To answer the questions concerning the hydrocarbon accumulation patterns and main controlling factors of Putaohua reservoirs in Chaochang area

Songliao Basin

we studied the hydrocarbon sources

accumulation features

main controlling factors as well as accumulation patterns of the reservoirs through source rock assessment

crude-source correlation

analyses of conduit systems

oil-water contact

and controlling factors of accumulation

and reservoir type identification.The results show that crude in the reservoirs are mostly from the first member of the Qingshankou Formation in Sanzhao sag in the west and Chaoyanggou terrace in the east.The underlying Fuyang oil-bearing layer also made some contribution.Faults in the area can be classified into three types:source rock-rooted faults

carrier faults and sealing faults

among which

the carrier faults dominate the area.Sandbodies are largely inner front channel sands in the northwest part

and outer front sheet sands in the southeast part

with the former having better storage capacity and physical properties than the latter.A comprehensive analysis comes to a conclusion that hydrocarbon accumulation in the area was gene-rally controlled by source rocks

source rock-rooted faults and sandbodies.There are mainly two types of accumulation pattern:near-source accumulation and updip accumulation. The study is meaningful in term of guiding the identification of future exploration targets and reserve estimation in Chaochang area.