| Name | Country | Market Cap (US$) |
|---|
| Dixie Pipeline Company | United States | Private |
| Dixon Ticonderoga Company | United States | Private |
| DK 6 | France | Private |
| DKCE Debreceni Kombinalt Ciklusu Eromu Korlatolt Felelossegu Tar | Hungary | Private |
| DLB Oil & Gas Inc. | United States | Private |
| Dlg Service A/S | Denmark | Private |
| Dno Yemen AS | Norway | Private |
| DOCKS PETROLI SRL | Italy | Private |
| DOCOIL SPA | Italy | Private |
| DOLNOSLASKA SPOLKA GAZOWNICTWA SP Z O O | Poland | Private |
| Dolphin As | Norway | Private |
| Dolphin Drilling Limited | United Kingdom | Private |
| Dolphin International AS | Norway | Private |
| Domain Energy Corporation | United States | Private |
| Dome Pipeline Corporation | Canada | Private |
| Dominion Aviation Services Inc | United States | Private |
| Dominion Cove Point | United States | Private |
| Dominion Exploration & Production, Inc. | United States | Private |
| Dominion Exploration Canada Ltd | Canada | Private |
| Dominion Nuclear Connecticut, Inc | United States | Private |
| Don Foster Oil Co | United States | Private |
| Don Thomas Petroleum Inc | United States | Private |
| DONALDSONS PROPERTY MANAGEMENT | United Kingdom | Private |
| Donar International Energy Llc | United States | Private |
| DONG E&p A/S | Denmark | Private |
| Dong E&P Norge AS | Norway | Private |
| DONG Energy A/S | Denmark | Private |
| Dong Energy AB | Sweden | Private |
| DONG Energy Gasforsyning A/S | Denmark | Private |
| DONG Gas Distribution A/S | Denmark | Private |
| Dong Il Petroleum Co., Ltd. | South Korea | Private |
| Dong Naturgas A/S | Denmark | Private |
| Dong Yang Fuel Company, Ltd. | South Korea | Private |
| Dooley's Petroleum, Inc. | United States | Private |
| Doppler Mineralöle Gesellschaft m.b.H. | Austria | Private |
| Dorchester Gas Corporation | United States | Private |
| Dorset Exploration Ltd. | Canada | Private |
| Dortmunder Energie- und Wasserversorgungs Gesellschaft mit besch | Germany | Private |
| Doussan Gas & Supply Llc | United States | Private |
| Dover Chemical Corporation | United States | Private |
| Dover Petroleum Corp | Canada | Private |
| Dow Hydrocarbons And Resources, Inc | United States | Private |
| Dow Pipeline Company | United States | Private |
| Dow Pipeline GmbH & Co.KG | Germany | Private |
| Dowdle Butane Gas Co Inc | United States | Private |
| Dowell Schlumberger Argentina S.A. | Argentina | Private |
| Dowell Schlumberger de México, S.A. de C.V. | Mexico | Private |
| Dowler-Karn Limited | Canada | Private |
| DRACOIL S.A. | Greece | Private |
| Dracoil S.A. | Greece | Private |
| Drake Petroleum Company Inc | United States | Private |
| DREOSSO S.R.L. | Italy | Private |
| Drilex International, Inc. | United States | Private |
| DRILLCORP LIMITED | Australia | Private |
| Drillers Technology Corporation | Canada | Private |
| Drummond Fuels (Ottawa) Ltd | Canada | Private |
| DSM Energie B.V. | Netherlands | Private |
| DSND Subsea | Norway | Private |
| Dte Gas & Oil Company | United States | Private |
| Du Pont Elastomers L.P. | United States | Private |
| Dual Drilling Company | United States | Private |
| Dual Exploration Inc. | Canada | Private |
| Dubai Petroleum Co | United States | Private |
| DUCKHAMS OILS LTD | United Kingdom | Private |
| DUCSA | Uruguay | Private |
| Dufour Petroleum, Inc | United States | Private |
| Dugan Production Corp | United States | Private |
| Duke Energy | Canada | Private |
| Duke Energy Canada Exchangeco Inc | Canada | Private |
| Duke Energy Merchants, Llc | United States | Private |
| Duke Energy Services Canada Ltd | United States | Private |
| Dukes Petroleum Co Inc | United States | Private |
| Dunai Finomito | Hungary | Private |
| DUNAJ PETROL TRADE, a.s. | Slovakia | Private |
| Duncan Oil Co | United States | Private |
| Dunlap Oil Company Inc | United States | Private |
| DYAS U K LTD | United Kingdom | Private |
| Dyersburg Electric Systems Inc | United States | Private |
| Dynamic Oil & Gas Inc. | Canada | Private |
| Dynatrade SA | Switzerland | Private |
| DYNEFF ESPANA SLU | Spain | Private |
| Dynegy Energy Partners L.P. | United States | Private |
| Dynegy Global Energy Inc | United States | Private |
| Dynegy Holdings, Inc. | United States | Private |
| Dynegy Marketing & Trade | United States | Private |
| Dyno Oil Co Inc | United States | Private |
| Dynoil, Llc | United States | Private |
| E & B Natural Resources Management Corporation | United States | Private |
| E & M Oil Company, Inc | United States | Private |
| E And V Energy Corporation | United States | Private |
| E M Gray & Son Inc | United States | Private |
| E O S A S | Estonia | Private |
| E ON VENDITA SRL | Italy | Private |
| E R Vine & Sons Inc | United States | Private |
| E-Can Oilfield Services Ltd | Canada | Private |
| E. F. OIL & GAS LTD | United Kingdom | Private |
| E. M. Haynes, Jr Inc | United States | Private |
| E.J.E.S.A. | Argentina | Private |
| E.On Gas Sverige AB | Sweden | Private |
| E.On Gashandel Sverige AB | Sweden | Private |
|
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