The Nigerian National Petroleum Corporation, NNPC, was established on April 1, 1977, under the statutory instrument-Decree No. 33 of same year by a merger of Nigerian National Oil Corporation, NNOC, with its operational functions and the Federal Ministry of Mines & Power with its regulatory responsibilities. This decree established NNPC, a public organization that would, on behalf of Government, adequately manage all government interests in the Nigerian Oil industry. In addition to its exploration activities, the Corporation was given powers and operational interests in refining, petrochemicals and products transportation as well as marketing. Between 1978 and 1989, NNPC constructed refineries in Warri, Kaduna and Port Harcourt and took over the 35, 000-barrel Shell Refinery established in Port Harcourt in 1965. In 1988, the NNPC was commercialised into 12 strategic business units, covering the entire spectrum of oil industry operations: exploration and production, gas development, refining, distribution, petrochemicals, engineering, and commercial investments. The subsidiary companies include: National Petroleum Investment Management Services (NAPIMS) Nigerian Petroleum Development Company (NPDC) The Nigerian Gas Company (NGC) The Products and Pipelines Marketing Company (PPMC) Integrated Data Services Limited (IDSL) Nigerian LNG limited (NLNG) National Engineering and Technical Company Limited (NETCO) Hydrocarbon Services Nigeria Limited (HYSON) Warri Refinery and Petrochemical Co. Limited (WRPC) Kaduna Refinery and Petrochemical Co. Limited (KRPC) Port Harcourt Refining Co. Limited (PHRC) Eleme Petrochemicals Co. Limited (EPCL) In addition to these subsidiaries, the industry is also regulated by the Department of Petroleum Resources (DPR) , a department within the Ministry of Petroleum Resources. The DPR ensures compliance with industry regulations; processes applications for licenses, leases and permits, establishes and enforces environmental regulations.