Gulfstream said the latest deal, which follows an earlier agreement in August to buy a 15% interest in the field from Germany's Wintershall, takes its working interest in Al Rayyan up to an 8100 barrel-per-day share of production with remaining proven reserves of 53 million barrels. That share of production is based on current total output from the Al Rayyan oilfield of 12,000 bpd from eight existing horizontal wells.