PLAY TYPES AND DISTRIBUTION FEATURES OF COEXISTENCE OF ORGANIC AND ABIOGENTIC HYDROCARBON IN THE CHANGLING FUALTED DEPRESSION OF SONGLIAO BASIN

The Changling faulted depression,a deep large depression developed in the intersection area of two systems of lithosphere faults,with abundant lacustrine and limnetic facies source rocks and sets of favorable plays,is an area with rich organic based hydrocarbon.It is also an rich abiogentic area with sets of abiogentic based natural gas plays,due to the most active volcanism and most abundant supply of deep abiogentic based gas.The above factors cause the coexistence of organic and abiogentic plays.Abiogentic and organic natural gas reservoirs have similar fluid migration pathways,such as fractures,unconformity surfaces,glutenite and volcanic bodies of different grades,as well as similar accumulation zones.Therefore,in the course of their common migration and accumulation,two fluids from different sources are mutually accelerated and affected.Abiogentic based fluid greatly improves the migration and accumulation pathways,increases migration and accumulation efficiency and provides migration force,which promotes deep hydrocarbon accumulation and increases deep hydrocarbon production and abundance.Apparent difference in supply volumes of abiogentic and organic matter causes the fact that the southeastern part is dominant with organic based plays,northeastern and southwestern part with abiogentic and organic combination,and northern and northwestern with abiogentic plays.Therefore,targeted exploration should be carried out in different types of zones.