A novel sedimentary pattern of wave-induced sandbars under high-angle wave incidence

Wave-induced sandbars, wave-reworked deposits, are considered to resemble bands parallel to shorelines as reflected by the traditional depositional model, which, however, ignore the fact that varying angles between wave incidence direction and shoreline orientation can lead to significant differences in sedimentary patterns. In combination with the sedimentary characteristics of modern wave-induced sandbars in both the Huizhou Sag, Pearl River Mouth Basin(PRMB), and Qinghai Lake, we investigate and summarize differential sedimentary patterns of wave-induced sandbars under high-angle wave incidence. Key findings are as follows: (1)Constrained by the Dongsha Uplift, local areas on the southern margin of the Huizhou Sag manifest significant “canyon effect”, leading to high-angle wave incidence. Moreover, due to the different hydrodynamic environments at varying occurrence positions during deposition, the sand bodies of two neighboring oilfields in the Huizhou Sag exhibit significantly distinct morphologies and scales postwave reworking; (2)Based on the dynamic sediment transport mechanism for shorelines, along with field geological survey results, wave-induced sandbars are categorized into three types:the totally closed shore-oblique type, the shoreparallel type, and the semi-open shore-oblique type. Moreover, a novel sedimentary pattern of wave-induced sandbars under high-angle wave incidence is developed; (3)Drilling results corroborate that under the novel sedimentary pattern, wave-induced sandbars on windward and leeward flanks differ enormously in morphology, scale, and superimposed style. Furthermore, lithologic hydrocarbon reservoirs with poor connectivity are prone to form between the sand bodies. The novel sedimentary pattern holds critical theoretical and practical significance for guiding the exploration and exploitation of reservoirs of wave-induced sandbars.