Controls on reservoir heterogeneity of tight sand oil reservoirs in Upper Triassic Yanchang Formation in Longdong Area, southwest Ordos Basin, China: Implications for reservoir quality prediction and oil accumulation

Zhou, Yong; Ji, Youliang; Xu, Liming; Che, Shiqi; Niu, Xiaobing; Lü, Wei; Zhou, Yuqi; Li, Zhicheng; You, Yonghua

doi:10.1016/j.marpetgeo.2016.09.006

Cited by 135 publications

(83 citation statements)

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“…Hence, it is inappropriate to simply treat pores and throats as a whole. 28,35 The shapes of the 20 constant-rate mercury capillary pressure curves can be generally divided into three types. The first type is the pore type, which shows that in the large-throat rock, the mercury injection volume of pores rises rapidly and always exceeds that of throats, even after the mercury injection approaches the equilibrium (Fig.…”

Section: Constant-rate Mercury Injectionmentioning

confidence: 99%

Pore-Throat Structure and Fractal Characteristics of Shihezi Formation Tight Gas Sandstone in the Ordos Basin, China

et al. 2018

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In order to better understand the impact of fractal features of pore-throat structures on effective physical properties of tight gas sandstones, this paper carried out constant-rate mercury ‡ ‡ Corresponding authors. This is an Open Access article published by World Scientific Publishing Company. It is distributed under the terms of the Creative Commons Attribution 4.0 (CC-BY) License. Further distribution of this work is permitted, provided the original work is properly cited. 1840005-1Fractals 2018.26. Downloaded from www.worldscientific.com by 13.66.222.141 on 04/01/19. Re-use and distribution is strictly not permitted, except for Open Access articles. H. Huang et al.injection tests, gas-water permeability analyses, helium-based porosity and nitrogen pulse decay permeability measurements, and SEM and casting thin-section analyses on 20 sandstone samples of the Shihezi Formation from 16 wells of the Sulige Gas Field in the Ordos Basin, China. The fractal dimensions of pores corresponding to two pore radius ranges, namely fractal dimensions D p2 and D p3 , and those of throats also corresponding to two throat radius ranges, namely fractal dimensions D t1 and D t2 , were then calculated using the constant-rate mercury injection data. Fractal dimensions D p2 and D p3 are negatively correlated with the average pore radius and pore volume as well as quartz content, and they are positively related to contents of clay minerals and lithic fragments. Compared with pore fractal dimensions, throat fractal dimensions have lower correlations with throat structural parameters, and show vague relations with mineral compositions. Although the effects imposed by mineral compositions upon throat structures are similar to those upon pore structures, the flake-like and curved shapes of throats result in irregularity of fractal dimensions. Tight gas sandstones, with smaller fractal dimensions D p2 and D p3 , have larger effective porosity, indicating that more gas volumes can be replaced by liquids. As for tight gas sandstones with lower fractal dimensions D p3 and D t2 , the effective gas permeability is relatively high. In such cases, gas can flow more easily through the reservoir.

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Section: Constant-rate Mercury Injectionmentioning

confidence: 99%

Pore-Throat Structure and Fractal Characteristics of Shihezi Formation Tight Gas Sandstone in the Ordos Basin, China

et al. 2018

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“…During the Late Triassic, the Yanchang Formation is dominated by fluvial, lacustrine, and deltaic sedimentation with a thickness of 1,000–1,300 m throughout most of the Ordos Basin (Figure ; Cui et al, ; Qiu, Liu, Wang, Deng, & Mao, ; Zou, Wang, Li, Tao, & Hou, ). Recent hydrocarbon exploration and outcrop studies have demonstrated that shallow‐lacustrine sand‐rich deltas developed extensively along the gentle slopes and central part of the basin, forming the main reservoir rocks of the Triassic oilfields (Zhou et al, ). The vertical facies succession indicates that the Yanchang Formation covers the entire lacustrine life cycle of the Late Triassic Ordos Basin (Figure ; Zou et al, ).…”

Section: Geological Backgroundmentioning

confidence: 99%

“…Diagenesis of the tight sandstone in Yanchang Formation has been reported in some published works, most of which are focused on the Chang 7 Member (e.g., Cui et al, ; Dou, Liu, Wu, Xu, & Feng, ; Wu et al, ; Zhang, Bao, Zhao, Jiang, & Gong, ; Zhu et al, ). However, limited attention has been paid to the Chang 8 Member (Liu, Liu, Wang, & Pan, ; Wang, Chang, Yin, Li, & Song, ; Zhou et al, ), as well as the relationship between diagenesis and reservoir quality based on the diagenetic geochemical system. Additionally, although the effects of diagenetic alterations have been well studied to provide valuable interpretations for tight sandstone reservoir quality, difficulties remain when applying the present results to predict the “sweet zones” of anomalously high porosity and permeability within the tight sandstone reservoirs of Chang 8 Member.…”

Section: Introductionmentioning

confidence: 99%

Tight oil sandstones in Upper Triassic Yanchang Formation, Ordos Basin, N. China: Reservoir quality destruction in a closed diagenetic system

et al. 2018

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An investigation of the Triassic Yanchang Formation, Ordos Basin, N. China, revealed that the diagenesis and quality of tight oil sandstone reservoirs (with an average porosity of 9.83% and an average permeability of 0.96 mD) were controlled by a closed diagenetic system. The carbonate cements observed in the sandstone were derived from decarboxylation of organic matter that occurred in the adjacent mudstones. These reactions supplied CO32−, which reacted with cations derived from grain dissolution in the sandstones. The average size of the diagenetic geochemical system with respect to carbonate cements was small (<6 × 10−2 m3), comprising sandstone and its adjacent mudstone(s). The carbonate cements tend to concentrate in the marginal sandstone, which is taken to indicate that the flux of CO32− into the sandstones limited the quantity of carbonate precipitated. In addition, the mass is near balance between the amount of feldspar dissolution and its by‐products in the central sandstone (distance to the sandstone/mudstone interface is mainly more than 1 m), where the permeability of sandstone will present a decreasing trend with the increase of feldspar dissolution pores. The pore space of central sandstone will be just redistributed, with primary intergranular pores converting to feldspar dissolution pores and clay mineral micropores. Thus, the best part of the sandstone reservoirs tends to be the central part of sandstone. In particular, sandstones that are more than 2 m thick could be the potential hydrocarbon reservoirs because they retain the best porosity (average of 13.6%) and permeability (average of 1.8 mD). The results of our study provide an important guide for the exploration of tight oil sandstones in other petroliferous basins over the world.

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“…The deposition in other sedimentary facies, floodplain, flood fan, etc, is mainly composed of silty mudstone, mudstone, and it is thin in thickness with low porosity and permeability. High‐quality reservoirs usually are found in the places where sandstones are massive or parallel superposed with favourable physical characteristics (Zhou et al, ). Therefore, it is assumed that the point bar and river channel sand bodies are the major reservoirs for gas in the Su6‐Zhao42 area.…”

Section: Characteristics Of Tight Gas Reservoirmentioning

confidence: 99%

Potentials of low permeability gas in intracratonic basin: Insights from sedimentary facies of the Shan1 Member in the Su6‐Zhao42 Block of the Sulige gas field, Ordos Basin

Wang

Liu

et al. 2017

Geological Journal

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The Sulige gas field is a typical low permeability gas field with multi‐thin layer of pay zones. The upper member of the Shanxi Formation (Shan1) is the primary productive layer of the Su6‐Zhao42 area, located in the north‐west of the Shanbei Slope of the Sulige gas field. The Shan1 Member could be divided into 3 tiny sequences by coring and well logging data. On the basis of sedimentary sequence analysis, the sedimentary environment and facies are studied combined with lithological information, logging data, and sampling. This paper summarizes the characteristics and distribution of the sedimentary facies of the Shan1 Member in the Su6‐Zhao42 area. During the deposition of the Shan1 Member, this area developed a meandering river sedimentary facies, which can be subdivided into meandering riverbed, river floodplain, and abandoned channel subfacies. The sedimentary facies of meandering river in the Shan1 Member are characterized by point bars, crevasse splays, floodplains, flood swamps, and abandoned channels. The sedimentary facies bands extend roughly east‐west parallel to the meandering river. It is indicated that the sand bodies deposited in river channel have better physical conditions and larger thickness for gas accumulation based on the analysis of physical characteristics and seismic attributes. The effective reservoir, being controlled by the sedimentary facies belt, distributes along a NE–SW trending belt where is the favourable area for the gas reservoir.

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Controls on reservoir heterogeneity of tight sand oil reservoirs in Upper Triassic Yanchang Formation in Longdong Area, southwest Ordos Basin, China: Implications for reservoir quality prediction and oil accumulation

Cited by 135 publications

References 54 publications

Pore-Throat Structure and Fractal Characteristics of Shihezi Formation Tight Gas Sandstone in the Ordos Basin, China

Pore-Throat Structure and Fractal Characteristics of Shihezi Formation Tight Gas Sandstone in the Ordos Basin, China

Tight oil sandstones in Upper Triassic Yanchang Formation, Ordos Basin, N. China: Reservoir quality destruction in a closed diagenetic system

Potentials of low permeability gas in intracratonic basin: Insights from sedimentary facies of the Shan1 Member in the Su6‐Zhao42 Block of the Sulige gas field, Ordos Basin

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