Reservoir Characterization and Log Analysis

Reservoir Characterization

• Goal: to identify and quantify reservoir properties that affect hydrocarbon flow and storage
• Types of data used:
  • Well logs (e.g. electrical, sonic, and nuclear logs)
  • Core analysis
  • Seismic data
• Key properties characterized:
  • Porosity
  • Permeability
  • Saturation
  • Pore throat size distribution
  • Fluid flow properties

Log Analysis

• Process of interpreting well log data to identify subsurface features and properties
• Types of log analysis:
  • Qualitative: visual inspection of logs to identify patterns and features
  • Quantitative: numerical analysis of log data to estimate reservoir properties
• Key log analysis techniques:
  • Cross-plotting: plotting log data against each other to identify trends and correlations
  • Regression analysis: statistical analysis of log data to estimate reservoir properties
  • Inversion: using mathematical models to estimate reservoir properties from log data

Geochemical Analysis

• Study of the chemical composition of rocks and fluids in the subsurface
• Types of geochemical data:
  • Whole rock geochemistry: analysis of rock samples for major and trace elements
  • Fluid inclusion analysis: study of tiny samples of fluid trapped in minerals
  • Organic geochemistry: analysis of organic-rich rocks and fluids
• Key applications:
  • Source rock evaluation: identifying potential source rocks and their hydrocarbon generating potential
  • Petroleum system analysis: reconstructing the history of hydrocarbon migration and accumulation

Petrophysics

• Study of the physical properties of rocks and their interactions with fluids
• Key petrophysical properties:
  • Porosity
  • Permeability
  • Saturation
  • Capillary pressure
  • Relative permeability
• Petrophysical models:
  • Darcy's law: describing fluid flow through porous media
  • Buckley-Leverett theory: describing two-phase flow in porous media

Formation Evaluation

• Process of evaluating the potential of a formation to produce hydrocarbons
• Key formation evaluation techniques:
  • Log analysis: using well logs to estimate reservoir properties
  • Core analysis: analyzing core samples to measure reservoir properties
  • Testing: conducting production tests to evaluate formation productivity
• Key formation evaluation outputs:
  • Hydrocarbon in place (HCIP) estimates
  • Recovery factor estimates
  • Formation permeability and porosity estimates

Reservoir Characterization

• Identifies and quantifies reservoir properties that affect hydrocarbon flow and storage
• Utilizes well logs, core analysis, and seismic data
• Characterizes porosity, permeability, saturation, pore throat size distribution, and fluid flow properties

Log Analysis

• Interprets well log data to identify subsurface features and properties
• Involves qualitative and quantitative analysis
• Uses cross-plotting, regression analysis, and inversion to estimate reservoir properties

Geochemical Analysis

• Studies the chemical composition of rocks and fluids in the subsurface
• Analyzes whole rock geochemistry, fluid inclusions, and organic geochemistry
• Applies to source rock evaluation and petroleum system analysis

Petrophysics

• Examines the physical properties of rocks and their interactions with fluids
• Focuses on porosity, permeability, saturation, capillary pressure, and relative permeability
• Employs Darcy's law and Buckley-Leverett theory to describe fluid flow

Formation Evaluation

• Evaluates a formation's potential to produce hydrocarbons
• Utilizes log analysis, core analysis, and testing
• Provides hydrocarbon in place estimates, recovery factor estimates, and formation permeability and porosity estimates