NBGI Private Equity has acquired a controlling stake in ATR Group, which rents out tools used in oil and gas maintenance work, from Glasgow-based Maven Capital Partners.
The deal is the first oil and gas transaction completed by NBGI Private Equity, a division of National Bank of Greece.
Lawrence Dean, a director at NBGI, said the company had been looking for a deal in Aberdeen that would take it into the sector for around three years.
The company made a big gain on its investment in Stirling-based Superglass Holdings after backing a management buyout of the insulation maker in 2005.
NBGI is one of a number of London-based investors that have spotted the potential to make good returns from investing in services business, amid the boom in oil and gas market activity.
In November, Doughty Hanson, one of Europe's biggest private equity firms, acquired Aberdeen oil and gas logistics group Asco, from Phoenix Equity partners.
"ATR's market-leading position and robust financial standing provide a strong platform for organic and acquisition-led growth," said Mr Dean.
NBGI private equity has backed ATR's management led by Keith Moorhouse, whom Mr Dean called "very backable". Mr Moorhouse led a management buyin at the firm in 2007. This was backed by Aberdeen Asset Management's private equity arm, which became Maven Capital Partners after being bought out of the fund manager.
Jock Gardiner, partner at Maven, said the deal provided "another profit-able exit" from an energy services business for Maven client funds and allows the ATR management team to continue its ambitious growth strategy.