Oil companies may struggle to develop complex new fields in deep water sites due to a shortage of skilled engineers, the chief executive of Schlumberger has warned.

Coming as industry observers expect offshore deep water drilling rates to double within the next five years, Andrew Gould, who is also the chairman of the world's largest oil services company, warned that many future projects could be hit by delays as a result of the industry failing to invest in the recruitment and training of key workers over the past few years.

"The only kit that is really, really difficult to get is the human kit," he told the Financial Times.

According to Mr Gould, his own company is currently in the process of developing around 18,000 workers it recruited between 2004 and 2007, with this next generation of engineers due to be trained in around half the time of their predecessors as the firm looks to fill offshore vacancies quickly so as to stave off fierce competition from countries with access to easier fields such as Russia and Venezuela.

It is estimated that, with oil currently selling for around $130 a barrel, delays of just one hour can cost an offshore company as much as $50,000.

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