In a burst of executive activity at the Aberdeen-based company Graham Forbes exercised 600,000 share options which were due to expire this year.
He immediately sold more than 540,000 at 149p each.
Having originally bought the shares at 123p, Mr Forbes used the profits, worth £75,540, to cover the purchase price, the company said.
He has retained 54,000 shares from the option, taking the total number he holds to 262,305. He has more than 1.2 million further options as well.
In total, senior figures at the firm increased their shareholdings by 154,000 yesterday, as non-executive director and Canadian oil executive Ron Brenneman decided to hold onto his 100,000 share options which were also due to expire this year.
Alec Carstairs has just been awarded 95,000 share options following his appointment to the board in 2013.
The firm's share price was previously hit by news that production on a central North Sea site had been delayed, dropping 11 per cent to 135p in early May. But a £93m deal with Sumitomo Corporation to buy three oil fields, announced in June, encouraged investors and the share price has edged up towards 150p this month.
The Aim-listed firm saw its pre-tax profits double, from $2.3m in the first quarter of last year to $4.6m in the same period this year after its acquisition of Valiant Petroleum in 2013 boosted production by 50 per cent.