scholarly journals Carbon isotope and origin of the hydrocarbon gases in the Junggar Basin, China

2018 ◽  
Vol 3 (5) ◽  
pp. 253-261
Author(s):  
Lixin Pei ◽  
Wenzhe Gang ◽  
Chuanzhen Zhu ◽  
Yazhou Liu ◽  
Wenjun He ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Junggar Basin ◽  
Hydrocarbon Gases

Characteristics of dissolved pores and dissolution mechanism of zeolite-rich reservoirs in the Wuerhe Formation in Mahu area, Junggar Basin

2021 ◽  
pp. 014459872110287
Author(s):  
Ji Li ◽  
Wenjie Zhang ◽  
Baoli Xiang ◽  
Dan He ◽  
Shengchao Yang ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Manganese Content ◽  
Junggar Basin ◽  
Dissolution Mechanism ◽  
Primary Role ◽  
High Iron Content ◽  
Thin Sections ◽  
Main Site ◽  
Dissolution Zone ◽  
Diagenetic Fluids

The reservoir in the Wuerhe Formation in the Mahu Sag, northwestern Junggar Basin, China, exhibits complex dissolution and cementation related to zeolite. The source and mechanism of diagenetic fluids are crucial in studying the reservoir genesis. Thus we investigated the key reservoirs fluids related to the zeolite and discussed their significance in the zeolite-rich reservoir of the Permian Wuerhe Formation in the Mahu Sag. Based on thin sections and electron microscope observations of rock samples and analyses of physical properties, C-O isotopes, and major elements, it is found that the reservoir underwent mainly two stages of fluid-related dissolution and cementation processes, in which the hydrocarbon-bearing fluid played the primary role in forming the high-quality reservoir. Dissolution pores are the most important storage space, and zeolite cement is the most important dissolution mineral. The geochemical characteristics of zeolite and calcite cement indicate the presence of two diagenetic fluids. The iron-rich calcite and orange-red heulandite is related to early diagenetic fluids with high iron content and higher carbon isotope values, whereas the calcites, with high manganese content and lower carbon isotope values, are formed by late acidic organic diagenetic fluids related to oil and gas activities. The hydrocarbon-bearing fluids form different spatial diagenetic zones, including the dissolution zone, buffer zone, and cementation zone, and the dissolution zone near the oil source fault is the main site of zeolite dissolution. The late fluid has the characteristics of multi-stage activity, which makes the spatial zoning expand gradually, resulting in multiple superpositions of dissolution and cementation and increasing the complexity and heterogeneity of the reservoir diagenesis. This study expands the understandings of the dissolution activities of different fluids in zeolite-rich reservoirs and also has reference significance for dissolution activity of hydrocarbon fluid in other types of reservoirs.

Stable carbon isotope characteristics of desert plants in the Junggar Basin, China

2011 ◽  
Vol 27 (1) ◽  
pp. 115-124 ◽  
Author(s):  
Jian-Ying Ma ◽  
Wei Sun ◽  
Hui-Ling Sun ◽  
Shao-Ming Wang
Keyword(s):  
Carbon Isotope ◽  
Stable Carbon Isotope ◽  
Junggar Basin ◽  
Desert Plants ◽  
Stable Carbon

scholarly journals Geochemical Characteristics of Gas and Flowback Water in Lake Facies Shale: A Case Study From the Junggar Basin, China

2021 ◽  
Vol 9 ◽  
Author(s):  
Lin Zhang ◽  
Dan Liu ◽  
Yongjin Gao ◽  
Min Zhang
Keyword(s):  
Carbon Isotope ◽  
Shale Gas ◽  
Isotope Composition ◽  
Ordos Basin ◽  
Junggar Basin ◽  
Source Rocks ◽  
Flowback Water ◽  
Lucaogou Formation ◽  
The Difference

The chemical and isotopic compositions of the natural gas and the co-produced flowback water from the XJC 1 well in Junggar Basin, China, were analyzed to determine the origin of gases in the Permian Lucaogou Formation (P2l) and the Triassic Karamay Formation (T2k) in the Bogda Mountain periphery area of the Southern Junggar Basin. The value of carbon isotope composition of the P2l lacustrine shale gas in the Junggar Basin was between the shale gas in Chang 7 Formation of Triassic (T1y7) in the Ordos Basin and that in the Xu 5 Formation of Triassic (T3x5) in the Sichuan Basin. The difference in gas carbon isotope is primarily because the parent materials were different. A comparison between compositions in the flowback water reveals that the P2l water is of NaHCO3 type while the T2k water is of NaCl type, and the salinity of the latter is higher than the former, indicating a connection between P2l source rock and the T2k reservoir. In combination with the structural setting in the study area, the gas filling mode was proposed as follows: the gas generated from the lacustrine source rocks of the Permian Lucaogou Formation is stored in nearby lithological reservoirs from the Permian. Petroleum was also transported along the faults to the shallow layer of the Karamay Formation over long distances before it entered the Triassic reservoir.

Hydrogen and Carbon Isotope Composition of Hydrocarbon Gases Generated during Pyrolysis of Peats from Different Environments

2018 ◽  
Vol 33 (7) ◽  
pp. 5944-5953 ◽  
Author(s):  
Yi Duan ◽  
Mingchen Duan ◽  
Yingzhong Wu ◽  
Jingli Yao ◽  
Zhongping Li ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Isotope Composition ◽  
Carbon Isotope Composition ◽  
Hydrocarbon Gases

scholarly journals Inversion Characteristics of Hydrocarbon Gases Carbon Isotopes Varying With Temperature and Implications for Shale Exploration

2021 ◽  
Vol 9 ◽  
Author(s):  
Yingqin Wu ◽  
Yanhong Liu ◽  
Tong Wang ◽  
Zhiyu Wang ◽  
Longmiao Yuan ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Carbon Isotopes ◽  
Thermal Evolution ◽  
Carbonaceous Shale ◽  
Maturity Stage ◽  
Hydrocarbon Gases ◽  
Pyrolysis Gas ◽  
Rock Types ◽  
High Maturity ◽  
Pyrolysis Experiment

In order to understand the influence of source rock types and maturity on hydrocarbon gases carbon isotope change more objectively, a closed-system pyrolysis experiment was carried out on six samples from 250 to 550°C. The values of δ13C1, δ13C2, and δ13C3 were ranged from −73.3 to −29.8%, from −36.3 to −9.5%, and from −38.5 to −12.4%, respectively. The range of δ13C1 was the largest, reaching a top value of 43.5%. The results showed that the temperature has an effect on the carbon isotope value of pyrolysis gas. With the increase of the degree of thermal evolution, the carbon isotope value of methane in all samples, except for huangxian gangue, had a change trend from heavy to light firstly, then got heavier. In addition, the carbon isotope values of methane, ethane and propane had the features of δ13C1 < δ13C2 < δ13C3 when the temperatures were under 550°C, which were made up of a series of positive carbon isotopes. However, when the temperature increased above 550°C, there was an inversion of the simulated gas carbon isotope values in Huangxian coal gangue, Minqin oil shale and Huaan carbonaceous shale, i.e., δ13C2 > δ13C3 and δ13C2 > δ13C1. It indicates that the secondary cracking has occurred at high maturity or over maturity stage.

Geochemical Characteristics of Oils from Chepaizi Area, Northwestern Junggar Basin, China

2009 ◽  
Vol 27 (2) ◽  
pp. 91-103 ◽  
Author(s):  
Luofu Liu ◽  
Weibin Wang ◽  
Lin Wu ◽  
Yande Zhao ◽  
Zhijun Chen ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Lower Layer ◽  
Junggar Basin ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Nitrogen Compounds ◽  
Chemical Compositions ◽  
Accumulation Pattern ◽  
Oil Source ◽  
Oil Gas

In recent years, great progress in petroleum exploration has been made obtained for Chepaizi Swell along the northwestern margin of Junggar Basin. But, the hydrocarbon sources of this area are still unknown, and this results in difficulty of determining the migration path system and migration trend. This also leads to difficulty in studying the oil-gas accumulation pattern of the area. In order to understand the oil sources, samples were systematically collected in the Swell and were analyzed for investigation of physical properties, chemical compositions and characteristics of bio-markers, carbon isotope and nitrogen compounds of the oils from Chepaizi. Through comparisons of physical and chemical characters, oils from different intervals of Chepaizi can be classified into two groups. One is the oils trapped in layers of Jurassic and below Jurassic (named as Lower Series of Strata oils), and another is those in layers of Cretaceous and above Cretaceous (named as Upper Series of Strata oils). Oils from the same group have similar densities, viscosities, group compositions and characteristics of saturated hydrocarbon, bio-marker and carbon isotope, while the oils from different groups are obviously different for the above-mentioned parameters. By fine oil-oil correlation, one can know that the lower-layer oils have the same oil source (from the Permian source rocks), and the upper-layer oils also have the same source (mainly from the Jurassic source rocks). In Chepaizi, the hydrocarbons stored in reservoirs originated mainly from Jurassic and Permian rocks. However, Cretaceous source rocks also have some contribution to oil-gas supply for oil pools. The oil-source division results based on nitrogen compounds (carbazoles) are completely identical with those by common geochemical indices, indicating that carbazoles are of importance in oil type division and oil-source correlation.

scholarly journals Origin of deep heavy oils in the northwestern Junggar Basin (NW China) and implications for gas migration

2020 ◽  
Vol 38 (4) ◽  
pp. 819-840 ◽  
Author(s):  
Aiguo Wang ◽  
Liping Yi ◽  
Baoli Xiang ◽  
Ji Li ◽  
Changyu Fan ◽  
...  
Keyword(s):  
Junggar Basin ◽  
Source Rocks ◽  
Heavy Oils ◽  
Gas Migration ◽  
Mixed Gas ◽  
Hydrocarbon Gases ◽  
Nw China ◽  
Genetic Types ◽  
Gas Washing ◽  
Migration Pathways

Whether the northwestern Junggar Basin (NW China) has natural gas potential is an urgent but unresolved question. In this study, we discuss the origin of deep heavy oils (>2900 m) and its implication for gas migration and accumulation, based on a comprehensive investigation into physicochemical and geological properties of hydrocarbons in the northern Zhongguai High. Our results indicate that multiple-episode migration of hydrocarbons created four genetic types of oils and three genetic types of hydrocarbon gases and induced widespread gas washing. Relatively low maturity and gas washing are both responsible for the formation of the deep heavy oils. In detail, the migrating late-stage humic-type gases washed the encountered early stage low-maturity oils. The oil reservoirs lost their light fraction and evolved into heavy oils, which are preserved in the deep layer to the present, while the light-end components continued to migrate upward and accumulated as mixed gas pools or vented out of the system. The spatial distributions pattern of source rocks, heavy oils, and mixed gas clearly indicates the migration pathways of humic-type gases, which otherwise are difficult to define in the study area. Because the gases finally migrate into fault belts, their poor preservation condition likely results in the rare discoveries of gas fields. The favorable exploration targets for gas in the area are expected to be fault traps in fault belts, stratigraphic traps along the pinch-out boundary of the Upper Wuerhe Formation, and, particularly, the deep traps in the Mahu Sag.

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