NEW YORK, July 11,—Admiral Porter’s official report of his operations during the siege of Vicksburg has been received by Secretary Welles. The Admiral say one steamer only has been barely disabled since our operations commenced, and six or seven men killed or wounded. While the army had a troublesome enemy in front and behind them, the gunboat marine brigade, under Gen. Ellet, and a small force of troops under Gen. Dennis and Gen. Dowry have kept at bay a large force of rebels, over 12,000 strong, accompanied by a large quantity of artillery; and though offered battle several times, and engaged, they inevitably fled, and satisfied themselves by assaulting half disciplined and unarmed blacks.