HALCYON P-17 — Well Integrity Decision Workbench (2026)

Reasoning Standard:

CONTEXT → VALIDATE → DETECT → COMPARE → INTERPRET → HYPOTHESISE → ASSESS BARRIERS → DECIDE → ACT

Executive Operational Disposition

RESTRICT PRODUCTION RATE & DENY INCREASE REQUEST

IR-P17-2026-04 ACTIVE

Decision Summary: The request by Production to open the choke by +10% (for an estimated +400 to +600 bopd) is REJECTED. Although B-annulus pressure (28.8 barg) remains well below the approved MAASP of 70 barg, the well exhibits an active sustained rebuild (~0.5 barg/day), a degraded SCSSV leak rate trend (0.44 L/min vs 0.50 L/min limit), instrument disagreement (PTX 27.1 vs local 31.0 barg), and overdue fingerprint gas sampling. Continued operation is approved only under Restricted Operating Envelope (gas-lift rate $\le 4.3$ MMscf/d).

CURRENT PROD 4,820 BOPD

REQUESTED PROD +500 BOPD (+10%)

B-PRESSURE / MAASP 28.8 / 70 BARG

PRIMARY HYPOTHESIS A/B Wellhead Seal

Critical Engineering Insights

Below MAASP $\neq$ Acceptable Integrity: Sustained pressure rebuild indicates active barrier communication regardless of absolute pressure margin.
Passed Test $\neq$ No Degradation: SCSSV passed formal leak test (0.44 L/min), but has degraded by +266% since 2024 (0.12 L/min).
Unresolved Data Quality: Overdue fingerprint gas sample prevents distinguishing lift gas from produced gas leak.

Confidence Level: MEDIUM (65%)

Multi-Year Annulus & Production Trend (2019–2026)

Monthly Average Data

Note step-change in B-annulus pressure following March 2025 gas-lift header pressure increase and subsequent steady rebuild trend.

Recent 30-Day Operational & Bleed Dynamics

05-Sep Bleed Test

Includes DQ01 historian spike (68 bar) and 05-Sep controlled bleed-down to 2.1 barg with rapid initial rebuild.

Benchmark Core Engineering Answers

1. What Has Changed?

B-annulus changed from historical 0–3 barg to 28–30 barg. SCSSV leak rate degraded from 0.12 to 0.44 L/min. Facility GL pressure increased in March 2025.

2. Data Trustworthiness?

68 barg PTX spike on 08-Sep is suspect. 31.0 barg local gauge vs 27.1 barg PTX is an active disagreement. B-annulus gas sample is overdue.

3. Normal vs Abnormal?

Normal: High A-annulus pressure (108 barg) due to active gas lift. Abnormal: Sustained B-annulus pressure rebuild and SCSSV leak trend worsening.

4. Plausible Failure Mechanisms?

H1: A/B Wellhead seal leak (Most likely, 65%). H2: 9 5/8" Production Casing connection leak (30%). H3: Thermal expansion alone (Disproved, 5%).

5. Barrier Implications?

Primary barrier intact but degrading (SCSSV). Secondary barrier (B-annulus/casing) experiencing active communication from A-annulus.

6. Escalation Triggers?

B-annulus pressure > 52.5 barg (75% MAASP), SCSSV leak > 0.50 L/min, or C-annulus pressure increase > 3 barg requires immediate shut-in.

HALCYON P-17 Subsurface & Wellhead Completion

Interactive barrier path visualization and physical element status

Primary Path Secondary Path

Barrier Element Condition Matrix

Barrier Element	Envelope	Latest Evidence	Status

Engineering Distinction Notice

A-Annulus High Pressure is Normal: A-annulus serves as the primary gas-lift injection channel (95–115 barg). High pressure in A-annulus is an operational requirement, NOT sustained casing pressure.

Secondary Containment Integrity: B-annulus pressure (28.8 barg) is abnormal compared to its 0–3 barg history. A pressure below MAASP (70 barg) confirms containment margin, but does NOT confirm acceptable integrity.

Data Quality Register & Instrument Discrepancy Log

Validation framework for filtering suspect, flatlined, or uncorroborated surveillance data

6 Active Data Issues Tracked

ID	Parameter	Time Interval	Type	Severity	Engineering Description	Required Decision Handling

DQ02: B-Annulus PTX vs Local Gauge Discrepancy

On 16-Sep-2026, manual operator log records local B-gauge at 31.0 barg while telemetry transmitter (PTX) reads 27.1 barg ($\Delta = 3.9 \text{ bar}$).

Engineering Protocol: Neither instrument is automatically assumed correct. For conservative barrier compliance and MAASP evaluation, the higher reading (31.0 barg) must be used until calibration gauge test is performed.

DQ06: Overdue Fingerprint Gas Sampling

Quarterly B-annulus fluid fingerprint sampling was due on 01-Sep-2026 under plan WSP-P17-2026 but remains uncompleted.

Decision Impact: Missing surveillance MUST NOT be interpreted as acceptable condition. Unresolved gas composition prevents confirming whether leak originates from lift gas (A-annulus) vs reservoir gas (tubing/packer).

Data View:

Showing 745 hourly samples

Interactive Surveillance Trend Explorer

Key Integrity Events & Interventions

Date/Time	Event Type	Result / Detail	Status

Subsurface & Tree Valve Test History

Test Date	Element	Leak (L/min)	Limit	Result

Multi-Hypothesis Failure Model & Diagnostic Evidence Matrix

Comparative engineering evaluation avoiding premature single-root-cause conclusions

Failure Mechanism Evidence Breakdown

Hypothesis	Plausibility	Supporting Evidence (+)	Contradicting Evidence (-)	Key Remaining Uncertainties	Next Diagnostic Step Required

Operational Scenario Controls

Test production, choke, lift, bleed, and surveillance scenarios

Select Benchmark Scenario Preset:

Choke Opening: 42%

Gas Lift Rate: 4.2 MMSCFD

SCSSV Leak Rate: 0.44 L/min

Fingerprint Gas Sample Completed Gauge Discrepancy Calibrated / Resolved

Scenario Physics & Decision Evaluation Engine

Real-time barrier impact, MAASP headroom, and governance policy compliance

EST. OIL RATE 4,820 bopd

EST. B-ANNULUS REBUILD 0.48 bar/day

MAASP HEADROOM 41.2 barg (59%)

REASONING CONFIDENCE MEDIUM (65%)

Technical Evaluation & Barrier Impact

What Threshold/Evidence Would Change This Recommendation?

Approved Governance Limits & Source Document Register

Distinguishing current approved operating limits from obsolete/superseded documentation

Document ID	Title	Rev	Effective Date	Status	Key Value / Requirement

MAASP Superseded Limit Caution

WI-ENV-P17-REV2 (85 barg MAASP) was officially SUPERSEDED on 01-Jul-2026 by WI-ENV-P17-REV4 (70 barg MAASP) based on updated casing wear calculations and derating. Engineering evaluations must strictly use 70 barg as the approved maximum allowable annulus surface pressure limit.

Active Temporary Restriction IR-P17-2026-04

Effective since 03-Sep-2026 following observed B-annulus pressure increase and SCSSV leak degradation. Mandatory restrictions: No production/choke increase without formal Well Integrity engineering signoff; Gas lift rate strictly capped at $\le 4.3$ MMscf/d.

Operational Shift Log Audit Trail

Timestamp	Role	Shift Log Comment