Oil and gas group Sterling Energy may have reported a strong increase in turnover in the first half, but profits and average production were lower than same period the year before, weighing on the share price on Monday.Revenue totalled $14.0m in the six months to June 30th, up from $9.5m previously. During the period, there was two liftings from Chinguetti resulting in a net 131,941 barrels sold (first half of 2011: 79,611 barrels sold, from one lifting).However, pre-tax profit slipped from $6.5m to $4.7m, as interest revenue and other finance losses totalled $0.1m, down from a net gain of $2.3m the year before.Meanwhile, average net group production fell from 626 barrels of oil per day (bopped) to 501 bopd due to two unplanned production shutdowns."Over the last six months we have made progress with both our existing projects and some potential new ventures; we anticipate building on this progress over the next six months with more visible and active exploration activity," said Chairman Alastair Beardsall.The group's cash position was slightly higher at $114.4m, from $113.4m the year before, and is expected to improve further with $7.1m expected in July from the sale of Chinguetti cargo lifted in June.Shares were down 1.41% at 35p by 13:50 on Monday.BC