Low-Permeability Petroleum Resource Assessment Methods of Triassic Yanchang Formation in Ordos Basin

2018 ◽  
Vol 08 (03) ◽  
pp. 475-483
Author(s):  
克 王
Keyword(s):  
Ordos Basin ◽  
Resource Assessment ◽  
Assessment Methods ◽  
Low Permeability ◽  
Yanchang Formation ◽  
Petroleum Resource

Pore structure and fractal characteristics of ultra-low permeability sandstone reservoirs in Upper Triassic Yanchang Formation, Ordos Basin

2021 ◽  
pp. 1-59
Author(s):  
Quanpei Zhang ◽  
Tao Jiao ◽  
Hao Huang ◽  
Zhao Qi ◽  
Tao Jiang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Quality Evaluation ◽  
Pore Space ◽  
Ordos Basin ◽  
Upper Triassic ◽  
Reservoir Quality ◽  
Low Permeability ◽  
Yanchang Formation ◽  
Fractal Characteristics ◽  
Sandstone Reservoirs

The complex pore structure and high heterogeneity of ultra-low permeability sandstone reservoirs have a significant effect on reservoir quality evaluation and hydrocarbon resource assessment. We collected 10 reservoir samples from the Upper Triassic Yanchang Formation Chang 8 in the Zhenbei area of the Ordos Basin. We measured the pore size distribution (PSD) and fluid occurrence characteristics of the reservoir by Pressure-controlled porosimetry (PCP), rate-controlled porosimetry (RCP) and nuclear magnetic resonance (NMR), and then analyzed the results via the fractal theory to determine the pore space fractal characteristics. Our analysis indicates that the three major pore types of these reservoirs are residual intergranular pores, dissolution pores and intercrystalline pores. The pore structure of the ultra-low permeability sandstone reservoirs is highly heterogeneous with pore throats of various scales, and the corresponding fractal characteristics are notably different, exhibiting multi-fractal features. Compared to macropores and mesopores, micropores are more uniform and regular in terms of their PSD and thus only slightly influence the reservoir quality. The complexity of the throat distribution and whole pore space is attributed to the development of dissolution pores and the content of feldspar minerals. Fractal features depend on the movable fluid pore space and effective pores, whose fractal dimensions reflect the complexity of interconnected pores and correlate well with the porosity and permeability. The development of different types and sizes of pore throats in these ultra-low permeability sandstone reservoirs resulted in the observed pore structure heterogeneity. The difference in mineral composition and content of these reservoirs aggravates the pore structure complexity and affects reservoir quality evaluation and further oilfield development.

scholarly journals Characteristics and Genetic Mechanism of Chang Eight Low Permeability and Tight Reservoir of Triassic Yanchang Formation in Central-East Ordos Basin

2022 ◽  
Vol 9 ◽  
Author(s):  
Xingying Wang ◽  
Na Liu ◽  
Junxiang Nan ◽  
Xiaolin Wang ◽  
Dazhong Ren
Keyword(s):  
Ordos Basin ◽  
Physical Property ◽  
Low Permeability ◽  
High Porosity ◽  
X Ray Diffraction ◽  
Yanchang Formation ◽  
Fine Grain ◽  
Tight Reservoir ◽  
Target Layer ◽  
Northern Shaanxi

In this article, the characteristics of Chang 8 reservoir of Triassic Yanchang Formation in northern Shaanxi are studied by using polarizing microscope, field emission scanning electron microscope, image particle size, X-ray diffraction analysis of clay, and constant pressure mercury intrusion. The study shows that the target layer is in a relatively stable and uniform sinking burial period after deposition, and the lithology composition in the area is relatively complex, mainly composed of debris–feldspar sandstone and feldspar sandstone, with the characteristics of fine grain and high content of interstitial material. The porosity of the reservoir is generally between 4% and 12%, with an average of 8.05%. The permeability is generally between 0.03 × 10−3 and 0.5 × 10−3 μm2, with an average of 0.16 × 10−3 μm2. Strong compaction and well-developed cementation of calcareous, siliceous, and authigenic illite are important reasons for the formation of extra-low porosity and extra-low permeability reservoirs. But at the same time, because of the protective effect of chlorite film, some residual intergranular pores are preserved, which makes the some reservoirs with relatively good physical property, forming a local relatively high-porosity and high-permeability section of the “highway.”

scholarly journals Reservoir characteristics of Chang 2 Member of Yanchang Formation in Area A, Ordos Basin

2021 ◽  
Vol 290 ◽  
pp. 03011
Author(s):  
Yajie Jing ◽  
Zhiwu Zhang ◽  
Peng Xu ◽  
Shasha Yang
Keyword(s):  
Ordos Basin ◽  
Low Permeability ◽  
Pore Characteristics ◽  
Yanchang Formation ◽  
Reservoir Characteristics ◽  
Fine Grained ◽  
The Ordos Basin ◽  
Seepage Properties ◽  
Low Permeability Reservoirs ◽  
Good Medium

With the continuous enhancement of exploration and development in the Ordos Basin, in-depth research has been carried out on the petrological and reservoir characteristics of Chang 2 reservoir in Area A, which provides a geological basis for the efficient development of oil reservoirs. Comprehensive use of reservoir sandstone thin section identification casting analysis, mercury intrusion analysis, logging analysis and other methods to systematically study the petrological characteristics, pore characteristics and reservoir physical properties of Chang 2 reservoir in Area A. The results show that the reservoirs in the study area are dominated by fine-grained sandstones, with low component maturity and high structural maturity. They are all medium-low porosity, low-permeability and ultra-low permeability reservoirs. Primary intergranular pores and residual intergranular pores are developed, the reservoir drainage pressure is low, which is good-medium, and the mercury removal efficiency is high, indicating that the reservoir has good storage performance and seepage properties.

Research on Diagenetic Facies of Low Permeability Reservoir: A Case Study of the Yanchang Formation in Longdong Area, Ordos Basin

2012 ◽  
Vol 616-618 ◽  
pp. 145-150
Author(s):  
Jing Fu ◽  
Sheng He Wu
Keyword(s):  
Ordos Basin ◽  
Low Permeability ◽  
Yanchang Formation ◽  
Significant Difference ◽  
Local Medium ◽  
Intensity Calculation ◽  
Diagenetic Facies

Based on data of cast thin section, cathode luminescence and scanning electron microscope, the present paper comprehensively investigated the types and quantitative intensity of reservoir diagenesis of the Upper Triassic Yanchang Formation in Longdong area of Ordos Basin, distinguished the types of diagenetic facies from the aspect of quantitative index. The intensity calculation and classification of compaction, cementation and dissolution indicates that the Yanchang Formation of Longdong area experienced strong compaction including medium to strong compaction and extremely strong compaction locally for the high contents of matrix. There is great difference in cementation intensity which presents mainly in weak cementation with local medium to strong cementation. Dissolution is strong in study area mainly in medium to strong. The reservoir could be divided into eight types of diagenetic facies, including medium compaction with strong dissolution face, medium compaction with medium dissolution face, medium compaction with medium cementation and medium dissolution face, strong compaction with strong dissolution face, strong compaction with medium dissolution face, medium compaction with strong cementation face, strong compaction with strong cementation face and extremely strong compaction face. The reservoir quality of different diagenetic facies has a significant difference.

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