Royal Dutch/Shell Group is carrying out feasibility studies on building USD 1 billion worth of new petrochemical plants in Singapore. The Anglo-Dutch oil giant will decide by the end of 2001 if it will proceed with the project, which would include an ethylene cracker, said Shell spokeswoman Wang Yean Sung. If the Shell project in Singapore gets the green light, it would begin in 2005 or 2006, Wang said.