Analysis on Structure Controlling Factors of Hydrocarbon-rich Depression in Northern South China Sea
|School||China University of Geosciences|
|Keywords||Hydrocarbon-rich depressions Northern South China Sea Huizhou Depression Structurally controlled conditions Quantitative analysis|
Thesis from the hydrocarbon-rich concept and its tectonic depressions control elements analyzed start by Huizhou Depression detailed seismic interpretation, to determine the structural characteristics of the basin tectonic features; divided the tectonic stage to determine its settlement evolution; analysis Huizhou Depression petroleum geology; structural elements of the basin static and dynamic structural elements of quantitative analysis; determined on the basis of such hydrocarbon-rich Huizhou Depression Depression construct quantitative indicators. The main thesis to obtain the understanding of the following: 1. Integrated basin structure, tectonic evolution and subsidence analysis of the results, Cenozoic evolution of the basin can be divided into three evolutionary stages: the faulted phase (Wenchang - Enping), broken Au conversion period (Zhuhai), depression period (Pearl Group - today), its interrupt trap on a T8 is the interface can be divided into two acts. Ⅰ faulted Wenchang curtain control the deposition of Huizhou Depression strongly faulted phase, the period of basin development isolated, controlled by a single fault grabens or half-grabens, often with a lower frequency, energy is strong, noninverting axis representing continuous reflective layer is deep in Wenchang iconic lacustrine mudstone reflect, but also within the main hydrocarbon sunken rocks; rift Ⅱ curtain control the deposition of Enping, ending the isolation of the early compartmentalization rift development, the formation of rift basins widely covered in the lower part of the graben or half-graben rift above - like the river marsh - Lakeside phase, is a rather important hydrocarbon and reservoir rocks. (2) development of a rich Huizhou Depression favorable for hydrocarbon accumulation structural style, composed mainly of hydrocarbon traps in Huizhou Depression. Huizhou depression formed during Cenozoic evolution of the different types of rich structural style, mainly in the same direction tilted fault block, reverse block, graben horst, hill drape structure, rolling and extrusion anticline anticline , single Broken Hill, basal deflection anticline, sedimentary roll band anticline and so on. These different types of structural - stratigraphic combination of style, can be formed on the bedrock uplift and fracture drape anticline anticline and a half on both sides of anticlines and other major oil and gas traps for hydrocarbon accumulation provided the space available. 3 Through comparative analysis of physical simulation results, and other aspects of dynamic background that is typical of Huizhou rift rift basins stretching diagonally. Paleocene northern South China Sea formed a series of NE-trending faults control the basic pattern of the Pearl River Mouth Basin, northern South China Sea late Gu Nanhai District subduction led north-south rifting occurred and led to expansion in the South China Sea, South China Sea has continued to expand stopped. These two factors jointly controlled Huizhou Depression of development, so that a typical Huizhou Depression rift basins stretching diagonally. The Huizhou Sag KRMcClay et al sandbox simulation experiments visible, resulting in Huizhou Depression oblique tensile force between the basin boundary to an angle of about 60 °. 4 summarizes the hydrocarbon-rich Huizhou Depression Depression as a static structure factor and the development of the dynamic structure factor quantitative indicators. Focusing on depression in Huizhou Huizhou 26 depression, Xijiang 24 depression, depression and peripheral Lufeng 13 Panyu four lying within four depression Depression can characterize hydrocarbon-rich structural elements of some static and dynamic structural elements of the quantitative calculation and analysis, and to This is the basis of refined hydrocarbon-rich major depression quantitative indicators of structural elements, ie, the depth of source rocks and thickness of hydrocarbon source rock section of sedimentation rate and fault activity rate and so on. Specifically: This four-rich hydrocarbon source rocks sag top boundary of the largest segments are more than 4000 meters depth, including Wenchang Formation source rocks in the bottom boundary of the maximum depth in excess of 6000 m, Enping Formation source rocks buried largest deep bottom boundary are more than 5600m; within each sag Wenchang and Enping Formation source rock thickness in excess of 1500 m, Lufeng 13 Wenchang Formation source rocks lying even to 3000 m; each section of the main hydrocarbon source rocks developmental stages faulting rate is also relatively high, in excess of 140 m / Ma, especially in Wenchang fault activity rate in excess of 150m/Ma, especially depression and Huizhou 26 Lufeng 13 depression, Wenchang fault activity rates in excess of 250 m / Ma, Enping Formation source rocks faulting rate is slightly smaller, at 150 m / Ma around; each Sag main hydrocarbon source rock section developmental stages, basin subsidence rates are also high, especially Wenchang, sedimentation rate were more than 270m/Ma, Lufeng 13 depression and depression in Huizhou 26 highest in 400m/Ma so. Enping Formation source rocks during basin subsidence rate lower but also 160m/Ma so. 5 Huizhou depression formed late faulting faults and inherited control of the activities of the concave boundary fault is the advantage of late hydrocarbon migration channels. Huizhou depression and peripheral of four hydrocarbon-rich structure sag structural study found that these hydrocarbon-rich late have suffered depression superimposed tectonic activity and transformation. In the early post-tectonic faults can be inherited in sexual activity or a series of new faults generated through communication and deep hydrocarbon source rocks and the shallow reservoir, constitute the advantage of transporting oil and gas channel.