QuickLinks -- Click here to rapidly navigate through this document

EXHIBIT 21

NOBLE ENERGY, INC.
SUBSIDIARIES

NAME	STATE OF JURISDICTION OF ORGANIZATION	REF
LaTex Resources Inc.	Colorado	(1	)
Noble Energy Marketing, Inc.	Delaware	(1	)
Noble Energy Production, Inc.	Delaware	(1	)
Noble Gas Pipeline, Inc.	Delaware	(2	)
Samedan of North Africa, Inc.	Delaware	(1	)
Noble Energy West Africa Ltd.	Delaware	(3	)
Noble Energy Hannah Ltd.	Cayman Islands	(3	)
EDC Ireland	Cayman Islands	(3	)
Noble Energy International Ltd.	Cayman Islands	(3	)
Noble Energy EG Ltd.	Cayman Islands	(4	)
Noble Energy JDZ Ltd.	Cayman Islands	(4	)
Alba Associates LLC	Cayman Islands	(9	)
Alba Plant LLC	Cayman Islands	(10	)
MachalaPower Cia. Ltda.	Cayman Islands	(4	)
Noble Energy Mediterranean Ltd.	Cayman Islands	(4	)
Yam Tethys Ltd.	Israel	(14	)
Noble Energy Suriname Ltd.	Cayman Islands	(4	)
AMPCO Marketing, L.L.C.	Michigan	(5	)
AMPCO Services, L.L.C.	Michigan	(5	)
Samedan Vietnam Limited	Cayman Islands	(3	)
Atlantic Methanol Capital Company	Cayman Islands	(5	)
Samedan Methanol	Cayman Islands	(6	)
Atlantic Methanol Associates LLC	Cayman Islands	(7	)
Atlantic Methanol Production Company LLC	Cayman Islands	(8	)
Samedan, Mediterranean Sea, Inc.	Delaware	(1	)
Samedan North Sea, Inc.	Delaware	(1	)
Samedan Oil of Canada, Inc.	Delaware	(1	)
Samedan Oil of Indonesia, Inc.	Delaware	(1	)
Samedan Pipe Line Corporation	Delaware	(1	)
Samedan Royalty Corporation	Delaware	(1	)
Samedan of Tunisia, Inc.	Delaware	(1	)
Noble Energy (Louisiana), LLC	Delaware	(1	)
Noble Energy, LLC	Delaware	(1	)
Noble Energy, LP	Delaware	(15	)
EDC Australia Ltd.	Delaware	(1	)
EDC Ecuador Ltd.	Delaware	(1	)
Noble Energy Ecuador Ltd.	Cayman Islands	(13	)
EDC Portugal Ltd.	Delaware	(1	)
Energy Development Corporation (Argentina), Inc.	Delaware	(1	)
Energy Development Corporation (China), Inc.	Delaware	(1	)
Energy Development Corporation (HIPS), Inc.	Delaware	(1	)
Gasdel Pipeline System Incorporated	New Jersey	(1	)
HGC, Inc.	Delaware	(1	)
Producers Service, Inc.	New Jersey	(1	)

140

EDC (UK) Limited	Delaware	(1	)
EDC (Denmark) Inc.	Delaware	(11	)
Noble Energy (Europe) Limited	United Kingdom	(11	)
Noble Energy (ISE) Limited	United Kingdom	(12	)
Noble Energy (Oilex) Limited	United Kingdom	(12	)
Brabant Oil Limited	United Kingdom	(12	)
SOCO Wattenberg Corporation	Delaware	(16	)
Patina Oklahoma Corp.	Delaware	(16	)
Patina San Juan Incorporated	Colorado	(16	)
Patina BNR Corporation	Delaware	(16	)
Patina Well Services, Inc.	Colorado	(16	)
Elysium Energy, L.L.C.	New York	(16	)
LeNorman Partners, LLC	Oklahoma	(17	)
Le Norman Loco, Inc.	Oklahoma	(17	)
LENOCO Supply, L.L.C.	Oklahoma	(17	)
North Texas Gathering Company	Texas	(18	)

REFERENCES:
(1)	100% directly owned by Noble Energy, Inc. (Registrant)
(2)	100% directly owned by Noble Energy Marketing, Inc.
(3)	100% directly owned by Samedan of North Africa, Inc.
(4)	100% directly owned by Noble Energy International Ltd.
(5)	50% directly owned by Samedan of North Africa, Inc.
(6)	100% directly owned by Atlantic Methanol Capital Company
(7)	50% directly owned by Samedan Methanol
(8)	90% directly owned by Atlantic Methanol Associates LLC
(9)	35% directly owned by Noble Energy International Ltd.
(10)	80% directly owned by Alba Associates LLC
(11)	100% directly owned by EDC (UK) Limited
(12)	100% directly owned by Noble Energy (Europe) Limited
(13)	100% directly owned by EDC Ecuador Ltd.
(14)	47.059% directly owned by Noble Energy Mediterranean Ltd.
(15)	1% General Partnership Interest by Noble Energy, Inc. (Registrant); 99% Limited Partnership Interest by Noble Energy, LLC
(16)	100% directly owned by Noble Energy Production, Inc.
(17)	100% directly owned by Patina Oklahoma Corp.
(18)	100% directly owned by Patina BNR Corporation

141

QuickLinks

EXHIBIT 21

NOBLE ENERGY, INC. SUBSIDIARIES