scholarly journals PORE-THROAT STRUCTURE AND FRACTAL CHARACTERISTICS OF SHIHEZI FORMATION TIGHT GAS SANDSTONE IN THE ORDOS BASIN, CHINA

Fractals ◽  
2018 ◽  
Vol 26 (02) ◽  
pp. 1840005 ◽  
Author(s):  
HEXIN HUANG ◽  
LEI CHEN ◽  
WEI SUN ◽  
FENGYANG XIONG ◽  
WEI JI ◽  
...  
Keyword(s):  
Pore Radius ◽  
Ordos Basin ◽  
Fractal Dimensions ◽  
Tight Gas ◽  
Pore Throat ◽  
Mercury Injection ◽  
Constant Rate ◽  
The Ordos Basin ◽  
Mineral Compositions ◽  
Tight Gas Sandstones

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 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 [Formula: see text] and [Formula: see text], and those of throats also corresponding to two throat radius ranges, namely fractal dimensions [Formula: see text] and [Formula: see text], were then calculated using the constant-rate mercury injection data. Fractal dimensions [Formula: see text] and [Formula: see text] 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 [Formula: see text] and [Formula: see text], have larger effective porosity, indicating that more gas volumes can be replaced by liquids. As for tight gas sandstones with lower fractal dimensions [Formula: see text] and [Formula: see text], the effective gas permeability is relatively high. In such cases, gas can flow more easily through the reservoir.

Insight into the Pore Structure of Tight Gas Sandstones: A Case Study in the Ordos Basin, NW China

2017 ◽  
Vol 31 (12) ◽  
pp. 13159-13178 ◽  
Author(s):  
Hao Wu ◽  
Youliang Ji ◽  
Ruie Liu ◽  
Chunlin Zhang ◽  
Sheng Chen
Keyword(s):  
Pore Structure ◽  
Ordos Basin ◽  
Tight Gas ◽  
Nw China ◽  
The Ordos Basin ◽  
Tight Gas Sandstones ◽  
Insight Into

Quantitative Evaluation of Micro Pore Throat Characteristics in Extra Low Permeability Sandstone Oil Reservoir of Yanchang Group in Ordos Basin Using Constant Rate Mercury Penetration Technique

2011 ◽  
Vol 361-363 ◽  
pp. 408-413
Author(s):  
Hui Gao ◽  
Wei Sun
Keyword(s):  
Pore Radius ◽  
Ordos Basin ◽  
Low Permeability ◽  
Oil Reservoir ◽  
Pore Throat ◽  
Throat Radius ◽  
Distribution Ranges ◽  
Constant Rate ◽  
Permeability Distribution ◽  
The Difference

Micro pore throat characteristics of extra low permeability sandstone oil reservoir of Yangchang group in Ordos basin are analyzed using constant rate mercury penetration technique. The results show that pore radius distributes similarly, in 100～200μm, peak values are about 140μm in extra low permeability sandstone oil reservoir. The lower the permeability is, the narrower the distribution ranges of throat are, content of smaller throats become high and variation is more sensitive to permeability, distribution ranges of pore throat radius ratio are wide and permeability has bigger influence on input mercury saturation of throat in extra low permeability sandstone oil reservoir. The difference of pore throat characteristics mainly depends on throat in extra low permeability sandstone oil reservoir. The impacts of pore and throat on total capillary curve are various to different permeability cores, Throat development should be paid more attention in middle or later stage of oil development to extra low permeability sandstone oil reservoir.

scholarly journals Pore structure and fractal characteristics of a tight gas sandstone: A case study of Sulige area in the Ordos Basin, China

2018 ◽  
Vol 36 (6) ◽  
pp. 1438-1460 ◽  
Author(s):  
Hao Wu ◽  
Youliang Ji ◽  
Ruie Liu ◽  
Chunlin Zhang ◽  
Sheng Chen
Keyword(s):  
Pore Structure ◽  
Ordos Basin ◽  
Tight Gas ◽  
Pore Throat ◽  
Gas Reservoirs ◽  
Throat Radius ◽  
Tight Gas Reservoirs ◽  
Fractal Characteristics ◽  
Rate Controlled ◽  
The Ordos Basin

To understand the pore structure and fractal characteristics of tight gas reservoirs, thin sections, nuclear magnetic resonance, rate-controlled mercury injection, microcomputed tomography scanning, and field emission scanning electron microscopy investigations under laboratory conditions were conducted on a suite of core samples from the Middle Permian Shihezi Formation of Sulige area in the Ordos Basin, China. The investigated tight gas sandstones comprise three types of pores, i.e. residual intergranular pore, secondary dissolution pore, and micropore. The pore–throat size distribution is extremely wide and multiscale (10 nm–400 μm) co-existing in tight gas reservoirs. The submicron- and micron-scale pore–throats with radius above 0.05 μm, which are characterized by combining rate-controlled mercury injection with nuclear magnetic resonance, are considered to be the effective pores and throats that dominated the reservoirs flow capacity. Tight gas sandstones have stage fractal characteristics, and the intrusion pressure of approximately 1 MPa is regarded as an inflection point. Fractal dimension is negatively correlated with permeability, average throat radius and mainstream throat radius, positively correlated with heterogeneous coefficient, while there are no obvious relationships with porosity and average pore radius. Additionally, the percolation characteristics of tight gas reservoirs can be characterized by fractal structure. When the pore structure does not follow the fractal structure (i.e. intrusion pressure is lower than 1 MPa), the mercury intrusion saturation is dominated by pores; in contrast, the mercury intrusion saturation is almost solely dominated by throats. This research sheds light on the pore–throat size distribution of tight gas reservoirs by identifying the role of multiple techniques and the relationships between the pore structure parameters and percolation characteristics of tight gas reservoirs and fractal dimension.

scholarly journals Fractal Characterization of Nanopore Structure in Shale, Tight Sandstone and Mudstone from the Ordos Basin of China Using Nitrogen Adsorption

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 583 ◽  
Author(s):  
Xiaohong Li ◽  
Zhiyong Gao ◽  
Siyi Fang ◽  
Chao Ren ◽  
Kun Yang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Pressure Range ◽  
Ordos Basin ◽  
Fractal Dimensions ◽  
Nitrogen Adsorption ◽  
Relative Pressure ◽  
Tight Sandstone ◽  
Porosity And Permeability ◽  
The Ordos Basin ◽  
Nanopore Structure

The characteristics of the nanopore structure in shale, tight sandstone and mudstone from the Ordos Basin of China were investigated by X-ray diffraction (XRD) analysis, porosity and permeability tests and low-pressure nitrogen adsorption experiments. Fractal dimensions D1 and D2 were determined from the low relative pressure range (0 < P/P0 < 0.4) and the high relative pressure range (0.4 < P/P0 < 1) of nitrogen adsorption data, respectively, using the Frenkel–Halsey–Hill (FHH) model. Relationships between pore structure parameters, mineral compositions and fractal dimensions were investigated. According to the International Union of Pure and Applied Chemistry (IUPAC) isotherm classification standard, the morphologies of the nitrogen adsorption curves of these 14 samples belong to the H2 and H3 types. Relationships among average pore diameter, Brunner-Emmet-Teller (BET) specific surface area, pore volume, porosity and permeability have been discussed. The heterogeneities of shale nanopore structures were verified, and nanopore size mainly concentrates under 30 nm. The average fractal dimension D1 of all the samples is 2.1187, varying from 1.1755 to 2.6122, and the average fractal dimension D2 is 2.4645, with the range from 2.2144 to 2.7362. Compared with D1, D2 has stronger relationships with pore structure parameters, and can be used for analyzing pore structure characteristics.

Application of 3D seismic attributes to optimize the placement of horizontal wells within a tight gas sand reservoir, Ordos Basin, China

Geophysics ◽  
2016 ◽  
Vol 81 (3) ◽  
pp. B77-B86 ◽  
Author(s):  
Zhiguo Wang ◽  
Jinghuai Gao ◽  
Xiaolan Lei ◽  
Xiaojie Cui ◽  
Daxing Wang
Keyword(s):  
Seismic Data ◽  
Ordos Basin ◽  
Horizontal Wells ◽  
Tight Gas ◽  
3D Seismic ◽  
Seismic Attribute ◽  
Horizontal Drilling ◽  
The Ordos Basin ◽  
Gas Bearing ◽  
3D Seismic Data

The Lower Permian Xiashihezi Formation in the Ordos Basin, China, is a quartz-sandstone reservoir with low porosity and low permeability. We have acquired 3D seismic data and well data from 18 vertical and four horizontal wells to indicate the potential of seismic attribute analyses in locating seismic sweet spots for lateral placement of horizontal wells. Using the analytic wavelet transform with a Morse wavelet, the integration of high tuning spectral components, high sweetness and high spectral attenuation helped us to estimate the distribution of gas-bearing tight sands in the Xiashihezi Formation. Our results revealed that the principal target of horizontal drilling and production was gas-bearing massive point bars in the braided river delta setting of the Ordos Basin. The integrated workflow of the seismic attribute analysis contributes to the optimal horizontal well planning by mining and exposing critical geological information of a tight gas sand reservoir from within 3D seismic data.

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