There is a direct correlation between downstream investment and concentration of economic power in the oil patch. The two most vertically integrated companies are RD/Shell and Exxon Mobil. These behemoths have also led the charge towards horizontal integration within the energy industry, investing heavily in natural gas, coal and uranium resources.
With the fall of the Berlin Wall Eastern Europe, Russia, the Balkans and Central Asian were opened to Big Oil. Exxon Mobil formed a joint venture with the Hungarian state oil company Afor before the Wall had even hit the ground. Russia and Central Asia contain over half of the world’s natural gas reserves. RD/Shell has led the way in tapping these reserves, forming a joint venture with Uganskneftegasin at a huge Siberia gas field in which Shell owns a 24.5% stake.
Shell has been the world’s #1 producer of natural gas since 1985. Much of this production is done through a joint venture with Exxon Mobil. In the growing US retail natural gas sector Chevron Texaco owns 100% of Dynegy, while Exxon Mobil owns 40% of Duke Energy.  Both were key players in the 2000 natural gas spikes that battered the economy of California and led to the bankruptcy of that state’s main utility provider- Pacific Gas & Electric. Exxon Mobil has extensive interests in power generation facilities around the world including full ownership of China Light & Power.
During the 1970s Big Oil invested $2.4 billion in uranium exploration.  Today they control over half the world’s uranium reserves, key to fueling nuclear power plants. Chevron Texaco and Shell developed a joint venture to build nuclear reactors, a job historically given over to Bechtel. 
Exxon Mobil is the leading coal producer in the US and has the second largest coal reserves after Burlington Resources, which in 2005 was bought by Conoco Phillips. RD/Shell owns coal mines in Wyoming (ENCOAL Corporation) and West Virginia (Evergreen Mining). Chevron Texaco owns Pittsburgh and Midway Coal Mining. Seven of the top fifteen coal producers are oil firms. Shell and Exxon Mobil are hastily buying up even more coal reserves, in this case moving upstream. Despite the move downstream by Big Oil, 80% of US oil reserves are still controlled by the nine biggest companies. These moves are not limited to the US. In Columbia, Exxon Mobil owns huge coal mines, BP owns vast oilfields and Big Oil controls all of the vast non-renewable resources. 
The Four Horsemen have invested heavily in other mining ventures as well. RD/Shell holds long term contracts with several Third World governments in supplying tin through its Billiton subsidiary, which has mines in countries like Brazil and Indonesia. Billiton is Indonesia’s largest gold producer. It merged with Australia’s Broken Hill Properties to become the world’s largest mining company- BHP Billiton. In 2010 the company announced plans to merge with the world’s second largest miner- Rio Tinto- a company which also has historical ties to Royal Dutch/Shell. Shell recently began investing heavily in the aluminum industry. Shell Canada is Canada’s top sulphur producer. It controls timber interests in Chile, New Zealand, Congo and Uruguay and a vast flower industry with farms in Chile, Mauritius, Tunisia and Zimbabwe. 
BP Amoco, through its ARCO subsidiary, has become one of the world’s top six producers of bauxite, from which aluminum derives. It has mines in Jamaica and other Caribbean nations. Chevron Texaco controls over 20% of the huge AMAX mining group, the leading producer of tungsten in the US with extensive holdings in South Africa and Australia. Exxon Mobil owns miners Superior Oil and Falconbridge Mining, the latter Canada’s largest producer of platinum and nickel. It also owns Hecla Mining, one of the world’s top copper and silver producers; and Carter Mining, one of the top five phosphate producers in the world with mines in Morocco and Florida. Phosphates are needed to process uranium, while phosphoric acid is essential to petrochemical production. 
Another vehicle for increased concentration in the oil sector is the joint venture (JV). Long before Chevron married Texaco in 2001, the companies worked in tandem. Their most important JV is Caltex, which has for decades marketed petroleum products in 58 countries. Caltex owns refineries in South Africa, Bahrain and Japan. Chevron and Texaco also operated Amoseas and Topco as JVs before merging. In the Philippines Caltex and RD/Shell control 58% of the oil sector. When Philippine strongman Ferdinand Marcos introduced martial law in 1972, Caltex Vice-President Frank Zingaro commented, “Martial law has significantly improved the business climate.”
RD/Shell and Exxon Mobil established a North Sea JV called Shell Expro in 1964, while in 1972 Shell tied up with Mitsubishi in a Brunei JV to supply oil to Japan. Shell owns 34% of Petroleum Development Oman with partner Exxon Mobil. They led the charge into China and Vietnam through Pecten International Shell Oil and Shell E&P Vietnam, respectively. A cozy relationship has long existed between Exxon and Mobil, who finally merged in 1999. They shared many JVs around the world including PT Stanvav Indonesia. ARAMCO, the Iranian Consortium, Iraqi Petroleum Company, Kuwait Oil Company and UAE’s ADCO all represent Four Horsemen JVs.
Dean Henderson is the author of five books:Big Oil & Their Bankers in the Persian Gulf: Four Horsemen, Eight Families & Their Global Intelligence, Narcotics & Terror Network, The Grateful Unrich: Revolution in 50 Countries, Das Kartell der Federal Reserve, Stickin’ it to the Matrix & The Federal Reserve Cartel. You can subscribe free to his weekly Left Hook column @www.hendersonlefthook.wordpress.com