How do you model multiphase flow in reservoirs?

1 Fluid Properties

The first step to model multiphase flow is to define the fluid properties of each phase, such as density, viscosity, compressibility, and saturation. These properties depend on the pressure, temperature, and composition of the fluid, and can be obtained from laboratory measurements, empirical correlations, or equations of state. Fluid properties are important for calculating the relative permeability, capillary pressure, and phase behavior of the multiphase system.

2 Flow Equations

The second step is to formulate the flow equations that describe the conservation of mass, momentum, and energy for each phase in the reservoir. The flow equations are usually derived from Darcy's law, which relates the fluid velocity to the pressure gradient and the permeability of the medium. The flow equations are coupled and nonlinear, and may include additional terms to account for gravity, capillarity, thermal effects, and chemical reactions.

3 Numerical Methods

The third step is to solve the flow equations using numerical methods, such as finite difference, finite element, or finite volume. Numerical methods discretize the reservoir into a grid of cells, and apply numerical schemes to approximate the derivatives and integrals in the flow equations. Numerical methods require boundary and initial conditions, as well as convergence criteria and time steps. Numerical methods can also handle complex geometries, heterogeneities, and fractures in the reservoir.

4 Simulation Software

The fourth step is to use simulation software to implement the numerical methods and run the multiphase flow model. Simulation software can provide a user-friendly interface, data management, visualization, and optimization tools for the modeling process. Simulation software can also support different types of multiphase flow models, such as black-oil, compositional, thermal, or reactive. Some examples of simulation software are Eclipse, CMG, and tNavigator.

5 Model Validation

The fifth step is to validate the multiphase flow model by comparing the simulation results with historical data, experimental data, or analytical solutions. Model validation is crucial for assessing the accuracy, reliability, and uncertainty of the model. Model validation can involve sensitivity analysis, error analysis, calibration, and verification techniques. Model validation can also help identify the sources of error and improve the model parameters and assumptions.

6 Model Application

The sixth and final step is to apply the multiphase flow model to various scenarios and objectives, such as reservoir characterization, production forecasting, reservoir management, enhanced oil recovery, or environmental assessment. Model application can provide valuable insights and recommendations for decision making and optimization in petroleum engineering. Model application can also reveal the limitations and challenges of the multiphase flow model and suggest further research and development.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?