Fig 1.
Geological and structural of the Huanghekou Sag (Modified from “Map of China”, Map Review Number: GS(2023)2767 and “Map of China’s Topography”, Map Review Number: GS(2016)1609; Source: China Standard Map Service - http://bzdt.ch.mnr.gov.cn/).
Fig 2.
Mineral composition of the Shahejie Formation in Huanghekou Sag (62 samples) (a. Mineral composition of the sample, b.Ternary diagram of shale; I Quartz-Feldspar dominated shale,II Carbonate dominated shale, III Clay dominated shale, IV Mixed mineral shale).
Fig 3.
The main bedding types of the Shahejie Formation in Huanghekou Sag (a. Layered clay dominated shale; b. Layered quartz-feldspar dominated shale; c. Layered mixed mineral shale; d. Massive sandstone).
Fig 4.
The measured and fitted TOC content of Well B-2.
Fig 5.
Lithofacies division scheme of the Shahejie Formation in Huanghekou Sag.
Fig 6.
The main lithofacies types of the Shahejie Formation in the Huanghekou Sag (a. High-organic layered limestone; b. Massive thick sandstone; c. Massive thin sandstone; d. High-organic layered quartz-feldspar dominated shale; e. High-organic layered clay dominated shale; f. High-organic layered mixed mineral shale; g. High-organic layered carbonate dominated shale).
Fig 7.
Fisher discriminant analysis data scatter plot.
Fig 8.
Application of lithofacies discriminant analysis in Well B-3.
Fig 9.
Lithofacies associations division of the Shahejie Formation in the Huanghekou Sag.
Fig 10.
Typical lithofacies associations by the data of well-seismic (a. Mixed mineral shale and quartz-feldspar shale with thin sandstone, Distal part of lake-bottom fan; b. Interbedded layers of clay shale and mixed mineral shale, Semi-deep and deep lake; c. Carbonate shale with thin calcareous sandstone, Mixed shoal-bar platform; d. Quartz-feldspar shale, Pre-delta).
Fig 11.
Seismic identification chart of lithofacies associations.
Fig 12.
Shale oil lithofacies development model of the Shahejie Formation in the Huanghekou sag.
Fig 13.
Lithofacies associations identification of the Shahejie Formation in the Huanghekou Sag (a. In the direction along the sediment source; b. In the direction perpendicular to the sediment source; ①Sandstone; ②associations dominated of clay shale; ③associations dominated of mixed mineral shale; ④associations dominated of quartz-feldspar shale).
Fig 14.
Sedimentary profile interpreted in north-south direction of the Lucaogou Formation.
Fig 15.
Lithofacies associations and sedimentary facies of the Shahejie Formation in the Huanghekou Sag (Modified from “Map of China’s Topography”, Map Review Number: GS(2016)1609; Source: China Standard Map Service - http://bzdt.ch.mnr.gov.cn/).