Discovery of the lower Cambrian high-quality source rocks and deep oil and gas exploration potential in the Tarim Basin, China

AAPG Bulletin ◽  
2018 ◽  
Vol 102 (10) ◽  
pp. 2123-2151 ◽  
Author(s):  
Guangyou Zhu ◽  
Feiran Chen ◽  
Meng Wang ◽  
Zhiyao Zhang ◽  
Rong Ren ◽  
...  
2013 ◽  
Vol 734-737 ◽  
pp. 377-383
Author(s):  
Qing Li ◽  
Xue Lian You ◽  
Wen Xuan Hu ◽  
Jing Quan Zhu ◽  
Zai Xing Jiang

The Cambrian dolomite reservoir is an important target in oil and gas exploration. The Penglaiba section in the Keping area is typically examined in studies dealing with the Cambrian dolomite reservoirs of northwestern Tarim Basin. Based on sedimentological, petrographic, and geochemical data, lithofacies and fluids are identified as the major factors that control the dolomite reservoir in the study area. Lithoacies are fundamental to reservoir evolution because they provide suitable channels for dolomitization and dissolution of fluids that, in turn, facilitate the formation of high quality reservoirs. The lithofacies which could form high-quality reservoirs in the study area are: slope slip (collapse) facies, gypsum related facies, and algae dolomite facies. The sources of fluids include seawater, meteoric freshwater, diagenetic/hydrocarbon fluid, and hydrothermal fluid. These fluids lead to dolomitization, penecontemporaneous meteoric dissolution, hypergene dissolution, organic acid dissolution and hydrothermal dissolution that result in secondary porosity, and as such, they have a significant contribution to reservoir evolution.


2018 ◽  
Vol 36 (4) ◽  
pp. 801-819 ◽  
Author(s):  
Shuangfeng Zhao ◽  
Wen Chen ◽  
Zhenhong Wang ◽  
Ting Li ◽  
Hongxing Wei ◽  
...  

The condensate gas reservoirs of the Jurassic Ahe Formation in the Dibei area of the Tarim Basin, northwest China are typical tight sandstone gas reservoirs and contain abundant resources. However, the hydrocarbon sources and reservoir accumulation mechanism remain debated. Here the distribution and geochemistry of fluids in the Ahe gas reservoirs are used to investigate the formation of the hydrocarbon reservoirs, including the history of hydrocarbon generation, trap development, and reservoir evolution. Carbon isotopic analyses show that the oil and natural gas of the Ahe Formation originated from different sources. The natural gas was derived from Jurassic coal measure source rocks, whereas the oil has mixed sources of Lower Triassic lacustrine source rocks and minor amounts of coal-derived oil from Jurassic coal measure source rocks. The geochemistry of light hydrocarbon components and n-alkanes shows that the early accumulated oil was later altered by infilling gas due to gas washing. Consequently, n-alkanes in the oil are scarce, whereas naphthenic and aromatic hydrocarbons with the same carbon numbers are relatively abundant. The fluids in the Ahe Formation gas reservoirs have an unusual distribution, where oil is distributed above gas and water is locally produced from the middle of some gas reservoirs. The geochemical characteristics of the fluids show that this anomalous distribution was closely related to the dynamic accumulation of oil and gas. The period of reservoir densification occurred between the two stages of oil and gas accumulation, which led to the early accumulated oil and part of the residual formation water being trapped in the tight reservoir. After later gas filling into the reservoir, the fluids could not undergo gravity differentiation, which accounts for the anomalous distribution of fluids in the Ahe Formation.


2016 ◽  
Vol 1 (1) ◽  
pp. 21-33 ◽  
Author(s):  
Guangyou Zhu ◽  
Feiran Chen ◽  
Zhiyong Chen ◽  
Ying Zhang ◽  
Xiang Xing ◽  
...  

2020 ◽  
Vol 17 (6) ◽  
pp. 1540-1555
Author(s):  
Jin-Jun Xu ◽  
Qiang Jin

AbstractNatural gas and condensate derived from Carboniferous-Permian (C-P) coaly source rocks discovered in the Dagang Oilfield in the Bohai Bay Basin (east China) have important implications for the potential exploration of C-P coaly source rocks. This study analyzed the secondary, tertiary, and dynamic characteristics of hydrocarbon generation in order to predict the hydrocarbon potentials of different exploration areas in the Dagang Oilfield. The results indicated that C-P oil and gas were generated from coaly source rocks by secondary or tertiary hydrocarbon generation and characterized by notably different hydrocarbon products and generation dynamics. Secondary hydrocarbon generation was completed when the maturity reached vitrinite reflectance (Ro) of 0.7%–0.9% before uplift prior to the Eocene. Tertiary hydrocarbon generation from the source rocks was limited in deep buried sags in the Oligocene, where the products consisted of light oil and gas. The activation energies for secondary and tertiary hydrocarbon generation were 260–280 kJ/mol and 300–330 kJ/mol, respectively, indicating that each instance of hydrocarbon generation required higher temperature or deeper burial than the previous instance. Locations with secondary or tertiary hydrocarbon generation from C-P coaly source rocks were interpreted as potential oil and gas exploration regions.


2013 ◽  
Vol 448-453 ◽  
pp. 3723-3727 ◽  
Author(s):  
Yun Pan ◽  
Zong Xiu Wang ◽  
Mao Pan

There are a lot of Permian volcanic rocks which are widely distributed in Tarim Basin. Because of the shielding effect of the volcanic rocks to the underlying structure, the distribution of the volcanic rocks in Tarim Basin is very important to the deep oil and gas exploration. However, with the progress of oil exploration in Tarim oil field in recent years, much more logging and seismic data is available. Based on the model of logging-seismic integrated identification, the distribution of the Permian volcanic rocks is revised by using the drilling, logging and seismic data. It shows that the rhyolite is mainly distributed in the north basin, and the basalt is widely distributed in the basin. Moreover, the basalt has larger area than which delineated by other people.


2017 ◽  
Vol 36 (4) ◽  
pp. 568-590 ◽  
Author(s):  
Bing Luo ◽  
Yu Yang ◽  
Gang Zhou ◽  
Wenjun Luo ◽  
Shujiao Shan ◽  
...  

Old Mesoproterozoic−Cambrian successions have been regarded as an important frontier field for global oil and gas exploration in the 21st century. This has been confirmed by a recent natural gas exploration breakthrough in the Sinian and Cambrian strata, central Sichuan Uplift, Sichuan Basin of SW China. However, the accumulation mechanism and enrichment rule of these gases have not been well characterized. This was addressed in this work, with aims to provide important guidance for the further exploration while enriching the general studies of the oil and gas geology in the old Mesoproterozoic–Cambrian strata. Results show that the gas field in the study area is featured by old target layers (Sinian–Lower Cambrian), large burial depth (>4500 m), multiple gas-bearing intervals (the second and fourth members of the Sinian Dengying Formation and the Lower Cambrian Longwangmiao Formation), various gas reservoir types (structural type and structural–lithologic type), large scale (giant), and superimposing and ubiquitous distribution. The giant reserves could be attributed to the extensive intercalation of pervasive high quality source rocks and large-scale karst reservoirs, which enables a three-dimensional hydrocarbon migration and accumulation pattern. The origin of natural gas is oil cracking, and the three critical stages of accumulation include the formation of oil reservoirs in Triassic, the cracking of oil in Cretaceous, and the adjustment and reaccumulations in the Paleogene. The main controlling factor of oil and gas enrichment is the inherited development of large-scale stable paleo-uplift, and the high points in the eastern paleo-uplift are the favorable area for ​natural gas exploration.


2013 ◽  
Vol 703 ◽  
pp. 139-142
Author(s):  
Hui Ting Hu ◽  
Hai Tao Xue ◽  
Xiang Qi Kong ◽  
Hong Peng Yao

Camck-Aral sea is one of the important China's developing overseas oil and gas exploration blocks. But conditioned by the degree of exploration, the hydrocarbon source rocks quality and resource potential of this block are not clear. Therefore, in this study, we analyzed the regional geological survey, hydrocarbon source rock condition and reservoir conditions. The results indicated that: The middle Jurassic formation in Camck-Aral sea block has a texture of interbeded sandstones and mudstones. Middle Jurassic hydrocarbon source rocks in Camck-Aral sea block is high in the abundance of organic matter,of which the matrix belongs to the type II2, and it has reached the maturity stage. This may mean that the study area should be based primarily on natural gas exploration.


2021 ◽  
Vol 257 ◽  
pp. 03010
Author(s):  
Fengyu Sun ◽  
Gaoshe Cao ◽  
Zhou Xing

The Upper Paleozoic strata in Southwestern Henan have good prospects for unconventional oil and gas exploration. This paper takes the Upper Paleozoic source rocks in the Yuzhou area and the Pingdingshan area in Southwestern Henan as the research object, and tests 107 samples from the Upper Paleozoic coal rock, mudstone and carbonate rock. Combined with the sedimentary environment background, the Upper Paleozoic source rocks in Southwestern Henan are comprehensively evaluated. The results show that the Upper Paleozoic source rocks in Southwestern Henan, including coal rocks, mudstone and carbonate rocks, can be used as potential source rocks. Vertically, the source rocks are continuously distributed in the lower layer below the sandstone of Shanxi Formation. The Dazhan sandstone is only locally developed; the distribution of Upper Paleozoic source rocks in Southwestern Henan is mainly related to the Late Paleozoic transgression.


2020 ◽  
Vol 600 (1) ◽  
pp. 012022
Author(s):  
Shengfei Qin ◽  
Tongshan Wang ◽  
Shizhen Tao

Abstract In response to the question of whether effective Cambrian source rocks are developed in the North China Plate, field investigations on the southern margin of North China have been carried out. High-quality marine argillaceous source rocks of continuous thickness of 35 m in the Lower Cambrian were discovered in the south-eastern margin of North China Plate. Phosphorus nodules are common in the source rocks. The TOC is 1.19%∼29.70%, with the average of 7.31%. The organic matter comes from low-level biological algae. Because the carbon isotope of kerogen is relatively more negative, it is judged to be mainly benthic algae. The converted vitrinite reflectance (Ro) from measured bitumen reflectance is 2.24%∼3.45%, which is an over-mature source rock. The Lower Cambrian source rocks in the southern margin of North China occurred under the background of rising sea levels. After the glaciers on the southern margin of the North China Plate melted, the Qinling rift trough developed and the stratum subsidence caused rapid transgression of seawater from southeast to northwest. At this time, algae multiply in large numbers, and after death they accumulate with phosphorus-containing materials to form phosphorus-containing organic matter. Benthic algae mainly live in deep-water shelf not affected by waves and tides. Therefore, the development of source rocks is mainly in the deep water shelf.


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