Reservoir petrofacies — A tool for characterization of reservoir quality and pore structures in a tight sandstone reservoir: a study from the sixth member of Upper Triassic Yanchang Formation, Ordos Basin, China

As an important type of unconventional hydrocarbon, tight sandstone oil has great present and future resource potential. Reservoir quality evaluation is the basis of tight sandstone oil development. A comprehensive evaluation approach based on the gray correlation algorithm is established to effectively assess tight sandstone reservoir quality. Seven tight sandstone samples from the Chang 6 reservoir in the W area of the AS oilfield in the Ordos Basin are employed. First, the petrological and physical characteristics of the study area reservoir are briefly discussed through thin section observations, electron microscopy analysis, core physical property tests, and whole-rock and clay mineral content experiments. Second, the pore type, throat type and pore and throat combination characteristics are described from casting thin sections and scanning electron microscopy. Third, high-pressure mercury injection and nitrogen adsorption experiments are optimized to evaluate the characteristic parameters of pore throat distribution, micro- and nanopore throat frequency, permeability contribution and volume continuous distribution characteristics to quantitatively characterize the reservoir micro- and nanopores and throats. Then, the effective pore throat frequency specific gravity parameter of movable oil and the irreducible oil pore throat volume specific gravity parameter are introduced and combined with the reservoir physical properties, multipoint Brunauer-Emmett-Teller (BET) specific surface area, displacement pressure, maximum mercury saturation and mercury withdrawal efficiency parameters as the basic parameters for evaluation of tight sandstone reservoir quality. Finally, the weight coefficient of each parameter is calculated by the gray correlation method, and a reservoir comprehensive evaluation indicator (RCEI) is designed. The results show that the study area is dominated by types II and III tight sandstone reservoirs. In addition, the research method in this paper can be further extended to the evaluation of shale gas and other unconventional reservoirs after appropriate modification.

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Diagenesis and its controls on reservoir properties and hydrocarbon potential in tight sandstone: a case study from the Upper Triassic Chang 7 oil group of Yanchang Formation, Ordos Basin, China

Arabian Journal of Geosciences ◽

10.1007/s12517-017-3023-z ◽

2017 ◽

Vol 10 (11) ◽

Cited By ~ 7

Author(s):

Yunlong Zhang ◽

Zhidong Bao ◽

Yan Zhao ◽

Li Jiang ◽

Fanhao Gong

Keyword(s):

Ordos Basin ◽

Upper Triassic ◽

Hydrocarbon Potential ◽

Tight Sandstone ◽

Reservoir Properties ◽

Yanchang Formation

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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

Marine and Petroleum Geology ◽

10.1016/j.marpetgeo.2016.09.006 ◽

2016 ◽

Vol 78 ◽

pp. 110-135 ◽

Cited By ~ 68

Author(s):

Yong Zhou ◽

Youliang Ji ◽

Liming Xu ◽

Shiqi Che ◽

Xiaobing Niu ◽

...

Keyword(s):

Ordos Basin ◽

Upper Triassic ◽

Oil Reservoirs ◽

Reservoir Quality ◽

Quality Prediction ◽

Oil Accumulation ◽

Yanchang Formation ◽

Reservoir Heterogeneity

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Multifractal Characteristics and Classification of Tight Sandstone Reservoirs: A Case Study from the Triassic Yanchang Formation, Ordos Basin, China

Energies ◽

10.3390/en11092242 ◽

2018 ◽

Vol 11 (9) ◽

pp. 2242 ◽

Cited By ~ 7

Author(s):

Zhihao Jiang ◽

Zhiqiang Mao ◽

Yujiang Shi ◽

Daxing Wang

Keyword(s):

Pore Structure ◽

Ordos Basin ◽

Type I ◽

Tight Sandstone ◽

Throat Radius ◽

Yanchang Formation ◽

Porosity And Permeability ◽

Sandstone Reservoir ◽

And Migration ◽

Mercury Injection Capillary Pressure

Pore structure determines the ability of fluid storage and migration in rocks, expressed as porosity and permeability in the macroscopic aspects, and the pore throat radius in the microcosmic aspects. However, complex pore structure and strong heterogeneity make the accurate description of the tight sandstone reservoir of the Triassic Yanchang Formation, Ordos Basin, China still a problem. In this paper, mercury injection capillary pressure (MICP) parameters were applied to characterize the heterogeneity of pore structure, and three types of pore structure were divided, from high to low quality and defined as Type I, Type II and Type III, separately. Then, the multifractal analysis based on the MICP data was conducted to investigate the heterogeneity of the tight sandstone reservoir. The relationships among physical properties, MICP parameters and a series of multifractal parameters have been detailed analyzed. The results showed that four multifractal parameters, singularity exponent parameter (αmin), generalized dimension parameter (Dmax), information dimension (D1), and correlation dimension (D2) were in good correlations with the porosity and permeability, which can well characterize the pore structure and reservoir heterogeneity of the study area, while the others didn’t respond well. Meanwhile, there also were good relationships between these multifractal and MICP parameters.

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