According to the concept of "petroleum accumulation system"

in combination with source rocks

source-reservoir relationship

reservoir characteristics and accumulation mechanism

we recognized two Mesozoic petroleum accumulation systems in the southern Ordos Basin

i.e.near-source system and far-source system.The near-source accumulation system is dominated by lithologic traps

and features in short migration distance

abnormal pressure as major driving force of migration

and implicit carrier system.Hydrocarbon accumulation in the near-source system is mainly controlled by high-quality source rocks and reservoirs as well as favorable structural setting

and the pattern of hydrocarbon accumulation can be described as "near-source and facies-control".The far-source system is dominated structural traps and structural-lithologic traps

and is characterized by long migration distance

buoyancy as the major driving force of migration and source rock-rooted faults containing the major carrier system.Hydrocarbon accumulation in the far-source system is mainly controlled by source rock-rooted faults

local structures and high-quality sandstone reservoirs

and the pattern of oil accumulation can be described as "far-source and fault-control".The source rock-reservoir relationship in the near-source system has a "sandwich-like" structure.The synchronism of peak hydrocarbon generation with hydrocarbon accumulation provides favorable conditions for widespread and large-scale hydrocarbon charging and accumulation near source rocks.The near-source systems are the priority of future exploration

and the top-ranking play fairways in the CH

9

-CH

8

-CH

7

near-source systems are the important exploration targets for large- and medium-sized oil and gas fields.