Study On The Characteristics Of Provenance And The Distribution Of Sedimentary System Of Sha-Ⅲ Member Of Paleogene In Huimin Depression

The western Huimin depression including linnan sag and its adjacent areas have advantageous conditions for hydrocarbon accumulation. Up to now, many oil and gas fields have been discovered, the main petroleum pools of which are structural petroleum pools. The sequence stratigraphy, provenance system, and the genesis and distribution of sand bodies of the third member of the Shahejie formation(Es3) in the western Huimin depression were systematically studied by application of the theories and methods of sequence stratigraphy, sedimeatology, and petroleum geology. The study promoted the exploration of subtle pools in the western Huimin depression.Based on the comprehensive analysis of seismic, well drilling and logging data, the third member and fourth member of Shahejie formation(Es3 and Es4) in Huimin depression can be divided into six the third order sequences. The lower part of Es4 is sequence 1, the upper part of Es4 is sequence 2, the lower part of Es3 is sequence 3, the middle part of Es3 is sequence 4, the underneath of the upper part of Es3 is sequence 5, and the topping of the upper part of Es3 and the lower part of the second member of Shahejie formation is sequence 6. It is more reasonable that the boundary of Es3 and Es4 in Huimin depression lies in the top of Panne sand bodies.Both the southern and northern provenance systems in Huimin depression existed during the depositional period of Es3. The northern provenance system in the western Huimin depression mainly comes from Lingxian uplift and the provenance directions include east-west-trending and north-north-west-trending. The northern provenance system controls the Panhe, Linyi, Shanghe, and Jishan sand bodies. The southern provenance system in the western Huimin depression mainly comes from Luxi uplife and controls the Shuangfeng, Jiangjiadian, and Wawu sand bodies, and so on.On the basis of core observation and correlative test analysis, the facies indicators of Es3 in Huimin depression was systematically summarized. The fan delta, delta, slump turbidite fan, storm deposits, and beach and bar were mainly developed during the depositional period of Es3 in Huimin depression. The fluvial-delta can be divided into braided river delta and meandering river delta. The meandering river delta also can be divided into shallow water delta and deep water delta. According to sand content chorisopleth, and the distribution of sand thickness and stratigraphic thickness, the distribution of the sedimentary system of the lower, middle, and upper part of Es3 was studied. The south mainly developed braided river delta and meandering river delta, the northwestward developed meandering river delta, and the middle part developed deep-semideep lake facies during depositional period of Es3 in the western Huimin depression, the scale of northwest delta gradually increased, and sedimentary area gradually advanced forward the east and southeast direction.The fluxoturbidite lithologic trap and stratum lateral pinchout lithologic trap are the main lithologic traps in the Shahejie formation in Huimin depression. The formation and distribution of lithologic trap are mainly controlled by basin structural characteristics, palaeogeomorphology characteristics and the intensity of multiphase tectonic activity.