Aberdeen entrepreneur Jamie Oag has been appointed chief executive officer of Aberdeen-based SPEX, the group behind the development of Shell's latest drilling tools for well closure and severance.

Mr Oag, who founded and built rig cooling company Optima before selling the business to Tetra in 2012, has made a number of investments in hi-tech businesses in the Scottish energy sector and is majority shareholder of SPEX, named Scotland's fastest-growing company of its size by Business Insider magazine in 2012.

He said: "We are uniquely positioned to take advantage of a number of opportunities to further bolster growth on top of recent awards the group has attained."

SPEX is in the process of developing a series of tools for Shell in Houston, and is working on a number of other high-profile projects with the multinational.