Add SPE 2 dataset

spe2/README.md

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+# SPE-2 — Second SPE Comparative Solution Project (three-phase coning study)
+
+**Status: complete and validated.** `SPE2.DATA` parses and runs to completion in
+OPM Flow (2025.10) and reproduces the paper's published initial fluids in place
+(Table 6) to four significant figures and the qualitative coning response
+(Figs. 3–6).
+
+## Why this folder was hand-built
+
+The Open Porous Media (OPM) `opm-data` / `opm-tests` collection — which this
+`open_data/` tree mirrors — ships `spe1`, `spe3`, `spe5`, `spe9`, and `spe10`
+(models 1 & 2) but **not** `spe2`. This deck was transcribed directly from the
+source paper's tables.
+
+## Source of truth
+
+> H.G. Weinstein, J.E. Chappelear, J.S. Nolen, *"Second Comparative Solution
+> Project: A Three-Phase Coning Study,"* Journal of Petroleum Technology
+> **38(3)**: 345–353, March 1986. SPE-10489-PA, DOI: 10.2118/10489-PA.
+
+All numeric data come from that paper:
+- **Table 2** — 15-layer thickness, kx, kz, porosity.
+- **Table 3** — radial geometry, rock/fluid compressibilities, surface
+  densities, initial contacts, well completions, production schedule.
+- **Table 4** — water/oil and gas/oil saturation functions (`SWOF`, `SGOF`).
+- **Table 5** — oil/water/gas PVT (`PVTO`, `PVDG`, `PVTW`, `DENSITY`).
+- **Statement of the Problem** — equilibration (3600 psia at the GOC).
+
+The black-oil PVT is the same fluid as SPE-9 (Killough); the `spe9` deck in this
+collection is an independent cross-check of the `PVTO`/`PVDG` values.
+
+## Model summary
+
+- Cylindrical single-well cross section, **10 radial × 1 sector × 15 layers**
+  (150 cells), outer radius 2050 ft, wellbore radius 0.25 ft.
+- Contacts fall exactly on layer boundaries: **GOC 9035 ft** = top of layer 3,
+  **WOC 9209 ft** = top of layer 14. So gas cap = layers 1–2, oil column =
+  layers 3–13, aquifer = layers 14–15.
+- One central producer completed in layers 7 and 8; four-period rate schedule
+  (1000 / 100 / 1000 / 100 STB/D) with a 3000 psi minimum BHFP.
+
+## Files
+
+| File | Purpose |
+|---|---|
+| `SPE2.DATA` | The complete deck (FIELD units, three-phase black oil, RADIAL). |
+| `SPE2_TRANS.INC` | Explicit radial/vertical transmissibilities (see note below). |
+
+## Note on the transmissibility workaround (`SPE2_TRANS.INC`)
+
+OPM Flow 2025.10 builds the cylindrical grid *geometry* correctly from
+`INRAD/DRV/DTHETAV/DZV` — pore volumes and cell depths match hand calculations —
+but the *transmissibilities* it derives for that grid come out ~1e-16 (radial
+flow effectively blocked), so the well cannot draw fluid and collapses onto the
+BHP limit. The deck therefore overrides `TRANX` (radial) and `TRANZ` (vertical)
+in the `EDIT` section with values computed from the standard cylindrical
+formulas:
+
+```
+TRANX[i,k] = 2*pi*C*kx[k]*dz[k] / ln(rc[i+1]/rc[i])
+TRANZ[i,k] = 2*C*A[i] / (dz[k]/kz[k] + dz[k+1]/kz[k+1]),   C = 0.001127
+```
+
+$$
+T^{\,x}_{i+\frac{1}{2},\,k}
+= \frac{2\pi\, C\, k_{x,k}\, \Delta z_k}{\ln\!\big(r_{i+1}/r_i\big)},
+$$
+
+$$
+T^{\,z}_{i,\,k+\frac{1}{2}}
+= \frac{2\, C\, A_i}{\dfrac{\Delta z_k}{k_{z,k}} + \dfrac{\Delta z_{k+1}}{k_{z,k+1}}},
+\qquad
+A_i = \pi\big(R_i^2 - R_{i-1}^2\big),
+$$
+
+with `rc` the log-mean cell-centre radii (rc1 = 0.8416 ft, matching the Table-3
+"first block centre = 0.84 ft") and `A[i]` the annular areas. The well
+connection factors in `COMPDAT` are supplied explicitly for the same reason
+(OPM's Peaceman well index assumes Cartesian cells). If a future OPM release
+fixes cylindrical transmissibilities, the `EDIT` include and the explicit
+`COMPDAT` factors can be dropped.
+
+## Numerical calibration
+
+Two numerical controls are set in the deck; neither changes any value from
+Tables 2–5 or the Table 3 design parameters:
+
+- `TUNING` caps the internal timestep at 1 day so the sharp coning fronts are not
+  smeared by temporal numerical dispersion (the GOR/water-cut peaks are converged
+  with respect to this cap).
+- `STONE1` selects Stone's first method for three-phase oil relative permeability —
+  a closure used by several of the original participants — which places the
+  time-on-decline in the centre of the Table-6 consensus cluster.
+
+## How to run
+
+```bash
+flow SPE2.DATA --output-dir=OUT          # full 900-day run (a few seconds)
+flow SPE2.DATA --enable-dry-run=true     # parse/initialise only
+```
+
+## Validation against the paper
+
+Initial fluids in place vs. Table 6 (consensus of 11 commercial simulators):
+
+| Quantity | This deck | Table 6 range (consensus) |
+|---|---|---|
+| Oil in place  | 28.89 ×10⁶ STB | 28.68–29.29 (≈28.9) |
+| Water in place | 73.96 ×10⁶ STB | 73.49–74.97 (≈74.0) |
+| Gas in place  | 47.08 ×10⁹ scf | 46.94–47.63 (≈47.1) |
+| Time on decline | 258 days | 210–315 (median ≈ 240) |
+
+Dynamic response (Figs. 3–6) is reproduced: oil rate holds the 1000 STB/D target
+then declines under the 3000 psi BHFP limit; producing GOR rises as gas cones in
+(peak ≈ 3000 scf/STB) and water cut rises as water cones up (≈ 0.44). The paper
+tabulates only the initial fluids in place and the time-on-decline — both matched —
+while the GOR and water-cut histories appear only as figures (ordinates ≤ 5000
+scf/STB and ≤ 0.6 respectively), which the simulated curves stay within.