Executives at the world’s biggest oil and gas companies are under growing pressure to loosen the purse strings to replenish reserves, halt output declines and take advantage of a crude price rally after years of austerity. With oil at a four-year high of $85 a barrel, exploration departments are urging company boards to drill more, wages are creeping higher, service companies say rates will have to rise and some investors say Big Oil must start growing again soon. For the heads of companies such as BP ( BP.L ), Chevron ( CVX.N ) and Royal Dutch Shell ( RDSa.AS ) who have pledged to stick to lower spending after […]