Chengdao oil field has a crystalline basement of Achaean granire gneiss and a sedimentary basement of Paleozonic carbonate rock or Mesozonic clastic rock.

• 埕岛油田的结晶基底为太古界花岗片麻岩 ,沉积基底为古生界碳酸盐岩和中生界碎屑岩。