Serica Energy's shares gained after the oil and gas company narrowed its pre-tax losses in the first half as it lowered its costs.Loss before tax came to $1.9m, down from last year's loss of $3.5m. Sales revenue fell to $3.5m from $8.4m but was offset by a reduction in cost of sales to $2.9m from $9.1m.A fall in expenses to $2.5m from $3.5m last year, cut the operating loss to $2m from $4.2m.Tony Craven Walker, Chairman and Interim Chief Executive Officer, said the company was entering a period of "significant activity"."Our drilling campaign kicks off in October with the spudding of our first well offshore Morocco and will be followed by a further well offshore Morocco in the first half of 2014 and a well in the UK (Doyle)," he said. "In Ireland efforts have commenced to identify partners to accelerate drilling on our Boyne and Muckish prospects. In Namibia, well planning activities have commenced in preparation for drilling in late 2014/15."He added that while financial markets remain difficult for exploration companies, the group has been able to secure finance from major international oil firms.The company has sufficient funds to meet its exploration and other commitments for 2013, but remains very tightly financed. As a result, the group is reviewing alternatives to strengthen its resources for 2014 and beyond and place it on a stronger footing to maintain its growth targets. Serica had unrestricted cash balances of $14.9m at the end of June.Shares were up 1.16% to 22.76p at 12:21 on Tuesday.RD