Principles at a Glance

Core

WBS is always deliverable‑pure

Every leaf must be a product you can accept with objective evidence. Do not branch by phase, method, contractor, or discipline.

Reality

Most leaves are systems and subsystems

In oil & gas, the typical leaves are physical/functional systems—but infrastructure and service‑type outcomes also belong as leaves when they are handover‑testable.

Clarity

No “systems inside services”

Systems belong to the product architecture. Services are accepted outcomes (e.g., license granted, training delivered). Keep them separate, co‑equal leaves.

WBS Leaves — A Clean Mental Model

1 Physical / Functional Systems

Typical case

Examples: “220‑001 — Fuel Gas Conditioning (System)”, “PR‑05 — Pipe Rack”, “B01 — Substation 01”, “Jetty Topsides”, “Fire Water Ring”.

Acceptance: MC/Commissioning certificates, ITRs, punch closure, energization, hydrotest dossiers.

2 Infrastructure & Non‑Process

Facilities and civils

Examples: Access roads, laydown yards, buildings, drainage, camp, TCF, bridges and jetty civil works, fencing.

Acceptance: Soils/compaction tests, as‑built drawings, QA records, functional tests (lighting, drainage), occupancy/use permits.

Still “systems” in the broad sense—assets you hand over.

3 Service / Information Products

Valid leaves when handover‑testable

Treat the service outcome as the product. Define explicit Rules of Credit (ROC).

  • Permitting & compliance: “Environmental License Granted”, “Marine Access Authorization in force”. Acceptance: approved license/docs, publication proof, validity dates.
  • Surveys & studies: “Geotechnical Investigation Package”, “As‑built Topographic Survey”. Acceptance: signed report, lab certificates, raw data package.
  • Training & OR: “Operator Training Program Delivered & Assessed”. Acceptance: attendance, assessments, materials, sign‑offs.
  • Vendor site services: “Compressor SAT & Handover Completed”. Acceptance: SAT protocol, punch‑A cleared, warranty start notice.

Rule: If it can’t be accepted with named artifacts, it shouldn’t be a WBS leaf.

Visual — The Deliverable‑Pure Tree

The WBS tree ends only in accept‑able leaves: systems, infrastructure assets, or service outcomes. Control Accounts form where a leaf meets an OBS node (one responsible CAM).

A stylized tree showing product‑architecture leaves (blue) and service‑outcome leaves (red), all ending in accept‑able deliverables. 220‑001 Fuel Gas (System) PR‑05 Pipe Rack B01 Substation 01 Environmental License Granted Compressor SAT & Handover Operator Training Delivered Product‑architecture leaves (systems, assets) Service‑outcome leaves (licenses, SAT, training)
All branches terminate in accept‑able products; no “effort” leaves.

Services: Control Accounts & Rules of Credit

Definition: A Control Account (CA) is the intersection of one WBS leaf and one OBS node (therefore one accountable CAM). For service leaves, define the Rule of Credit explicitly so that Earned Value traces objective evidence.

Service Leaf

Environmental License (Jetty Works)

  • OBS Node: Owner.Permitting
  • CA Name: Jetty Environmental License × Owner.Permitting
  • CAM: Permitting Manager
  • Typical WPs (WM/0‑100): Scoping → EIA submission → Public consultation → License issued (evidence at each step)
Infrastructure Leaf

Access Road R1

  • OBS Node: EPC.Civil
  • CA: R1 × EPC.Civil
  • CAM: Civil Construction Manager
  • WPs (units/WM): Earthworks (Units), Sub‑base/Base (WM), Paving (Units), QA/As‑built (0/100)
System Leaf

220‑001: Fuel Gas Conditioning (System)

  • OBS Node: EPC.Construction
  • CA: 220‑001 × EPC.Construction
  • CAM: Area Construction Manager (Systems)
  • WP Leads supervised: Piping Lead, Structure Lead
  • Typical WPs: Pipe spool installation & supports (units/WM), Steel structures & platforms (units), Hydrotest & reinstatement (0/100)
VS Vendor Service Leaf

Compressor SAT & Handover

  • OBS Node: EPC.MAC (Machinery)
  • CA: Compressor SAT × EPC.MAC
  • CAM: Machinery Lead
  • WPs (0/100 & WM): SAT execution (0/100), Training (WM), Warranty start (0/100)
Mini‑Graphic

CA = Leaf × OBS → One CAM

WBS Leaf 220‑001 Fuel Gas (System) OBS Node EPC.Construction Control Account220‑001 × EPC.Construction → CAM

Answering the Key Question

“Do you have systems inside services?”

No. Systems belong to the product architecture. Services create accepted outcomes that support or enable those systems. Model services as service‑deliverable leaves (with evidence), not as containers that hold systems.

Practical Guardrails

Purity

Keep WBS deliverable‑pure

  • Never branch by phase, discipline, contractor, cost, or method.
  • Allow four families of leaves: process/utility systems, infrastructure/non‑process facilities, pipelines/marine assets, and service/information products (when acceptance is objective).
Accountability

Same CA rule everywhere

  • One WBS leaf × one OBS node → one CAM.
  • Work Package slicing by discipline → phase → only boundaries that change acceptance / ownership / logic / EV / risk (Area, Subsystem/MC, Test Pack/Feeder, Contractor, etc.).

Call‑out — “Service Deliverables” (Oil & Gas)

Definition: A Service Deliverable is a non‑tangible outcome that becomes tangible via named acceptance artifacts. Treat it as a WBS leaf only when you can point to the evidence.

Examples

  • Environmental License Granted → Gazette/publication, validity letter, terms & conditions.
  • Geotechnical Investigation Package → Final signed report + lab certificates + raw data.
  • Operator Training Delivered & Assessed → Attendance, exam results, materials, sign‑offs.
  • Compressor SAT & Handover Completed → SAT protocol, punch‑A cleared, warranty start.

Non‑Examples

  • Follow‑up meetings held” (no acceptance artifact).
  • “Procurement support provided” (effort vs outcome).
  • “QA involvement ongoing” (not accept‑able as a product).
If you can’t name the evidence, it’s not a leaf.
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