There are 3 caprocks that control the vertical distribution of oil and gas in the middle-shallow sequences of Nanpu sag

namely the mudstone caprock of the Lower Minghuazhen Formation(Nm)

the volcanic caprock of the third member of Guantao Formation(Ng

3

)and the mudstone caprock of the second member of Dongying Formation(Ed

2

).The sealing abilities of the caprocks were destroyed in different degrees due to faulting.Based on analysis of the thresholds of juxtaposition thickness of faults in these caprocks and in combination the vertical positions of fault cutting cross the caprocks

areal fault distribution and faulting history

we built 3 oil-controlling models of caprock-fault combinations.①Full sealing at the bottom.This model is favorable for oil accumulation under the mudstone caprock of the 2nd members of Dongying Formation;②Open at the bottom but sealing in the middle.This model is favorable for oil accumulation under the volcanic caprock of Ng

3

;③Limited sealing at the bottom and middle.This model is favorable for oil accumulation all the reservoirs under the mudstone caprock of Ed

2

in Nanpu sag.According to these 3 models and the characteristics of caprock and faults in Nanpu 1-5 block

we predicted the horizons favorable for oil accumulation in the study area.Area under the control of fault f1-3 and f2-12 is the second model

and favorable horizons for oil accumulation are the 4th member of Guantao Formation

the 1st member and the reservoirs below the 2nd member of Dongying Formation.Area under control of fault f4-48 is the first model

and the favorable horizons for oil accumulation are reservoirs below the caprock of the second member of Dongying Formation.Area under control of fault f13-1 is the third model

and all reservoirs under the caprock of the Lower Minghuazhen Formation are favorable for oil accumulation.These models have effectively guided the prediction of potential exploration targets.