Give the SSHIFT volume shift to the saturations - #7391
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Build volume fractions from SSHIFT-corrected phase volumes so reservoir saturations are consistent with the shifted densities. This uses correctedMolarVolume() from opm-common PR OPM#5322.
Register compositional/SIMPLE_COMP_SSHIFT.DATA for output comparison with flow_comp, using flow_comp3_2p as the development simulator. The three-component CO2 injection case uses shifts of both signs and exercises their effect on density, viscosity and phase volumes.
Separate the compressibility factors stored in the fluid state from the translated volume factors used to calculate saturations. Compute the stored factors from the unshifted cached molar volume to retain the EOS definition Z = p V_EOS / (R T).
Use L V_L / (L V_L + (1 - L) V_V) for the hydrocarbon liquid volume fraction. The p/(R T) factors in Z cancel only when they are equal between phases; molar volumes express the volume fraction directly without that assumption.
Reservoir saturations now use corrected molar volumes directly. Remove the intermediate translated Z values and keep the EOS factors stored in the fluid state. Print Vm_L and Vm_V in the verbose saturation output.
Use corrected molar volumes for wellbore saturations so component storage and mixture density use consistent phase volumes and densities. Preserve the unshifted EOS factors used by the single-phase label check.
Allow test component registration with configurable SSHIFT values. Run the AD-versus-central-difference checks with shifts of both signs, alongside the existing zero-shift case. Require a change in mixture density to verify that the shifted configuration is active before checking its derivatives.
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The regression lacks reference outputs, its tolerance masks the target signal, and the wellbore test does not directly verify saturation changes.
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Pull request overview
Applies SSHIFT-corrected molar volumes when calculating compositional phase saturations in reservoir and wellbore flashes.
Changes:
- Uses translated molar volumes for oil/gas saturation calculations.
- Preserves unshifted EOS roots for compressibility factors.
- Adds wellbore derivative and compositional regression coverage.
File summaries
| File | Description |
|---|---|
opm/models/ptflash/flashintensivequantities.hh |
Corrects reservoir saturations. |
flowexperimental/comp/wells/CompWellFlash.hpp |
Corrects wellbore saturations. |
tests/test_compwell_jacobian.cpp |
Adds shifted wellbore testing. |
regressionTests.cmake |
Registers the SSHIFT regression case. |
Review details
- Files reviewed: 4/4 changed files
- Comments generated: 3
- Review effort level: Balanced
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Record oil and gas saturations in the wellbore test helper and require them to change when SSHIFT is enabled. Check that both phases are present before testing derivatives. Use an absolute tolerance of 1e-3 for SIMPLE_COMP_SSHIFT so the default 0.02 tolerance cannot mask small saturation changes. Validation: both compositional well tests pass. Reverting the wellbore saturation translation makes the new assertion fail. SSHIFT output matches a saved local run at the tighter tolerance; official reference generation remains a CI prerequisite.
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Depends on OPM/opm-common#5322 : this calls correctedMolarVolume(), which that PR adds, so it does not build on its own.
Saturations are volume fractions, but they were built from the unshifted molar volume while the densities beside them carried the shift. An SSHIFT deck got corrected densities next to phase volumes that did not match them. The reservoir path and the wellbore flash both did this; both now take the corrected volume. The compressibility factors stay on the unshifted equation-of-state root, which is what the single-phase label check reads.
Verified against reference runs of the same deck with and without the shift: the saturation response to the shift was zero on our side and 0.0135 on the reference's, and now matches to the digits printed. Densities and viscosities are unchanged.
Adds a regression test on compositional/SIMPLE_COMP_SSHIFT.DATA and a nonzero-shift case to the wellbore derivative test. The regression test fails until its reference data is generated.