Abstract: During the study of the deposition characteristics of the Upper Jurassic Akshabulak formation of S oilfield in the South Turgay basin, Kazakhstan, a set of widely-distributed shale layers with high natural gamma values and low resistivities are found in almost the whole oilfield. With the viewpoint of sequence stratigraphy, the paper analyzes the shale layers and concludes that the shale layers are a set of condensed layers deposited during the maximum flooding period. According to the lateral distribution characteristics of the condensed layers and combined with geological and seismic data, a sedimentary model of the stratum is proposed. Analysis of the sedimentary characteristics of J0-0 sand member in Akshabulak formation above the condensed layer shows that the sedimentary thickness of the sand member varies greatly on the eastern slope of the oilfield due to the development of progradation delta facies during high-stand periods. The delta front is the most favorable stratigraphic-lithologic oil and gas reservoir development area, which has been well verified in wells S53 and S34. The paper provides a method of looking for lacustrine condensed layers and puts forward a new way to discover stratigraphic-lithologic oil and gas reservoirs.