The company, which provides services to oil producers including BP Plc, said it was cautious about its full-year outlook, but anticipated a stronger second half.
"First half performance is down on 2016 and weaker than anticipated," John Wood Group said in a statement on Thursday.
The company, however, said activity in the U.S. onshore shale market had improved since the beginning of the year, and that it had secured infrastructure construction projects in Ohio.
Oil companies have cut back on spending for exploration drilling and maintenance, reducing demand for engineering firms such as John Wood Group, which provides services including overhaul of compressors, pumps, generators and rotating equipment.
