Igneous rock reservoir characteristics and accumulation pattern of lower Cretaceous in Lujiapu depression

Mesozoic igneous reservoirs in Lujiapu depression of Liaohe peripheral basin are mainly distributed in the early cretaceous volcanic sedimentary sequence.The igneous rock types mainly include five kinds of lithology,namely volcanic lava,volcanic clastic lava,pyroclastic rocks,pyroclastic rock,and hypabyssal intrusive rocks.Favorable reservoirs are mainly developed in facies belts,such as cryptoexplosive breccia subfacies,the upper subfacies of eruption phase,eruption phase empty fall subfacies and intrusive facies hypabyssal intrusive belt.The reservoir space with igneous reservoir is more of pore-fracture combination.Jiufotang formation was at rapid fault depression period,and the argillaceous rock of under-compensation deposition during the period of deep lake-half deep lacustrine and oil shale,acting as the resource basis of the igneous reservoirs formation.Igneous reservoirs are controlled by the supply of hydrocarbon source rock,tectonic stress action,and volcanic mechanism characteristics.According to occurrence horizon of igneous rock reservoir and the reservoir rock types,the igneous rock reservoirs can be divided into three types,intrusive rock reservoir of Jiufotang formation,volcanic clastic rock reservoirs of Jiufotang formation and igneous reservoir of Yixian formation,and the corresponding accumulation models have been established.