Simulation Planning

Reservoirs Models can be large and complex so it is wise to begin with simplest model and coarsest reservoir description (model refinements can be added later). Accuracy of the simulation depends upon input not the sophistication of model.

Important factors for a successful simulation include:

• reliability of the available data
• reservoir engineering analysis
• prevailing producing mechanisms

Major steps in the conduct of a simulation study:

• input data gathering
• history matching procedure
• performance prediction

Input Data Gathering

Data required can be classified into three groups:

1. reservoir rock properties
2. fluid properties
3. field production history

Primary Data Required for a Reservoir Simulation Study

Laboratory Measurements

• relative permeabilities
• irreducible water saturation
• irreducible oil saturation (water-oil-gas systems)
• critical gas saturation
• capillary pressure
• PVT data
• reservoir temperature
• gas and oil gravity
• bubble point pressure
• reservoir fluid density-compressibility-viscosity ( reservoir pressure & temperature)
• rock compressibility

Layer & Cell Grid Data (Note: rock data within grid cell assumed uniform)

• number of layers
• grid dimension
• reservoir maps constructed from well data
  • elevation (structure map)
  • thickness (gross and net isopach maps)
  • permeability map (horizontal & vertical)
  • porosity map
  • fluid saturation map

Production History Data

• location and perforation intervals of wells
• oil, water, and gas production rates with time
• pressure history

Source of Common Reservoir Data

1. Permeability - pressure transient testing, core analyses and permeability vs porosity crossplots

2. Porosity - core analyses and petrophysical analyses

3. Relative permeability - laboratory core flow tests and history matching by iterative simulation runs

4. Capillary pressures are determined from laboratory core flow tests

5. Saturations are determined by petrophysical analyses, conventional & pressured core analyses and single well tracer tests

6. PVT data sources are from laboratory analyses of recombined samples, analogs from similar reservoirs and standard correlation charts (SPE handbook)