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Petrophysical Interpretation Report — 15-135-24,937-00-00


Well (UWI)	15-135-24,937-00-00
Log date	Tue Aug 04 17-12-41 2009
Service company	Log Tech
Acquisition date (header)	Tue Aug 04 17-12-41 2009
PLSS location	Sec 23 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	`df574ffab7ee`
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)

This evaluation of well 15-135-24,937-00-00 should be read as a bracketed estimate rather than a firm result, given that key inputs remain uncalibrated and the run did not converge. Across the 295.0 m gross interval, pay develops as only a thin fraction of the section, with net-to-gross of 0.043 and net pay spanning a wide 4.1 to 38.4 m between the P10 and P90, against a P50 of 12.3 m — a spread that reflects genuine uncertainty rather than precision. Where pay is present, the rock looks reasonable, carrying effective porosity of about 0.198, water saturation near 0.299, and a modest shale volume of 0.193, consistent with a clean, porous, hydrocarbon-bearing reservoir if the interval is real. That said, the net-pay outcome is driven chiefly by the cementation exponent m, which here is a regional default with no core calibration; this dominant uncertainty (an 8.1 m swing), together with one unresolved mechanical objection, means the numbers above must be treated as a plausible range pending better-constrained parameters, not as a confident estimate.

Net pay P10 / P50 / P90 = 4.1 / 12.3 / 38.4 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, PHID_SVC←DPOR, RHOB←RHOB, RMED←RILM, RT←RILD, RXO←RLL3, SP←SP
Logged interval: 59.44–1335.18 m
Log date: Tue Aug 04 17-12-41 2009
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 150
hard_range_mask	RMED	count 56
hard_range_mask	RHOB	count 1
range_warn	GR	count 2
range_warn	NPHI	count 27
spike_removal	—	83 edits
degradation	—	2 edits

4. Standardization

Raw mnemonics mapped to canonical curve names:

Canonical	Raw mnemonic
DCAL	DCAL
DRHO	RHOC
GR	GR
NPHI	CNLS
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=34.4, gr_p95=116.0
Bad-hole: GOOD=0.717, DEGRADED=0.255, EXCLUDED=0.028
Low-resistivity: rt_threshold=1.35, n_flagged=816, intervals=[[281.9, 284.1], [292.9, 294.4], [296.1, 307.1], [308.6, 316.5], [317.4, 345.9], [352.5, 353.7], [367.0, 367.9], [371.7, 373.2], [420.6, 421.1], [423.7, 425.3]]

6. Data preparation

Edits applied before compute (by type): degradation: 2, hard_range_mask: 4, range_warn: 2, spike_removal: 83, unit_conversion: 1.

7. Interval definition

Logged interval: 59.44–1335.18 m
Analysis window (analyst-restricted): 1035.0–1330.0 m — gross and NTG are measured over this window
Gross evaluated interval: 295.0 m
Computed net-pay runs (pre-merge): 12
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=34.4, gr_p95=116.0

10. Resistivity analysis

Low-resistivity scan: rt_threshold=1.35, n_flagged=816, intervals=[[281.9, 284.1], [292.9, 294.4], [296.1, 307.1], [308.6, 316.5], [317.4, 345.9], [352.5, 353.7], [367.0, 367.9], [371.7, 373.2], [420.6, 421.1], [423.7, 425.3]].

Invasion profile (multi-depth resistivities, 8134 samples): fraction with shallow reading above deep (Rxo/RT > 1.2, invaded/permeable indication): 0.655; reversed (< 0.8): 0.074; median Rxo/RT 1.392; median Rmed/RT 0.989. 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: 0.167, limestone: 0.264, dolomite: 0.165. 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: 7.0 m swing.

13. Figures

Composite log

Composite log

Pickett plot

Pickett plot

Neutron-density crossplot

Neutron-density crossplot

Buckles plot

Buckles plot

Hingle plot

Hingle plot

Distributions

Distributions

Sensitivity tornado

Sensitivity tornado

Net-pay Monte-Carlo distribution

Net-pay Monte-Carlo distribution

14. Derived parameters

Bulk-volume water (BVW = PHIE*Sw): mean 0.0484 v/v
Porosity-thickness (Phi·H over net pay): 2.389 m
Hydrocarbon pore thickness (HCPV = Σ PHIE·(1−Sw)·step): 1.665 m
Buckles constant (BVW at P10 of net pay): 0.0328 → Swirr (mean) ≈ 0.161 over 77 pay samples

15. Permeability (uncalibrated)

perm_timur: mean k = 22.66 mD

_Uncalibrated screening estimate (no core); Sw used as the Swirr proxy._

16. Rock quality (uncalibrated)

rqi: mean = 0.093

_Built on the uncalibrated permeability; indicative only._

17. Electrofacies

Unsupervised k-means on 1754 samples into 4 electrofacies (sample counts: facies 0: 610, facies 1: 216, facies 2: 338, facies 3: 590). Descriptive only — no core labels.

18. Water saturation

Mean Sw (Simandoux 1963 (shaly sand)) = 0.682 (a=1.00, m=2.00, n=2.00, Rw=0.0208 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	0.868
sw_simandoux	0.682	✓
sw_indonesia	0.721

19. Zonation (net-pay intervals)

Raw net-pay runs merged into 11 geological intervals (gap tolerance 1.5 m).

Interval	Top (m)	Base (m)	Net pay (m)	Avg PHIE	Avg Sw	Avg Vsh
Z1	1035.1	1038.5	3.5	0.278	0.215	0.223
Z2	1043.0	1043.6	0.8	0.210	0.467	0.100
Z3	1065.7	1068.2	1.5	0.215	0.370	0.215
Z4	1110.1	1111.1	1.2	0.191	0.447	0.103
Z5	1203.7	1205.6	2.1	0.158	0.358	0.198
Z6	1213.0	1214.2	1.4	0.147	0.198	0.109
Z7	1221.8	1221.8	0.2	0.101	0.491	0.199
Z8	1258.2	1258.5	0.5	0.143	0.257	0.295
Z9	1306.5	1306.5	0.2	0.107	0.417	0.294
Z10	1317.2	1318.1	1.1	0.130	0.188	0.281
Z11	1329.8	1330.0	0.3	0.121	0.239	0.142

20. Results

Quantity	Value
Gross interval	295.0 m
Net pay (P10/P50/P90)	4.1 / 12.3 / 38.4 m
Net-to-gross	0.043
Avg PHIE (net pay)	0.198
Avg Sw (net pay)	0.299
Avg Vsh (net pay)	0.193

21. Uncertainty and sensitivity

Monte Carlo, 500 realizations (seed 42). Net pay swing per parameter (one-at-a-time):

Parameter	Net-pay swing (m)
m	8.1
Rw	7.0
a	3.7
n	2.3

Dominant uncertainty: m (swing 8.1 m).

Multi-seed robustness: P50 stable (spread 0.3 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.

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 default are 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, PHID_SVC←DPOR, RHOB←RHOB, RMED←RILM, RT←RILD, RXO←RLL3, SP←SP.

QC edits applied before compute — degradation: 2, hard_range_mask: 4, range_warn: 2, spike_removal: 83, unit_conversion: 1.

Validator	Type	Detail
vsh_phie_anticorrelation	support	Vsh-PHIE Pearson 0.67 > 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: crossplot"]
    act_2["tool_call: crossplot"]
    dec_3["decision: step: review_attempts"]
    act_3["tool_call: review_attempts"]
    dec_4["decision: step: interval_stats"]
    act_4["tool_call: interval_stats"]
    dec_5["decision: step: set_zone_of_interest"]
    act_5["tool_call: set_zone_of_interest"]
    dec_6["decision: step: validate_choice"]
    act_6["tool_call: validate_choice"]
    dec_7["decision: step: derived_parameters"]
    act_7["tool_call: derived_parameters"]
    dec_8["decision: step: lithology"]
    act_8["tool_call: lithology"]
    dec_9["decision: step: permeability"]
    act_9["tool_call: permeability"]
    dec_10["decision: wasted no-op: permeability"]
    dec_11["decision: step: rock_quality"]
    act_10["tool_call: rock_quality"]
    dec_12["decision: step: electrofacies"]
    act_11["tool_call: electrofacies"]
    dec_13["decision: wasted no-op: lithology"]
    dec_14["decision: wasted no-op: permeability"]
    dec_15["decision: step: compute_sw"]
    act_12["tool_call: compute_sw"]
    dec_16["decision: step: rw_evidence"]
    act_13["tool_call: rw_evidence"]
    dec_17["decision: step: apply_cutoffs"]
    act_14["tool_call: apply_cutoffs"]
    dec_18["decision: step: run_uncertainty"]
    act_15["tool_call: run_uncertainty"]
    dec_19["decision: wasted no-op: permeability"]
    dec_20["decision: wasted no-op: rock_quality"]
    dec_21["decision: wasted no-op: permeability"]
    dec_22["decision: wasted no-op: rock_quality"]
    dec_23["decision: wasted no-op: lithology"]
    dec_24["decision: wasted no-op: permeability"]
    dec_25["decision: wasted no-op: lithology"]
    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: rock_quality"]
    dec_30["decision: wasted no-op: permeability"]
    dec_31["decision: wasted no-op: lithology"]
    dec_32["decision: wasted no-op: permeability"]

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

The interpretation of well 15-135-24,937-00-00 did not converge, and the result carries a bracketed confidence tier; it should be used as a range for screening purposes only, not as a basis for a firm reserves or completion decision. Over the 295.0 m gross interval the net-to-gross is 0.043, and net pay is best expressed as the P10/P50/P90 range of 4.1 / 12.3 / 38.4 m — the width of that range is the headline result, not the P50 midpoint. The pay quality indicators, where pay is flagged, are internally consistent with a reservoir-quality rock: effective porosity of about 0.198, water saturation near 0.299, and shale volume of 0.193.

The single largest control on the net-pay answer is the cementation exponent m, which is a regional default with no core calibration and which alone drives an 8.1 m swing in net pay. This uncalibrated parameter, combined with two validator objections — one of them an unresolved mechanical objection that triggered abstention — is why the run is not a confident estimate. To move this well from bracketed toward a firmer footing, the priorities are core or offset calibration of m and Rw, and resolution of the outstanding mechanical objection. Until then, the figures reported here should be read as a plausible range that documents how well-supported the numbers are, and no confident point estimate should be inferred from them.

Appendix A — Ledger excerpt (traceability)

{
  "net_pay_total_m": 12.649200000000008,
  "net_pay_p10_p50_p90": [
    4.1148000000000025,
    12.268200000000007,
    38.42004000000003
  ],
  "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	✓