Larsen & Toubro (L&T) has secured a Rs 1,000 crore turnkey project order from Oil & Natural Gas Corporation (ONGC) for four well platforms and inter-connecting pipelines to be installed in Mumbai High North and Bassein fields.According to a release issued by L&T to the BSE today, three platforms, with six wells each, will be of the latest tripod design to be engineered by Valdel. "Valdel is a joint venture company of L&T and US-based Worlex Parsons," the release added.The fourth platform having nine wells will be designed to handle corrosive sour gas from the Bassein field. "It will be constructed of special materials like duplex stainless steel and incolloy cladded material for the topsides and pipeline," the release added.