The lower Cambrian Niutitang Formation, a widespread black shale deposition, is of geological interest because of its polymetallic beds, Cambrian explosion, depositional ages, dramatic environmental changes and so on....The lower Cambrian Niutitang Formation, a widespread black shale deposition, is of geological interest because of its polymetallic beds, Cambrian explosion, depositional ages, dramatic environmental changes and so on. Previous study focused mainly on inorganic geochemistry and few studies have investigated the organic fractions of upper Neoproterozoic-lower Cambrian strata in South China. Here we report a study of biomarkers plus organic carbon isotopes for black shales from Ganziping, Hunan Province （China）. All the saturated hydrocarbon fractions have a unimodal distribution of n-alkanes, a high content of short-chain alkanes and maximize at C 19 or C 20 （C 23 for sample Gzh00-1）. The C 27 /C 29 sterane ratio ranges from 0.77 to 1.20 and 4-methylsteranes are in low abundance. These parameters indicate that algae and bacteria are the important primary producers. Furthermore, biomarker maturity proxies show the samples to be higher maturity. The low Pr/Ph values （0.7） suggest that the samples were deposited under anoxic conditions and, likely, under stratified water columns. In addition, 25-norhopanes and gammacerane are present as diagnostic indicators of normal marine salinity and dysoxic to anoxic conditions. During the Early Tommotian, known to coincide with a transgression event, small shelly fossils increased in abundance and diversity. Moreover, positive δ 13 C org excursions close to 1.4‰ occur at the base of the Tommotian stage. In summary, the Early Cambrian black shales were deposited under dramatic paleoenvironmental changes, including oceanic anoxia, higher primary productivity and sea-level rise.展开更多
Carbon Dioxide (CO2) storage and sequestration in unconventional shale resources has been attracting interest since last couple of years due to the very unique characteristics of such formations have made them a feasi...Carbon Dioxide (CO2) storage and sequestration in unconventional shale resources has been attracting interest since last couple of years due to the very unique characteristics of such formations have made them a feasible option for this object. Shale formations are found all around the world and the conventional assets are easily accessible, and also the huge move of operators toward developing unconventional reservoirs during past years leaves many of such formations ready for sequestering CO2. Today, the use of long horizontal wells that are drilled on a pad has the lowest amount of environmental footprint in which for storage and sequestration purpose also provides much more underground pore spaces available for CO2. In this paper we study the state of the art of the technology of CO2 storage and sequestration and provide different and fresh look for its complex phenomena from a mathematical modeling point of view. Moreover, we hope this study provides valuable insights into the use of depleted shale gas reservoirs for carbon sequestration, which as a result, a cleaner atmosphere will be achieved for the life of our next generations. Also, we present that the depleted shale gas reservoirs are very adequate for this purpose as they already have much of the infrastructure required to perform CO2 injection available in sites.展开更多
Control of various factors, including mineral components, primary productivity and redox level, on the total organic carbon(TOC) in the lower Cambrian black shale from southeastern margin of Upper Yangtze(Taozichong, ...Control of various factors, including mineral components, primary productivity and redox level, on the total organic carbon(TOC) in the lower Cambrian black shale from southeastern margin of Upper Yangtze(Taozichong, Longbizui and Yanbei areas) is discussed in detail in this article. Mineral components in the study strata are dominated by quartz and clay minerals. Quartz in the Niutitang Formation is mainly of biogenic origin, and the content is in positive correlation with TOC, while the content of clay minerals is negatively correlated with TOC. Primary productivity, represented by the content of Mobio(biogenic molybdenum), Babio(biogenic barium) and phosphorus, is positively correlated with TOC. The main alkanes in studied samples are nCC, and odd–even priority values are closed to 1(0.73–1.13), which suggest the organic matter source was marine plankton. Element content ratios of U/Th and Ni/Co and compound ratio Pr/Ph indicate dysoxic–anoxic bottom water, with weak positive relative with TOC. In total, three main points can be drawn to explain the relationship between data and the factors affecting organic accumulation:(1) quartz-rich and clay-mineral-poor deep shelf–slope–basin environment was favorable for living organisms;(2) high productivity provided the material foundation for organic generation;(3) the redox conditions impact slightly on the content of organic matter under high productivity and dysoxic–anoxic condition.展开更多
Based on the drilling data of the Silurian Longmaxi Formation in the Sichuan Basin and periphery, SW China, the Ro lower limits and essential features of the carbonization of organic matter in over-high maturity marin...Based on the drilling data of the Silurian Longmaxi Formation in the Sichuan Basin and periphery, SW China, the Ro lower limits and essential features of the carbonization of organic matter in over-high maturity marine shale were examined using laser Raman, electrical and physical property characterization techniques. Three preliminary conclusions are drawn:(1) The lower limit of Ro for the carbonization of Type I-II1 organic matter in marine shale is 3.5%; when the Ro is less than 3.4%, carbonization of organic matter won't happen in general; when the Ro ranges from 3.4% to 3.5%, non-carbonization and weak carbonization of organic matter may coexist; when the Ro is higher than 3.5%, the carbonization of organic matter is highly likely to take place.(2) Organic-rich shale entering carbonization phase have three basic characteristics: log resistivity curve showing a general "slender neck" with low-ultralow resistance response, Raman spectra showing a higher graphite peak, and poor physical property(with matrix porosity of only less than 1/2 of the normal level).(3) The quality damage of shale reservoir caused by the carbonization of organic matter is almost fatal, which primarily manifests in depletion of hydrocarbon generation capacity, reduction or disappearance of organic pores and intercrystalline pores of clay minerals, and drop of adsorption capacity to natural gas. Therefore, the lower limit of Ro for the carbonization of Type I-II1 organic matter should be regarded as the theoretically impassable red line of shale gas exploration in the ancient marine shale formations. The organic-rich shale with low-ultralow resistance should be evaluated effectively in area selection to exclude the high risk areas caused by the carbonization of organic matter. The target organic-rich shale layers with low-ultralow resistance drilled during exploration and development should be evaluated on carbonization level of organic matter, and the deployment plan should be adjusted according to the evaluation results in time.展开更多
Sillimanite is a brittle mineral as a metamorphic mineral product which is generally derived from clay, along with an increase in pressure and high temperature (600°C - 900°C), and kaliophilite is also a bri...Sillimanite is a brittle mineral as a metamorphic mineral product which is generally derived from clay, along with an increase in pressure and high temperature (600°C - 900°C), and kaliophilite is also a brittle mineral as a potassium bearing in the sand-shale series, which contributes to the clay diagenesis process. In the development of shale hydrocarbon in the Brownshale formation in the Bengkalis Trough, Central Sumatra Basin, using the correlation of the XRD (bulk and clay oriented), TOC, Ro, and MBT analysis results from the drill cuttings of well BS-03, so that the fracable zone interval can be determined. From this correlation, it shows that the presence of sillimanite and kaliophilite minerals as minor minerals greatly affects the changes in shale character and hydrocarbon generation, where at depth intervals of 10,780 ft downward (sand series-shale) there is an interesting phenomenon, <i>i.e. </i> low MBT, low TOC, and high Ro, so it is believed that the depth interval of 10,780 ft downward is a fracable zone interval (brittle shale) which is a good candidate for hydraulic fracking planning, while the upper depth interval is a fracture barrier.展开更多
This paper presents new geological and geochemical data from the Shuanghu area in northern Tibet, which recorded the Early Toarcian Oceanic Anoxic Event. The stratigraphic succession in the Shuanghu area consists most...This paper presents new geological and geochemical data from the Shuanghu area in northern Tibet, which recorded the Early Toarcian Oceanic Anoxic Event. The stratigraphic succession in the Shuanghu area consists mostly of grey to dark-colored alternating oil shales, marls and mudstones. Ammonite beds are found at the top of the Shuanghu oil shale section, which are principally of early Toarcian age, roughly within the Harplocearas falciferrum Zone. Therefore, the oil shale strata at Shuanghu can be correlated with early Toarcian black shales distributing extensively in the European epicontinental seas that contain the records of an Oceanic Anoxic Event. Sedimentary organic matter of laminated shale anomalously rich in organic carbon across the Shuanghu area is characterized by high organic carbon contents, ranging from 1.8% to 26.1%. The carbon isotope curve displays the δ 13C values of the kerogen (δ 13Ckerogen) fluctuating from –26.22 to –23.53‰ PDB with a positive excursion close to 2.17‰, which, albeit significantly smaller, may also have been associated with other Early Toarcian Oceanic Anoxic Events (OAEs) in Europe. The organic atomic C/N ratios range between 6 and 43, and the curve of C/N ratios is consistent with that of the δ 13Ckerogen values. The biological assemblage, characterized by scarcity of benthic organisms and bloom of calcareous nannofossils (coccoliths), reveals high biological productivity in the surface water and an unfavorable environment for the benthic fauna in the bottom water during the Oceanic Anoxic Event. On the basis of organic geochemistry and characteristics of the biological assemblage, this study suggests that the carbon-isotope excursion is caused by the changes of sea level and productivity, and that the black shale deposition, especially oil shales, is related to the bloom and high productivity of coccoliths.展开更多
Graphite and graphite-like materials widely are present at black shale and magmatic ores. The nature of these carbon materials (CM) is multifarious. In what cause connects a mineralization with carbon. The great numbe...Graphite and graphite-like materials widely are present at black shale and magmatic ores. The nature of these carbon materials (CM) is multifarious. In what cause connects a mineralization with carbon. The great numbers of parameters, namely, the temperature, the pressure, the shear stress, the catalytic species, the host-rock lithology, the time and etc., have an influence on the graphitization process. Accumulations of gold and platinum group elements in black graphite shale and extraction of these metals from rocks depend in considerable degree from structural properties of CM. Raman spectroscopy has wide applied for various carbon modifications, including nano-structuring materials. The first and second-order Raman spectrum have been correlated with changes in the structure of graphite. There is a linear relationship between temperature and Raman R2 and R1 parameters (derived from the area and intensity of the defect band (D) relative to the ordered graphite band (G), respectively). The purpose of the present study is to characterize the rocks and CM from carbon-rich rocks of gold-ore deposits of the black-shale formation and magmatic ores using micro-Raman spectroscopy technique (Horiba Jobin Ivon LabRam spectrometer). Exciting was performed with 325 nm line of He-Cd laser. The graphite and graphite-like samples from many ore deposits of Russia and Kazahstan are investigations. R1 and R2 ratio indicate variable degree of organisation CM in the samples. The results show different spectral variations of CM with metamorphic grade: the well-ordered graphite from magmatic rocks, more - ordered and the disordered less graphitized CM from black-shale ores. For the first time in the world practice the Raman spectroscopy technique has been applied to determine the temperature of graphitizing for CM at gold-ore deposits of the black-shale formation. The temperatures obtained on carboniferous substance for the gold deposits range from 405°С to 280°С. Temperature of CM formation from Pt-low sulphide ores of the Talnakh deposit ranges from 4700C to 6500C. It has been shown that the carbon-rich phases from black-shale and magmatic rocks have various degrees of graphitization and different carbon forms.展开更多
基金supported by the "CAS Hundred Talents"Foundation of the Chinese Academy of Sciences to H.Z.,National Natural Science Foundation of China (Grant No.41102066, 40972084)Natural Science Foundation Project of CQ CSTC (Grant No. 2009BB7383)Opening Foundation of the State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences
文摘The lower Cambrian Niutitang Formation, a widespread black shale deposition, is of geological interest because of its polymetallic beds, Cambrian explosion, depositional ages, dramatic environmental changes and so on. Previous study focused mainly on inorganic geochemistry and few studies have investigated the organic fractions of upper Neoproterozoic-lower Cambrian strata in South China. Here we report a study of biomarkers plus organic carbon isotopes for black shales from Ganziping, Hunan Province （China）. All the saturated hydrocarbon fractions have a unimodal distribution of n-alkanes, a high content of short-chain alkanes and maximize at C 19 or C 20 （C 23 for sample Gzh00-1）. The C 27 /C 29 sterane ratio ranges from 0.77 to 1.20 and 4-methylsteranes are in low abundance. These parameters indicate that algae and bacteria are the important primary producers. Furthermore, biomarker maturity proxies show the samples to be higher maturity. The low Pr/Ph values （0.7） suggest that the samples were deposited under anoxic conditions and, likely, under stratified water columns. In addition, 25-norhopanes and gammacerane are present as diagnostic indicators of normal marine salinity and dysoxic to anoxic conditions. During the Early Tommotian, known to coincide with a transgression event, small shelly fossils increased in abundance and diversity. Moreover, positive δ 13 C org excursions close to 1.4‰ occur at the base of the Tommotian stage. In summary, the Early Cambrian black shales were deposited under dramatic paleoenvironmental changes, including oceanic anoxia, higher primary productivity and sea-level rise.
文摘Carbon Dioxide (CO2) storage and sequestration in unconventional shale resources has been attracting interest since last couple of years due to the very unique characteristics of such formations have made them a feasible option for this object. Shale formations are found all around the world and the conventional assets are easily accessible, and also the huge move of operators toward developing unconventional reservoirs during past years leaves many of such formations ready for sequestering CO2. Today, the use of long horizontal wells that are drilled on a pad has the lowest amount of environmental footprint in which for storage and sequestration purpose also provides much more underground pore spaces available for CO2. In this paper we study the state of the art of the technology of CO2 storage and sequestration and provide different and fresh look for its complex phenomena from a mathematical modeling point of view. Moreover, we hope this study provides valuable insights into the use of depleted shale gas reservoirs for carbon sequestration, which as a result, a cleaner atmosphere will be achieved for the life of our next generations. Also, we present that the depleted shale gas reservoirs are very adequate for this purpose as they already have much of the infrastructure required to perform CO2 injection available in sites.
基金supported by the National Natural Science Foundation Research (Grant 41672130, 41728004)the National Key S&T Special Projects (Grant 2016ZX05061-003-001)+1 种基金the National Postdoctoral Innovative Talent Support Program (Grant BX201700289)China Postdoctoral Science Foundation (Grant 2017M620296)
文摘Control of various factors, including mineral components, primary productivity and redox level, on the total organic carbon(TOC) in the lower Cambrian black shale from southeastern margin of Upper Yangtze(Taozichong, Longbizui and Yanbei areas) is discussed in detail in this article. Mineral components in the study strata are dominated by quartz and clay minerals. Quartz in the Niutitang Formation is mainly of biogenic origin, and the content is in positive correlation with TOC, while the content of clay minerals is negatively correlated with TOC. Primary productivity, represented by the content of Mobio(biogenic molybdenum), Babio(biogenic barium) and phosphorus, is positively correlated with TOC. The main alkanes in studied samples are nCC, and odd–even priority values are closed to 1(0.73–1.13), which suggest the organic matter source was marine plankton. Element content ratios of U/Th and Ni/Co and compound ratio Pr/Ph indicate dysoxic–anoxic bottom water, with weak positive relative with TOC. In total, three main points can be drawn to explain the relationship between data and the factors affecting organic accumulation:(1) quartz-rich and clay-mineral-poor deep shelf–slope–basin environment was favorable for living organisms;(2) high productivity provided the material foundation for organic generation;(3) the redox conditions impact slightly on the content of organic matter under high productivity and dysoxic–anoxic condition.
基金Supported by the CAS Strategic Pilot Project(XDA14010101)National Science and Technology Major Project(2017ZX05035001)PetroChina Exploration&Production Shale Gas Resource Evaluation and Strategic Selection Project(kt2017-10-02)
文摘Based on the drilling data of the Silurian Longmaxi Formation in the Sichuan Basin and periphery, SW China, the Ro lower limits and essential features of the carbonization of organic matter in over-high maturity marine shale were examined using laser Raman, electrical and physical property characterization techniques. Three preliminary conclusions are drawn:(1) The lower limit of Ro for the carbonization of Type I-II1 organic matter in marine shale is 3.5%; when the Ro is less than 3.4%, carbonization of organic matter won't happen in general; when the Ro ranges from 3.4% to 3.5%, non-carbonization and weak carbonization of organic matter may coexist; when the Ro is higher than 3.5%, the carbonization of organic matter is highly likely to take place.(2) Organic-rich shale entering carbonization phase have three basic characteristics: log resistivity curve showing a general "slender neck" with low-ultralow resistance response, Raman spectra showing a higher graphite peak, and poor physical property(with matrix porosity of only less than 1/2 of the normal level).(3) The quality damage of shale reservoir caused by the carbonization of organic matter is almost fatal, which primarily manifests in depletion of hydrocarbon generation capacity, reduction or disappearance of organic pores and intercrystalline pores of clay minerals, and drop of adsorption capacity to natural gas. Therefore, the lower limit of Ro for the carbonization of Type I-II1 organic matter should be regarded as the theoretically impassable red line of shale gas exploration in the ancient marine shale formations. The organic-rich shale with low-ultralow resistance should be evaluated effectively in area selection to exclude the high risk areas caused by the carbonization of organic matter. The target organic-rich shale layers with low-ultralow resistance drilled during exploration and development should be evaluated on carbonization level of organic matter, and the deployment plan should be adjusted according to the evaluation results in time.
文摘Sillimanite is a brittle mineral as a metamorphic mineral product which is generally derived from clay, along with an increase in pressure and high temperature (600°C - 900°C), and kaliophilite is also a brittle mineral as a potassium bearing in the sand-shale series, which contributes to the clay diagenesis process. In the development of shale hydrocarbon in the Brownshale formation in the Bengkalis Trough, Central Sumatra Basin, using the correlation of the XRD (bulk and clay oriented), TOC, Ro, and MBT analysis results from the drill cuttings of well BS-03, so that the fracable zone interval can be determined. From this correlation, it shows that the presence of sillimanite and kaliophilite minerals as minor minerals greatly affects the changes in shale character and hydrocarbon generation, where at depth intervals of 10,780 ft downward (sand series-shale) there is an interesting phenomenon, <i>i.e. </i> low MBT, low TOC, and high Ro, so it is believed that the depth interval of 10,780 ft downward is a fracable zone interval (brittle shale) which is a good candidate for hydraulic fracking planning, while the upper depth interval is a fracture barrier.
文摘This paper presents new geological and geochemical data from the Shuanghu area in northern Tibet, which recorded the Early Toarcian Oceanic Anoxic Event. The stratigraphic succession in the Shuanghu area consists mostly of grey to dark-colored alternating oil shales, marls and mudstones. Ammonite beds are found at the top of the Shuanghu oil shale section, which are principally of early Toarcian age, roughly within the Harplocearas falciferrum Zone. Therefore, the oil shale strata at Shuanghu can be correlated with early Toarcian black shales distributing extensively in the European epicontinental seas that contain the records of an Oceanic Anoxic Event. Sedimentary organic matter of laminated shale anomalously rich in organic carbon across the Shuanghu area is characterized by high organic carbon contents, ranging from 1.8% to 26.1%. The carbon isotope curve displays the δ 13C values of the kerogen (δ 13Ckerogen) fluctuating from –26.22 to –23.53‰ PDB with a positive excursion close to 2.17‰, which, albeit significantly smaller, may also have been associated with other Early Toarcian Oceanic Anoxic Events (OAEs) in Europe. The organic atomic C/N ratios range between 6 and 43, and the curve of C/N ratios is consistent with that of the δ 13Ckerogen values. The biological assemblage, characterized by scarcity of benthic organisms and bloom of calcareous nannofossils (coccoliths), reveals high biological productivity in the surface water and an unfavorable environment for the benthic fauna in the bottom water during the Oceanic Anoxic Event. On the basis of organic geochemistry and characteristics of the biological assemblage, this study suggests that the carbon-isotope excursion is caused by the changes of sea level and productivity, and that the black shale deposition, especially oil shales, is related to the bloom and high productivity of coccoliths.
文摘Graphite and graphite-like materials widely are present at black shale and magmatic ores. The nature of these carbon materials (CM) is multifarious. In what cause connects a mineralization with carbon. The great numbers of parameters, namely, the temperature, the pressure, the shear stress, the catalytic species, the host-rock lithology, the time and etc., have an influence on the graphitization process. Accumulations of gold and platinum group elements in black graphite shale and extraction of these metals from rocks depend in considerable degree from structural properties of CM. Raman spectroscopy has wide applied for various carbon modifications, including nano-structuring materials. The first and second-order Raman spectrum have been correlated with changes in the structure of graphite. There is a linear relationship between temperature and Raman R2 and R1 parameters (derived from the area and intensity of the defect band (D) relative to the ordered graphite band (G), respectively). The purpose of the present study is to characterize the rocks and CM from carbon-rich rocks of gold-ore deposits of the black-shale formation and magmatic ores using micro-Raman spectroscopy technique (Horiba Jobin Ivon LabRam spectrometer). Exciting was performed with 325 nm line of He-Cd laser. The graphite and graphite-like samples from many ore deposits of Russia and Kazahstan are investigations. R1 and R2 ratio indicate variable degree of organisation CM in the samples. The results show different spectral variations of CM with metamorphic grade: the well-ordered graphite from magmatic rocks, more - ordered and the disordered less graphitized CM from black-shale ores. For the first time in the world practice the Raman spectroscopy technique has been applied to determine the temperature of graphitizing for CM at gold-ore deposits of the black-shale formation. The temperatures obtained on carboniferous substance for the gold deposits range from 405°С to 280°С. Temperature of CM formation from Pt-low sulphide ores of the Talnakh deposit ranges from 4700C to 6500C. It has been shown that the carbon-rich phases from black-shale and magmatic rocks have various degrees of graphitization and different carbon forms.
