Oil companies must resist slashing exploration and development activities during the economic downturn if industry expects to supply energy to meet projected long-term demand, chief executives said Feb. 10 during an energy conference in Houston.Various speakers at the Cambridge Energy Research Associates annual conference said their current business strategy involves avoiding the mistakes of past downturns. They referred to the 1980s when industry cut budgets and drilling activity to the point that consumers faced tight oil and gas supply after the economy recovered.Jeroen Van der Veer, chief executive of Royal Dutch Shell PLC, said Shell believes it’s important to keep investing in...