| Sediment provenance analysis is an important basic work for the study of sedimentary system distribution and the prediction of reservoir distribution. The Third Member of the Funing Formation is an important stratigraphic unit of hydrocarbon exploration, during the Dainan stage, the tilting reformation of the depositional stratum in the basin caused the change of the occurrence of the sedimentary basin of the Third Member of the Funing Formation, which changed the prototype basin, and made it difficult to determine the direction of sediment provenance, which in turn affected the prediction of the sedimentary system framework, the analysis of oil and gas accumulation conditions, and the evaluation and deployment of exploration. Based on sedimentology principles and seismic stratigraphy methods, logging, well logs, seismic facies and attributes, sand petrographic maturity, heavy mineral composition and core samples were comprehensively used to analyze the direction of sediment provenance of the Third Member of the Funing Formation in the central part of the sag. The following understandings were obtained: (1) Based on provenance synthesis analysis methods of the reflection features of seismic progradational and concave facies, the distribution of the seismic-sensitive attribute for lithology, the trend of sand petrographic maturity and heavy mineral composition, and the spatial distribution of sandbodies, the large sediment provenance from the southeast Taizhou Paleo-Uplift was found in the central part of the Qintong Sag. (2) The sediment in the central part of the Qintong Sag controlled by the southeast provenance during the depositional stage of the Third Member of the Funing Formation was pointed out, and this large delta, which sourced from the southeast provenance area in this period, was both broad in scale and wide in scope. The Qintong Sag was served by both the southeast and north provenance, which developed a sedimentary filling model characterized by multi-provenance during the sedimentary period of the Third Member of the Funing Formation. (3) The Qintong Sag, considered to belong to a superimposed basin, was characterized by multi-stage evolution and late intense reformation, the paleo-topography and property of the basin underwent changes, and the development of the late “half graben fault depression” resulted in the basin tilting. As a result, the east part of the sag was greatly subsided, and the depositional area of southeast provenance was deeply buried. However, the west part of the sag was uplifted due to tilting, which led to partial denudation of the depositional stratum of north provenance and incomplete preservation of the sedimentary system. Additionally, the central part of the sag has become a large slope zone, the phenomenon of progradation in the original stratum was transformed into the onlap pseudophase, which brought difficulty for provenance identification. (4) The development area of the sedimentary subfacies of delta front controlled by southeast provenance was considered as the development area of the favorable reservoir facies, and also a favorable area for lithologic reservoir exploration. These new understandings deepen the recognition of sediment provenance of the Third Member of the Funing Formation in the Qintong Sag, and provide useful reference for the sediment provenance analysis of the reformed and superimposed basin. |