Integrated Assessment of Marine-Continental Transitional Facies Shale Gas of the Carboniferous Benxi Formation in the Eastern Ordos Basin

Zhao, Wenjin; Wen, Zhigang; Hui, Zhang; Wu, Chenjun; Yan, Long; Song, Huanxin; Zhang, Liwen; Xi, Yingyang; Sun, Lei

doi:10.3390/en14248500

Cited by 7 publications

(5 citation statements)

References 19 publications

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“…This indicates that the samples were deposited with a high salinity variation during deposition (Figure a). However, this salinity variation in the water column controls the reduction (dysoxic to anoxic conditions), − as indicated by the correlation between the two ratios: the Sr/Ba and V/Ni (Figure b). The proportions of major elements, i.e., Ca and Fe, and their Ca/Ca + Fe ratios also provide salinity inferences .…”

Section: Discussionmentioning

confidence: 99%

Characteristics of Cenomanian–Turonian Oceanic Anoxic Event 2 and its Impact on Organic Carbon Accumulation in the Abu Roash (F) Organic-Rich Carbonate Rocks in the Abu Gharadig Field, Egypt

Hamed,

Hakimi,

Lotfy

et al. 2024

ACS Earth Space Chem.

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The Cenomanian−Turonian was a period of climatic perturbations associated with extraordinary marine production of organic carbon during the redox conditions in the southern Neo-Tethys Ocean. The Abu Roash-F carbonates in the northwestern desert of Egypt were deposited during this period. This work revealed some organic and inorganic geochemical results combined with microscopic examinations of the carbonate rocks of the mid-Cretaceous Abu Roash-F Member from two exploration wells in the Abu Gharadig Basin, Egypt. This work was designed to understand the paleoenvironmental conditions during Cenomanian− Turonian oceanic anoxic event 2 (OAE2) and its impact on the organic carbon-rich accumulation in Abu Roash (F) carbonates. Geochemical proxies indicated that AR-F contains total organic matter and sulfur contents in the ranges of 0.89−3.32 and 0.30−2.73 wt %, respectively, confirming the marine environment for the studied samples. The presence of a marine environment, ranging from deep sea to slope and deep shelf, was also inferred by the large quantities of planktic forams and other marine skeletal assemblages, including bivalves and echinoderms, with rare ostracods. The Ni and V geochemical proxies, together with their ratios and enrichment factors, confirmed that these facies were mainly found in low oxygen environments, ranging from dysoxic to anoxic nonsulfidic conditions, thereby contributing to the preservation of organic matter. An Rb/Sr ratio of less than 0.1 indicated that the facies were accumulated in warm and humid climates, thereby resulting in an intensity of subaerial weathering. The dominant presence of warm-water plankton species (i.e., Globigerinoides sp.) together with a large number of primary producers (i.e., algae and dinocysts) in the Cenomanian−Turonian AR-F carbonate facies further suggested that warm climatic conditions occurred during OAE2. These warm climatic conditions can be the source of a mass influx of nutrients into the basins, which could be attributed to increased productivity of the water column. The high productivity was further supported by the presence of the shelf nannofossil taxon Zeugrhabdotus erectus. Such conditions resulted in high productivity and preservation of organic matter during OAE2, and thus, organic carbon-rich accumulation in the carbonate-rich sediments within the AR-F Member.

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Section: Discussionmentioning

confidence: 99%

Characteristics of Cenomanian–Turonian Oceanic Anoxic Event 2 and its Impact on Organic Carbon Accumulation in the Abu Roash (F) Organic-Rich Carbonate Rocks in the Abu Gharadig Field, Egypt

Hamed,

Hakimi,

Lotfy

et al. 2024

ACS Earth Space Chem.

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“…Analysis of major and trace elements was performed in the laboratory of China University of Petroleum (Beijing). Analysis was performed using a PW4400/40 X‐ray fluorescence spectrometer with an analytical accuracy of better than 2% (Zhao et al, 2021; Yadav et al, 2023). Trace elements were analyzed by an X Series II inductively coupled plasma mass spectrometer with an accuracy of better than 5% (Hausler, 1987; Krachler et al, 2002).…”

Section: Methodsmentioning

confidence: 99%

Mechanism of organic matter enrichment in a basin with shallow biogenic gas: a case study of Pleistocene shale in the Qaidam Basin

Liu,

Jiang,

Tang

et al. 2024

J Quaternary Science

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Organic matter is the material basis of shale gas. The Qaidam Basin is a key exploration and development area for shallow biogenic shale gas in China. In this study, we have focused on Quaternary Pleistocene shale in the Qaidam Basin, and the mechanism of organic matter enrichment was investigated in terms of water column stratification and paleoclimate. The results show that the K9–K7 section has greater biological productivity than the K5–K4 section. During the early–middle Pleistocene (K9–K7 deposition period), due to a warm and humid climate, the water column was strongly stratified and herbaceous plants developed, resulting in increased biological productivity. Stronger stratification also led to a reducing environment in the lower layer, which was conducive to the preservation of organic matter from the upper layer. During the late Pleistocene (K5–K4 deposition period), with a dry and hot climate, stratification became weaker and the vegetation evolved into woody plants, reducing biological productivity. Weaker stratification led to destruction of the reducing environment, which was not conducive to enrichment of the sedimentary organic matter. Moreover, the increased temperatures increased the activity of methanogenic bacteria, which consumed a lot of the organic matter.

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“…The shale of the Permian Longtan Formation in southern China is a promising target for future shale gas exploitation. Previous research predicted that the potential exploration area, which has a good continuity of shale thickness and a wide distribution, is more than 30 × 10 4 km 2 [9]. In addition, several wells drilled in marine-continental transitional shale in Permian strata have been tested successfully, and good test production has been suggested.…”

Section: Introductionmentioning

confidence: 99%

“…The testing productions of these wells ranged from 3.02-35.85 × 10 4 m 3 /day. In addition, in the Qinshui Basin the wells drilled for Permian shale gas showed a large gas content ranging from 0.79 m 3 /t to 4.03 m 3 /t for Well Shizhuangbei 306 and Well Wuyuan 01 [2][3][4][5][6][7][8][9][10]. All of the above drilling results show great potential for future marine-continental transitional shale gas exploration in the Ordos Basin and Sichuan Basin [11].…”

Section: Introductionmentioning

confidence: 99%

Study on the Sedimentary Environments and Its Implications of Shale Reservoirs for Permian Longtan Formation in the Southeast Sichuan Basin

Chen

Shi²,

et al. 2023

Minerals

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Marine–continental transitional shale is one of the most promising targets for shale gas exploration in the Lower Yangtze region. To investigate the sedimentary environments and the regularity of the enrichment of the Longtan shale, multiple techniques including core and thin-section observations, geochemical and elemental analyses, X-ray diffraction, scanning electron microscopy (SEM), and low-pressure nitrogen adsorption (LPNA) were used to analyze the sedimentology, mineralogy, and pore structure of the Longtan shale. The core descriptions and thin-section observations showed that the Longtan shale was deposited in marine–delta transitional environments including delta-front, shore swamp, mixed tidal flat and shallow shelf environments. The Sr/Cu, V/Cr, CIA, EF (Mo), EF (U), and other major and trace element results indicated warm and moist climates and water-reducing conditions in the Longtan period. Both the climate and water conditions were favorable for organic matter production and preservation. The geochemical results showed that the Longtan shale was in the overmature stage (Ro values ranging from 2.4% to 3.57%) and that the average total organic carbon (TOC) content was 5.76%. The pore system of the Longtan shale consisted of inorganic pores with a small number of organic pores and microfractures. The porosity and specific surface area were mainly affected by the TOC and clay mineral contents. An effective combination of brittle mineral particles, organic matter, and clay minerals provided the necessary conditions for pore preservation. The organic pores, intergranular pores in clay minerals, and brittle mineral pores formed the main network system for the Longtan shale. In summary, the lithological combinations, organic geochemistry, and pore structure system were all affected by the sedimentary environments.

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Integrated Assessment of Marine-Continental Transitional Facies Shale Gas of the Carboniferous Benxi Formation in the Eastern Ordos Basin

Cited by 7 publications

References 19 publications

Characteristics of Cenomanian–Turonian Oceanic Anoxic Event 2 and its Impact on Organic Carbon Accumulation in the Abu Roash (F) Organic-Rich Carbonate Rocks in the Abu Gharadig Field, Egypt

Characteristics of Cenomanian–Turonian Oceanic Anoxic Event 2 and its Impact on Organic Carbon Accumulation in the Abu Roash (F) Organic-Rich Carbonate Rocks in the Abu Gharadig Field, Egypt

Mechanism of organic matter enrichment in a basin with shallow biogenic gas: a case study of Pleistocene shale in the Qaidam Basin

Study on the Sedimentary Environments and Its Implications of Shale Reservoirs for Permian Longtan Formation in the Southeast Sichuan Basin

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