exported
equivalent
wellhead
IRI:
http://www.inf.ufrgs.br/ontologies/copi#Wellhead
Generated on 2026-04-15
Natural Language Definition
EN
A wellhead is an assembly that bears a well surface control function and provides the structural and control interface between a wellbore and surface equipment.
PT-BR
Um cabeçal de poço é um conjunto que porta uma função de controle superficial do poço e fornece a interface estrutural e de controle entre um poço e os equipamentos de superfície.
Formal Axioms
Semi-formal (Aristotelian)
Every wellhead is an assembly that bears a well surface control function and has component parts including casing hangers and connection to wellbore
First-Order Logic Theory
Loading…
▸ Stored override
∀x(Wellhead(x) ↔ Assembly(x) ∧ ∃f(WellSurfaceControlFunction(f) ∧ bearerOf(x,f)) ∧ ∃h(CasingHanger(h) ∧ hasComponentPartAtAllTimes(x,h)) ∧ ∃w(Wellbore(w) ∧ hasConnectionTo(x,w)))
OWL 2 / Turtle
@prefix copi: <https://www.inf.ufrgs.br/ontologies/copi/> .
@prefix : <https://www.inf.ufrgs.br/ontologies/copi/> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix bfo: <http://purl.obolibrary.org/obo/> .
@prefix iof-core: <https://spec.industrialontologies.org/ontology/construct/> .
@prefix iof-av: <https://spec.industrialontologies.org/ontology/annotation/> .
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
@prefix qudt: <http://qudt.org/schema/qudt/> .
@prefix dcterms: <http://purl.org/dc/terms/> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
@prefix apv: <http://inf.ufrgs.br/ontologies/apv#> .
### COPI — Core Ontology for Petroleum Installations
### Class module: Wellhead
<https://www.inf.ufrgs.br/ontologies/copi>
rdf:type owl:Ontology ;
dcterms:title "Core Ontology for Petroleum Installations (COPI)"@en ;
dcterms:title "Ontologia Core para Instalações de Petróleo (COPI)"@pt-br ;
dcterms:description "BFO/IOF-Core conformant ontology of equipment classes for petroleum production plants, developed using the five-step RDL enrichment method."@en ;
skos:scopeNote "Material artifacts (bfo:material_entity) that (i) are part of a petroleum production plant, and (ii) bear at least one function whose realization involves the transport (e.g. production and injection), processing (separation and other processes), control, monitoring, measurement, containment or offloading of material or energy."@en ;
skos:scopeNote "Artefatos materiais (bfo:material_entity) que (i) fazem parte de uma planta de produção de petróleo, e (ii) possuem ao menos uma função cuja realização envolve o transporte (p. ex. produção e injeção), processamento (separação e outros processos), controle, monitoramento, medição, contenção ou escoamento de material ou energia."@pt-br ;
skos:scopeNote "COPI provides high-level equipment categories defined by function to demonstrate the defined-class mechanism. Equipment subtypes are annotated with references to CFIHOS and PCA RDL terms. COPI is not a reference data library; organizations should use CFIHOS, PCA RDL, or ISO 14224 for comprehensive equipment classification."@en ;
skos:scopeNote "COPI fornece categorias de alto nível de equipamentos definidas por função para demonstrar o mecanismo de classe definida. Os subtipos de equipamentos são anotados com referências aos termos do CFIHOS e do PCA RDL. COPI não é uma biblioteca de dados de referência; organizações devem utilizar o CFIHOS, o PCA RDL ou a ISO 14224 para classificação abrangente de equipamentos."@pt-br ;
owl:versionInfo "1.1.0" ;
owl:imports <https://spec.industrialontologies.org/ontology/core/Core/> ;
owl:imports <http://purl.obolibrary.org/obo/bfo/2020/bfo.owl> ;
dcterms:creator "Nicolau Oyhenard dos Santos"@en ;
dcterms:contributor "Cauã Antunes" ;
dcterms:contributor "Haroldo Rojas" ;
dcterms:contributor "Rafael Petry" ;
dcterms:contributor "Régis Romeu" ;
dcterms:contributor "Mara Abel" ;
dcterms:isPartOf <https://inf.ufrgs.br/projetos/OntoKG> ;
dcterms:publisher "Universidade Federal do Rio Grande do Sul (UFRGS)"@en ;
dcterms:license <https://creativecommons.org/licenses/by/4.0/> ;
dcterms:created "2026-04-08"^^xsd:date ;
dcterms:modified "2026-10-07"^^xsd:date ;
apv:GlobalMinLanguageCoverage "en pt-br" ;
apv:ClassURIFormationRule "https://www[.]inf[.]ufrgs[.]br/ontologies/copi/(COPI_[0-9]{7}|[A-Z][A-Za-z0-9]*)" ;
apv:ClassMinAnnotationCoverage "rdfs:label https://spec.industrialontologies.org/ontology/annotation/naturalLanguageDefinition" .
iof-av:naturalLanguageDefinition rdf:type owl:AnnotationProperty ;
apv:MinAnnotationLength 20 .
### Identity-giving function
:COPI_0000695 rdf:type owl:Class ; # WellSurfaceControlFunction
rdfs:subClassOf iof-core:DesignedFunction ;
rdfs:subClassOf [
rdf:type owl:Restriction ;
owl:onProperty bfo:BFO_0000054 ; # realizedIn
owl:allValuesFrom :COPI_0000696 # WellSurfaceControlProcess
] ;
rdfs:subClassOf [
rdf:type owl:Restriction ;
owl:onProperty bfo:BFO_0000054 ; # realizedIn
owl:someValuesFrom :COPI_0000696 # WellSurfaceControlProcess
] ;
rdfs:label "well surface control function"@en ;
rdfs:label "função de controle de superfície do poço"@pt-br .
### Process type
:COPI_0000696 rdf:type owl:Class ; # WellSurfaceControlProcess
rdfs:subClassOf :COPI_0000010 ; # FlowControl
rdfs:label "well surface control process"@en ;
rdfs:label "processo de controle de superfície do poço"@pt-br .
:COPI_0000010 rdf:type owl:Class . # FlowControl
:COPI_0000696 # WellSurfaceControlProcess
rdfs:subClassOf [
rdf:type owl:Restriction ;
owl:onProperty iof-core:hasInput ;
owl:someValuesFrom :COPI_0000390 # FormationFluid
] ;
rdfs:subClassOf [
rdf:type owl:Restriction ;
owl:onProperty iof-core:hasSpecifiedOutput ;
owl:someValuesFrom :COPI_0000390 # FormationFluid
] .
### Equipment universal: Wellhead
:COPI_0000377 rdf:type owl:Class ; # Wellhead
owl:equivalentClass [
rdf:type owl:Class ;
owl:intersectionOf (
iof-core:Assembly
[
rdf:type owl:Restriction ;
owl:onProperty iof-core:hasFunction ; # Object branch (MaterialArtifact/Assembly/Object/FiatObjectPart)
owl:someValuesFrom :COPI_0000695 # WellSurfaceControlFunction
]
[
rdf:type owl:Restriction ;
owl:onProperty iof-core:hasComponentPartAtAllTimes ;
owl:someValuesFrom :COPI_0000697 # WellheadSpool
]
)
] ;
rdfs:label "wellhead"@en ;
rdfs:label "cabeçal de poço"@pt-br ;
iof-av:naturalLanguageDefinition "A wellhead is an assembly that bears a well surface control function and provides the structural and control interface between a wellbore and surface equipment."@en ;
skos:definition "A wellhead is an assembly that bears a well surface control function and provides the structural and control interface between a wellbore and surface equipment."@en ;
iof-av:naturalLanguageDefinition "Um cabeçal de poço é um conjunto que porta uma função de controle superficial do poço e fornece a interface estrutural e de controle entre um poço e os equipamentos de superfície."@pt-br ;
iof-av:semiFormalNaturalLanguageAxiom "Every wellhead is an assembly that bears a well surface control function and has component parts including casing hangers and connection to wellbore"@en ;
iof-av:firstOrderLogicAxiom "∀x(Wellhead(x) ↔ Assembly(x) ∧ ∃f(WellSurfaceControlFunction(f) ∧ bearerOf(x,f)) ∧ ∃h(CasingHanger(h) ∧ hasComponentPartAtAllTimes(x,h)) ∧ ∃w(Wellbore(w) ∧ hasConnectionTo(x,w)))"@en ;
skos:definition "[ISO 15926-4] A <WELLHEAD> is an <ARTEFACT> that is the top of the casing of a production oil well including the attached control and flow valves"@en ;
skos:definition "[CFIHOS] The wellhead is assembled from, or incorporates facilities for, the upper casing and tubing hangers. This effectively provides the upper termination of the wellbore and provides a mounting position for the surface flow-control equipment or Christmas tree."@en ;
skos:definition "[SLB Glossary] The system of spools, valves and assorted adapters that provide pressure control of a production well."@en ;
skos:definition "[OnePetro] The mechanical connection between the tree and the casing. May house tubular hangers, annular access valves. It is connected to the casing by welding, threads, hydraulic forming or set screws."@en .
:COPI_0000697 rdf:type owl:Class ; # WellheadSpool
rdfs:subClassOf iof-core:MaterialArtifact ;
rdfs:label "spool de cabeçal de poço"@pt-br ;
rdfs:label "wellhead spool"@en .
# Disjointness: Wellhead and Separator
[] rdf:type owl:AllDisjointClasses ;
owl:members ( :COPI_0000377 :COPI_0000084 ) . # Wellhead, Separator
# Disjointness: Wellhead and HeatExchanger
[] rdf:type owl:AllDisjointClasses ;
owl:members ( :COPI_0000377 :COPI_0000092 ) . # Wellhead, HeatExchanger
# Disjointness: Wellhead and Compressor
[] rdf:type owl:AllDisjointClasses ;
owl:members ( :COPI_0000377 :COPI_0000073 ) . # Wellhead, Compressor
Axiomatization Decision Log
1
Identity-Giving Function
Function class
WellSurfaceControlFunction
⊑ DesignedFunction
Realized in
WellSurfaceControlProcess
⊑ FlowControl
The wellhead's identity-giving function is to provide surface control of well operations - pressure control, flow control, mounting for other equipment like Christmas trees, and serving as the interface between subsurface and surface systems. This is distinct from the WellFluidControlFunction of Christmas trees which focuses on production flow control.
2
Genus Determination
Assembly
bfo:Object (BFO_0000030)
Causally unified material artefact composed of physically connected,
separable MaterialComponent parts. Satisfies
Assembly ⊑ MaterialArtifact ⊑ bfo:Object.
Wellhead is clearly an assembly of multiple physically connected components (spools, valves, adapters, hangers, housings) that function as a causally unified unit with a single maintainable boundary. It's more complex than a simple MaterialArtifact but exists as one integrated Object. No domain-specific superclass exists in the parent candidates that would be more appropriate.
3
Necessary Parts
| Part class | Parent | Relation |
|---|---|---|
| WellheadSpool | MaterialArtifact | hasComponentPartAtAllTimes |
These parts represent the minimal necessary components for any wellhead to fulfill its surface control function - wellbore interface (casing hanger), structural integrity (spool/body), and safety (pressure containment).
4
Process Participation Signature ⟨I, O, T⟩
Inputs (I)
FormationFluid
— from wellbore, various phases and pressures
Outputs (O)
FormationFluid
— controlled pressure and flow to surface equipment
Transformation (T)
pressure and flow control without phase change
Wellhead receives well fluids from the wellbore and provides controlled interface to surface equipment. The transformation is control-based rather than thermodynamic or chemical.
5
Axiom Mode Decision
Necessary + Sufficient
— modelled as a defined class
(≡, EquivalentClass). Automatic classification is
appropriate for this concept.
Disjointness Axioms
Separator
HeatExchanger
Compressor
C2: Compressor. C4: Separator, HeatExchanger. Wellhead provides well control interface function which is incompatible with separation processes, heat transfer processes, or compression processes that change fluid properties
Cross-Standard Observations
Definitions show some variation in emphasis: ISO 15926 focuses on casing top with attached valves, CFIHOS emphasizes the assembly nature and Christmas tree mounting, SLB focuses on pressure control system, OnePetro emphasizes mechanical connection aspects. All converge on the concept of surface well control interface.
