Characteristics and controlling factors of lacustrine tight oil reservoirs of the Triassic Yanchang Formation Chang 7 in the Ordos Basin, China

Xu, Zhengjian; Liu, Luofu; Wang, Tieguan; Wu, Kangjun; Dou, Wenchao; Song, Xin; Feng, Chenyang; Li, Xiaozhong; Ji, Haitao; Yang, Yueshu; Liu, Xiaoxiang

doi:10.1016/j.marpetgeo.2017.02.012

Cited by 68 publications

(30 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A series of Cenozoic rift basins separate the Ordos basin from adjoining mountains [17]. The Ordos basin can be divided into six structural units: the Yimeng uplift zone in the north, the Weibei uplift zone in the south, the Jinxi flexural fold zone in the east, the Yishan slope in the midsection, the Xiyuan obduction zone, and the Tianhuan depression in the west ( Figure 1(a); [16,[18][19][20][21][22][23]). The study area of this paper is located in the west Ordos basin (mainly the Yishan Slope and Tianhuan Depression), and abundant hydrocarbons are produced from the oil fields located in this area, including the Jiyuan, Heshui, Wu 464, Zhengning, and Huachi oil fields ( Figure 1).…”

Section: Geologic Settingmentioning

confidence: 99%

Origin and Distribution of Carbonate Cement in Tight Sandstones: The Upper Triassic Yanchang Formation Chang 8 Oil Layer in West Ordos Basin, China

et al. 2017

View full text Add to dashboard Cite

Two generations of carbonate cement as Type I (microcrystalline calcite and dolomite) and Type II (mainly Fe-calcite and Fedolomite) are recognized in Chang 8 sandstones, Ordos basin. Carbonate cement in Chang 8 sandstones is closely related to the dissolved carbon from thermal maturation of organic matters. Carbonate cement in the loosely packed framework grains precipitated shortly after deposition, and late-stage ferroan calcite and ferroan dolomite formed with progressive burial. The early diagenetic carbonate cement is partially to completely replaced by late-stage ferroan calcite and ferroan dolomite. Carbonate cement is much more commonly observed in sand bodies adjacent to Chang 7 source rocks. With increasing distance from the Chang 7 oil layers, the carbonate cement content gradually decreases. However, some tight carbonate cemented zones also occur at the sandstone-mudstone interfaces. Dissolution of Ca-feldspars by organic acids-rich fluids, together with clay mineral transformations such as illitization of smectite, would provide Ca 2+ and Mg 2+ ions for carbonate cementation. Organic acids and CO 2 rich fluids would charge into the reservoirs with the hydrocarbons, and when the CO 2 and acids were buffered by the framework grain dissolution, carbonate cement would precipitate with a decrease in CO 2 concentration.

show abstract

Section: Geologic Settingmentioning

confidence: 99%

Origin and Distribution of Carbonate Cement in Tight Sandstones: The Upper Triassic Yanchang Formation Chang 8 Oil Layer in West Ordos Basin, China

et al. 2017

View full text Add to dashboard Cite

show abstract

“…The fluorescence colours and spectral features of the oil are generally associated with the chemical composition and thermal maturity (McLimans, ; Stasiuk & Snowdon, ; Xu et al, ). The peak wavelength of QGF‐E spectra and the TSF spectra can be indicative of different hydrocarbon compositions (Liu & Eadington, ; Liu et al, ).…”

Section: Discussionmentioning

confidence: 99%

The diagenetic and tectonic significance of hydrocarbon accumulation in the southern Junggar Basin, NW China

Tian

Zhang

et al. 2017

Geological Journal

View full text Add to dashboard Cite

The Jurassic petroleum system plays an increasingly important role in petroleum explorations in the southern Junggar Basin. To assess the hydrocarbon distribution and the accumulation history of the Jurassic reservoirs in this area, we carried out reservoir petrographic, fluorescence spectroscopic, and fluid inclusion petrographic analyses on the core and cutting samples from the QQ‐2 well in the Qigu Anticline. The oil accumulation has the partiality for high‐quality sandstone reservoirs that have the high porosity and permeability with values of 14–18% and (1–450) × 10−2 μm2, respectively, in the Middle Jurassic Toutunhe Formation (J2t) reservoirs. The pores are big with average diameters of 60–100 μm, and the pore throats are wide with values of 3.45–6.92 μm in the oil reservoirs. The intergranular pores survive thanks to the poor compaction and the poor cementation, and the dissolved and mould pores develop attributed to the strong dissolution in the oil reservoirs. Two episodes of oil charging and one episode of gas invasion were identified in the Middle Jurassic reservoirs in the southern Junggar Basin. The low‐maturity paleo‐oil charged the sandstone reservoirs at about 35 Ma when the paleo‐traps took shape during the Cretaceous–Eocene. A large number of faults and anticlinal traps was developed in the southern Junggar Basin at about 7 Ma, caused by the reactivation of the Tianshan Mountains in the late Cenozoic. Simultaneously, the leakage of the paleo‐oil, the accumulation of late oil, and the gas invasion all took place. Fault activities led to the leakage of paleo‐oil and helped the oil and gas accumulate in the Middle Jurassic reservoirs in the anticlinal trap shaping at about 7–8 Ma in the southern Junggar Basin.

show abstract

“…The Ordos Basin, which is a typical Mesozoic-Cenozoic continental basin, is located in central northern China (Fig. 1a), and its tectonic position belongs to the western part of the North China Platform (Xu et al, 2017b;Yang et al, 2017). According to the structural features, the Ordos Basin can be roughly divided into six tectonic units, including the Yimeng Uplift, Weibei Uplift, Jinxi Fold Belt, Yishan Slope, Tianhuan Depression and Western Thrusted Zone (Fig.…”

Section: Geological Settingmentioning

confidence: 99%

Characteristics of Tight Sandstone Reservoirs and Controls of Reservoir Quality: A Case Study of He 8 Sandstones in the Linxing Area, Eastern Ordos Basin, China

Gao

Wang

et al. 2019

Acta Geologica Sinica (Eng)

View full text Add to dashboard Cite

Determining the process of densification and tectonic evolution of tight sandstone can help to understand the distribution of reservoirs and find relatively high‐permeability areas. Based on integrated approaches of thin section, scanning electron microscopy (SEM), cathode luminescence (CL), nuclear magnetic resonance (NMR), X‐ray diffraction (XRD), N2 porosity and permeability, micro‐resistivity imaging log (MIL) and three‐dimensional seismic data analysis, this work discussed the reservoir characteristics of the member 8 of the Permian Xiashihezi Formation (He 8 sandstones) in the Linxing area of eastern Ordos Basin, determined the factors affecting reservoir quality, and revealed the formation mechanism of relatively high‐permeability areas. The results show that the He 8 sandstones in the Linxing area are mainly composed of feldspathic litharenites, and are typical tight sandstones (with porosity <10% and permeability <1 mD accounting for 80.3% of the total samples). Rapid burial is the main reason for reservoir densification, which resulted in 61% loss of the primary porosity. In this process, quartz protected the original porosity by resisting compaction. The cementation (including carbonate, clay mineral and siliceous cementation) further densified the sandstone reservoirs, reducing the primary porosity with an average value of 28%. The calcite formed in the eodiagenesis occupied intergranular pores and affected the formation of the secondary pores by preventing the later fluid intrusion, and the Fe‐calcite formed in the mesodiagenetic stage densified the sandstones further by filling the residual intergranular pores. The clay minerals show negative effects on reservoir quality, however, the chlorite coatings protected the original porosity by preventing the overgrowth of quartz. The dissolution of feldspars provides extensive intergranular pores which constitute the main pore type, and improves the reservoir quality. The tectonic movements play an important role in improving the reservoir quality. The current tectonic traces of the study area are mainly controlled by the Himalayan movement, and the high‐permeability reservoirs are mainly distributed in the anticline areas. Additionally, the improvement degree (by tectonic movements) of reservoir quality is partly controlled by the original composition of the sandstones. Thus, the selection of potential tight gas well locations in the study area should be focused on the anticline areas with relatively good original reservoir quality. And the phenomena can be referenced for other fluvial tight sandstone basins worldwide.

show abstract

Characteristics and controlling factors of lacustrine tight oil reservoirs of the Triassic Yanchang Formation Chang 7 in the Ordos Basin, China

Cited by 68 publications

References 55 publications

Origin and Distribution of Carbonate Cement in Tight Sandstones: The Upper Triassic Yanchang Formation Chang 8 Oil Layer in West Ordos Basin, China

Origin and Distribution of Carbonate Cement in Tight Sandstones: The Upper Triassic Yanchang Formation Chang 8 Oil Layer in West Ordos Basin, China

The diagenetic and tectonic significance of hydrocarbon accumulation in the southern Junggar Basin, NW China

Characteristics of Tight Sandstone Reservoirs and Controls of Reservoir Quality: A Case Study of He 8 Sandstones in the Linxing Area, Eastern Ordos Basin, China

Contact Info

Product

Resources

About