Distribution and characteristics of lacustrine tight oil reservoirs in China

Wu, Songtao; Zhu, Rixiang; Zhi, Yang; Mao, Zhiguo; Cui, Jingwei; Zhang, Xiangxiang

doi:10.1016/j.jseaes.2018.05.013

Cited by 60 publications

(18 citation statements)

References 30 publications

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“…The hydrocarbon-bearing properties were determined according to differences in the fluorescent colours, brightness, and the luminous sites of the hydrocarbons and other organic matter in the rocks under ultraviolet excitation, and samples were identified using a Nikon 80i, THMGS 600, Maya 2000 pro three-channel advanced fluorescence microscope under standard the SY/T5614-2011 of China. X-Ray Diffraction (XRD) was conducted using a Rigaku Ultima type IV X-ray diffractometer from Japan (Cu Ka, k = 0.154 nm), in accordance with standard SY/T 5163-2010 (Wu et al, 2018;Zeng et al, 2010).…”

Section: Experimental Methodsmentioning

confidence: 99%

“…With the successful exploration and development of unconventional oil and gas sources, tight oil and gas have increased in importance in the global energy market and become the priority choice for alternate energy generation (Al-Otaibi et al, 2015;Denne et al, 2014;Jia et al, 2012;Kuhn et al, 2012;Landon et al, 2001;LeFever et al, 2013;Sonnenberg and Pramudito, 2009;Sonnenberg, 2015Sonnenberg, , 2017Sonnenberg et al, 2018;Wu et al, 2016Wu et al, , 2018Zou et al, 2011Zou et al, , 2012aZou et al, , 2012b. Chlorite is an essential diagenetic mineral that forms in tight sandstone reservoirs, and its content, morphology and occurrence characteristics play crucial roles in reservoir control.…”

Section: Introductionmentioning

confidence: 99%

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The formation mechanism of authigenic chlorite in tight sandstone and its effect on tight oil adsorption during hydrocarbon filling

Zhou

Chen

et al. 2021

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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Authigenic chlorite, which is frequently found in sandstone, has a controlling effect on the reservoirs in which tight oil is adsorbed during hydrocarbon filling. In this study, the content, occurrence state, timing, mechanism and influence of authigenic chlorite on the micro-occurrence states of tight oil were studied using Thin Section (TS), Fluorescent Thin Section (FTS), X-Ray Diffraction (XRD), Field Emission-Scanning Electron Microscopy (FE-SEM), Environmental Scanning Electron Microscopy (ESEM), and Energy Dispersive Spectroscopy (EDS). The results indicate: (1) a spatial coupling between chlorite development, a brackish water delta front facies depositional environment, and biotite-rich arkosic sandstone. (2) Authigenic chlorite can be divided into three types: grain-coating chlorite, pore-lining chlorite, and rosette chlorite. Chlorite forms after early compaction but before other diagenetic phases, and grows via precipitation from pore waters that contain products released during the dissolution of volcanic rock fragments and biotites. Porewater is also pressure-released from feldspars and mudstone. (3) The micro-occurrence states of tight oil can be divided into five types: emulsion form, cluster form, throat form, thin-film form, and the isolated or agglomerated particle form. (4) During hydrocarbon filling, tight oil mainly occurs on the surface of grain-coating and pore-lining chlorite in the form of a thin film, the granular or agglomerated forms are mainly enriched within the intercrystalline pores within the authigenic chlorite, and the cluster forms are mainly enriched in dissolution pores. Isolated or agglomerated particles of tight oil primarily occur in the intercrystalline pores of the rosette chlorite. (5) The specific surface area and the authigenic chlorite’s adsorption potential of authigenic chlorite control the micro-occurrence of tight oil on the surface of the chlorite and in intercrystalline pores. The adsorption capacity of chlorite lies in the following order: pore-lining chlorite intercrystalline pores > rosette chlorite > chlorite in feldspar dissolution pores > pore-lining chlorite surface > grain-coating chlorite intercrystalline pores > grain-coating chlorite surface.

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Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The formation mechanism of authigenic chlorite in tight sandstone and its effect on tight oil adsorption during hydrocarbon filling

Zhou

Chen

et al. 2021

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

View full text Add to dashboard Cite

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“…The whole-rock and clay fraction mineralogy have been identified using a Rigaku Ultima type IV X-ray diffractometer of Japan (Cu Kα, λ = 0.154 nm), according to the SY/T 5163–2010 standard (Wu et al., 2019). The samples were hand-milled into powder firstly, and then the whole-rock was identified.…”

Section: Samples and Methodsmentioning

confidence: 99%

“…With the successful exploration and development of unconventional oil and gas, tight oil and gas have become more and more important in world energy, being the priority choice for energy replacement (Alotaibi et al., 2015; Denne et al., 2014; Jia et al., 2012; Kuhn et al., 2012; Landon et al., 2001; LeFever et al., 2013; Sonnenberg et al., 2018; Wu et al., 2016, 2019; Zou et al., 2012). The tight oil reservoirs in China are mainly lacustrine deposits, and the production of lacustrine tight oil has reached 1.5 million tons per year (Wu et al., 2019). In lacustrine clastic reservoirs, the content and type of clay minerals have a significant influence on the reservoir's physical properties.…”

Section: Introductionmentioning

confidence: 99%

Formation mechanism of authigenic chlorite in tight sandstone and its influence on tight oil adsorption, Triassic Ordos Basin, China

Zhou

et al. 2020

Energy Exploration & Exploitation

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In this study, the formation mechanism of authigenic chlorite in tight reservoirs and its influence on the adsorption capacity to tight oil have been analyzed. The occurrence states of chlorite and the formation mechanism have been analyzed by thin section (TS) and field emission scanning electron microscopy (FE-SEM) measurements. Due to the alteration of volcanic rock fragments, the mudstone pressurized water, and the dissolution of early chlorite, the material source has been provided for the formation of chlorite. The formation time of chlorite with different occurrence states is in the following order: grain-coating chlorite → pore-lining chlorite → pore-lining chlorite in dissolved pores → rosette chlorite. Authigenic chlorite developed in the reservoirs has influenced the change of the reservoir quality in two respects. On the one hand, authigenic chlorite can protect the residual pores, improve the anti-compaction capacity of the reservoir, and provide certain inter-crystalline space. On the other hand, it can hinder pore space and inhibit throat, resulting in a decrease in the connectivity of pores and the increase in the heterogeneity of the reservoir. Tight oil absorbed by the chlorite is mainly in the form of the thin film and aggregates. Through in situ testing of environmental scanning electron microscope (ESEM) and energy dispersive spectrum (EDS), the adsorption capacity of chlorite with different occurrence states to tight oil, being in the following order: rosette chlorite > pore-lining chlorite > pore-lining chlorite in dissolved pores > grain-coating chlorite. Furthermore, the controlling factors on reservoir quality, the content of chlorite and content of Fe and K have been investigated, and the adsorption capacity of different chlorite types has been studied, which can provide guidance for analysis of the control factors on the difference in adsorption capacity of different occurrence states of chlorite to tight oil in tight reservoirs.

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“…"Tight oil" refers to oil resources stored in reservoir rocks such as tight (low permeability) sandstones and carbonates in close proximity to, and/or within the same formation as, the related source rocks (e.g. Jia et al, 2012;Wu et al, 2019;Cao et al, 2017). Tight oils occur widely in China and commercial-sized tight oil reservoirs have been found in the Sichuan, Ordos, Junggar, Bohai Bay and Songliao Basins (Fang et al, 2019;Sun et al, 2019;Song et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Composition of Light Hydrocarbons in Jurassic Tight Oils in the Central Sichuan Basin, China: Origin and Source Rock Correlation

Wei³

et al. 2022

Journal of Petroleum Geology

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Crude oil reserves in tight Middle and Lower Jurassic reservoirs are of increasing exploration interest in the central Sichuan Basin, SW China. However, the origin of these “tight oils” is poorly understood. In this study, sixteen samples of light oils/condensates from tight Middle and Lower Jurassic reservoir rocks were analysed using gas chromatography (GC) and isotope ratio mass spectrometry to investigate the oils’ origin and to classify them into genetic families. The tight oils can be divided into two families. Family I oils occur in the Gongshanmiao oilfield where reservoir units comprise the Da'anzhai Member of the Lower Jurassic Ziliujing Formation, the Lower Jurassic Lianggaoshan Formation, and the First Member of the Middle Jurassic Shaximiao Formation. Family I oils are characterized by relatively low values of the methylcyclohexane (MCH) and cyclohexane (CH) indexes, low values of Mango's parameter K2 for light hydrocarbon composition, and relatively negative δ13C values ranging from ‐30.8‰ to ‐28.9‰. Family I oils are inferred to be self‐sourced by lacustrine shales in the Da'anzhai Member and the Lianggaoshan Formation in the study area, both of which are rich in sapropelic organic matter. These source rocks also charged reservoirs in the First Member of the Shaximiao Formation. By contrast, the newly discovered Family II oils, which occur at the Jinhua oilfield and the as‐yet undeveloped Qiulin and Bajiaochang structures, are reservoired in the Second Member of Shaximiao Formation. Family II oils have higher values of the MCH index, CH index and Mango's K2 parameter, and δ13C values varying from ‐27.5‰ to ‐25.4‰. These oils have similar light hydrocarbon compositions and δ13C values to oils derived from source rocks in the Upper Triassic Xujiahe Formation which contain dominantly humic organic matter. Family II oils are therefore inferred to be derived from the coaly mudstones in the Xujiahe Formation.The different compositions of the tight oils in the First and Second Members of the Shaximiao Formation appear to be controlled by the distribution and thickness of source rocks in the study area. Thus, the Gongshanmiao oilfield where Family I oils occur in the First Member is close to the depocentre of source rocks in the Da'anzhai Member and Lianggaoshan Formation. These source rocks are inferred to have charged the First Member reservoirs which may also be present in nearby oil‐ and gas‐bearing structures such as Nanchong and Yingshan. By contrast, Family II oils occur in tight reservoirs in the Second Member in areas with thick successions of Upper Triassic Xujiahe Formation mudstone source rocks, such as the Jinhua oilfield. In areas where both source rocks are present such as the Zhongtaishan and Lianchi oilfields, Shaximiao Formation reservoirs appear to contain both Family I and Family II oils.

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Distribution and characteristics of lacustrine tight oil reservoirs in China

Cited by 60 publications

References 30 publications

The formation mechanism of authigenic chlorite in tight sandstone and its effect on tight oil adsorption during hydrocarbon filling

The formation mechanism of authigenic chlorite in tight sandstone and its effect on tight oil adsorption during hydrocarbon filling

Formation mechanism of authigenic chlorite in tight sandstone and its influence on tight oil adsorption, Triassic Ordos Basin, China

Composition of Light Hydrocarbons in Jurassic Tight Oils in the Central Sichuan Basin, China: Origin and Source Rock Correlation

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