Concept of “seeking for oil and gas deep down depressions” in Liaohe peripheral Mesozoic basin

Small-scale strip Mesozoic sags in the Liaohe Oilfield peripheral basin are strongly divided and close to massifs, so they are mainly proximal and multisource deposits. Reservoirs in the sags have poor properties and are multidirectional, intersected sources which form sand-shale alternating deposits. Low permeability in the reservoirs causes oil and gas to migrate in short distances horizontally and vertically, and is distributed close to or in hydrocarbon kitchens horizontally and close to oil source vertically. The principle of “seeking for oil and gas deep down depressions” was proposed. Since its practice in 2004, good exploration results have been achieved. The next exploration targets in this area are Wushijiazimiao, Jiaolige and Sanshifangdi subsags in Lujiabu sag, Hulihai subsag in Qianjiandian sag, Eertu subsag in Longwantong sag, Zhanggutai and Qijiazi subsags in Zhangqiang sag, central subsag in Yuanbaoshan sag, and central subsag in Naiman sag.