This paper aims to identify the favorable interval for shale oil prospecting in the cored interval of the lower section of the third member of the Shahejie Formation (Es

3L

) from Well L69 in Zhanhua Sag

Jiyang Depression

Bohai Bay Basin.To study their oil content and occurrence

typical lithofacies samples from the cored intervals of Es

3L

in wells with commercial shale oil production

Well L69 and Well XYS9

were comparatively analyzed with routine Rock-Eval pyrolysis method and thermal desorption method

and the favorable interval for shale oil prospecting and factors affecting shale oil production were assessed.Results show that the total content of free oil

especially the content of free oil S

1-1

after light hydrocarbon correction

for the organic-rich lamellar argillaceous limestones at a depth of 3 040.35m to 3 072.10m in Well L69

is obviously lower than that of cored interval with commercial shale oil production in Well XYS9

and the average Oil Saturation Index(OSI) is only 67 mg/g

both of which indicate no exploration potential for shale oil.The total content of free oil

especially the content of free oil S

1-1

after light hydrocarbon correction

for organic-rich lamellar argillaceous limestones at a depth of 3 116.90m to 3 126.70m in Well L69

is obviously lower than that of cored interval of the Es

3(L)

with commercial shale oil production from Well XYS9

though the OSIs are usually larger than 100mg/g with an average of 204mg/g

suggesting a lower shale oil exploration potential.The total content of free oil

especially the content of free oil S

1-1

after light hydrocarbon correction

and the OSI of organic-rich laminar argillaceous limestones and calcareous mudstones at a depth of 2 994.10m to 3 010.90m in Well XYS9

are similar or almost equal to those of the cored interval of the Es

3(L)

with commercial shale oil production from Well XYS9; characterized by developed micro-fractures

abnormal pressure

high contents of brittle minerals and contribution of mature oil migration

the cored interval at the depth of 2 994.10m to 3 010.90m should be a favorable interval for shale oil exploration.