Hydrocarbon generation characteristics, reserving performance and preservation conditions of continental coal measure shale gas: A case study of Mid-Jurassic shale gas in the Yan’an Formation, Ordos Basin

2016 ◽  
Vol 145 ◽  
pp. 609-628 ◽  
Author(s):  
Dong-dong Wang ◽  
Long-yi Shao ◽  
Zhi-xue LI ◽  
Ming-pei LI ◽  
Dawei Lv ◽  
...  
Keyword(s):  
Shale Gas ◽  
Ordos Basin ◽  
Coal Measure ◽  
Hydrocarbon Generation ◽  
Preservation Conditions

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.

Sequential distribution of gas reservoirs in the Hangjinqi area, Ordos Basin, North China: Application of continuous and discontinuous hydrocarbon accumulation mode

2020 ◽  
pp. 1-49
Author(s):  
Haikuan Nie ◽  
Xiaoliang Wei ◽  
Jinchuan Zhang ◽  
Qian Chen ◽  
Guangxiang Liu ◽  
...  
Keyword(s):  
Shale Gas ◽  
Ordos Basin ◽  
Water Soluble ◽  
Source Rocks ◽  
Formation Mechanisms ◽  
Burial Depth ◽  
Hydrocarbon Generation ◽  
Distribution Characteristics ◽  
Gas Reservoirs ◽  
Continuous Accumulation

Gas reservoirs can be divided into two types based on the migration and accumulation processes, and distribution characteristics associated with the reservoirs: continuous accumulation that is within or adjacent to the source rocks and discontinuous accumulation that is in the reservoir rocks. Correspondingly, reservoirs can also be classified as conventional reservoirs, unconventional reservoirs and reservoirs in a transitional state. In order to demonstrate differences and regularities in the distribution characteristics and formation mechanisms of the two accumulation types, the continuous and discontinuous hydrocarbon accumulations in the Hangjinqi area of the Ordos Basin, China, is systematically analyze. Continuous accumulation (coalbed methane, shale gas, basin-centered gas, water-soluble gas) and discontinuous accumulation reservoirs (various traps) are located in the southern and northern regions of the Hangjinqi area, respectively, and they may be changed with the source rock quality, migration force, reservoir capacity and trapping condition. Several factors, such as hydrocarbon generation ability, porosity, and cap rock-trap combinations, are recognized here as essential factors for the formation and current distribution of gas reservoirs in the study area. Understanding the distribution characteristics of continuous accumulation and discontinuous accumulation can predict the potential gas reservoirs types based on discovered gas reservoirs. It is recommended to explore anticline gas reservoirs in the north of Boerjianghaizi fault, and CBM, shale gas and basin-centered gas reservoirs in the south of Boerjianghaizi fault. Though shale gas exploration activity is still lacking in the study area, we believe that the maturity and the burial depth of the marine-continental organic-rich shale in the Permian Shanxi-Taiyuan Formations are suitable for shale gas generation and preservation, indicating further research on the upper Paleozoic shale source rocks is required.

scholarly journals Coevolutionary Dynamics of Organic-Inorganic Interactions, Hydrocarbon Generation, and Shale Gas Reservoir Preservation: A Case Study from the Upper Ordovician Wufeng and Lower Silurian Longmaxi Formations, Fuling Shale Gas Field, Eastern Sichuan Basin

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-21
Author(s):  
Zhijun Jin ◽  
Haikuan Nie ◽  
Quanyou Liu ◽  
Jianhua Zhao ◽  
Ruyue Wang ◽  
...  
Keyword(s):  
Shale Gas ◽  
Sichuan Basin ◽  
Hydrocarbon Generation ◽  
Upper Ordovician ◽  
Gas Field ◽  
Pressure System ◽  
Lower Silurian ◽  
Eastern Sichuan Basin ◽  
Eastern Sichuan

Shale gas deposits are self-sourced, self-accumulating, and self-preserving in the Upper Ordovician Wufeng Formation and Lower Silurian Longmaxi Formation of the Fuling Shale Gas Field in the eastern Sichuan Basin. They were both seemingly mixed by secondary oil cracking and kerogen cracking gases during the high maturation window. The reservoir space primarily consists of mineral pores and organic matter (OM) pores, and the shale gas was mainly trapped by a high-pressure system. In this study, the Fuling O3w-S1l Shale Gas Field in the eastern Sichuan Basin was used as a case study to discuss the coevolutionary process and organic-inorganic interactions of hydrocarbon generation, accumulation, and preservation. The results indicate that the processes and mechanisms of organic-inorganic interactions and coevolution of hydrocarbon generation and reservoir preservation are quite different among the shale graptolite zones (GZ) with respect to hydrocarbon generation, types and characteristics of shale gas reservoirs, seal characteristics, and their spatiotemporal relations. In the WF2-LM4 GZ, the favorable OM, biogenic authigenic quartz and organic-inorganic interactions are highly coupled, leading to the high level of coevolution demonstrated within the field, as well as to the favorable conditions for shale gas accumulation. Conversely, the overlying LM5-LM8 GZ seemingly exhibits early densification and late charge and has a reverse mode of reservoir development (i.e., low degree of coevolution). These two coevolutionary processes were conducive to the development of a high degree of spatiotemporal matching between the reservoir (i.e., WF2-LM4 GZ) and the seal (i.e., LM5-LM8 GZ). This is due to underlying differences in their coevolutionary histories. The synthetic work presented here on the coevolutionary processes and mechanisms of formation for organic-inorganic interactions and hydrocarbon generation and reservoir preservation reveals insights into the driving mechanisms of shale gas enrichment, providing a basis for effectively predicting favorable enrichment intervals for shale gas worldwide.

scholarly journals Upper Paleozoic Transitional Shale Gas Enrichment Factors: A Case Study of Typical Areas in China

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 194
Author(s):  
Feiteng Wang ◽  
Shaobin Guo
Keyword(s):  
Shale Gas ◽  
Ordos Basin ◽  
Enrichment Factors ◽  
Upper Permian ◽  
Hydrocarbon Generation ◽  
Coal Seams ◽  
Gas Generation ◽  
Upper Paleozoic ◽  
Southwestern Guizhou ◽  
Pore Evolution

Based on the shale gas research experience in North America, large-scale geological evaluations have been conducted in China to determine the enrichment characteristics of deep marine shale gas, leading to the discovery of the Fuling, Changning and Weiyuan shale gas fields. However, research on Upper Paleozoic transitional shale gas remains limited, restricting the subsequent exploration and development. Therefore, taking the Lower Permian Shanxi and Pennsylvanian Taiyuan Formations in the northeastern Ordos Basin and the Upper Permian Longtan Formation in southwestern Guizhou as examples, gas logging, gas desorption, thermal simulation, maximum vitrinite reflectance (Rmax), and X-ray diffraction (XRD) were used to study the influence of lithological associations, sedimentary facies, gas generation thresholds, and pore evolution on transitional shale gas, and then Upper Paleozoic transitional shale gas enrichment factors of the northeastern Ordos Basin and southwestern Guizhou were analysed. The results show that carbonaceous mudstone adjacent to coal seams presents a high gas content level, and is primarily developed in swamps in the delta plain environment, and swamps and lagoons in the barrier coastal environment. The gas generation threshold maturity (Rmax) of transitional shale is 1.6% and the corresponding threshold depths of the northeastern Ordos Basin and southwestern Guizhou are estimated to be 2265 m and 1050 m. Transitional shale pore evolution is jointly controlled by hydrocarbon generation, clay minerals transformation, and compaction, and may have the tendency to decrease when Rmax < 1.6% or Rmax > 3.0%, but increase when Rmax ranges between 1.6% and 3.0%, while the main influential factors of pore evolution differ in each period. Continuous distribution of transitional shale gas enrichment areas can be formed along the slope adjacent to coal seams with a moderate maturity range (1.6%–3.0%) in the northeastern Ordos Basin, and transitional shale gas can be enriched in the areas adjacent to coal seams with a moderate maturity range (1.6%–3.0%), abundant fractures, and favorable sealing faults in southwestern Guizhou.

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