The state-controlled oil firm is expected to produce second-quarter net profit of 1.87 billion zlotys ($509.94 million) based on an average forecast from seven banks and brokerages. This would put PKN's net profit in the first half of 2017 at 3.79 billion zlotys.
Polish state-run refiners, PKN and its smaller rival Lotos, have benefited from new legislation introduced in August 2016 to curb black market sales.
PKN's adjusted operating profit, the so-called EBIT LIFO which removes the impact of crude oil price changes, is expected to be 2.49 billion zlotys in the second quarter.
PKN said earlier this month that its refining margin rose to $6.90 per barrel in the second quarter from $5.30 per barrel in the previous quarter and $6.00 per barrel a year ago.