Cape said higher UK margins and gains stemming from its restructuring plan drove the industrial services giant to a strong first half.
But Middlesex-based Cape, which has accepted a £332million-plus takeover bid from French group Altrad, said market conditions in the UK were still a challenge.
Despite a small recovery in oil prices, demand from the North Sea upstream sector remained subdued in the first six months of 2017.
Cape said demand for its construction and maintenance services was down and that customers were still focused on cutting costs, resulting in ongoing prices pressure across the upstream sector.
On a more positive note, the company did manage to secure two three-year maintenance contracts worth more than £150million in the UK North Sea with BP.
Cape said the contracts had safeguarded 400 jobs at the firm when it announced the agreements in June.
First-half pre-tax profits at Cape soared to £32.9million from £1.4million last year. Revenues jumped 46.8% to £581.9million.
Cape, which employs about 5,200 people in the UK, including hundreds in Aberdeen, said 2018 would be a more challenging year due.
It is currently enjoying high levels of construction activity in Asia Pacific, but expects to be less busy there next year.
The impact of project delays and margin pressures in the Middle East will also put a dent in the firm’s performance.
Cape Joe Oatley said: “We have delivered a very strong operational and financial performance in the period.
“Revenue, operating profit, margins and cash conversion have all improved, reflecting operational excellence in the delivery of key projects in Australia and South Korea, and effective management of the group’s working capital.
“The group was also successful in securing strategic contract wins in the UK, with the renewal of the long-term maintenance contract with BP, and in Australia, with the award of an initial contract at the Ichthys onshore LNG project.
“The board’s expectation for the group’s full year performance remains unchanged with the anticipated reduction in construction related activities in Asia Pacific resulting in the group’s earnings being strongly weighted towards the first half of 2017.”