The multi-national firm, which employs around 3800 people across Aberdeen and Montrose, has seen a slowing of business in Iraq and Saudi Arabia, where it is bidding to build pipelines and processing plants.
However, chief financial officer Tim Weller said the projects are still going ahead although some tenders have slipped to 2013.
However, analysts are concerned those delays could hit full-year profits and the shares dipped 81p to 1486p leaving the company's market capitalisation at £5.14 billion.
Numis analyst Sanjeev Bahl said the end of the Muslim holy month of Ramadan could have a beneficial effect.
He said: "Management have suggested the potential for a flurry of larger awards post-Ramadan, which we believe is required to provide comfort in 2013 consensus forecasts."
In half-year results covering the first six months of 2012, revenue at Petrofac increased almost 20% from $2.7 billion (£1.72bn) to $3.2bn while pre-tax profit jumped 38% from $300m to $414m.
In the onshore engineering and construction arm revenue grew 25.1% to $2.4bn with greater activity in Turkmenistan, Algeria and Abu Dhabi. Net profit in the division was up 21.7% to $250.6m.
In offshore projects and operations – which is mainly focused on the UK Continental Shelf but also has activities in United Arab Emirates, Iraq, Malaysia and Thailand – revenue rose 13.9% from $581m to $661.7m but net profit dipped from $31.8m to $30.7m.
However the figure from the previous year benefited from a provision release at the end of a long-term maintenance services contract. Stripping that out, net profit in the division, Laggan-Tormore gas plant project on Shetland, was up 26%.
The engineering and consulting services section saw a 7.9% increase in revenue from $96.2m to $103.8m with net profit down from $14.8m to $5m.
Integrated Energy Services saw income up 25.7% from $256.7m to $322.7m with net profit soaring from $6m to $65m reflecting the sale of a 75% stake in a floating production facility on the Greater Stella Area development in the North Sea and profitable risk sharing contracts in Malaysia.
Ayman Asfari, Petrofac's chief executive, said: "We have delivered good operational and financial performance in the first half of the year and remain on course to deliver net profit growth in 2012 of at least 15%.
"We remain confident of achieving our target of more than doubling our recurring group 2010 earnings by 2015."
