TEHRAN, April 12 (Shana) - National Iranian Oil Company (NIOC) and German company Winstershall signed a memorandum of understanding (MoU) for carrying out appraisal studies on 4 Iranian oil fields in western Iran. From Iran, Roknoddin Javadi, managing director of NIOC, and From Wintershall, Mario Mehren, CEO, signed the MoU in Tehran on Tuesday....