	plains plns posts reserves increases plains resources inc said that as of december its estimated proved oil and gas reserves rose by pct to mln barrels from mln barrels and proved developed reserves rose pct to four mln barrels from mln barrels a year ago the company said its year end reserves did not include the oil and gas reserves of houston oil fields co which recently agreed to merge with it pending shareholder approval in mid april if approved the merger will add another mln barrels to the company s reserve base reuter 
