Formation conditions, accumulation models and exploration direction of large-scale gas fields in Sinian-Cambrian, Sichuan Basin, China

Wei, Guoqi; Yang, Wei; Xie, W.; Xie, Zengye; Zeng, Fangming; Mo, Wuling; Shen, Jian; Jin, Hui

doi:10.1016/j.jnggs.2016.04.002

Cited by 12 publications

(12 citation statements)

References 3 publications

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“…The measured borehole temperature and R o that was derived from Raman spectroscopy analyses were used to calibrate thermal maturation results. Organic matter in the Qiongzhusi source rocks is mainly type I kerogen (Wei, Du, et al, 2015; Wei, Yang, et al, 2015). A NULL chemical kinetic model was used to simulate oil generation history (Braun & Burnham, 1987; Burnham et al, 1987).…”

Section: Samples and Methodsmentioning

confidence: 99%

“…The Sichuan Basin, located in the southwest part of China, is a superimposed petroliferous basin that developed on the Precambrian basement of the Yangtze Craton, covering an area of 1.8 × 10 5 km 2 (Figure 1a,b; Ma et al, 2007; Wei, Yang et al, 2015). The Sichuan Basin is tectonically bound by the Longmenshan orogenic belts in the northwest, the Micangshan Fold Belt in the north, the Dabashan Thrust Belt in the northeast, the Qiyueshan Fault in the southeast, and the Emeishan–Liangshan Fold Belt in the southwest (Figure 1a; Liu, Deng et al, 2016, Liu, Qiu, et al 2016).…”

Section: Geological Settingmentioning

confidence: 99%

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Maturity assessment of solid bitumen in the Sinian carbonate reservoirs of the eastern and central Sichuan Basin, China: Application for hydrocarbon generation modelling

Chen

Guo

et al. 2022

Geological Journal

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Maturity assessment of solid bitumen is significant for the reconstruction of the thermal evolution history and obtaining the key periods of hydrocarbon generation for the Qiongzhusi source rocks in the eastern and central Sichuan Basin because of the absence of vitrinite in the marine mudstones. Based on the Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy analyses of solid bitumen, the thermal maturity of solid bitumen in the Sinian reservoir was evaluated, which was used to calibrate the thermal maturation history modelling results of the Qiongzhusi source rocks. The FTIR spectrums of solid bitumen are characterized by depleted aliphatic carbon and C O group, and enrichment of aromatic carbon, which indicates that the vitrinite reflectance equivalent (VR eq ) values of solid bitumen in the Sichuan Basin exceed at least 1.3%. The calculated VR eq values of solid bitumen inferred by Raman spectroscopy analysis are 3.8%-4.09% and 3.51%-3.77% in the eastern and central Sichuan Basin, respectively. The calculated VR eq values of bitumen in fluorite and calcite inclusions of the central Sichuan Basin vary from 3.54% to 3.64%. The thermal evolution history of the Qiongzhusi source rocks can be divided into two heating-cooling stages. At the end of the second heating stage, which is the Late Cretaceous, the Qiongzhusi source rocks reached the highest temperature of 250 and 225 C in the eastern and central Sichuan Basin, respectively. The different burial and thermal history of the Qiongzhusi source rocks controls their key periods of hydrocarbon generation in the eastern and central Sichuan Basin. Two episodes of intense oil generation of the Qiongzhusi source rocks were determined at 440-380 Ma and 290-260 Ma, and one phase of gas generation from oil cracking was from 260 to 85 Ma in the eastern Sichuan Basin. The intense oil generation of the Qiongzhusi source rocks occurred at 240-185 Ma and the oil cracking phase was from 185 to 90 Ma in the central Sichuan Basin.

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Section: Samples and Methodsmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Maturity assessment of solid bitumen in the Sinian carbonate reservoirs of the eastern and central Sichuan Basin, China: Application for hydrocarbon generation modelling

Chen

Guo

et al. 2022

Geological Journal

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“…Sichuan Basin contains six first-ordered tectonic units (Figure 1A), and the research area (the North Slope of central Sichuan Basin) is located in the Central Gentle Tectonic Belt. The Gaoshiti-Moxi area is a large-scaled uplift shaped in the Caledonian movement at the end of Silurian and preserved to date (Zou et al, 2014;Wei et al, 2015c). The North Slope mainly refers to the large-scaled monoclinic structure adjacent to the north of the Gaoshiti-Moxi area.…”

Section: Geological Backgroundmentioning

confidence: 99%

“…In contrast, the carbon isotope of C 2+ , such as ethane (δ 13 C 2 ), varies little with increasing thermal maturity but primarily varies with the type of parent material (kerogen) (Xie et al, 1999). Thus, the carbon isotope of C 2+ is a better indicator for gas-source correlation than that of methane (Yanhua et al, 2006;Wei et al, 2015c;Wu et al, 2016b). However, as shown in Figure 5, neither the carbon isotopes of methane nor ethane from Dengying reservoirs can be correlated effectively with those from Qiongzhusi.…”

Section: Figurementioning

confidence: 99%

Dynamic reconstruction of the hydrocarbon generation, accumulation, and evolution history in ultra-deeply-buried strata

Song

Ding

Zhang³

et al. 2022

Front. Earth Sci.

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The evolution mechanism of hydrocarbons in ultra-deeply-buried and ultra-old strata is the core issue of petroleum geology moving towards Deep Earth. Reconstructing the evolutionary history of ultra-deeply-buried hydrocarbons is the key to shedding light on deep hydrocarbon accumulation and evolution mechanisms. Furthermore, it can help point out directions for oil and gas exploration in Deep Earth. Anyue gas field in the central Sichuan Basin is the Frontier of deep natural gas exploration in China. This study selected the natural gas reservoirs of the Upper Sinian Dengying Formation in the central Sichuan Basin as the research object. By integrating analysis of natural gas geochemical characteristics, source rock evaluation, reservoir bitumen-source correlation, inclusion analysis, one-dimensional and two-dimensional hydrocarbon accumulation simulations, the generation and evolution of hydrocarbons in different structural regions, namely the inherited paleo-uplift and slope area in central Sichuan Basin, have been dynamically restored and compared. The results show that: 1) The natural gas of the ultra-deeply-buried Sinian Dengying formation in central Sichuan is typical oil-cracking gas from the paleo-oil reservoir. The Sinian gas is mainly sourced from the Qiongzhusi/Maidiping Formation. 2) The formation of Sinian gas reservoirs includes three stages: the formation of paleo-oil-reservoirs; the cracking of paleo-oil-reservoirs into paleo-gas-reservoirs; the adjustment of the paleo-gas-reservoirs. 3) Source rock and reservoir evaluation, quantitative solid bitumen analysis, and hydrocarbon accumulation simulation show that the natural gas accumulation conditions in the slope area are better than in the inherited uplift area. The scale of the paleo-oil-reservoirs in the slope area may be greater than that in the inherited uplift area.

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“…The interface between the Z 2 dn 4 and the overlying Maidiping Formation (Є 1 m) or Qiongzhusi Formation (Є 1 q) is a disconformity. It is widely understood that the disconformity is a consequence of meteoric freshwater leaching and eroding after the regional tectonic uplift of the Tongwan Movement episode II (Luo et al, 2015;Yang et al, 2016;Wei et al, 2016;Zhou et al, 2016;Luo et al, 2017;Hao et al, 2017), though a debate co-exists on which karstification type (eogenetic, hypogenetic, or epigenetic) dominates the formation of numerous karst products in the Z 2 dn 4 (Tang et al, 2013;Luo et al, 2015;Zhou et al, 2016;Jin et al, 2017;Che et al, 2019;Li et al, 2019;Jin et al, 2020;Zhou et al, 2020). Karstification is regarded as the vital diagenetic alteration in the formation of Z 2 dn 4 reservoirs in the Gaoshiti-Moxi area (Luo et al, 2017;Shan et al, 2017;Duan et al, 2019;Zhou et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Multi-Factor Evaluation of Deep Karst Dolomite Reservoir Based on Paleogeomorphological Reconstruction, a Case Study From the 4th Member of the Dengying Formation in the Central Sichuan Basin, China

Zhou

Wang²,

Yang³

et al. 2022

Front. Earth Sci.

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The evaluation of reservoirs is of great importance in exploration practices, and reservoir distribution is dependent on multiple geological factors. The carbonate platform of the fourth member (Z2dn4) of the Dengying Formation (Z2dn) in the Gaoshiti-Moxi area (GMA) was uplifted above sea level during episode II of the Tongwan movement and underwent prolonged karstification by meteoric freshwater in the terminal Sinian, leading to a strong heterogeneity in reservoirs. Paleogeomorphology reflects hydraulic gradients that can affect the intensities of surface karstification and may be approximated by terrain slope gradients. Karst products (especially solution vugs and caverns) exist prevailingly in the Z2dn4; their development mirrors the extents of internal dissolution. Based on paleogeomorphological reconstruction using the elevation method, the slope angles of single boreholes were calculated through the digital elevation model (DEM). In accordance with single-borewell Fullbore Formation MicroImager (FMI) logging data, four electrofacies (host rock, vug, fracture, and cave) were identified in boreholes possessing FMI data. The identified electrofacies were matched with corresponding conventional logging curves to obtain the training data. A model generalized for other boreholes without FMI data was established with the random forest algorithm and the thicknesses of the four electrofacies in each borehole were determined to characterize the extent of karstification. Slope gradients and electrofacies thicknesses, together with multiple physical parameters of reservoirs in boreholes, were utilized for factor analysis. Four factors were obtained and fused into one comprehensive score based on their ratios of variance proportions. The favorability of reservoirs was described by the comprehensive scores of each borehole. These analyses showed that the most advantageous reservoirs are distributed in the vicinity of the platform margin in the west of the GMA, where they enjoy several benefits. Deposition of porous mound-shoal complexes occurs predominantly in the platform margin where large-scale caves are more developed in the mixing karst zone of seawater and freshwater. Meanwhile, the transmeridional lateral migration of hydrocarbons from the regional hydrocarbon-generating center abutting the west of the GMA contributes to earlier entrapment and accumulation in the mound-shoal complexes in the platform margin.

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Formation conditions, accumulation models and exploration direction of large-scale gas fields in Sinian-Cambrian, Sichuan Basin, China

Cited by 12 publications

References 3 publications

Maturity assessment of solid bitumen in the Sinian carbonate reservoirs of the eastern and central Sichuan Basin, China: Application for hydrocarbon generation modelling

Maturity assessment of solid bitumen in the Sinian carbonate reservoirs of the eastern and central Sichuan Basin, China: Application for hydrocarbon generation modelling

Dynamic reconstruction of the hydrocarbon generation, accumulation, and evolution history in ultra-deeply-buried strata

Multi-Factor Evaluation of Deep Karst Dolomite Reservoir Based on Paleogeomorphological Reconstruction, a Case Study From the 4th Member of the Dengying Formation in the Central Sichuan Basin, China

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