(Sharecast News) - Premier Oil's post-tax profit more than doubled in the first half as rising oil prices more than offset reduced production. Profit after tax for the six months to the end of June rose to $98.4m (£76m) from $40.7m as revenue increased to $643.3m from $566.3m. Operating profit increased to $185.5m from $141.4m.The FTSE 250 company benefited from rising oil and gas prices during the period. The average price for Brent crude was $70.6 a barrel in the first half compared with $51.7 a barrel a year earlier.Premier's production averaged 76,200 barrels a day in the first half, down from 82,100 barrels a day a year ago. The reduction was caused by asset sales, natural field decline and planned shutdowns.Those factors were partly offset by production from Premier's Catcher field in the North Sea, which the company said had reached plateau production of up to 70,000 barrels a day. Catcher's increased activity has taken recent group production to more than 90,000 barrels a day.Nevertheless, Premier left its 2018 production guidance unchanged at 80-85,000 barrels a day.Tony Durrant, the company's chief executive, said: "Premier met its operational targets for the period. The Catcher Area is now at plateau production rates which, together with higher commodity prices, is driving free cash flow generation and net debt reduction. We have progressed our development projects while maintaining strict capital discipline."Premier sanctioned its Tolmount Main gas field in the southern North Sea on 20 August, with the company adding in its results that there was "significant upside in the greater Tolmount area".