Analysis of the Oldest Carbonate Gas Reservoir in China——New Geological Significance of the Dengying Gas Reservoir in the Weiyuan Structure, Sichuan Basin

论文摘要

The Weiyuan Structure is the largest surface structure in the Sichuan Basin. However, the abundance of the Dengying Formation gas reservoir in the Weiyuan Structure is low. The height of the gas column is 244 m, but the integrated abundance is only 26.4%. After nearly 40 years of exploration, the Gaoshi1 Well and Moxi8 Well yielded gas flows that marked an important exploration success after the discovery of the Sinian Dengying Formation gas reservoir in the Weiyuan Structure, Sichuan Basin, Lower-Paleozoic in 1964. Combined with research examples of oil and gas migration and gas chimneys around the world, the authors used comprehensive geological-geophysical-geochemical research methods to provide a reasonable explanation of the low abundance of the gas reservoir in the Weiyuan Structure based on the surface and subsurface data. The latest research results show that（1） currently, the Weiyuan Structure is the apex of the Dengying Formation in the Mid-Sichuan Basin. The Guang’an, Longnüsi, Gaoshiti-Moxi, and Weiyuan structures are a series of traps in the Dengying Formation with gradual uplifting spill and closure points during the regional uplift of the Himalayan period. The natural gas of the Dengying Formation accumulated in different ways over a wide range and long distance in the Sichuan Basin.（2） At approximately 40 Ma, the Weiyuan area started to uplift and form the present structure, and it is the only outcropped area with the Triassic Jialingjiang Formation and Leikoupo Formation in the surface of the Sichuan Basin（except the steep structural belt in East Sichuan）. Caused by the uplift and denudation, the core of the Weiyuan Structure has formed an escaping "skylight" for natural gas. The evidence of a gas chimney includes（1） the component percentage of non-hydrocarbon gas, which decreased from the bottom to the top,（2） the pressure coefficient is normal because the gas reservoir from the Upper Sinian to the Lower Permian commonly have a normal pressure coefficient（an average of 1.0）, and（3） the isotope geochemistry of the argon mostly represents abiogenic characteristics of a deep source, and the 40 Ar/36 Ar ratio is as high as 2 855–5 222 in the Upper Permian. All of these characteristics provide sufficient evidence for a gas chimney effect. The characteristics of low abundance in the Weiyuan Structure can be a reference example for studying the late reconstruction of deep oil and gas reservoirs in the superimposed basins of western China.

论文目录

• 0 INTRODUCTION
• 1 GEOLOGICAL SETTING
•   1.1 Stratigraphy
•   1.2 Structure
•   1.3 Main Structural Trap Features of the Sinian Dengying Formation in the Sichuan Basin
• 2 CHARACTERISTICS AND EFFECTS OF A GAS CHIMNEY IN THE WEIYUAN STRUCTURE
•   2.1 Features of a Gas Chimney in Marine and Land Forma-tions
•     2.1.1 Gas chimney features in an ocean
•     2.1.2 Gas chimney features on land
•   2.2 Mechanism Differences between Marine and Land Chimneys
•   2.3 Gas Chimney Structure and Characteristics of Its Effects on the Weiyuan Structure
•     2.3.1 Seismic features of a gas chimney
•     2.3.2 Pressure coefficient
•     2.3.3 Isotope geochemistry
•     2.3.4 Non-hydrocarbon gas composition
• 3 IMPORTANT ROLE OF THE WEIYUAN STRUC-TURE ON DIFFERENTIAL ACCUMULATION OF THEDENGYING FORMATION GAS RESERVOIRS IN THESICHUAN BASIN
•   3.1 Formation Mechanism and Geological Significance of a Gas Chimney in the Weiyuan Structure
•   3.2 New Model of Differential Accumulation—Evolution from the Paleo-Gas Reservoirs of the Dengying Formation （Gas Storage Center） to Present Gas Reservoirs （Gas Preservation Center）
•   3.3 Relationship between Gas Chimneys and Hydrocarbon Accumulation （Dengying Formation） in the Sichuan Basin
• 4 CONCLUSION

文章来源

类型: 期刊论文

作者: Xiao Liang,Shugen Liu,Shubei Wang,Bin Deng,Siyu Zhou,Wenxin Ma

来源: Journal of Earth Science 2019年02期

年度: 2019

分类: 基础科学,工程科技Ⅰ辑

专业: 地质学,石油天然气工业

单位: State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Institute of Geological Exploration and Development of CNPC Chuanqing Drilling Engineering,Research Institute of Petroleum Exploration and Development,Petro China Southwest Oil&Gas Field Company,BGP Inc.,China National Petroleum Corporation

基金: financially supported by the Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,the 973 Program of China (No. 2012CB214805),the SINOPEC research project (No. P16109),the National Science and Technology Major Project of China (No. 2017ZX05005003-007)

分类号: P618.13

页码: 348-366

总页数: 19

文件大小: 12440K

下载量: 27