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Площадь: 140728.23 км²
Yinggehai Basin
The Yinggehai Basin, lying at the junction of the north continental margin and west continental margin of the South China Sea (Figs. 1 and 2) on an indosinian fold belt basement, is a large deep basin in northwest direction of high temperature resulted from Cenozoic strike slipping and extension, which is divided into the Yingdong Slope, the Yingzhong Depression and the Yingxi Slope. The Paleogene System in Yingzhong Depression was composed of three sags in the north, middle and south, which merged into a large sag in the Neogene and Quaternary, and in the center of the depression developed Neogene diapiric structures (Figs. 1 and 2).
Fig. 1. Distribution of gas fields in the Yinggehai Basin.
The
Huangliu mudstone has TOC of 0.39%-2.60%, and 1.06% on average; The Meishan
thick mudstone has TOC of 0.44%-3.17%, and 1.45% on average; both of them have
kerogen of humic hybrid and humic types. It is inferred that the Middle Miocene
Meishan Fm is the major source bed in the basin. Meanwhile, it is concluded
from geotemperature data and rock thermophysical properties from well drilling
that the basin is a hydrothermal one with a high temperature. The thermal
gradient in the central depression is higher than 50.0 0C/km (the
average thermal gradient is 45.0 0C/km). Analysis of
13C1 value shows Ro of shallow gas
layers is generally higher than 1.2%, indicating a highly-matureepostmature
stage. Under the co-control of source and heat, the basin mainly produces
natural gas, which distributes mostly in Pliocene Yinggehai anticlinal structures
in shallow diapiric zones of normal temperature and pressure, and also in the
Upper Miocene Huangliu Fm of high temperature and pressure.
Fig. 2. Geologic section showing high temperature and overpressure natural gas accumulation mode in the Yinggehai Basin
Petroleum exploration in the Yinggehai Basin started in the 1950s and some gas fields have been discovered in the anticlinal and lithologic traps in the central anticlinal zone in the Yingzhong Depression, among which Dongfang1-1 and Dongfang13 gas fields (including Dongfang13-1 and Dongfang13-12) are all large gas fields of a hundred billion cubic meter magnitude. It has been demonstrated by exploration and research findings that the Yinggehai Basin is a gas-typed basin.
Data source: Analysis of the orderly distribution of oil and gas fields in China based on the theory of co-control of source and heat. Zhang G.C., Jin Li, Lan Lei, Zhao Zhao. 2015
Следующий Бассейн: Central Myanmar Tertiary