Quantitative impact of diagenesis on reservoir quality of the Triassic Chang 6 tight oil sandstones, Zhenjing area, Ordos Basin, China

Li, Yang; Chang, Xiangchun; Yin, Wei; Sun, Tao; Song, Tingting

doi:10.1016/j.marpetgeo.2017.07.005

Cited by 76 publications

(49 citation statements)

References 34 publications

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“…In order to investigate the carbon source of the biotic carbonate minerals and then further understand the relationship between carbonate biomineralization and the microorganisms, stable carbon isotope values of biotic and abiotic carbonate minerals were determined through Isotope Analyzer (Picarro G2121-i, Picarro Inc., Santa Clara, CA, USA), according to the method in previous studies [50][51][52][53][54][55].…”

Section: Stable Carbon and Nitrogen Isotope Analysesmentioning

confidence: 99%

Bio-Precipitation of Carbonate and Phosphate Minerals Induced by the Bacterium Citrobacter freundii ZW123 in an Anaerobic Environment

Sun

Zhao

et al. 2020

Minerals

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In this study, a facultative anaerobic strain isolated from marine sediments and identified as Citrobacter freundii, was used to induce the precipitation of carbonate and phosphate minerals in the laboratory under anaerobic conditions. This is the first time that the ability of C. freundii ZW123 to precipitate carbonate and phosphate minerals has been demonstrated. During the experiments, carbonic anhydrase, alkaline phosphatase and ammonium released by the bacteria not only promoted an increase in pH, but also drove the supersaturation and precipitation of carbonate and phosphate minerals. The predominant bio-mediated minerals precipitated at various Mg/Ca molar ratios were calcite, vaterite, Mg-rich calcite, monohydrocalcite and struvite. A preferred orientation towards struvite was observed. Scanning transmission electron microscopy (STEM) and elemental mapping showed the distribution of magnesium and calcium elements within Mg-rich calcite. Many organic functional groups, including C=O, C–O–C and C–O, were detected within the biominerals, and these functional groups were also identified in the associated extracellular polymeric substances (EPS). Fifteen kinds of amino acid were detected in the biotic minerals, almost identical to those of the EPS, indicating a close relationship between EPS and biominerals. Most amino acids are negatively charged and able to adsorb cations, providing an oversaturated microenvironment to facilitate mineral nucleation. The X-ray photoelectron spectroscopy (XPS) spectrum of struvite shows the presence of organic functional groups on the mineral surface, suggesting a role of the microorganism in struvite precipitation. The ZW123 bacteria provided carbon and nitrogen for the formation of the biotic minerals through their metabolism, which further emphasizes the close relationship between biominerals and the microorganisms. Thermal studies showed the enhanced thermal stability of biotic minerals, perhaps due to the participation of the bacteria ZW123. The presence of amino acids such as Asp and Glu may explain the high magnesium content of some calcites. Molecular dynamics simulations demonstrated that the morphological change and preferred orientation were likely caused by selective adsorption of EPS onto the various struvite crystal surfaces. Thus, this study shows the significant role played by C. freundii ZW123 in the bioprecipitation of carbonate and phosphate minerals and provides some insights into the processes involved.

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Section: Stable Carbon and Nitrogen Isotope Analysesmentioning

confidence: 99%

Bio-Precipitation of Carbonate and Phosphate Minerals Induced by the Bacterium Citrobacter freundii ZW123 in an Anaerobic Environment

Sun

Zhao

et al. 2020

Minerals

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“…As one of the most common diagenetic processes, compaction can be divided into two types: mechanical compaction and chemical compaction [57]. The detrital texture of the samples indicated different degrees of compaction in Huixi and Huidong.…”

Section: Compactionmentioning

confidence: 99%

Coupling between Diagenetic Environment and Porosity Evolution—A Quantitative Study of the Zhuhai Formation in the Huizhou Sag, Pearl River Mouth Basin, South China Sea

et al. 2020

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The diagenetic environment is vital in controlling reservoir quality by influencing diagenetic processes, especially porosity evolution. The Zhuhai Formation is a critical exploration target in the Huizhou Sag. However, there are considerable differences between the reservoirs in the west (Huixi) and east (Huidong) Huizhou Sag with only a 400 m difference in burial depth. To investigate causes of these differences, scanning electron microscopy (SEM), cathodoluminescence analysis, fluorescence analysis, and fluid inclusion analysis are employed for the petrological and diagenetic characterization of the target formation. Moreover, image analysis software is used to qualitatively evaluate the impacts of diagenesis on porosity. The results show that the digenetic environments in Huixi and Huidong are different. Huixi is characterized by a high content of feldspar with a stronger dissolution phenomenon than that observed in Huidong. The main cement types in Huixi are siliceous cement and kaolinite. Moreover, Huixi had a low palaeo-temperature, low palaeo-salinity, and low palaeo-pH diagenetic environment. In contrast, Huidong is accessible via deep faults and rich in lithic fragments which show visible deformation. Moreover, cements in this area include carbonate, gypsum, quartz overgrowth, kaolinite, and chlorite. This evidence confirms that the diagenetic environment in Huidong was a high palaeo-temperature and high palaeo-salinity environment with high palaeo-pH. Additionally, the palaeo-pH evolved following the sequence of weakly alkaline, acidic, alkaline and acidic. Microscopy evidence indicates that the Dongsha Uplift was a likely source of Huixi sediments during the deposition of the Zhuhai Formation. The determination of the porosity evolution shows that compaction and lithic fragment content are the main controlling factors on the reservoir quality of the Zhuhai Formation.

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“…Previous studies have proved that there are many factors, such as pore structure, organic carbon content, mineral composition, gas content and fracture development affecting the heterogeneity of the shale reservoir, among which pore structure is one of the most important factors [11,12]. As the shale gas reservoir is characterized by sedimentary bedding, organic nanopore development and strong grain orientation, the parameters and methods for evaluating the heterogeneity of unconventional reservoirs such as tight gas sandstone are not fully applicable to shale reservoir [13][14][15][16][17][18][19][20]. In recent years, many qualitative and quantitative multidisciplinary techniques have been used to characterize shale pores.…”

Section: Introductionmentioning

confidence: 99%

Micropore Structural Heterogeneity of Siliceous Shale Reservoir of the Longmaxi Formation in the Southern Sichuan Basin, China

Tang

Zheng

2019

Minerals

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In recent years, the shale gas in the southern Sichuan Basin has achieved great commercial development, and the Silurian Longmaxi Formation is the main development stratum. In order to solve the problems of great difference production and inaccurate gas content of the Longmaxi Formation shale gas field in the southern Sichuan Basin, based on thin section identification, argon ion polishing-field emission scanning electron microscopy, high pressure mercury injection, low temperature nitrogen adsorption and the fractal method, the micropore structural heterogeneity of the siliceous shale reservoir of the Longmaxi Formation has been studied. The results show the following: The pores of siliceous shale are mainly intergranular pores and organic pores. Image analysis shows that there are obvious differences in size and distribution of shale pores among different types. The micropore structural heterogeneity is as follows: intragranular pore > intergranular pore > organic pore. In the paper, the combination of low temperature nitrogen adsorption method and high-pressure mercury injection method is proposed to characterize the micropore size distribution and fractal dimension, which ensures the credibility of pore heterogeneity. The shale pores are mainly composed of mesopores (2–20 nm), followed by macropores (100–300 nm). For different pore sizes, the fractal dimension from large to small is mesopore, micropore and macropore. Shale pore structure and fractal dimension are correlated with mineral composition and total organic carbon (TOC) content, but the correlation is significantly different in different areas, being mainly controlled by the sedimentary environment and diagenesis.

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Quantitative impact of diagenesis on reservoir quality of the Triassic Chang 6 tight oil sandstones, Zhenjing area, Ordos Basin, China

Cited by 76 publications

References 34 publications

Bio-Precipitation of Carbonate and Phosphate Minerals Induced by the Bacterium Citrobacter freundii ZW123 in an Anaerobic Environment

Bio-Precipitation of Carbonate and Phosphate Minerals Induced by the Bacterium Citrobacter freundii ZW123 in an Anaerobic Environment

Coupling between Diagenetic Environment and Porosity Evolution—A Quantitative Study of the Zhuhai Formation in the Huizhou Sag, Pearl River Mouth Basin, South China Sea

Micropore Structural Heterogeneity of Siliceous Shale Reservoir of the Longmaxi Formation in the Southern Sichuan Basin, China

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