Schlumberger Ltd., the world's biggest oilfield-services company, tackled the "uncertain environment" of plummeting crude prices head-on by cutting 9,000 jobs and lowering costs at a vessels unit. The 7.1 percent workforce cutback, along with the reduction and reassessment of its WesternGeco fleet, were among steps leading to a $1.77 billion fourth-quarter charge in anticipation of lower spending by customers in 2015, the Houston- and Paris- based company said in an earnings report Thursday.