Shale gas content evolution in the Ordos Basin

In the Benxi Formation of the Carboniferous system of the Upper Paleozoic in the Ordos Basin, there are many sets of coal measures dark organic-rich shale, being marine continental transitional facies, with significant unconventional natural gas potential. Previous studies are only limited to the evaluation of tight sandstone reservoir in this set of strata, with no sufficient study on gas bearing and geological characteristics of organic-rich shale, restricting the exploration and evaluation of shale gas resources. In this study, analysis has been conducted on the organic carbon content, the major elements, the trace elements, and the mineral composition of core samples from the Benxi Formation in key drilling sections. In addition, qualitative and quantitative pore observation and characterization of core samples have been conducted. The sedimentary environments and reservoir characteristics of the shale of the Benxi Formation have been analyzed. Combined with the gas content analyzing the results of the field coring samples, the shale gas resource potentials of the Benxi Formation have been studied, and the geological characteristics of the Benxi Formation shale gas in the eastern Ordos Basin have been made clear, to provide a theoretical basis for shale gas resource evaluation of the Benxi Formation in the Ordos Basin. The results show that (1) in the Hutian Member, Pangou Member, and Jinci Member of the Benxi Formation, organic-rich shale is well developed, with the characteristics of seawater input as a whole. There is a slight difference in sedimentary redox index, which shows that the reducibility increases gradually from bottom to top. (2) There is an evident difference in the mineral characteristics of shale in these three members. The Hutian Member is rich in clay minerals, while the Jinci Member is high in quartz minerals. (3) The pores are mainly inorganic mineral intergranular pores, clay interlayer fractures, and micro fractures, and organic matter pores are developed on the surface of local organic matter. (4) The mud shale in the Jinci Member has a large cumulative thickness, has relatively high gas-bearing property, and is rich in brittle minerals. The Jinci Member is a favorable section for shale gas exploration of the Benxi Formation.

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Lacustrine Shale Gas Reservoir in the Ordos Basin

Lacustrine Shale Gas ◽

10.1016/b978-0-12-813300-2.00003-9 ◽

2017 ◽

pp. 93-178

Author(s):

Xiangzeng Wang

Keyword(s):

Shale Gas ◽

Ordos Basin ◽

Gas Reservoir ◽

Shale Gas Reservoir ◽

The Ordos Basin ◽

Lacustrine Shale

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Shale Gas Content Calculation of the Triassic Yanchang Formation in the Southeastern Ordos Basin, China

Energies ◽

10.3390/en10121949 ◽

2017 ◽

Vol 10 (12) ◽

pp. 1949 ◽

Cited By ~ 5

Author(s):

Jiao Su ◽

Yingchu Shen ◽

Jin Hao ◽

Bo Liu

Keyword(s):

Shale Gas ◽

Ordos Basin ◽

Gas Content ◽

Yanchang Formation

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Reservoir-Forming Condition Analysis and Favorable Zone Prediction for the Shale Gas in the Upper Paleozoic Taiyuan Formation in the Ordos Basin

Energy Exploration & Exploitation ◽

10.1260/0144-5987.31.3.381 ◽

2013 ◽

Vol 31 (3) ◽

pp. 381-394 ◽

Cited By ~ 1

Author(s):

Shaobin Guo ◽

Yigang Wang

Keyword(s):

Shale Gas ◽

Ordos Basin ◽

Taiyuan Formation ◽

Upper Paleozoic ◽

The Ordos Basin ◽

Forming Condition

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A novel productivity evaluation approach based on the morphological analysis and fuzzy mathematics: insights from the tight sandstone gas reservoir in the Ordos Basin, China

Journal of Petroleum Exploration and Production Technology ◽

10.1007/s13202-019-00822-2 ◽

2019 ◽

Vol 10 (4) ◽

pp. 1263-1275

Author(s):

Shanyong Liu ◽

Gongyang Chen ◽

Yishan Lou ◽

Liang Zhu ◽

Daoyao Ge

Keyword(s):

Ordos Basin ◽

Gas Content ◽

Practical Significance ◽

Fuzzy Mathematics ◽

Tight Gas ◽

Test Results ◽

Gas Reservoirs ◽

Tight Gas Reservoirs ◽

Morphological Theory ◽

The Ordos Basin

AbstractTight gas reservoirs have rich potential resources, which are hot spots in unconventional oil and gas exploration and development. Due to their strong heterogeneity and complex pore structures, the conventional approaches of productivity evaluation always have difficulty in predicting the gas content. This study aims to devise a new method to interpret the productivity of LX Block in the Ordos Basin using the morphological theory and fuzzy mathematics. First, core test results were used to investigate the reservoir quality and physical properties. Then, the change law of gas content was defined by the morphological theory of logging and mud logging curves. Assignments of those factors that affected the final production were provided based on fuzzy mathematics. Finally, the prediction model of productivity was established. The results show that the lower limit of the reservoir thickness in the LX Block is 3.1 m, whereas the porosity and permeability are 5% and 0.15 × 10−3 μm2, respectively. The morphological characteristic of the gas logging curve for those layers with high potential production normally presents a box shape with a high relative number of serration. The reservoir in the studied area can be classified into four categories according to the relationship between the logging curve shape and daily production, and each category is automatically identified. The coincidence rate between the prediction results and the gas test results is 84.1%, which satisfies the demand on the field. The findings have important theoretical and practical significance for screening the location of fracturing spots and predicting the production of tight gas reservoirs.

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Shale favorable area optimization in coal-bearing series: A case study from the Shanxi Formation in Northern Ordos Basin, China

Energy Exploration & Exploitation ◽

10.1177/0144598717748951 ◽

2017 ◽

Vol 36 (5) ◽

pp. 1295-1309 ◽

Cited By ~ 4

Author(s):

Wei Guo ◽

Weijun Shen ◽

Shangwen Zhou ◽

Huaqing Xue ◽

Dexun Liu ◽

...

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Total Organic Carbon ◽

Shale Gas ◽

Ordos Basin ◽

Sedimentary Facies ◽

Gas Content ◽

Burial Depth ◽

Organic Carbon Content ◽

River Channels

Shales in the Well district of Yu 106 of the Shanxi Formation in the Eastern Ordos Basin is deposited in the swamp between delta plains, distributary river channels, natural levee, the far end of crevasse splay, and depression environments. According to organic geochemistry, reservoir physical property, gas bearing capacity, lithology experimental analysis, combined with the data of drilling, logging, testing and sedimentary facies, the reservoir conditions of shale gas and the distribution of an advantageous area in Shanxi Formation have been conducted. The results show that the total organic carbon content of the Shanxi Formation is relatively high, with an average content value of 5.28% in the segment 2 and 3.02% in segment 1, and the organic matter is mainly kerogen type II2 and III. The maturity of organic matter is high with 1.89% as the average value of Ro which indicates the superior condition for gas generation of this reservoir. The porosity of shales is 1.7% on average, and the average permeability is 0.0415 × 10−3 µm2. The cumulative thickness is relatively large, with an average of 75 m. Brittle mineral and clay content in shales are 49.9% and 50.1%, respectively, but the burial depth of shale is less than 3000 m. The testing gas content is relatively high (0.64 × 104 m3/d), which shows a great potential in commercial development. The total organic carbon of the segment 2 is higher than that of the segment 1, and it is also better than segment 1 in terms of gas content. Based on the thickness of shale and the distribution of sedimentary facies, it is predicted that the advantageous area of shale gas in the segment 2 is distributed in a striped zone along the northeast and the northsouth direction, which is controlled by the swamp microfacies between distributary river channels.

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