Oil sector stocks advanced across the board during the morning session. China Oilfield Services Limited (02883) rose 4.76% to HK$10.57. CNOOC (00883) increased by 3.87% to HK$26.30. PetroChina (00857) climbed 2.94% to HK$9.82. Sinopec (00386) gained 0.92% to HK$5.50.