###### Abstract  
Shallow-water deltas serve as a critical area for the exploration and development of terrestrial lacustrine oil and gas reservoirs. Current research on oil and gas exploration and development in China's terrestrial lacustrine basins primarily focuses on their delta front facies zones. Despite extensive discussions on the sedimentary characteristics of shallow-water deltas by predecessors, there is a lack of comprehensive analysis on the combined effects of dynamic factors such as climate change, lake level fluctuations, and sediment supply. This paper, through a detailed examination of 12 core samples and integrating data from 493 exploratory, appraisal, and development wells in the study area, establishes a stratigraphic correlation framework using well-seismic integration techniques. It identifies two main sedimentary facies types in the southern Da'anbei area of the Songliao Basin: shallow-water deltas and lake facies, which can be further subdivided into four sub-facies and nine microfacies. Two depositional models for the shallow-water deltas of the Southern Songliao Nenjiang Formation are established: a deeper water background with channel-river mouth bar sequences forming the delta front framework and a shallower water background with channel-sheet sand sequences forming the delta front framework. This paper also discusses the controlling effects of paleoclimate, sediment supply, and lake level changes on sedimentary evolution, providing a scientific basis for the exploration of lithologic oil and gas reservoirs in the Nenjiang Formation of the study area and the deployment of horizontal wells. Songliao Basin; Nenjiang Formation; shallow-water delta; sedimentary evolution; main controlling factors +
Footnote †: journal:  
that the underwater distributary channels in shallow-water deltas exhibit a continuous superimposed morphology and under conditions of reduced wave action, they do not lead to the formation of river mouth bar microfacies. [PERSON] [26] and [PERSON] [27] proposed a superimposed shallow-water delta depositional model based on modern sedimentary simulations. [PERSON] [28] noted that due to the strong energy of the water body, braided river shallow-water deltas generally do not develop river mouth bar microfacies, while meandering river shallow-water deltas commonly do. [PERSON] [29] analyzed the depositional evolution of lobate shallow-water deltas quantitatively through flume simulation experiments, stating that lobate shallow-water deltas primarily undergo three evolutionary stages: initial channel formation, distributary channel system formation, and continuous stable evolution. These analyses, primarily based on modern sedimentology and sedimentary simulation perspectives, systematically describe and categorize the sand body distribution and morphology in shallow-water deltas. Within this framework, the characteristics of distributary channel sand bodies are lobate and superimposed, influenced by both fluvial dynamics and lake wave dynamics. On the other hand, the branch-like channel sand bodies are mainly controlled by fluvial dynamics, exhibiting a branch-like superposition. These two perspectives form the two main schools of thought regarding the distribution of sand bodies in shallow-water deltas. Several scholars have summarized the sedimentary characteristics of shallow-water deltas based on the patterns of sand body associations, identifying two main depositional modes for these deltas, although differing views remain on the distribution of depositional sand bodies within these modes. For instance, [PERSON] [30], based on wave base and the ratio of river depth to basin depth, classified shallow-water deltas into very shallow and moderately shallow types and defined two end-member types from a depositional architecture perspective: distributary sand bar and digitate sand bar shallow-water deltas. [PERSON] [31] observed that under arid climate conditions, the delta front of shallow-water deltas exhibits digitate sand bar characteristics where \"rivers run over bars\".