Several international oil companies are active in Iraqi Kurdistan. Oil output from the semi-autonomous region of Kurdistan helps boost exports that provide Iraq with about 95% of its federal revenue.

The Kurdistan Regional Government (KRG) says it holds reserves of 45 billion barrels. That has not been verified and contrasts with other estimates, such as the 2 billion barrels in proven reserves given by the U.S. Energy Information Administration.

Iraqi Oil Minister Abdul Kareem Luaibi says the 2011 federal budget includes the expectation of shipments of 150,000 barrels per day from the KRG through the Iraqi export network.

Kurdish officials have said they only have the capacity to export 100,000 bpd.

Exports for Iraq as a whole are roughly 2.0 million bpd, out of total production that has now reached 2.7 million bpd.

KRG shipments stopped in 2009 because of a dispute between the KRG, which runs three provinces in northern Iraq, and Baghdad, which meant companies were not being paid.

Baghdad has declared illegal more than 40 production and exploration deals signed between the KRG and international oil companies and prevented companies working in Iraq's Kurdish region from taking part in two oilfield tenders held in 2009.

Luaibi has said he expected the halted shipments to resume soon.

Iraq still lacks a new oil and gas law that would cover the whole country, while the KRG agreed its own hydrocarbons law in 2007.

Thorny issues to resolve include a clause in the hastily drawn-up post-invasion constitution that Kurdish officials interpret as meaning KRG rules apply in the event of a legal disagreement between Baghdad and Iraqi Kurdistan.

Authorities also need to work out how to align the production sharing contracts agreed by the KRG and the service contracts Baghdad negotiated with foreign companies.

The following outlines some of the companies present in Kurdistan's more than 40 oil blocks:

The two biggest northern producing fields, excluding Kirkuk — which lies outside the Kurdish region and is operated by the federal authorities — are Tawke and Taq Taq.

According to documents obtained by Reuters from Kurdish opposition officials, and the KRG Ministry of Natural Resources, Norway's DNO has a 55% share in Tawke and Turkey's Genel has 25%, with the rest held by the KRG. Genel is also active in Taq Taq, together with Sinopec unit Addax Petroleum.

North America
Numerically, the United States and Canada have the strongest representation in Iraq's Kurdish region. U.S. companies established there include Aspect Energy, Marathon Oil Corporation, Hillwood International Energy, Hunt Oil, Prime and Murphy Oil. Marathon and Murphy are recent entrants to the region.

Canada
Canadian companies are Forbes and Manhattan, Western Zagros Resources, Talisman Energy Inc, NIKO Resources, Ground Star and Shamaran.

Norway
Norway's DNO International has been the most prominent oil company investing in both downstream and upstream sectors in Iraqi Kurdistan. Its share price has fluctuated in line with uncertainties on the ground.

Others:
South Korea
Korea National Oil Company

Turkey
Genel Enerji, Petoil, Dogan

Britain
Gulf Keystone Petroleum, Sterling Energy, Heritage Oil plus Anglo-French company Perenco

The following countries all are believed to have one company active in the Kurdish region:
Austria
OMV AG

China
China acquired a significant presence in Iraqi Kurdistan after Sinopec Group bought Addax Petroleum in 2009.

Hungary
MOL

India
Reliance Industries

Papua New Guinea
Oil Search

Russia
Norbest

United Arab Emirates
Dana Petroleum