NIGERIA needs to ensure that Shell safely dismantles its old infrastructure or pays to remove them from the Niger Delta before its exit, says a report on the environmental impact of the activities of multinational companies. Shell is set to exit from Nigeria's onshore oil and gas operations after agreeing in January to sell the business to a consortium of five mostly local companies for $2.4 billion. The deal is the latest by an international oil company seeking to divest from Nigeria's troubled onshore oil sector. But the cost of dismantling old assets could leave the country with environmental degradation, according to…