Please see the below link. it is the directory of oil and gas companies in Pakistan. http://www.ppisonline.com/downloads/ongdirectory/index.html
Good companies to apply in Islamabad are:
BHP Billiton, BP Paksistan, Dewan Petroleum, MOL Pakistan, Paige Ltd, Petronas, BGP, Halliburton, Schlumberger (good company for females as well), sprint, Baker Oil Tools, clough engineering, hagler bailey, Weatherford.
courtesy of Sir Shahzad Javed