Has product
sub property of: causativeRelationship
comment: س <لديه المنتج> ع. س هو مصدر المنتج ع مع عنصر معالجة. على سبيل المثال: "قطع الجذور" <لديه المنتج> "نفايات قطع الأخشاب" اسبانيا <لديها المنتج> الخمر شيري @ar
comment: X<有产品>Y。X是产品Y的来源，其中有加工处理的要素。例如：“森林采运”<有产品>“砍伐损失”，“ 西班牙”<有产品>“雪利酒”。 @zh
comment: X <имеет продукт> Y. X является источником продукта Y, с элементом переработки. Например, "брожение" <имеет продукт> "ферментированные продукты", "Испания" <имеет продукт> "херес". @ru
comment: X <tiene el producto> Y. X es la fuente del producto Y, con un elemento de procesamiento. Ej. “Aprovechamiento de la madera” <tiene el producto> “Residuos de explotación forestal”, “España” <tiene el producto> “Jerez”. @es
comment: X <has product> Y. X is the source of product Y, with a processing element. E.g. “logging”<has product> “logging wastes”, “Spain” <has product> “sherry”.
comment: X <a le produit> Y. X est la source du produit Y, avec un élément de traitement. Par exemple: "exploitation forestière" <a le produit> "déchet d'exploitation forestière", "Espagne" <a le produit> "xérès". @fr
label: 有产品 @zh
label: لديه المنتج @ar
label: имеет продукт @ru
label: Tiene el producto @es
label: A le produit @fr

Is used as
sub property of: processRelationship
comment: X <用作> Y. 例如 : "山梨醇" <用作> "甜味剂"; "乙醇" <用作> "燃料". @zh
comment: X <se utiliza como> Y. Ej. "Sorbitol" <se utiliza como> "Edulcorante"; "Etánol" <se utiliza como> "Combustible". @es
comment: X <is used as> Y. E.g. "sorbitol" <is used as> "sweetener"; "ethanol" <is used as> "fuel".
comment: X <est utilisé comme> Y. Par exemple: "sorbitol" <est utilisé comme> "édulcorant"; "éthanol" <est utilisé comme> "combustible". @fr
comment: X <مستعمل ك> Y: "سربتول" <مستعمل ك> "محليات"; "إيثانول" <مستعمل ك> "وقود". @ar
comment: X <направлен на> Y. X направлен на цель или процесс Y. Например, "ветеринарные услуги" <направлен на> "здоровье животных", "рубки обновления" <направлен на> "естественное возобновление". @ru
label: 用作 @zh
label: مستعمل ك @ar
label: используется как @ru
label: Se utiliza como @es
label: Est utilisé comme @fr

AGROVOC
type: ConceptScheme

óleo bruto
type: Label
in dataset: Agrovoc
created: 2023-05-22T22:26:11
notation: 9d76e888

petrol
type: Label
in dataset: Agrovoc
created: 2020-07-10T11:34:06.015+02:00
notation: a8075384

ნედლი ნავთობი
type: Label
in dataset: Agrovoc
created: 2017-06-07T09:22:20Z
modified: 2017-06-14T14:16:05Z
notation: f10374b2

ham petrol
type: Label
in dataset: Agrovoc
created: 2011-11-20T20:31:09Z
modified: 2014-07-03T18:35:45Z
notation: 10178

原油
type: Label
in dataset: Agrovoc
created: 2002-12-12T00:00:00Z
is acronym of: 石油
has synonym: 石油
notation: 10178

น้ำมันดิบ
type: Label
in dataset: Agrovoc
created: 2005-08-19T00:00:00Z
is acronym of: ปิโตรเลียม
has synonym: ปิโตรเลียม
notation: 10178

surový olej
type: Label
in dataset: Agrovoc
created: 2005-12-16T00:00:00Z
is acronym of: ropa
has synonym: ropa
notation: 10178

сырая нефть
type: Label
in dataset: Agrovoc
created: 2009-01-30T00:00:00Z
is acronym of: нефть
has synonym: нефть
notation: 10178

óleo bruto
type: Label
in dataset: Agrovoc
created: 1998-08-04T00:00:00Z
is acronym of: petróleo
has synonym: petróleo
modified: 2021-06-16T21:24:42Z
notation: 10178

Olej surowy
type: Label
in dataset: Agrovoc
created: 2006-12-19T00:00:00Z
is acronym of: Ropa naftowa
has synonym: Ropa naftowa
notation: 10178

원유
type: Label
in dataset: Agrovoc
created: 2009-12-02T00:00:00Z
is acronym of: 석유
has synonym: 석유
notation: 10178

原油
type: Label
in dataset: Agrovoc
created: 2005-08-09T00:00:00Z
is acronym of: 石油
has synonym: 石油
notation: 10178

Olio grezzo
type: Label
in dataset: Agrovoc
created: 2006-12-05T00:00:00Z
is acronym of: Petrolio
has synonym: Petrolio
notation: 10178

nyersolaj
type: Label
in dataset: Agrovoc
created: 2006-12-06T00:00:00Z
is acronym of: kõolaj
has synonym: kõolaj
notation: 10178

क्रूड आँयल
type: Label
in dataset: Agrovoc
created: 1981-01-26T00:00:00Z
is acronym of: पेट्रोलियम (खनिज तेल)
has synonym: पेट्रोलियम (खनिज तेल)
notation: 10178

نفت خام
type: Label
in dataset: Agrovoc
created: 2007-04-20T00:00:00Z
is acronym of: نفت طبیعی
has synonym: نفت طبیعی
notation: 10178

Crudos
type: Label
in dataset: Agrovoc
created: 1990-06-18T00:00:00Z
is acronym of: Petróleo
has synonym: Petróleo
notation: 10178

crude oil
type: Label
in dataset: Agrovoc
created: 1981-01-26T00:00:00Z
is acronym of: petroleum
has synonym: petroleum
modified: 2012-01-20T17:47:23Z
notation: 10178

Rohöl
type: Label
in dataset: Agrovoc
created: 2012-01-06T16:38:08Z
modified: 2012-01-20T17:46:47Z
notation: 1325839088842

surový olej
type: Label
in dataset: Agrovoc
created: 2003-03-27T00:00:00Z
is acronym of: ropa
has synonym: ropa
notation: 10178

mafuta ya petroli
type: Label
in dataset: Agrovoc
created: 2023-11-29T14:50:42Z
modified: 2023-12-14T10:44:19
notation: 5747

petróleo
type: Label
in dataset: Agrovoc
created: 2023-05-22T22:24:47
notation: 5747

нафта
type: Label
in dataset: Agrovoc
created: 2021-01-21T09:42:02
notation: 5747

țiței
type: Label
in dataset: Agrovoc
created: 2020-07-10T11:31:32.327+02:00
notation: 5747

ნავთობი
type: Label
in dataset: Agrovoc
created: 2017-06-07T09:22:04Z
modified: 2017-06-14T14:16:07Z
notation: 5747

petrol kökenli kaynak
type: Label
in dataset: Agrovoc
created: 2011-11-20T20:20:23Z
modified: 2017-09-22T13:58:19Z
notation: 5747

石油
type: Label
in dataset: Agrovoc
created: 2002-12-12T00:00:00Z
is acronym of: 原油
has synonym: 原油
notation: 5747

ปิโตรเลียม
type: Label
in dataset: Agrovoc
created: 2005-08-19T00:00:00Z
is acronym of: น้ำมันดิบ
has synonym: น้ำมันดิบ
notation: 5747

ropa
type: Label
in dataset: Agrovoc
created: 2005-12-16T00:00:00Z
is acronym of: surový olej
has synonym: surový olej
notation: 5747

нефть
type: Label
in dataset: Agrovoc
created: 2009-01-30T00:00:00Z
is acronym of: сырая нефть
has synonym: сырая нефть
notation: 5747

petróleo
type: Label
in dataset: Agrovoc
created: 1998-08-04T00:00:00Z
is acronym of: óleo bruto
has synonym: óleo bruto
modified: 2021-06-16T21:24:42Z
notation: 5747

Ropa naftowa
type: Label
in dataset: Agrovoc
created: 2006-12-19T00:00:00Z
is acronym of: Olej surowy
has synonym: Olej surowy
notation: 5747

ປີໂຕຼລ້ຽນ
type: Label
in dataset: Agrovoc
created: 2005-12-16T00:00:00Z
notation: 5747

석유
type: Label
in dataset: Agrovoc
created: 2009-12-02T00:00:00Z
is acronym of: 원유
has synonym: 원유
notation: 5747

石油
type: Label
in dataset: Agrovoc
created: 2005-08-09T00:00:00Z
is acronym of: 原油
has synonym: 原油
notation: 5747

Petrolio
type: Label
in dataset: Agrovoc
created: 2006-12-12T00:00:00Z
is acronym of: Olio grezzo
has synonym: Olio grezzo
notation: 5747

kõolaj
type: Label
in dataset: Agrovoc
created: 2006-12-06T00:00:00Z
is acronym of: nyersolaj
has synonym: nyersolaj
notation: 5747

पेट्रोलियम (खनिज तेल)
type: Label
in dataset: Agrovoc
created: 1981-01-09T00:00:00Z
is acronym of: क्रूड आँयल
has synonym: क्रूड आँयल
notation: 5747

pétrole
type: Label
in dataset: Agrovoc
created: 1981-01-21T00:00:00Z
modified: 2021-05-24T17:34:42Z
notation: 5747

نفت طبیعی
type: Label
in dataset: Agrovoc
created: 2007-04-20T00:00:00Z
is acronym of: نفت خام
has synonym: نفت خام
notation: 5747

Petróleo
type: Label
in dataset: Agrovoc
created: 1981-01-23T00:00:00Z
is acronym of: Crudos
has synonym: Crudos
modified: 2012-11-27T00:15:53Z
notation: 5747

petroleum
type: Label
in dataset: Agrovoc
created: 1981-01-09T00:00:00Z
is acronym of: crude oil
has synonym: crude oil
modified: 2012-01-20T17:47:23Z
notation: 5747

Erdöl
type: Label
in dataset: Agrovoc
created: 2012-01-06T16:37:30Z
modified: 2015-03-12T18:14:17Z
notation: 1325839050185

ropa
type: Label
in dataset: Agrovoc
created: 2003-03-27T00:00:00Z
is acronym of: surový olej
has synonym: surový olej
notation: 5747

نفط
type: Label
in dataset: Agrovoc
created: 2002-12-12T00:00:00Z
notation: 5747

xDef ad8249b3
has source: National Institute of Environmental Health Sciences, 2024. Environmental Health Sciences Glossary https://www.niehs.nih.gov/health/topics/glossary citing U.S. National Library of Medicine
created: 2024-07-05T16:17:38
value: An oily liquid, made of a complex mixture of hydrocarbons with small amounts of other substances, that occurs in many places in the upper strata of the earth; is prepared for use as gasoline, naphtha, or other products by various refining processes.

prefLabel
comment: A resource has no more than one value of skos:prefLabel per language tag.

petroleum
type: Concept
narrower: gasolina
narrower: diesel oil
narrower: mineral oils
alternative label: óleo bruto @pt-br
alternative label: petrol @ro
alternative label: ნედლი ნავთობი @ka
alternative label: ham petrol @tr
alternative label: 原油 @zh
alternative label: น้ำมันดิบ @th
alternative label: surový olej @sk
alternative label: сырая нефть @ru
alternative label: Olej surowy @pl
alternative label: 원유 @ko
alternative label: Olio grezzo @it
alternative label: nyersolaj @hu
alternative label: क्रूड आँयल @hi
alternative label: نفت خام @fa
alternative label: Crudos @es
alternative label: crude oil
alternative label: Rohöl @de
in dataset: Agrovoc
created: 2011-11-20T20:31:09Z
Has product: paraffin
Is used as: fuels
related: oil-water interface
related: oil-gas interface
related: petroleum geology
related: oil and gas fields
related: oil and gas industries
related: petroleum engineering
related: oil and gas production
related: organic sediments
related: bitumen
related: oil spills
in scheme: AGROVOC
alt label: óleo bruto
alt label: petrol
alt label: ნედლი ნავთობი
alt label: ham petrol
alt label: 原油
alt label: น้ำมันดิบ
alt label: surový olej
alt label: сырая нефть
alt label: Olej surowy
alt label: 원유
alt label: Olio grezzo
alt label: nyersolaj
alt label: क्रूड आँयल
alt label: نفت خام
alt label: Crudos
alt label: crude oil
alt label: Rohöl
pref label: mafuta ya petroli
pref label: petróleo
pref label: нафта
definition: xDef ad8249b3
preferred label: mafuta ya petroli @sw
preferred label: petróleo @pt-br
preferred label: нафта @sr
preferred label: țiței @ro
preferred label: ნავთობი @ka
preferred label: petrol kökenli kaynak @tr
preferred label: 石油 @zh
preferred label: ปิโตรเลียม @th
preferred label: ropa @sk
preferred label: нефть @ru
preferred label: Ropa naftowa @pl
preferred label: نفط @ar
preferred label: Erdöl @de
preferred label: Petróleo @es
preferred label: نفت طبیعی @fa
preferred label: pétrole @fr
preferred label: पेट्रोलियम (खनिज तेल) @hi
preferred label: kõolaj @hu
preferred label: Petrolio @it
preferred label: 석유 @ko
preferred label: ປີໂຕຼລ້ຽນ @lo
modified: 2024-07-05T16:17:38
broader: mineral resources

gasolina
type: Concept
preferred label: petroli @sw
preferred label: бензин @sr
preferred label: benzină @ro
preferred label: ბენზინი @ka
preferred label: petrol
preferred label: 汽油 @zh
preferred label: น้ำมันเบนซิน @th
preferred label: benzín @sk
preferred label: غازولين @ar
preferred label: Benzin @de
preferred label: Gasolina @es
preferred label: بنزین @fa
preferred label: essence @fr
preferred label: पेट्रोल @hi
preferred label: benzin @hu
preferred label: Benzina @it
preferred label: ガソリン @ja
preferred label: 가솔린 @ko
preferred label: ນຳມັນ @lo
preferred label: Benzyna @pl
broader: petroleum

diesel oil
type: Concept
preferred label: дызельнае паліва @be
preferred label: óleo diesel @pt-br
preferred label: mafuta ya dizeli @sw
preferred label: дизел гориво @sr
preferred label: dizel yakıtı @tr
preferred label: дизельне паливо @uk
preferred label: დიზელის საწვავი @ka
preferred label: 柴油 @zh
preferred label: น้ำมันดีเซล @th
preferred label: motorová nafta @sk
preferred label: дизельное топливо @ru
preferred label: زيت الديزل @ar
preferred label: Dieselöl @de
preferred label: Aceite diesel @es
preferred label: روغن دیزل @fa
preferred label: carburant diésel @fr
preferred label: डीजल तेल @hi
preferred label: gázolaj @hu
preferred label: Gasolio @it
preferred label: ディーゼル油 @ja
preferred label: 디젤유 @ko
preferred label: ນ້ຳມັນກາຊວນ @lo
preferred label: Olej napędowy @pl
broader: petroleum

mineral oils
type: Concept
preferred label: óleo mineral @pt-br
preferred label: mafuta ya madini @sw
preferred label: минерална уља @sr
preferred label: мінеральні олії @uk
preferred label: მინერალური ზეთი @ka
preferred label: uleiuri minerale @ro
preferred label: madeni yağ @tr
preferred label: 矿物油 @zh
preferred label: น้ำมันแร่ @th
preferred label: minerálne oleje @sk
preferred label: минеральное масло @ru
preferred label: زيوت معدنية @ar
preferred label: minerální oleje @cs
preferred label: Mineralöl @de
preferred label: Aceite mineral @es
preferred label: روغن معدنی @fa
preferred label: huile minérale @fr
preferred label: खनिज-तेल @hi
preferred label: ásványolaj @hu
preferred label: Oli minerali @it
preferred label: 鉱油 @ja
preferred label: 광유 @ko
preferred label: ນຳ້ມັນແຮ່ທາດ @lo
preferred label: Olej mineralny @pl
broader: petroleum

paraffin
type: Concept
preferred label: Parafina @es
preferred label: mafuta ya taa @sw
preferred label: ნავთი @ka
preferred label: parafină @ro
preferred label: parafin @nb
preferred label: 石蜡 @zh
preferred label: พาราฟิน @th
preferred label: parafín @sk
preferred label: парафин @ru
preferred label: بارافين @ar
preferred label: Paraffin @de
preferred label: پارافین @fa
preferred label: paraffine @fr
preferred label: पैराफिन (मोम) @hi
preferred label: Paraffina @it
preferred label: パラフィン @ja
preferred label: 파라핀 @ko
preferred label: ພາຣາຟີນ @lo
preferred label: parafina @pt
product of: petroleum

fuels
type: Concept
preferred label: Combustibles @ca
preferred label: Combustible @es
preferred label: fueli @sw
preferred label: combustível @pt-br
preferred label: Brennstoff @de
preferred label: brensel @nb
preferred label: топливо @ru
preferred label: паливо @uk
preferred label: combustibil @ro
preferred label: საწვავი @ka
preferred label: ఇంధనాలు @te
preferred label: yakıt @tr
preferred label: 燃料 @zh
preferred label: เชื้อเพลิง @th
preferred label: وقود @ar
preferred label: paliva @cs
preferred label: سوخت‌ها @fa
preferred label: combustible @fr
preferred label: ईंधन @hi
preferred label: energiahordozó @hu
preferred label: Combustibili @it
preferred label: 연료 @ko
preferred label: ເຊື້ອໄຟ @lo
preferred label: Paliwo @pl
preferred label: palivá @sk
is use of: petroleum

oil-water interface
type: Concept
preferred label: interface óleo-água @pt-br
preferred label: поверхность раздела "вода-нефть" @ru
preferred label: واجهة النفط والماء @ar
preferred label: eneo linalomilikiwa na sehemu mbili ya mafuta-maji @sw
preferred label: 油水界面 @zh
preferred label: interface huile-eau @fr
preferred label: Öl-Wasser-Grenzfläche @de
preferred label: yağ-su arayüzü @tr
preferred label: Interfase aceite-agua @es
related: petroleum

oil-gas interface
type: Concept
preferred label: interface óleo-gás @pt-br
preferred label: газонефтяной контакт @ru
preferred label: واجهة النفط والغاز @ar
preferred label: kiolesura cha mafuta na gesi @sw
preferred label: 油气界面 @zh
preferred label: Iinterfase aceite-gas @es
preferred label: interface huile-gaz @fr
preferred label: Öl-Gas-Grenzfläche @de
preferred label: yağ-gaz arayüzü @tr
related: petroleum

petroleum geology
type: Concept
preferred label: jiolojia ya petroli @sw
preferred label: Geología del petróleo @es
preferred label: géologie du pétrole @fr
preferred label: Geologia del petroli @ca
preferred label: 石油地质学 @zh
preferred label: petroleumsgeologi @nb
preferred label: جيولوجية النفط @ar
preferred label: нефтяная геология @ru
preferred label: petrol jeolojisi @tr
preferred label: ნავთობის გეოლოგია @ka
preferred label: geologie ropy @cs
preferred label: geologia petrolului @ro
preferred label: нафтова геологія @uk
preferred label: Erdölgeologie @de
related: petroleum

oil and gas fields
type: Concept
preferred label: zăcăminte de petrol și gaze @ro
preferred label: maeneo ya mafuta na gesi @sw
preferred label: Campo de petróleo y gas @es
preferred label: حقول النفط والغاز @ar
preferred label: 油气田 @zh
preferred label: нефтяные и газовые месторождения @ru
preferred label: ნავთობისა და გაზის საბადო @ka
preferred label: ropná a plynová pole @cs
preferred label: Öl- und Gasfeld @de
preferred label: petrol ve gaz sahası @tr
preferred label: gisement de pétrole et de gaz @fr
preferred label: olje- og gassfelt @nb
related: petroleum

oil and gas industries
type: Concept
preferred label: viwanda vya mafuta na gesi @sw
preferred label: Industria de petróleo y gas @es
preferred label: صناعات النفط والغاز @ar
preferred label: 石油天然气工业 @zh
preferred label: нефтегазовая промышленность @ru
preferred label: industrie du pétrole et du gaz @fr
preferred label: olje- og gassindustri @nb
preferred label: ropný a plynárenský průmysl @cs
preferred label: Öl- und Gasindustrie @de
preferred label: Industrie petrolifere e del gas @it
preferred label: industria petrolului și a gazelor @ro
preferred label: petrol ve gaz endüstrisi @tr
related: petroleum

petroleum engineering
type: Concept
preferred label: inginerie petrolieră @ro
preferred label: uhandisi wa petroli @sw
preferred label: petrol mühendisliği @tr
preferred label: 石油工程 @zh
preferred label: нефтяное машиностроение @ru
preferred label: هندسة البترول @ar
preferred label: Ingeniería petrolera @es
preferred label: technique du pétrole @fr
preferred label: Enginyeria petroliera @ca
preferred label: petroleumsteknologi @nb
related: petroleum

oil and gas production
type: Concept
preferred label: uzalishaji wa mafuta na gesi @sw
preferred label: produção de gás e óleo @pt-br
preferred label: إنتاج النفط والغاز @ar
preferred label: 油气生产 @zh
preferred label: нефтегазовое производство @ru
preferred label: produkce ropy a plynu @cs
preferred label: Produzione di petrolio e gas @it
preferred label: petrol ve gaz üretimi @tr
preferred label: Öl- und Gasproduktion @de
preferred label: olje- og gassproduksjon @nb
preferred label: Petróleo y producción de gas @es
preferred label: production de pétrole et de gaz @fr
related: petroleum

organic sediments
type: Concept
preferred label: sedimento orgânico @pt
preferred label: Sedimenti organici @it
preferred label: sedimenti za kikaboni @sw
preferred label: Sedimento orgánico @es
preferred label: органические отложения @ru
preferred label: الرواسب العضوية @ar
preferred label: 有机沉积物 @zh
preferred label: sédiment organique @fr
preferred label: organisches Sediment @de
preferred label: organik çökel @tr
preferred label: органски седимент @sr
related: petroleum

bitumen
type: Concept
preferred label: lami @sw
preferred label: бітум @be
preferred label: битумен @sr
preferred label: бітумні матеріали @uk
preferred label: битум @ru
preferred label: bitum @ro
preferred label: ბიტუმი @ka
preferred label: bitüm @tr
preferred label: 沥青 @zh
preferred label: น้ำมันดิน @th
preferred label: asfalt @sk
preferred label: betume @pt
preferred label: بتيومين @ar
preferred label: Bitumen @de
preferred label: Betún @es
preferred label: قیر @fa
preferred label: bitume @fr
preferred label: बिटुमैन/ डामर @hi
preferred label: Bitume @it
preferred label: ビチューメン、瀝青 @ja
preferred label: 역청 @ko
preferred label: ຢາງປູທາງ @lo
preferred label: Bitumin @pl
related: petroleum

oil spills
type: Concept
preferred label: изливање нафте @sr
preferred label: ნავთობის დაღვრა @ka
preferred label: mafuta yanamwagika @sw
preferred label: الانسكابات النفطية @ar
preferred label: розливи нафти @uk
preferred label: oljeutslipp @nb
preferred label: petrol dökülmesi @tr
preferred label: 石油泄露 @zh
preferred label: คราบน้ำมัน @th
preferred label: ropné škvrny @sk
preferred label: ropné skvrny @cs
preferred label: Ölpest @de
preferred label: Derrame de petróleo @es
preferred label: نشت‌هاي نفتي @fa
preferred label: déversement d'hydrocarbures @fr
preferred label: तेल या गिराना @hi
preferred label: olajkiömlés @hu
preferred label: Fuoriuscite di petrolio @it
preferred label: 油漏れ @ja
preferred label: 유적지 @ko
preferred label: Wycieki ropy naftowej @pl
preferred label: derramamento de petróleo @pt
preferred label: разливы нефти @ru
related: petroleum

mineral resources
type: Concept
preferred label: Recurso mineral @es
preferred label: rasilimali za madini @sw
preferred label: минерални извори @sr
preferred label: resurse minerale @ro
preferred label: მინერალური რესურსები @ka
preferred label: mineral kaynak @tr
preferred label: 矿产资源 @zh
preferred label: ทรัพยากรแร่ @th
preferred label: zásoby nerastných surovín @sk
preferred label: минеральные ресурсы @ru
preferred label: موارد معدنية @ar
preferred label: zásoby nerostných surovin @cs
preferred label: Mineralvorkommen @de
preferred label: منابع معدنی @fa
preferred label: ressource minérale @fr
preferred label: खनिज-स्त्रोत @hi
preferred label: ásványi erõforrás @hu
preferred label: Risorse minerali @it
preferred label: 鉱物資源 @ja
preferred label: 광물자원 @ko
preferred label: ຊັບພະຍາກອນແຮ່ທາດ @lo
preferred label: Bogactwa mineralne @pl
preferred label: recurso mineral @pt
narrower: petroleum