reservoir simulation - a basic tool of reservoir … · 2020-03-25 · reservoir simulation as an...

RESERVOIR SIMULATION - A BASIC TOOL OF RESERVOIR MANAGEMENT

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Use of fine-grid reservoir models can translate laboratory results to field applications.

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Simulation of Oil Recovery Methods With Finite Difference Simulators.

Reservoir Rock Idealizations

Single Porosity: described by a normal distribution function in each geologic layer.

Dual Porosity: where two distinct types of porosity coexist in a representative rock volume such as naturally fractured reservoirs.

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Single Permeability: fit a log-normal distribution function in each geologic unit.

Dual Permeability: is the idealization of the reservoir systems where both the matrix and fracture network have continuity and transmissivity is not insignificant compared to that of the fracture.

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Reservoir Fluid Classification

Black Oil: the critical point is far to the right of the bubble point.

Volatile Oil: Bubble-points are fairly close to the critical point.

Gas Condensate: the critical point is to the left of the reservoir dew point.

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Wet Gas: solely exists as gas in the reservoir without condensing any liquids. In surface separators, liquids are formed.

Dry Gas: exist as gas in the reservoir and in the surface

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Enhanced Oil Recovery

Primary and secondary oilproduction: are simulated by black oil or compositional formulations.

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Enhanced oil recovery

aimed primarily at reducing the water flood residual oil.

The most notable of these processes are steam injection, polymer or alkaline water flood, micellar-polymer flood, and miscible gas flood.

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Window Modeling, Local Mesh Refinement, and Non-neighbor Connections

It is practice to model a window area of a reservoir using a fine gridsystem.

Boundary conditions of the window area are hard to determine. One solution to this problem is to use the local mesh refinement in the window area while using coarse grid in the rest of the field.

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Non-neighbor connections are used to connect nodes for two different but adjacent layers on both sides of a fault.

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Infill Drilling and Well Recompletion

Infill drilling in San Andres carbonates has resulted in recovering large amounts of by water flooding.

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Fine gridding

a. track water-oil interface.

b. evaluate the possible benefits of a perforating recompletion program.

c. determine the optimal location of infill wells.

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Reservoir Simulation As An Aid To Reservoir Description

1. Reservoir heterogeneities:

generally we rely on the development or production geologists to describe the reservoir and build up a geological model that can be used to construct a mathematical model of the reservoir.

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2. Fine Vs. Coarse-Grid Simulation

Example:

Inverted five-spot water flood pattern.

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3. Accuracy and Reliability of Finite-Difference simulators

Numerical errors: truncation errors, round off errors, and numerical dispersion.

Coarseness of the grid and time step size could cause errors: future may solve this problem by super computers.

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Conclusion

Combination of new super computers and fine-grid models: will provide the capabilities to resolve reservoir heterogeneities and location of by-passed mobile oil in the reservoir.

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