辽中凹陷北洼斜坡带源汇系统特征及砂体展布样式OA

In the early stages,it was believed that the second member of Shahejie Formation in the North Sag of the Liaozhong Depression in the Bohai Sea lacked sediment sources during depositional period and had poorly de-veloped reservoirs.However,a recent exploration well in the JZ25-C structural area encountered a relatively thick sandbody with a total thickness of 62.5 m.To further clarify the development scale of this sandbody,it is crucial to redefine the source-to-sink system characteristics and the sandbody distribution patterns in the study area.Therefore,we conducted heavy and light mineral comparative analysis,zircon dating,paleogeomorphology restor-ation,and seismic facies specification,based on which the matching relationship between the source-sink system and sedimentary bodies in the study area was clarified,and the stacking pattern and distribution style of the sand bodies determined.Results indicate that the study area developed braided river delta deposits sourced from the Fuzhou River system in the Jiaoliao Uplift,with well-defined source-to-sink relationships among depositional lobes.The restrictive negative paleogeomorphology and slope break zones in the depositional area,combined with the left-stepping dextral strike-slip fault development patterns,controlled the sedimentary unloading and lateral migration of braided river delta sand bodies.This tectonic-sedimentary setting resulted in the lateral distribution of sand bodies along strike-slip faults in vertical multi-stage oblique stacking.The large-scale sand body develop-ment in the Second Member of the Shahejie Formation in the North Sag of the Liaozhong Depression was re-vealed,and favorable sand body accumulation zones delineated,providing critical geological evidence to effect-ively guide the next phase of oil and gas exploration evaluation in this region.