In the Liaozhong sag

Bohai Sea

complex fault zones give rise to numerous secondary accommodation normal faults

which form and control a large number of fault block traps.Well data have confirmed that the vertical oil migration ability of source tapping faults

which connect mature source rocks with fault block traps located on top of it

is of great importance to abundance of oil and gas accumulation in these traps.The study regards that the geometry of source tapping fault's surface and its contact area within the mature source rocks control the oil and gas migration.Thus

the seismic data are used to elaborately interpret source tapping faults

to depict the three-dimensional geometry of fault section and its contact area within mature source rocks.Under the control of the above two geological factors

the migration ability was estimated by numerical simulation

and combined with logging data

we identified fault-associated fracture zones.Thus the model of oil and gas migration in LD oilfield is established based upon these results.The results are as follows:The oil migration ability of the six studied source tapping faults varies significantly.There are 24 charging points to the oil reservoir of the oilfield with diverse contributions

and result in different reserve abundance in different fault blocks.The intensity of associated fracture zone of the source tapping fault is different on either walls of the fault

with the better developed fractures and improved porosity and permeability near the downthrown side

where the selective hydrocarbon migration from the charging points occurs.And based on these results

we established the migration model of oil and gas in the study area

which matches well with the actual drilling results.