东海陆架盆地西湖凹陷平湖组发育大量潮汐沉积,具有较大的油气勘探潜力.综合利用岩心与测井资料,对西湖凹陷W井区平湖组岩相及沉积微相类型进行分析,并通过对江苏省东南部如东-东台沿海地区的现代沉积考察,进行比较沉积学研究,结合平湖组发育情况及现代潮汐沉积平面展布,明确了研究区平湖组潮汐沉积特征及发育规律,建立了沉积模式.研究结果表明:研究区平湖组发育一套潮控三角洲—潮坪沉积体系,沉积亚相主要包括三角洲前缘、潮上带和潮间带,可进一步识别出水下分流河道、分流间湾、河口坝、席状砂、沼泽、泥坪、砂坪、混合坪、潮汐水道共9种沉积微相.在沉积体系分析的基础上,建立了研究区潮控三角洲-潮坪沉积模式.

A large number of tidal deposits are developed in the Pinghu Formation in Xihu Sag of the East China Sea Shelf Basin, which has great potential for oil and gas exploration. In this paper, core and logging data are used to analyze the lithofacies and sedimentary microfacies of Pinghu Formation in W well block of Xihu Sag, and comparative sedimentology study is conducted through modern sedimentary investigation in Rudong-Dongtai coastal area in Southeast Jiangsu Province, then the tidal sedimentary characteristics and development law of Pinghu Formation in the study area are clarified, and the sedimentary model is established. The results show that a set of tidal-controlled delta tidal flat depositional systems are developed in the Pinghu Formation in the study area, and the sedimentary subfacies mainly include delta front, supra-tidal zone and intertidal zone. Nine types of sedimentary microfacies, including underwater distributary channel, interdistributary bay, estuary bar, sheet sand, swamp, mud flat, sand flat, mixed flat, and tidal channel are further identified. Based on the analysis of the sedimentary system, a tidal delta-tidal flat sedimentary model in the study area is established, which provides reference and guidance for tidal sand body prediction and oil and gas exploration of Pinghu Formation.