Petrophysical Interpretation Report — 15-135-25402-00-00
| Well (UWI) | 15-135-25402-00-00 |
| Log date | Tue Jul 31 09-25-21 2012 |
| Service company | Log Tech |
| Acquisition date (header) | Tue Jul 31 09-25-21 2012 |
| PLSS location | Sec 19 T19S R21W (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)
Well 15-135-25402-00-00 contains a thin pay interval within a gross section of 639.7 m, where net-to-gross is 0.020 and net pay ranges widely from 1.5 m (P10) to 66.7 m (P90) with a median of 12.0 m. Within that pay, average effective porosity is 0.157, water saturation is 0.408, and shale volume is 0.162, indicating a moderately clean, porous rock that is more than half filled with hydrocarbon. These results are bracketed rather than firmly estimated because the dominant uncertainty is the parameter a, a regional default that remains uncalibrated by core and drives a 22.9 m swing in net pay; the validation loop also did not converge, with 2 validator objections raised of which 1 is an unresolved mechanical objection, so the pay figure should be read as a broad range, not a point estimate.
Net pay P10 / P50 / P90 = 1.5 / 12.0 / 66.7 m.
Net pay is dominated by 'a', 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: 59.44–1339.75 m
- Log date: Tue Jul 31 09-25-21 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 186 |
| hard_range_mask | RMED | count 24 |
| hard_range_mask | RHOB | count 1 |
| hard_range_mask | DRHO | count 4 |
| hard_range_mask | PHID_SVC | count 5 |
| range_warn | RHOB | count 4 |
| range_warn | NPHI | count 29 |
| spike_removal | — | 162 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=23.4, gr_p95=102.7
- Bad-hole: GOOD=0.734, DEGRADED=0.219, EXCLUDED=0.047
- Low-resistivity: rt_threshold=1.58, n_flagged=806, intervals=[[237.4, 237.7], [282.2, 284.4], [288.3, 288.3], [289.0, 290.3], [293.1, 346.3], [351.1, 354.3], [357.2, 358.3], [367.9, 369.3], [372.6, 374.0], [406.6, 407.1]]
6. Data preparation
Edits applied before compute (by type): degradation: 3, hard_range_mask: 6, range_warn: 2, spike_removal: 162, unit_conversion: 1.
7. Interval definition
- Logged interval: 59.44–1339.75 m
- Analysis window (analyst-restricted): 700.0–1339.7 m — gross and NTG are measured over this window
- Gross evaluated interval: 639.7 m
- Computed net-pay runs (pre-merge): 27
- 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=23.4, gr_p95=102.7
10. Resistivity analysis
Low-resistivity scan: rt_threshold=1.58, n_flagged=806, intervals=[[237.4, 237.7], [282.2, 284.4], [288.3, 288.3], [289.0, 290.3], [293.1, 346.3], [351.1, 354.3], [357.2, 358.3], [367.9, 369.3], [372.6, 374.0], [406.6, 407.1]].
Invasion profile (multi-depth resistivities, 8055 samples): fraction with shallow reading above deep (Rxo/RT > 1.2, invaded/permeable indication): 0.775; reversed (< 0.8): 0.050; median Rxo/RT 1.555; median Rmed/RT 0.993. 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: 0.102, limestone: 0.243, dolomite: 0.119. 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: 8.5 m swing.
13. Figures
Composite log
Pickett plot
Neutron-density crossplot
Buckles plot
Hingle plot
Distributions
Sensitivity tornado
Net-pay Monte-Carlo distribution
14. Derived parameters
- Bulk-volume water (BVW = PHIE*Sw): mean 0.0530 v/v
- Porosity-thickness (Phi·H over net pay): 1.484 m
- Hydrocarbon pore thickness (HCPV = Σ PHIE·(1−Sw)·step): 0.888 m
- Buckles constant (BVW at P10 of net pay): 0.0425 → Swirr (mean) ≈ 0.249 over 57 pay samples
15. Permeability (uncalibrated)
- perm_timur: mean k = 4.71 mD
_Uncalibrated screening estimate (no core); Sw used as the Swirr proxy._
16. Electrofacies
Unsupervised k-means on 4102 samples into 4 electrofacies (sample counts: facies 0: 397, facies 1: 1221, facies 2: 1528, facies 3: 956). Descriptive only — no core labels.
17. Rock quality (uncalibrated)
- rqi: mean = 0.059
_Built on the uncalibrated permeability; indicative only._
18. Water saturation
Mean Sw (Simandoux 1963 (shaly sand)) = 0.774 (a=1.00, m=2.00, n=2.00, Rw=0.0213 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 | 0.902 | |
| sw_simandoux | 0.774 | ✓ |
| sw_indonesia | 0.774 |
19. Zonation (net-pay intervals)
Raw net-pay runs merged into 24 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 | 760.9 | 762.5 | 0.9 | 0.186 | 0.469 | 0.044 |
| Z2 | 823.0 | 824.8 | 0.8 | 0.132 | 0.481 | 0.276 |
| Z3 | 838.7 | 839.3 | 0.8 | 0.119 | 0.494 | 0.286 |
| Z4 | 886.7 | 887.1 | 0.6 | 0.132 | 0.465 | 0.094 |
| Z5 | 890.2 | 891.2 | 0.6 | 0.233 | 0.349 | 0.229 |
| Z6 | 933.1 | 933.6 | 0.6 | 0.183 | 0.380 | 0.201 |
| Z7 | 966.4 | 966.7 | 0.5 | 0.159 | 0.453 | 0.254 |
| Z8 | 1053.1 | 1053.5 | 0.6 | 0.189 | 0.472 | 0.101 |
| Z9 | 1118.8 | 1119.1 | 0.5 | 0.142 | 0.477 | 0.114 |
| Z10 | 1120.6 | 1122.0 | 1.5 | 0.180 | 0.436 | 0.067 |
| Z11 | 1176.5 | 1177.0 | 0.6 | 0.129 | 0.396 | 0.103 |
| Z12 | 1185.2 | 1185.8 | 0.8 | 0.157 | 0.403 | 0.079 |
| Z13 | 1213.7 | 1214.2 | 0.6 | 0.128 | 0.301 | 0.113 |
| Z14 | 1221.9 | 1222.6 | 0.8 | 0.125 | 0.233 | 0.058 |
| Z15 | 1262.3 | 1262.9 | 0.8 | 0.190 | 0.263 | 0.221 |
20. Results
| Quantity | Value |
|---|---|
| Gross interval | 639.7 m |
| Net pay (P10/P50/P90) | 1.5 / 12.0 / 66.7 m |
| Net-to-gross | 0.020 |
| Avg PHIE (net pay) | 0.157 |
| Avg Sw (net pay) | 0.408 |
| Avg Vsh (net pay) | 0.162 |
21. Uncertainty and sensitivity
Monte Carlo, 500 realizations (seed 42). Net pay swing per parameter (one-at-a-time):
| Parameter | Net-pay swing (m) |
|---|---|
| a | 22.9 |
| m | 21.5 |
| Rw | 8.5 |
| n | 6.4 |
Dominant uncertainty: a (swing 22.9 m).
Multi-seed robustness: P50 UNSTABLE across seeds (spread 0.5 m across 4 seeds).
Net pay is dominated by 'a', which is a regional DEFAULT (uncalibrated). This is the single largest uncertainty — the result is bracketed, not a confident point estimate.
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 a — 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: 6, range_warn: 2, spike_removal: 162, unit_conversion: 1.
| Validator | Type | Detail |
|---|---|---|
| vsh_phie_anticorrelation | support | Vsh-PHIE Pearson 0.85 > 0.3 (dirty rock + high porosity) |
| rt_sw_consistency | mechanical | 45 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: set_zone_of_interest"]
act_2["tool_call: set_zone_of_interest"]
dec_3["decision: step: compare_methods"]
act_3["tool_call: compare_methods"]
dec_4["decision: step: validate_choice"]
act_4["tool_call: validate_choice"]
dec_5["decision: step: lithology"]
act_5["tool_call: lithology"]
dec_6["decision: step: derived_parameters"]
act_6["tool_call: derived_parameters"]
dec_7["decision: step: permeability"]
act_7["tool_call: permeability"]
dec_8["decision: step: compare_methods"]
act_8["tool_call: compare_methods"]
dec_9["decision: step: electrofacies"]
act_9["tool_call: electrofacies"]
dec_10["decision: wasted no-op: permeability"]
dec_11["decision: step: rock_quality"]
act_10["tool_call: rock_quality"]
dec_12["decision: wasted no-op: lithology"]
dec_13["decision: step: compute_sw"]
act_11["tool_call: compute_sw"]
dec_14["decision: wasted no-op: compute_sw"]
dec_15["decision: step: apply_cutoffs"]
act_12["tool_call: apply_cutoffs"]
dec_16["decision: step: run_uncertainty"]
act_13["tool_call: run_uncertainty"]
dec_17["decision: wasted no-op: compute_sw"]
dec_18["decision: wasted no-op: lithology"]
dec_19["decision: wasted no-op: compute_sw"]
dec_20["decision: wasted no-op: compute_sw"]
dec_21["decision: wasted no-op: permeability"]
dec_22["decision: step: mhi_scan"]
act_14["tool_call: mhi_scan"]
dec_23["decision: wasted no-op: permeability"]
dec_24["decision: wasted no-op: lithology"]
dec_25["decision: wasted no-op: compute_sw"]
dec_26["decision: wasted no-op: permeability"]
dec_27["decision: wasted no-op: lithology"]
dec_28["decision: wasted no-op: permeability"]
dec_29["decision: wasted no-op: lithology"]
dec_30["decision: wasted no-op: permeability"]
dec_31["decision: wasted no-op: lithology"]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): a (calibrated by core SCAL — tortuosity factor a).
- 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 is not a confident estimate; 1 unresolved mechanical objection remains. Net pay is bracketed at 1.5 / 12.0 / 66.7 m (P10 / P50 / P90) over a 639.7 m gross interval with net-to-gross of 0.020. Pay averages are PHIE 0.157, Sw 0.408, and Vsh 0.162. The single largest uncertainty is parameter a, an uncalibrated regional default responsible for a 22.9 m swing in net pay. Two validator objections were raised in total. These numbers should be read as a range, not a point estimate.
Appendix A — Ledger excerpt (traceability)
{
"net_pay_total_m": 12.649200000000008,
"net_pay_p10_p50_p90": [
1.524000000000001,
12.039600000000007,
66.72072000000014
],
"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 | ✓ |