Performance

• Developing Inflow Performance Relationship (IPR) curves for both saturated and undersaturated reservoirs using Vogel’s and Darcy’s flow equations.
• Analyzing tubing performance curves (TPC) to optimize production rates and manage backpressure against the reservoir.
• System analysis through nodal analysis, identifying bottlenecks in the flow path from the reservoir rock into the wellbore and up through the completion string.

Transient Well Testing

• Interpreting pressure drawdown and buildup tests to estimate reservoir permeability, skin factor (damage or stimulation), and the distance to reservoir boundaries.
• Using type curve matching to characterize complex reservoir geometries, such as fractured reservoirs or reservoirs with dual-porosity behavior.

Recovery Optimization and Modeling

Unconventional Reservoir Engineering

• Analyzing low-permeability reservoirs (shales and tight gas) focusing on micro-darcy flow regimes and the necessity of hydraulic fracturing.
• Evaluating stimulated reservoir volume (SRV) and its correlation to long-term production decline rates.

Decline Curve Analysis (DCA)

• Applying Arps’ decline models (exponential, hyperbolic, and harmonic) to estimate remaining reserves and forecast future production rates.
• Adjusting decline models to account for operational constraints, such as liquid loading, changing choke sizes, or intervention activities.

Numerical Simulation Fundamentals

• Structuring grid systems and layering models to represent reservoir heterogeneity accurately in computer-aided simulation.
• Managing history matching procedures to align historical production and pressure data with simulation models for reliable forecasting of future development scenarios.