Identification and distribution of marine hydrocarbon source rocks in the Ordovician and Cambrian of the Tarim Basin

Zhang, Shuichang; Gao, Zhiyong; Li, Jianjun; Zhang, Baomin; Gu, Qiaoyuan; Yu-hong, LU

doi:10.1016/s1876-3804(12)60046-9

Cited by 45 publications

(16 citation statements)

References 5 publications

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“…However, the Middle‐Upper Ordovician just distributes around the No. 1 Fault Belt and the nearby North Slope, and that is missing in most regions of the Tazhong area (Zhang et al, ). The O 2+3 source rocks entered the hydrocarbon generation threshold (0.5%R equ ) during the Carboniferous, and that are mainly at the late mature stage (1.0% < R equ < 1.3%) at the present‐day (Figure b).…”

Section: Resultsmentioning

confidence: 99%

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Origins and accumulation processes of the Ordovician gas condensate in the Tazhong area, Tarim Basin, northwest China

et al. 2017

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Abundant gas condensates have been proven in the Ordovician carbonate reservoirs in the Tazhong area, the centre of the Tarim Basin, where complicated geological evolution and multiple hydrocarbon accumulations have occurred. Property, geochemistry, and stable carbon isotopes of the Ordovician condensate are characterized to identify the oil and gas origins in the Tazhong area. Fluid inclusion data, combined with numerical modelling methods was used to determine petroleum accumulation processes. Our results suggest that oils are characterized by mixed sources, with 64% of contributions from the Middle‐Upper Ordovician (O2+3) source rocks and 36% of contributions from the Lower‐Middle Cambrian (Є1+2) source rocks. Gases are primarily generated from the thermal cracking of pre‐existing oils in the underlying strata, with a small amount derived from kerogen cracking accompanied with oil generation. Three petroleum filling stages are determined, including the filling of the Є1+2‐derived oils during the Late Hercynian period, filling of the O2+3‐derived oils during the Yanshan period and oil‐cracking‐gas charge during the Himalayan period. The accumulation processes and relative contribution ratios of the two source rocks vary among the reservoirs and are mainly related to the transport system. Due to the lack of faults in the regions away from the No. 1 Fault Belt, the Є1+2‐derived oils are difficult to fill into the Ordovician reservoirs through the gypsolyte, and thus the accumulated oils are mainly from the O2+3 source rocks. The percentage of the O2+3‐derived oils is high in the southeast and northwest segments of the No. 1 Fault Belt, but relatively low in the middle segment and the vicinity of the No. 10 Structure Belt. Likewise, the late gas charge intensity is controlled by regionally varying conduit systems. Gas condensate formed in reservoirs with high gas/oil ratios. Otherwise, light oil retains with respect to low gas/oil ratios.

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Section: Resultsmentioning

confidence: 99%

“…The distribution of O 2+3 source rocks is limited in the Tazhong area, which is developing around the No. 1 Fault Belt and the nearby North Slope (Zhang et al, ). Resulting from the good conductive capability in the No.1 Fault Belt, oils and gases derived from Є 1+2 source rocks can migrate through the Middle Cambrian gypsolyte.…”

Section: Discussionmentioning

confidence: 99%

Origins and accumulation processes of the Ordovician gas condensate in the Tazhong area, Tarim Basin, northwest China

et al. 2017

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“…Lower Ordovician source rocks have been encountered in several exploration wells drilled in the east Tarim Basin,such as wells TD 1 and TD 2 (Huang et al, 2016;Zhang et al, 2012). One core sample collected from well TD 2 was investigated in the present study (Table 2), with its depth indicating that it belonged to the Lower Ordovician succession (Cai et al, 2014).…”

Section: Cambrian -Lower Ordovician Source Rocksmentioning

confidence: 99%

Geochemical Composition of Ordovician Oils From the Tuoputai Region, Northern Tarim Basin, Nw China: Source Rock Correlation

Cheng

Liu

Xian

et al. 2021

Journal of Petroleum Geology

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Molecular and stable carbon isotope compositions of 46 Ordovician crude oil samples from wells in the Tuoputai region of the northern Tarim Basin were investigated using GC–MS, MRM GC–MS and IRMS to determine their genetic relationships and to identify possible source rocks. Thirty‐three source rock samples from outcrops and cores were also investigated. The oil samples varied from light to heavy crudes and showed very narrow δ13C value ranges for the whole oil, saturated and aromatic fractions. The majority of the oils displayed very similar molecular compositions with relatively high concentrations of n‐alkanes and isoprenoids and low concentrations of terpenoids and steroids. Comparison of the compositions of these crude oils strongly suggested their genetic affinity, while maturity parameters indicated maturity variations from the peak to the late oil generation stages. The samples also showed the characteristics of mixtures of biodegraded and fresh oil charges.Bitumen extracts from Cambrian and Ordovician source rocks were studied in detail. The oil compositions suggested a marine marl source deposited in anoxic, hypersaline conditions with significant bacterial and algal organic matter inputs. The distributions of C26–C28 triaromatic steroids, tricyclic terpanes and regular steranes appear to have been greatly influenced by thermal maturation, making them unreliable for correlating the oils and the source rocks. In contrast, dinosteranes and triaromatic dinosteroids seem not to have been affected by maturation and were more useful for correlation studies. They indicated that there was no or little genetic relationship between the Cambrian – Lower Ordovician source rocks and the oils, but in general suggested a possible Middle – Upper Ordovician source for the oil accumulations in the Tuoputai field. However, the occurrence of triaromatic dinosteroids in oil from well TP28XCX may also suggest a minor contribution from Cambrian – Lower Ordovician source rocks.

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“…Thus, the sources of oil and gas in some giant fields are still controversial. For example, it is unclear whether the Jingbian gas field of the Ordos Basin contains oilformed gas from Ordovician shales and carbonate rocks or coal-formed gas from the Carboniferous-Permian coal measure strata (Chen 1994(Chen , 2002Dai et al 2005b;Huang et al 1996;Wang et al 2009b;Chen et al 2011;Liu et al 2012b) and whether the Lower Paleozoic oil and gas in the Tarim Basin are mainly from the Cambrian or Ordovician strata (Liang et al 2000;Li et al 2010;Zhang et al 2012;Tian et al 2012a, b). Because of the lack of widely recognized key geochemical samples, the main hydrocarbon source in the Tarim Basin will be debated for a long time, which will affect accurate spatial and temporal localization of the hydrocarbon source rock and hydrocarbon supply zone (Jin 2014).…”

Section: Multiple Source Rock Discriminationmentioning

confidence: 99%

Formation and distribution characteristics of Proterozoic–Lower Paleozoic marine giant oil and gas fields worldwide

et al. 2017

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There are rich oil and gas resources in marine carbonate strata worldwide. Although most of the oil and gas reserves discovered so far are mainly distributed in Mesozoic, Cenozoic, and upper Paleozoic strata, oil and gas exploration in the Proterozoic-Lower Paleozoic (PLP) strata-the oldest marine strata-has been very limited. To more clearly understand the oil and gas formation conditions and distributions in the PLP marine carbonate strata, we analyzed and characterized the petroleum geological conditions, oil and gas reservoir types, and their distributions in thirteen giant oil and gas fields worldwide. This study reveals the main factors controlling their formation and distribution. Our analyses show that the source rocks for these giant oil and gas fields are mainly shale with a great abundance of type I-II organic matter and a high thermal evolution extent. The reservoirs are mainly gas reservoirs, and the reservoir rocks are dominated by dolomite. The reservoir types are mainly karst and reef-shoal bodies with well-developed dissolved pores and cavities, intercrystalline pores, and fractures. These reservoirs are highly heterogeneous. The burial depth of the reservoirs is highly variable and somewhat negatively correlated to the porosity. The cap rocks are mainly thick evaporites and shales, with the thickness of the cap rocks positively correlated to the oil and gas reserves. The development of high-quality evaporite cap rock is highly favorable for oil and gas preservation. We identified four hydrocarbon generation models, and that the major source rocks have undergone a long period of burial and thermal evolution and are characterized by early and long periods of hydrocarbon generation. These giant oil and gas fields have diverse types of reservoirs and are mainly distributed in paleo-uplifts, slope zones, and platform margin reef-shoal bodies. The main factors that control their formation and distribution were identified, enabling the prediction of new favorable areas for oil and gas exploration.

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Identification and distribution of marine hydrocarbon source rocks in the Ordovician and Cambrian of the Tarim Basin

Cited by 45 publications

References 5 publications

Origins and accumulation processes of the Ordovician gas condensate in the Tazhong area, Tarim Basin, northwest China

Origins and accumulation processes of the Ordovician gas condensate in the Tazhong area, Tarim Basin, northwest China

Geochemical Composition of Ordovician Oils From the Tuoputai Region, Northern Tarim Basin, Nw China: Source Rock Correlation

Formation and distribution characteristics of Proterozoic–Lower Paleozoic marine giant oil and gas fields worldwide

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