Sedimentary Model of Lacustrine Small Fine-grained Shallow Water Delta

doi:10.3969/j.issn.1006-6535.2021.05.011

Abstract

Abstract: Lacustrine shallow water delta has become major target for lithologic hydrocarbon reservoir exploration in continental basins in China. To clarify its sedimentary characteristics and sedimentary models, a comprehensive study of the sedimentary characteristics of small fine-grained shallow water deltas in Member 2 of Shahejie Formation in the upthrown block of Southern Dagang Fault, Qikou Sag was carried out on the basis of rock, electrical and seismic data, and a sedimentary model was established. With analysis of the denudation range and distribution characteristics of heavy minerals in Member 2 of Shahejie Formation, the sediment source was mainly from the northeast; the sedimentary microfacies, such as overwater distributary channels, estuarine dams, submerged distributary channels and sheet sands were identified based on rock, electrical and seismic characteristics; finally, the distribution characteristics of planar sedimentary facies were determined in combination with the sand-to-formation ratio. It was found in the study that the main controlling factors of small fine-grained lacustrine shallow water deltas were tectonic conditions, climate, provenance supply, water depth, lake level variation and topographic slope; under the background of stable tectonic conditions, relatively arid climate, low provenance supply, shallow water depth, declining lake level and gentle topography, local uplift provided sediment sources, and small fine-grained shallow water deltas were developed mainly in delta front and more developed at the estuarine dams. The results of the study provide a new perspective for a comprehensive understanding of the sedimentary characteristics of lacustrine shallow deltas and prospects for hydrocarbon exploration.

Key words: Qikou Sag, upthrown block of Southern Dagang Fault, Member 2 of Shahejie Formation, small fine-grained shallow water delta, sedimentary model

CLC Number:

TE121.3

Guan Xutong, Li Shengli, Ma Shuiping, Liu Sheng, Huang Xiaodi. Sedimentary Model of Lacustrine Small Fine-grained Shallow Water Delta[J]. Special Oil & Gas Reservoirs, 2021, 28(5): 77-85.

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