An introduction to seismic exploration of the Micang-Dabashan foothill belt in the Sichuan Basin

2018 ◽  
Vol 6 (4) ◽  
pp. SM39-SM50
Author(s):  
Jingbo Wang ◽  
Zhongshan Qi ◽  
Penggui Jing ◽  
Tianfa Zheng ◽  
Yanqi Li ◽  
...  
Keyword(s):  
Sichuan Basin ◽  
Oil And Gas ◽  
Seismic Exploration ◽  
Small Scale ◽  
Marine Strata ◽  
Piedmont Zone ◽  
Migration Imaging ◽  
Imaging Results ◽  
Platform Margin ◽  
The Sichuan Basin

Geologic studies indicate that the platform-margin reef-shallow facies in Permo-Triassic marine strata in the Micang-Dabashan foothill belt in the Sichuan Basin are favorable exploration targets for oil and gas exploration. However, the typical dual-complexity problem (complex surface condition and subsurface structure) brings a great challenge for seismic technology targeting of those potential oil and gas reservoirs. To overcome this problem, varieties of advanced seismic acquisition and processing methods have been used to improve the imaging quality of piedmont seismic data since 2000. Some improvements have been achieved: The reflection waves from the far offset and deep layer can be acquired in shot gathers from limestone outcropped areas, and the signal-to-noise ratio (S/N) of reflection and diffraction waves in the stack section has been enhanced significantly so as to reveal amounts of valuable geologic information. The resolution and the S/N of seismic migration imaging for the strong fold zone in marine strata have been improved partially, so that the structure of the step-fault zone and the enveloping of gypsum rock are clearer than those revealed by the old seismic section. Even so, actual drilling data demonstrate that the subsurface structures of the foothill belt are far more complex than those revealed by the current seismic imaging results. Therefore, postdrilling evaluation for the validity of seismic techniques implemented in the Nanjiang and Zhenba piedmont zone has been carried out. The results indicate that the current acquisition scheme and processing workflow cannot completely fulfill the requirements of high-precision velocity modeling and migration imaging of complex structures (such as footwalls of thrust fault and small-scale fault blocks) in the piedmont zone, especially when the rugged surface and the widespread limestone outcrop appear simultaneously. Finally, we have developed some potential needs of seismic theories and techniques in the foothill belt, including seismic wave propagation, acquisition, and processing technology.

Quantitative prediction of oil and gas prospects of the Sinian-Lower Paleozoic in the Sichuan Basin in central China

Energy ◽  
2019 ◽  
Vol 174 ◽  
pp. 861-872 ◽  
Author(s):  
Wenyang Wang ◽  
Xiongqi Pang ◽  
Zhangxin Chen ◽  
Dongxia Chen ◽  
Tianyu Zheng ◽  
...  
Keyword(s):  
Sichuan Basin ◽  
Oil And Gas ◽  
Central China ◽  
Quantitative Prediction ◽  
Lower Paleozoic ◽  
The Sichuan Basin

scholarly journals Characteristics of the temperature–pressure field evolution of Middle Permian system in the northwest of Sichuan Basin

2018 ◽  
Vol 36 (4) ◽  
pp. 705-726 ◽  
Author(s):  
Qiuchen Xu ◽  
Nansheng Qiu ◽  
Wen Liu ◽  
Anjiang Shen ◽  
Xiaofang Wang ◽  
...  
Keyword(s):  
Sichuan Basin ◽  
Oil And Gas ◽  
Vitrinite Reflectance ◽  
Middle Permian ◽  
Key Factors ◽  
Reduction Stage ◽  
Three Stages ◽  
The Sichuan Basin ◽  
Thermal Indicators ◽  
Oil Cracking

The Sichuan Basin is one of the richest oil and gas basins in China. The Middle Permian units (the Qixia and Maokou Formations) in the northwest Sichuan Basin have great potential for gas exploration. A new thermal history was reconstructed using the integrated thermal indicators of apatite and zircon (uranium–thorium)/helium ages, zircon fission tracks, and vitrinite reflectance data. The modeled results indicated that the northwest Sichuan Basin experienced gradual cooling, during which the heat flow at Middle Permian time (70–90 mW/m2) decreased to its current level of approximately 50 mW/m2. This study used basin modeling to reconstruct the paleo-pressure, which showed that the Middle Permian in the northwest Sichuan Basin generally developed overpressure. The pressure evolution of the Middle Permian can be divided into three stages: (1) a slight overpressure stage (T2–T3), (2) an intensive overpressure stage (J1–K2), and (3) an overpressure reduction stage (K2–present). Oil cracking and rapid tectonic subsidence are key factors that affect overpressure. The evolution of temperature–pressure has great significance with respect to hydrocarbon accumulation.

scholarly journals Formation pressure evolution and its causes for the reservoirs of the upper Triassic Xujiahe formation in the northeast portion of the Sichuan basin, China

2021 ◽  
pp. 014459872110124
Author(s):  
Cunjian Zhang ◽  
Jingdong Liu ◽  
Youlu Jiang
Keyword(s):  
Late Cretaceous ◽  
Middle Jurassic ◽  
Sichuan Basin ◽  
Oil And Gas ◽  
Upper Triassic ◽  
Hydrocarbon Generation ◽  
Formation Pressure ◽  
Xujiahe Formation ◽  
The Sichuan Basin ◽  
Early Late

Overpressure is one of the most important factors for oil and gas charging in petroliferous basins. Research on overpressure evolution and its formation mechanisms is of great significance for predicting formation pressures in oil and gas reservoirs before drilling. However, research methods addressing overpressure evolution are not without issues. Based on the measured formation pressures and fluid inclusions, the evolution of the formation pressures in the Xujiahe Formation in the northeast part of the Sichuan Basin was investigated by PVT and basin simulations and the causes of overpressure were also analyzed. The results show that overpressure in the continental strata began to develop at the bottom of the Middle Jurassic Shaximiao Formation. The pressure coefficients of the Upper Triassic Xujiahe Formation range from 1.01 to 1.90, and belong to the normal pressure and overpressure regimes. The present-day overpressure of the Xujiahe Formation is mainly caused by hydrocarbon generation and tectonic compression. The tight reservoirs are conducive to the formation and preservation of overpressure. The pressures in the Xujiahe Formation experienced two evolution processes, namely an “increase-decrease-increase” (eastern area) process and an “increase-decrease” (western area) process. Overpressure began to develop in the Middle Jurassic(J2) period. Due to the hydrocarbon generation taking place, the formation pressures increased rapidly from the Middle Jurassic(J2) period to the early Late Cretaceous (the early part of K2) period. The degree of development of overpressure in the western part of the study area was greater than that in the eastern part of the study during the critical charging period (J3–K1). Since the early Late Cretaceous, the formation pressure has gradually decreased due to tectonic uplift and erosion. From the Oligocene (E3) period to the present, the formation pressures have increased again in local areas due to tectonic compression.

3D Crustal Structure and Seismicity Characteristics of Changning–Xingwen Area in the Southwestern Sichuan Basin, China

2020 ◽  
Vol 110 (5) ◽  
pp. 2154-2167 ◽  
Author(s):  
Kezhen Zuo ◽  
Cuiping Zhao ◽  
Haijiang Zhang
Keyword(s):  
Sichuan Basin ◽  
Source Area ◽  
Double Difference ◽  
Small Scale ◽  
Low Velocity ◽  
Aftershock Activity ◽  
Velocity Anomaly ◽  
Crustal Structures ◽  
The Sichuan Basin ◽  
Tomography Method

ABSTRACT Using seismic data recorded on permanent and temporary stations around the Changning area in the Sichuan basin, the high-resolution 3D crustal VP, VS, VP/VS models and earthquake locations in the Changning–Xingwen area are obtained using the VP/VS model consistency-constrained double-difference seismic tomography method. The results show that crustal structures in the source area of the 2019 Ms 6.0 Changning earthquake have significant variations, especially in the depth of 0–7 km. Seismic activity in the Shuanghe and Yutan anticline areas before the Ms 6.0 Changning earthquake outlined several northeast-trending stripes, implying pre-existing small-scale faults that are perpendicular to the major northwest-striking faults in the Changning–Shuanghe anticline system. We found that the Ms 6.0 Changning earthquake broke through these pre-existing small-scale faults and extended from the Shuanghe to the Yutan anticlines. Both the rupture process and aftershock activity were influenced by the pre-existing small-scale faults. Most earthquakes within the Changning area are located in a slant zone that gradually deepens from the Shuanghe anticline on the east to the Yutan anticline on the west with the maximum depth from 5 to 10 km, which are associated with obvious high-VS and low-VP/VS features. The relocated seismic clusters in the Luochang–Jianwu syncline area have different strikes and dips, which are mainly located at the edge of low-velocity anomaly bodies and correspond to the low-VP/VS area.

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