Characterization of Low Molecular Weight Hydrocarbons in Jingbian Gas Field and its Application to Gas Sources Identification

Hu, Guoyi; Zhang, Shuichang

doi:10.1260/0144-5987.29.6.777

Cited by 20 publications

(23 citation statements)

References 25 publications

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“…The P 1 s-P 1 x gas in the Hangjinqi area displays the characteristics of gases from humic organic matter and generally follows the maturity trend in correlation diagram of 2 H-C 1 versus 13 C 1 (Figure 9(a)), suggesting the genetic type of coal-type gas. The O 1 m gas in the Jingbian gas field also displays the characteristics of gases from humic organic matter, which indicates that the gas is dominated by coal-type gas, and this is consistent with the conclusions of previous studies [19,53]. The Pt 2 gas from the Gongkahan zone is plotted in the mixing or transitional zone, and it is adjacent to the zone of humic gases in correlation diagram of 2 H-C 1 versus 13 C 1 (Figure 9(a)), which indicates that the Pt 2 gas is dominated by coal-type gas and has been mixed by a small amount of oiltype gas.…”

Section: Origin Of Tight Gassupporting

confidence: 91%

Genetic Types and Source of the Upper Paleozoic Tight Gas in the Hangjinqi Area, Northern Ordos Basin, China

Liu

et al. 2017

Geofluids

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The molecular and stable isotopic compositions of the Upper Paleozoic tight gas in the Hangjinqi area in northern Ordos Basin were investigated to study the geochemical characteristics. The tight gas is mainly wet with the dryness coefficient (C 1 /C 1-5 ) of 0.853-0.951, and 13 C 1 and 2 H-C 1 values are ranging from −36.2‰ to −32.0‰ and from −199‰ to −174‰, respectively, with generally positive carbon and hydrogen isotopic series. Identification of gas origin indicates that tight gas is mainly coal-type gas, and it has been affected by mixing of oil-type gas in the wells from the Shilijiahan and Gongkahan zones adjacent to the Wulanjilinmiao and Borjianghaizi faults. Gas-source correlation indicates that coal-type gas in the Shiguhao zone displays distalsource accumulation. It was mainly derived from the coal-measure source rocks in the Upper Carboniferous Taiyuan Formation (C 3 t) and Lower Permian Shanxi Formation (P 1 s), probably with a minor contribution from P 1 s coal measures from in situ Shiguhao zone. Natural gas in the Shilijiahan and Gongkahan zones mainly displays near-source accumulation. The coal-type gas component was derived from in situ C 3 t-P 1 s source rocks, whereas the oil-type gas component might be derived from the carbonate rocks in the Lower Ordovician Majiagou Formation (O 1 m).

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Section: Origin Of Tight Gassupporting

confidence: 91%

Genetic Types and Source of the Upper Paleozoic Tight Gas in the Hangjinqi Area, Northern Ordos Basin, China

Liu

et al. 2017

Geofluids

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“…The C 6 and C 7 oil correlation ternary diagram has been widely used to gain geochemical information (Hu et al 1990;Dai 1992Dai , 1993Odden et al 1998;Odden 1999;Jarvie 2001;Hu and Zhang 2011). Based on these diagrams, the indices of methylcyclohexane (MCH index) and cyclohexane (CA index) have been developed by many scholars as optimum indices for parent material type and maturity (Hu et al 1990;Dai 1992Dai , 1993Hu and Zhang 2011).…”

Section: Methylcyclohexane Index and Cyclohexane Indexmentioning

confidence: 99%

“…Based on these diagrams, the indices of methylcyclohexane (MCH index) and cyclohexane (CA index) have been developed by many scholars as optimum indices for parent material type and maturity (Hu et al 1990;Dai 1992Dai , 1993Hu and Zhang 2011). The formula of these two parameters are: MCH The ternary diagram of the C 7 LHs show that the relative content of methylcyclohexane is 49 %-74 %, which is higher than those of dimethylcyclopentane (14 %-26 %) and nheptane (0 %-36 %).…”

Section: Methylcyclohexane Index and Cyclohexane Indexmentioning

confidence: 99%

The effect of slight to minor biodegradation on C6 to C7 light hydrocarbons in crude oils: a case study from Dawanqi Oilfield in the Tarim Basin, NW China

Yang

Zhang

et al. 2016

Acta Geochim

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Light hydrocarbons (LHs) are one of the main petroleum fractions in crude oils, and carry much information regarding the genetic origin and alteration of crude oils. But secondary alterations-especially biodegradation-have a significant effect on the composition of LHs in crude oils. Because most of the LHs affected in oils underwent only slight biodegradation (rank 1 on the biodegradation scale), the variation of LHs can be used to describe more the refined features of biodegradation. Here, 23 crude oils from the Dawanqi Oilfield in the Tarim Basin, NW China, eleven of which have been biodegraded to different extents, were analyzed in order to investigate the effect of slight to minor biodegradation on C 6 -C 7 LHs. The study results showed that biodegradation resulted in the prior depletion of straight-chained alkanes, followed by branched alkanes. In slight and minor biodegraded oils, such biodegradation scale could not sufficiently affect C 6 -C 7 cycloalkanes. For branched C 6 -C 7 alkanes, generally, monomethylalkanes are biodegraded earlier than dimethylalkanes and trimethylalkanes, which indicates that branched alkanes are more resistant to biodegradation, with the increase of substituted methyl groups on parent rings. The degree of alkylation is one of the primary controlling factors on the biodegradation of C 6 -C 7 LHs. There is a particular case: although 2,2,3-trimethylbutane has a relative higher alkylation degree, 2,2-dimethylpentane is more resistant to biodegradation than 2,2,3-trimethylbutane. 2,2-Dimethylpentane is the most resistant to biodegradation in branched C 6 -C 7 alkanes. Furthermore, the 2-methylpentane/3-methylpentane and 2-methylhexane/3-methylhexane ratios decreased steadily with increasing biodegradation, which implies that isomers of bilateral methyl groups are more prone to bacterial attack relative to mid-chain isomers. The position of the alkyls on the carbon skeleton is also one of the critical factors controlling the rate of biodegradation. With increasing biodegradation, Mango's LH parameters K1 values decrease and K2 values increase, the values of n-heptane and isoheptane decrease, and the indices of methylcyclohexane and cyclohexane increase.

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“…The former type mainly distribute in the eastern Kelasu structural belt with the n-alkanes ratio of the Well Kela201, Kela3 and Keshen204 being 37.0%, 36.0% and 41.4%, respectively, much higher than those of the latter type (28% in average) (Table 1 Methylcyclohexane (MCC6), n-heptanes and dimethylpentanes of all kinds of structures (ΣDMCC5) are also favorable indicators for genetic types of the condensates. The MCC6 mainly originates from the ignin, cellulose and carbohydrate of the higher plants which is a good indicator for terrigenous source materials and coal-derived hydrocarbon; The ΣDMCC5 mainly originate from the lipid of the aquatic organisms; The n-heptanes mainly originate from the bacteria and algae which is a favorable indicator for sapropelic hydrocarbons (Dai et al, 1992;Hu et al, 2011). The MCC6 values of Well Kela201 and Keshen204 are 41.1% and 45.6%, respectively, the lowest among the total samples while their n-heptanes contents are 48.9% and 50.0%, respectively, the highest among the total samples, indicating a sapropelic origin.…”

Section: Light Hydrocarbon Analysismentioning

confidence: 99%

Geochemical Characteristics of the Condensates and Their Evaporative Fractionation in Kuqa Depression of Tarim Basin, NW China

Gong

Yang

et al. 2014

Energy Exploration & Exploitation

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After analyzing 21 samples in 12 oil and gas fields in Kuqa depression, two genetic types of condensates are identified. One type is the sapropelic condensate mainly derived from the Upper-Middle Triassic lacustrine source rocks which has a relatively higher content of C 5-7 n-alkanes (>35%) and lower methylcyclohexane content (<48%), pristane/phytane ratio (0.95~1.56) and carbon isotope values (-27.8‰ ~ -32.3‰); the other type is the coal-derived condensate derived from the Middle-Lower Jurassic terringenous source rocks which has a lower C5-7 n-alkanes content (28% in average) and relatively higher content of methylcyclohexane (>50%), pristane/phytane ratio (1.70 4.62) and carbon isotope values (-26.2‰ in average). Based on a comprehensive study on the n-alkanes, light hydrocarbons and carbon isotopes, it is found the condensates in Kuqa depression have widely experienced evaporative fractionation with a high aromaticity (>0.8) and their high molecules suffered loss. With the evaporative fractionation becoming more significant, the bulk carbon isotopic values of the condensates become heavier, indicating the multistages of the evaporative fractionation. The structural or lithologic traps in the Tertiary and the Jurassic tend to be favorable exploration targets for future oil exploration in Kuqa depression.

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Characterization of Low Molecular Weight Hydrocarbons in Jingbian Gas Field and its Application to Gas Sources Identification

Cited by 20 publications

References 25 publications

Genetic Types and Source of the Upper Paleozoic Tight Gas in the Hangjinqi Area, Northern Ordos Basin, China

Genetic Types and Source of the Upper Paleozoic Tight Gas in the Hangjinqi Area, Northern Ordos Basin, China

The effect of slight to minor biodegradation on C6 to C7 light hydrocarbons in crude oils: a case study from Dawanqi Oilfield in the Tarim Basin, NW China

Geochemical Characteristics of the Condensates and Their Evaporative Fractionation in Kuqa Depression of Tarim Basin, NW China

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