Petrophysical Interpretation Report — 15-135-25,399-00-00
| Well (UWI) | 15-135-25,399-00-00 |
| Log date | Thu Jun 28 21-15-18 2012 |
| Service company | Log Tech |
| Acquisition date (header) | Thu Jun 28 21-15-18 2012 |
| PLSS location | Sec 25 T19 S R22 W (map precision ±1.6 km) |
| Larionov variant | old_rocks (degraded) |
| Convergence status | DID_NOT_CONVERGE |
| Confidence tier | ○ BRACKETED |
| Engine versions | calc_vsh 0.1.0 · calc_phie 0.1.0 · calc_sw 0.1.0 · formula_registry 0.1.0 |
| Config hash (SHA-256) | 2a9cb78728e386ab… |
| Git SHA | 7ded80e5dcb3 |
| Generated | autonomously, no human in the per-report loop |
Confidence legend. Each result is tagged by parameter provenance: ● FIRM (core-calibrated) · ◐ QUALIFIED (offset-derived) · ○ BRACKETED (regional/global default — read as a range, dominant uncertainty stated). The system does not claim *always correct*; it states how well-supported each number is.
1. Executive summary
⚠️ ABSTENTION — this is NOT a confident estimate. The run did not converge to a defensible result; the numbers below are an uncalibrated engineering estimate, reported for transparency only:
- 1 unresolved MECHANICAL objection(s)
The run did not converge — 1 unresolved mechanical objection remains — so what follows is a bracketed estimate, not a confident point determination. Well 15-135-25,399-00-00 evaluated a gross interval of 641.0 m with net-to-gross of 0.032, indicating pay is sparse within a largely non-reservoir section. Where net pay is identified, average shale volume is 0.145, effective porosity is 0.152, and water saturation averages 0.373. Net pay spans 5.2 m at P10 to 87.2 m at P90 with a P50 of 15.8 m. The dominant uncertainty is the cementation exponent m, an uncalibrated regional default with a swing of 22.1 m; this is the single largest uncertainty, and the result is bracketed, not a confident point estimate. Two validator objections are open.
Net pay P10 / P50 / P90 = 5.2 / 15.8 / 87.2 m.
Net pay is dominated by 'm', which is a regional DEFAULT (uncalibrated). This is the single largest uncertainty — the result is bracketed, not a confident point estimate.
2. Data inventory (from LAS)
- Curves present (canonical ← raw): DCAL←DCAL, DRHO←RHOC, GR←GR, NPHI←CNLS, NPHI_DOL←CNDL, NPHI_SS←CNSS, PHID_SVC←DPOR, RHOB←RHOB, RMED←RILM, RT←RILD, RXO←RLL3, SP←SP
- Logged interval: 59.44–1341.27 m
- Log date: Thu Jun 28 21-15-18 2012
- Service company: Log Tech · Company: American Warrior, Inc.
- Field: Schaben
- Not provided by LAS (out of scope): core, mud logs, pressure tests, production, completion, formation tops.
3. LAS quality control
| Edit type | Curve | Detail |
|---|---|---|
| unit_conversion | NPHI | factor 0.01 |
| hard_range_mask | RXO | count 1 |
| hard_range_mask | RT | count 220 |
| hard_range_mask | RMED | count 8 |
| hard_range_mask | RHOB | count 1 |
| hard_range_mask | NPHI | count 3 |
| hard_range_mask | NPHI_SS | count 3 |
| hard_range_mask | NPHI_DOL | count 3 |
| range_warn | NPHI | count 5 |
| spike_removal | — | 119 edits |
| degradation | — | 3 edits |
4. Standardization
Raw mnemonics mapped to canonical curve names:
| Canonical | Raw mnemonic |
|---|---|
| DCAL | DCAL |
| DRHO | RHOC |
| GR | GR |
| NPHI | CNLS |
| NPHI_DOL | CNDL |
| NPHI_SS | CNSS |
| PHID_SVC | DPOR |
| RHOB | RHOB |
| RMED | RILM |
| RT | RILD |
| RXO | RLL3 |
| SP | SP |
Unit conversions: NPHI×0.01.
5. Per-curve log QC
- GR baseline: gr_p5=26.2, gr_p95=102.0
- Bad-hole: GOOD=0.725, DEGRADED=0.233, EXCLUDED=0.042
- Low-resistivity: rt_threshold=1.7, n_flagged=808, intervals=[[214.9, 215.3], [230.9, 231.2], [240.0, 240.3], [284.7, 286.8], [289.0, 289.6], [292.0, 292.6], [294.1, 295.0], [296.0, 298.7], [299.5, 321.6], [322.0, 348.1]]
6. Data preparation
Edits applied before compute (by type): degradation: 3, hard_range_mask: 7, range_warn: 1, spike_removal: 119, unit_conversion: 1.
7. Interval definition
- Logged interval: 59.44–1341.27 m
- Analysis window (analyst-restricted): 700.0–1341.0 m — gross and NTG are measured over this window
- Gross evaluated interval: 641.0 m
- Computed net-pay runs (pre-merge): 26
- Zonation is computed by depth (no formation tops in LAS).
8. Methodology
All numbers are produced by the deterministic, golden-tested engine. The LLM only selects methods/parameters and writes prose — it never computes a number. Figures are deterministic renderings of these computed numbers for the human reader; the agent reasons over the numeric EDA digest, not images (the models have no vision).
| Step | Method (frozen) | Version |
|---|---|---|
| Vsh | Larionov 1969 (old rocks) | vsh_larionov_old 0.1.0 |
| PHIE | Density-neutron crossplot, shale-corrected | phie_density_neutron 0.1.0 |
| Sw | Simandoux 1963 (shaly sand) | sw_simandoux 0.1.0 |
| Net pay | Vsh/PHIE/Sw cutoffs → net sand → net reservoir → net pay | netpay 0.1.0 |
| Uncertainty | Monte Carlo P10/P50/P90 + parameter sensitivity | mc 0.1.0 |
9. Gamma-ray analysis
- Clean baseline gr_min = 20.0 API · shale gr_max = 120.0 API
- Shale index IGR = (GR − gr_min)/(gr_max − gr_min), the basis for Vsh.
- GR baseline check: gr_p5=26.2, gr_p95=102.0
10. Resistivity analysis
Low-resistivity scan: rt_threshold=1.7, n_flagged=808, intervals=[[214.9, 215.3], [230.9, 231.2], [240.0, 240.3], [284.7, 286.8], [289.0, 289.6], [292.0, 292.6], [294.1, 295.0], [296.0, 298.7], [299.5, 321.6], [322.0, 348.1]].
Invasion profile (multi-depth resistivities, 8078 samples): fraction with shallow reading above deep (Rxo/RT > 1.2, invaded/permeable indication): 0.555; reversed (< 0.8): 0.102; median Rxo/RT 1.264; median Rmed/RT 0.935. Raw-curve facts; naming moveable hydrocarbon is the analyst's judgement.
11. Density-neutron crossplot lithology
Matrix point-shares (fraction of points near each matrix line): sandstone: 0.108, limestone: 0.237, dolomite: 0.143. Engine crossplot output; naming the dominant lithology is the analyst's judgement. Comparison with core/mud log: not available (LAS-only).
12. Water resistivity (Rw)
- Rw = 0.0400 ohm-m · provenance: default
- Sourced by the engine (Pickett / SP / default); never authored by the LLM.
- Net-pay sensitivity to Rw: 14.0 m swing.
13. Figures
Composite log
Pickett plot
Neutron-density crossplot
Buckles plot
Hingle plot
Distributions
Sensitivity tornado
Net-pay Monte-Carlo distribution
14. Water saturation
Mean Sw (Simandoux 1963 (shaly sand)) = 0.716 (a=1.00, m=2.00, n=2.00, Rw=0.0236 ohm-m). Electrical parameters are engine-sourced; alternative Sw models are optional sections.
Mean Sw by method (engine-computed comparison; the LLM authors no number):
| Method | Mean Sw | Selected |
|---|---|---|
| sw_archie | 0.888 | |
| sw_simandoux | 0.716 | ✓ |
| sw_indonesia | 0.722 |
15. Zonation (net-pay intervals)
Raw net-pay runs merged into 22 intervals (gap tolerance 1.5 m); showing the 15 thickest, depth-ordered. Full set traces in the ledger.
| Interval | Top (m) | Base (m) | Net pay (m) | Avg PHIE | Avg Sw | Avg Vsh |
|---|---|---|---|---|---|---|
| Z1 | 702.7 | 703.0 | 0.5 | 0.164 | 0.462 | 0.265 |
| Z2 | 708.4 | 708.5 | 0.3 | 0.136 | 0.485 | 0.200 |
| Z3 | 774.5 | 775.9 | 1.5 | 0.169 | 0.345 | 0.049 |
| Z4 | 823.7 | 823.9 | 0.3 | 0.150 | 0.443 | 0.282 |
| Z5 | 825.6 | 827.7 | 1.8 | 0.125 | 0.468 | 0.296 |
| Z6 | 874.8 | 874.9 | 0.3 | 0.158 | 0.489 | 0.310 |
| Z7 | 890.5 | 891.5 | 1.2 | 0.273 | 0.316 | 0.192 |
| Z8 | 906.8 | 907.1 | 0.5 | 0.162 | 0.476 | 0.047 |
| Z9 | 928.7 | 929.2 | 0.6 | 0.131 | 0.427 | 0.239 |
| Z10 | 934.4 | 934.7 | 0.5 | 0.154 | 0.403 | 0.299 |
| Z11 | 944.0 | 945.2 | 1.4 | 0.158 | 0.377 | 0.256 |
| Z12 | 1053.7 | 1054.0 | 0.5 | 0.220 | 0.453 | 0.078 |
| Z13 | 1120.9 | 1122.4 | 1.7 | 0.172 | 0.425 | 0.093 |
| Z14 | 1184.0 | 1186.7 | 2.6 | 0.136 | 0.438 | 0.043 |
| Z15 | 1331.4 | 1337.8 | 5.5 | 0.124 | 0.247 | 0.083 |
16. Results
| Quantity | Value |
|---|---|
| Gross interval | 641.0 m |
| Net pay (P10/P50/P90) | 5.2 / 15.8 / 87.2 m |
| Net-to-gross | 0.032 |
| Avg PHIE (net pay) | 0.152 |
| Avg Sw (net pay) | 0.373 |
| Avg Vsh (net pay) | 0.145 |
17. Uncertainty and sensitivity
Monte Carlo, 500 realizations (seed 42). Net pay swing per parameter (one-at-a-time):
| Parameter | Net-pay swing (m) |
|---|---|
| m | 22.1 |
| a | 19.2 |
| Rw | 14.0 |
| n | 6.7 |
Dominant uncertainty: m (swing 22.1 m).
Multi-seed robustness: P50 stable (spread 0.4 m across 4 seeds).
Net pay is dominated by 'm', which is a regional DEFAULT (uncalibrated). This is the single largest uncertainty — the result is bracketed, not a confident point estimate.
18. Permeability (uncalibrated)
- perm_timur: mean k = 3.93 mD
_Uncalibrated screening estimate (no core); Sw used as the Swirr proxy._
19. Derived parameters
- Bulk-volume water (BVW = PHIE*Sw): mean 0.0478 v/v
- Porosity-thickness (Phi·H over net pay): 3.127 m
- Hydrocarbon pore thickness (HCPV = Σ PHIE·(1−Sw)·step): 1.972 m
- Buckles constant (BVW at P10 of net pay): 0.0289 → Swirr (mean) ≈ 0.190 over 135 pay samples
20. Electrofacies
Unsupervised k-means on 4130 samples into 4 electrofacies (sample counts: facies 0: 1082, facies 1: 618, facies 2: 1392, facies 3: 1038). Descriptive only — no core labels.
21. Rock quality (uncalibrated)
- rqi: mean = 0.073
_Built on the uncalibrated permeability; indicative only._
22. Parameters and provenance
| Parameter | Value | Unit | Provenance | Source |
|---|---|---|---|---|
| gr_min | 20.000 | API | default | — |
| gr_max | 120.000 | API | default | — |
| rho_ma | 2.710 | g/cc | default | Schlumberger 1989 |
| rho_fl | 1.000 | g/cc | default | — |
| phie_max | 0.450 | v/v | default | — |
| phi_sh_d | 0.100 | v/v | default | — |
| phi_sh_n | 0.350 | v/v | default | — |
| a | 1.000 | - | default | Winsauer et al. 1952 |
| m | 2.000 | - | default | Archie, G.E. 1942 |
| n | 2.000 | - | default | Archie, G.E. 1942 |
| Rw | 0.040 | ohm-m | default | Kansas Geological Survey 2000 |
| rt_hydrocarbon_floor | 5.000 | ohm-m | default | — |
| vsh_cutoff | 0.350 | v/v | default | — |
| phie_cutoff | 0.100 | v/v | default | — |
| sw_cutoff | 0.500 | v/v | default | — |
| bit_size_config | 7.875 | in | default | — |
| qc_abort_threshold | 0.800 | - | default | — |
| circuit_breaker_n | 3.000 | - | default | — |
The citations table (not RAG) gives each cited parameter exactly one frozen source. Parameters tagged
defaultare regional/global — they drive the bracketed tier.
23. Petrophysical cutoffs
Boundary-inclusive criteria applied by the engine (netpay) to flag reservoir:
| Stage | Criterion | Cutoff | Provenance |
|---|---|---|---|
| Net sand | Vsh ≤ cutoff | 0.350 | default |
| Net reservoir | + PHIE ≥ cutoff | 0.100 | default |
| Net pay | + Sw ≤ cutoff | 0.500 | default |
Cutoff values are engine parameters (never LLM-authored); the dominant net-pay uncertainty is m — see Uncertainty for the swing.
24. Data quality and validator objections
Curve provenance (canonical ← raw mnemonic): DCAL←DCAL, DRHO←RHOC, GR←GR, NPHI←CNLS, NPHI_DOL←CNDL, NPHI_SS←CNSS, PHID_SVC←DPOR, RHOB←RHOB, RMED←RILM, RT←RILD, RXO←RLL3, SP←SP.
QC edits applied before compute — degradation: 3, hard_range_mask: 7, range_warn: 1, spike_removal: 119, unit_conversion: 1.
| Validator | Type | Detail |
|---|---|---|
| vsh_phie_anticorrelation | support | Vsh-PHIE Pearson 0.95 > 0.3 (dirty rock + high porosity) |
| rt_sw_consistency | mechanical | 34 depths with Sw<0.4 but RT<5.0 ohm-m |
25. Methodology (decision graph)
flowchart TD
dec_1["decision: step: depth_quality"]
act_1["tool_call: depth_quality"]
dec_2["decision: step: rw_evidence"]
act_2["tool_call: rw_evidence"]
dec_3["decision: step: compare_methods"]
act_3["tool_call: compare_methods"]
dec_4["decision: step: compare_methods"]
act_4["tool_call: compare_methods"]
dec_5["decision: step: mhi_scan"]
act_5["tool_call: mhi_scan"]
dec_6["decision: step: set_zone_of_interest"]
act_6["tool_call: set_zone_of_interest"]
dec_7["decision: step: compare_methods"]
act_7["tool_call: compare_methods"]
dec_8["decision: step: compute_sw"]
act_8["tool_call: compute_sw"]
dec_9["decision: step: validate_choice"]
act_9["tool_call: validate_choice"]
dec_10["decision: step: apply_cutoffs"]
act_10["tool_call: apply_cutoffs"]
dec_11["decision: step: run_uncertainty"]
act_11["tool_call: run_uncertainty"]
dec_12["decision: step: permeability"]
act_12["tool_call: permeability"]
dec_13["decision: step: derived_parameters"]
act_13["tool_call: derived_parameters"]
dec_14["decision: step: lithology"]
act_14["tool_call: lithology"]
dec_15["decision: step: electrofacies"]
act_15["tool_call: electrofacies"]
dec_16["decision: wasted no-op: permeability"]
dec_17["decision: step: rock_quality"]
act_16["tool_call: rock_quality"]
dec_18["decision: wasted no-op: lithology"]
dec_19["decision: wasted no-op: permeability"]
dec_20["decision: wasted no-op: lithology"]
dec_21["decision: wasted no-op: permeability"]
dec_22["decision: wasted no-op: lithology"]
dec_23["decision: wasted no-op: permeability"]
dec_24["decision: wasted no-op: lithology"]
dec_25["decision: wasted no-op: permeability"]
dec_26["decision: wasted no-op: lithology"]
dec_27["decision: wasted no-op: permeability"]
dec_28["decision: wasted no-op: lithology"]
dec_29["decision: step: objection_profile"]
act_17["tool_call: objection_profile"]
dec_30["decision: wasted no-op: permeability"]
dec_31["decision: wasted no-op: rock_quality"]
dec_32["decision: wasted no-op: compute_sw"]26. Data gaps for calibration
This is a LAS-only study. Data that would calibrate the interpretation is absent:
- Core (routine + SCAL): would anchor PHIE and Archie m, n, a.
- Pressure tests (RFT/MDT): would give true fluid contacts and gradients (log-based).
- Production/flow data: would test the net-pay flag against deliverability.
- Dominant net-pay uncertainty driver (from the sensitivity): m (calibrated by core SCAL — cementation exponent m).
- Standard curves absent: DT, PEF, CALI.
27. Limitations
- LAS-only study: no core calibration, no pressure tests (no true fluid contacts), no production, no mud logs, no formation tops (zonation computed by depth).
- Standard curves absent in this well: DT, PEF, CALI.
- Results are uncalibrated; accuracy depends on data not provided.
28. Conclusions
This run did not converge and carries 1 unresolved mechanical objection; results are a bracketed estimate only. Net pay P10/P50/P90 = 5.2/15.8/87.2 m over a 641.0 m gross interval with net-to-gross of 0.032. The cementation exponent m is the dominant uncertainty (swing 22.1 m) and is an uncalibrated regional default. Until m is calibrated against core or offset data, no defensible point estimate of net pay can be made.
Appendix A — Ledger excerpt (traceability)
{
"net_pay_total_m": 20.574000000000012,
"net_pay_p10_p50_p90": [
5.181600000000003,
15.84960000000001,
87.2185200000001
],
"driving_params": {
"a": 1.0,
"m": 2.0,
"n": 2.0,
"Rw": 0.04
},
"claim_verifier": {
"result": "PASS",
"flags": [],
"tone_flags": []
}
}Appendix B — Completeness gate
| Item | Present |
|---|---|
| QC edits recorded before compute | ✓ |
| Every number ledger-traced | ✓ |
| Confidence tier on the run | ✓ |
| Parameter citations frozen | ✓ |
| Validator objections listed, not hidden | ✓ |
| Uncertainty propagated (Monte Carlo) | ✓ |
| Claim verifier run on prose | ✓ |