Mercury injection (Mercury)
Mercury injection is used to calculate drainage capillary pressure for initializing reservoir simulations (Leverett J function) and to determine the pore size distribution (EOR and rock typing). Entering data takes just a few minutes and computation is quite instantaneous.
- Direct opening of the ASCII file generated by the experimental apparatus,
- Powerful data smoothing by spline functions,
- Calculation of 3 types of pore size distributions,
- Interpretation of first injection, withdrawal and second injection.
- Calculation of reservoir capillary pressure curve
- Permeability estimate (Swanson, Kamath, …)
- Automatic reporting.
Absolute permeability (PERM)
Absolute permeability is generally calculated with a simple spreadsheet in Microsoft Excel. However, the use of CYDAR minimizes the risk of errors (quality control), and improves the accuracy by taking into account the varaitions of emperature during the experiment.
- Gas and liquid permeability, steady-state et transient (pulse decay)
- Account for temperature and atmospheric pressure variations during experiment (not possible with a simple spreadsheet),
- Determination of the inertial coefficient (Forchheimer correction),
- Determination of the Klinkenberg correction,
- Correction for pressure drop in tubings,
- Automatic reporting.
Two-phase flow experiments (TPF)
CYDAR can simulate any kind of two-phase flow in a homogeneous sample:
- Kr steady-state and unsteady-state,
- Semidynamic method,
- Spontaneous displacements (immersion of a sample into a fluid, drainage or imbibition),
- Gravity flow,
- Centrifuge displacements,
- Porous plate (with pressure drop inside the porous plates).
Most of laboratory experiments are pre-programmed in CYDAR and boundary conditions, which are specific to each experiments, are adjusted accordingly:
In addition, the user may also simulate non-programmed experiments by setting inlet and outlet boundary conditions.
For any experiment, all variables (flow rates, effluent volumes, pressures, saturations…) are dynamically displayed during the simulation; and the simulation can be stopped at any time.
The Two-phase flow module can be used either for direct simulations to design an experiment knowing the properties of the sample, or to determine unknown parameters (inverse calculation). For all experiments, Kr and Pc curves can be adjusted by manual or automatic history matching. The simulated results (production, saturation profile and pressures) are compared to the experimental data; the difference is minimized in an optimization loop.
Centrifuge (Centri)
Capillary pressure
The centrifuge module converts the average values measured during the experiment to local capillary pressures determined at the entrance of the sample.
- Both drainage and imbibition,
- Choice of several interpretation methods (Hassler Brunner, Forbes and spline functions),
- Accounts for foot bath,
- Automatic reporting.
Relative permeability
Kr from transient production during a centrifuge experiment
Relative permeabilities (RelPerm)
Determination of relative permeabilities is the main objective of special core analysis and it is well recognized in the profession that a numerical interpretation accounting for capillary effects is absolutely necessary.
In CYDAR, relative permeabilities can be determined by history matching of any transient experiment using the general Two phase flow module (Steady state and unsteady state displacements, centrifuge, semidynamic, …).
In addition, a special module (RelPerm) is devoted to the standard unsteady and steady state methods.
- For unsteady , analytical calculation using JBN or Jones and Roszelles methods
- For steady state, analytical calculation using the asumption of uniform saturation
- For both USS and SS methods, numerical simulation with capillary pressure and determination of Kr using manual or automatic optimization (history matching). Optimization can use the experimental pressures, productions or saturation profiles
- Automatic reporting