The Continental Scientific Drilling in the Songliao Basin has been done since 2005,which include the SK1,having finished in 2007,and the SK2 that started drilling in 2014 and is expected to finish in 2017.The purposes of the project are as followings,to drilling through the whole Cretaceous sequence of the Songliao Basin,to obtain continuous high resolution continental geological records by the means of the so-called2 wells 4holes drilling procedures,to research the Cretaceous greenhouse climate changes in order to be better prepared with the challenge caused by the nowadays global warming event.According to the goals above we proposed the rules for the site selection of the SK2as follows.Firstly,stratigraphic sedimentary records should be continuous.Secondly,sedimentary rocks are preferred,especially the lacustrine fine clastic rocks. Thirdly,thickness of the overburden cap rocks should be as thin as possible.Fourthly,faults should be avoided of. At last,ground conditions should be as good as possible such as roads,electric power,water supply,and so forth.We finally chose the site of SK2 in the Songzhan area where the lacustrine mudstone is well developed in the Xujiaweizi faulted depression of the Songliao Basin.The major target drilling succession is the Lower Cretaceous,namely,Yingcheng,Shahezi,and Huoshiling Formations.The strata under drilling are interbedding sequence of sandstone,siltstone,mudstone and coal,which are intercalated with volcanic rocks and pyroclastic rocks.They are mainly dark rocks of lacustrine facies which reflect the reduced environment. We shall drill through the top boundary(T_4) and bottom boundary (T_5) of rift fill successions,the boundary between the Upper and Lower Cretaceous,the boundary between Cretaceous and Jurassic(K/J).All these boundaries indicate important geological events which reflect changes of regional tectonics and basin filling styles.With the continuous coring section,we can also obtain some other important geological records with global meanings such as the Cretaceous normal polarity superchron(CNS)and oceanic anoxic event(OAE-1).