Reservoir Simulation Flashcards
When did the Reservoir simulation has been practiced
since the beginning of petroleum engineering in the 1930’s
Before 1960-Analytical methods
zero-dimensional material balances, and one-dimensional (1D) Buckley-Leverett calculations
What is the term simulation mean
predictive method that evolve from computer programs that allow solutions of large sets of finite-difference equation
What are the large sets of
finite-difference equation
✓ Two- and three-dimentional
✓ Transient
✓ Multiphase flow in heterogeneous porous media
What are the 3 hydrocarbon -recovery methods
✓ Primary Recovery
✓ Secondary Recovery
✓ Tertiary Recovery
Classification of Primary Recovery
✓ Solution-Gas Drive
✓ Gas-Cap Expansion
✓ Gravity Drainage
✓ Rock Expansion
✓ Water Drive
Classification of Secondary Recovery
✓ Waterflooding
✓ Pressure Maintenance
Classification of Tertiary Recovery
✓ Chemical
✓ Thermal
✓ Miscible
Chemical in Tertiary Recovery includes
✓ Polymer Flooding
✓Surfactant Flooding
✓ Reverse Wetting Agent
✓ Carbonated Waterflood
Thermal in Tertiary Recovery includes
✓Steam Injection
✓ Hot-Water Injection
✓In-Situ Combustion
✓ Wellbore Heating
Miscible in Tertiary Recovery includes
✓ Vaporizing-Gas Drive
✓ Enriched-Gas Drive
✓ Alcohol Flooding
✓ CO2 Flooding
✓ Miscible Hydrocarbon Flooding
During 1970, Conventional includes
✓ Depletion
✓ Pressure maintenance
During 1970, Enhance include
✓ Miscible flooding
✓ Chemical flooding
✓ CO2 injection
✓ Steam or hot-water flooding
✓ In-situ combustion
A good Simulator must be able to:
✓ Reflect chemical absorption and degradation
✓ Show the emulsifying and interfacial(IFT) reduction effects
✓ Show reaction kinetics
✓ Model thermal effects and equilibrium phase behavior
The tools of Reservoir Simulation
✓ Intuition and Judgment
✓ Complex mathematical models
✓ Digital computers
Model
✓ Physical
✓ Mathematical
Model is usually compose of _____
grid system (cells or gridblocks)
Types of Models
✓ One-dimentional horizontal
✓ One-dimentional vertical
✓ Areal (two-dimentional)
✓ Cross-sectional (two-dimentional)
✓ Three-dimentional
• Used to define a bottom water drive
• Determine aquifer activity
• Yield an accurate material balance
• Serve as a screening tool prior to a large complex study
• Gravity drainage simulation
• Sensitivity studies
One Dimensional Model
2 types of Two Dimensional Model
✓ Areal Model
✓ Cross-sectional model
It is used if there is very little movement of fluids
Areal Model
It is used to simulate a sliced field
Cross-sectional model
types of Three Dimensional Model
✓ Cartesian model
✓ Radial model
It is used when fluid migration is expected parallel to the strike of a thick steeply dipping bed
Cartesian model
• It is use to study shale breaks, well test, vertical permeability effects, heterogeneity, determine maximum producing rate.
• referred to as “conning” models
Radial model
Model equation types:
✓ Black Oil (Beta) models
✓ Compositional Simulator
similar to black oil model in dimension and solution technique
Compositional Simulator
_____ field into large cells is used to save time and money
• uses fully implicit formulation
Cartesian model
IMPES
Implicit Pressure, Explicit Saturation
it is current in pressure and solves for saturations after pressures are known
IMPES
it solves for both pressure and saturations simultaneously
Fully Implicit formulation
Data requirements for cell location dependent
• length
• width
• thickness
• porosity
• absolute permeabilities (directional)
• elevation
• pressures
• saturations
Data requirements for pressure dependent
• solution gas-oil ratio
• formation volume factor
• viscosities
• densities
• compressibilities
Data requirements for saturation dependent
• relative permeability
• capillary pressure
Data requirements for well data
• production (or injection) rate
• location in grid system
• production limitations
refers to cell location by column (∆x)
i
refers to width (∆y)
j
refers to layer (∆z)
k
can be obtain by superimposing grid system on a field map and measuring appropriate distances
length
measured in the same manner as lengths
widths
obtained from seismic data, net isopach maps (for areal and 3D simulations), well records, core analysis and logs (for cross-sectional models)
thickness
the ratio of void space per bulk volume
porosity
the ratio of interconnected pore space to volume
Effective Porosity
the pore space occupied by oil and gas to bulk volume
Hydrocarbon porosity
Porosity is independent on _____ but is dependent on type of _____
rock grain size ; packing
may be found using logs, laboratory analysis, correlations, isoporosity contour maps
porosity
a measure of rock capability to transmit fluids
Absolute Permeability
3 techniques in calculating average permeability values:
• Arithmetic (or parallel)
• Reciprocal (or Series/harmonic)
• Geometric averaging
Relative permeability must be between _____
zero and one
it is the directional trend of permeabilities
Anisotropy
it is required for cross-sectional and 3D models
Vertical permeabilities
it can be calculated using density gradient adjustment for all cells
pressures
may be assigned to each cell if any given datum is known (gas-oil contact and water-oil contact)
Saturations (So, Sw, Sg)
dissolved gas is required as a function of pressure and based on the pressure in each cell
Solution gas-oil ratio (Rs)
gas which is released from solution remains in contact with the oil
Flash Liberation
the free gas is removed while maintaining the pressure
Differential Liberation
• below bubble point pressure, a decrease in _____ yield lesser volume
• above bubble point, (in undersaturated) a decrease in pressure releases no solution gas
Oil formation volume factor
______ increases with decreasing pressure due to expansion
Gas formation volume factor
it is a reduction of flow capability due to the presence of another fluid
relative permeability
relative permeability is based on:
• pore geometry
• wettability
• fluid distribution
• saturation history
at the critical (connate) water saturation, the water relative permeability is zero
Water-oil relative permeability
the ability of the fluid to coat the rock surface
wettability
determined by laboratory air-oil data or by estimating capillary values based on height of the transition zone
Gas-oil capillary pressure
production limitations
• bottom-hole pressures
• skin factors
• maximum GOR or WOR limits
