scholarly journals Characteristics of microscopic pore-throat structure of tight oil reservoirs in Sichuan Basin measured by rate-controlled mercury injection

Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 675-684 ◽  
Author(s):  
Xinli Zhao ◽  
Zhengming Yang ◽  
Wei Lin ◽  
Shengchun Xiong ◽  
Yunyun Wei
Keyword(s):  
Sichuan Basin ◽  
Pore Radius ◽  
Oil Reservoirs ◽  
Tight Oil ◽  
Pore Throat ◽  
Tight Sandstone ◽  
Throat Radius ◽  
Mercury Injection ◽  
Rate Controlled ◽  
Tight Oil Reservoirs

Abstract Based on the results of rate-controlled mercury-injection experiments, the microscopic pore-throat structure characteristics of tight sandstone in Sha-1 Section and tight limestone in Da’anzhai Section of Sichuan Basin were quantitatively characterized. The results show that the pore radius distribution characteristics of tight oil reservoirs are similar. The main distribution is between 100~190 μm, and the average pore radius is 160 μm. While the distribution of the throat radius of tight sandstone and limestone is quite different, the distribution of the throat of sandstone samples is relatively concentrated, and the distribution of the throat of limestone samples is relatively sparse. There is a good positive correlation between the average throat radius and permeability, but the correlation between fractal dimension and permeability is not obvious. This indicates that the permeability is mainly affected by the radius of the throat. The pore-throat ratio in tight oil reservoirs is relatively large, and the resistance to seepage is greater during development. Therefore, during the development of tight oil, measures should be taken to increase the radius of the throat, reduce the ratio of pore radius to pore-throat radius, and improve the seepage capacity of the reservoir, thereby improving the development of tight oil.

A full-scale characterization method and application for pore-throat radius distribution in tight oil reservoirs

2020 ◽  
Vol 187 ◽  
pp. 106857 ◽  
Author(s):  
Qianhua Xiao ◽  
Zhengming Yang ◽  
Zhiyuan Wang ◽  
Zhilin Qi ◽  
Xuewu Wang ◽  
...  
Keyword(s):  
Full Scale ◽  
Oil Reservoirs ◽  
Tight Oil ◽  
Pore Throat ◽  
Throat Radius ◽  
Tight Oil Reservoirs ◽  
Scale Characterization

scholarly journals Novel method for determining the lower producing limits of pore-throat radius and permeability in tight oil reservoirs

2021 ◽  
Vol 7 ◽  
pp. 1651-1656
Author(s):  
Qianhua Xiao ◽  
Zhiyuan Wang ◽  
Zhengming Yang ◽  
Zuping Xiang ◽  
Zhonghua Liu ◽  
...  
Keyword(s):  
Oil Reservoirs ◽  
Tight Oil ◽  
Pore Throat ◽  
Throat Radius ◽  
Novel Method ◽  
Tight Oil Reservoirs

scholarly journals An improved method to characterize the pore-throat structures in tight sandstone reservoirs: Combined high-pressure and rate-controlled mercury injection techniques

2020 ◽  
Vol 38 (6) ◽  
pp. 2389-2412
Author(s):  
Wenkai Zhang ◽  
Zejin Shi ◽  
Yaming Tian
Keyword(s):  
High Pressure ◽  
Size Distribution ◽  
Great Influence ◽  
Pore Throat ◽  
Tight Sandstone ◽  
Throat Radius ◽  
Thin Sections ◽  
Mercury Injection ◽  
Rate Controlled ◽  
Sandstone Reservoirs

The pore-throat size determines the oil and gas occurrence and storage properties of sandstones and is a vital parameter to evaluate reservoir quality. Casting thin sections, field emission scanning electron microscopy, high-pressure mercury injection and rate-controlled mercury injection are used to qualitatively and quantitatively investigate the pore-throat structure characteristics of tight sandstone reservoirs of Xiaoheba Formation in the southeastern Sichuan Basin. The results show that the pore types include intergranular pores, intragranular dissolved pores, matrix pores, intercrystalline pores in clay minerals, and microfractures, and the pore-throat sizes range from the nanoscale to the microscale. The high-pressure mercury injection testing indicates that the pore-throat radius is in range of 0.004–11.017 µm, and the pore-throats with a radius >1 µm account for less than 15%. The rate-controlled mercury injection technique reveals that the tight sandstones with different physical properties have a similar pore size distribution (80–220 µm), but the throat radius and pore throat radius ratio distribution curves exhibit remarkable differences separately. The combination of the high-pressure mercury injection and rate-controlled mercury injection testing used in this work effectively reveals the total pore-throat size distribution in the Xiaoheba sandstones (0.004–260 µm). Moreover, the radius of the pore and the throat is respectively in range of 50–260 µm and 0.004–50 µm. The permeability of the tight sandstones is mostly affected by the small fraction (<40%) of relatively wide pore-throats. For the tight sandstones with good permeability (>0.1 mD), the larger micropores and mesopores exert a great influence on the permeability. In contrast, the permeability is mainly influenced by the larger nanopores. Furthermore, the proportion of narrow pore-throats in tight sandstones increases with reducing permeability. Although the large number of narrow pore-throat (<100 nm) makes a certain contribution to both reservoir porosity and permeability, they have contribution to the former is far more than to the latter.

scholarly journals OVERALL PSD AND FRACTAL CHARACTERISTICS OF TIGHT OIL RESERVOIRS: A CASE STUDY OF LUCAOGOU FORMATION IN JUNGGAR BASIN, CHINA

Fractals ◽  
2019 ◽  
Vol 27 (01) ◽  
pp. 1940005 ◽  
Author(s):  
XIXIN WANG ◽  
JIAGEN HOU ◽  
YUMING LIU ◽  
PEIQIANG ZHAO ◽  
KE MA ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Pore Radius ◽  
Junggar Basin ◽  
Oil Reservoirs ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Mercury Injection ◽  
Fractal Characteristics ◽  
Tight Oil Reservoir ◽  
Tight Oil Reservoirs

Lucaogou tight oil reservoir, located in the Junggar Basin, Northwest of China, is one of the typical tight oil reservoirs. Complex lithology leads to a wide pore size distribution (PSD), ranging from several nanometers to hundreds of micrometers. To better understand PSD and fractal features of Lucaogou tight oil reservoir, the experiment methods including scanning electron microscope (SEM), rate-controlled mercury injection (RMI) and pressure-controlled mercury injection (PMI) were performed on the six samples with different lithology. The results indicate that four types of pores exist in Lucaogou tight oil reservoir, including dissolution pores, clay dominated pores, microfractures and inter-granular pores. A combination of PMI and RMI was proposed to calculate the overall PSD of tight oil reservoirs, the overall pore radius of Lucaogou tight oil reservoir ranges from 3.6[Formula: see text]nm to 500[Formula: see text][Formula: see text]m. The fractal analysis was carried out based on the PMI data. Fractal dimension (Fd) values varied between 2.843 and 2.913 with a mean value of 2.88. Fd increases with a decrease of quartz content and an increase of clay mineral content. Samples from tight oil reservoirs with smaller average pore radius have stronger complexity of pore structure. Fractal dimension shows negative correlations with porosity and permeability. In addition, fractal characteristics of different tight reservoirs were compared and analyzed.

Effects of Water Immersion and Acidification on Nano-Pores in Tight Sandstones—A Case Study of the Gaotaizi Reservoir, Songliao Basin

2021 ◽  
Vol 21 (1) ◽  
pp. 615-622
Author(s):  
Min Wang ◽  
Chenxue Jiao ◽  
Nengwu Zhou ◽  
Chuanming Li ◽  
Mingming Tang ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Water Immersion ◽  
Songliao Basin ◽  
Oil Reservoirs ◽  
Tight Oil ◽  
Core Flooding ◽  
Carbonate Minerals ◽  
Tight Sandstone ◽  
Content Type ◽  
Tight Oil Reservoirs

Hydraulic fracturing and acidification are among the most commonly used methods for stimulating the tight oil reservoirs and improving oil recovery. Therefore, examining the effects of water immersion and acidification on tight oil reservoirs is important for oilfield development plans. Core flooding testing, which analyzes the influence of core permeability variations before and after acid injection on the reservoir quality, is the conventional research method; however, it is difficult to observe the changes in minerals and pores caused by acidulation and water immersion in situ. In this study, we conduct field-emission scanning electron microscopy (FE-SEM), MAPS, the quantitative evaluation of minerals through scanning electronic microscopy (QEM-SCAN), and describe the types of pores in tight sandstone. Further, the effects of water immersion and acidification on pores in tight sandstone were studied. The results indicate that: (1) intergranular pores, intragranular dissolution pores, clay mineral intercrystalline pores, and micro-cracks were developed in the Gaotaizi tight sandstone in Songliao Basin, with the intergranular pores observed to be dominant; (2) the hydration of clay minerals induced by water injection caused plugging of pores at the nanometer– micrometer scale, and plane porosity is slightly reduced (˜0.86%); (3) acidification resulted in the dissolution of carbonate minerals, increasing the porosity of the reservoir, therefore, the increase in porosity is influenced by the carbonate mineral content. We recommend that future studies should investigate the content, type, and distribution of carbonate minerals in the operation area. During the process of reservoir stimulation, such as acidification and CO2 injection- and-production, the influence of carbonate minerals dissolution on oil production should be considered.

scholarly journals Research on Characterization and Heterogeneity of Microscopic Pore Throat Structures in Tight Oil Reservoirs

ACS Omega ◽  
2021 ◽  
Author(s):  
Xinli Zhao ◽  
Zhengming Yang ◽  
Sibin Zhou ◽  
Yutian Luo ◽  
Xuewei Liu ◽  
...  
Keyword(s):  
Oil Reservoirs ◽  
Tight Oil ◽  
Pore Throat ◽  
Tight Oil Reservoirs

scholarly journals Pore throat characteristics of tight reservoirs by a combined mercury method: A case study of the member 2 of Xujiahe Formation in Yingshan gasfield, North Sichuan Basin

2021 ◽  
Vol 13 (1) ◽  
pp. 1174-1186
Author(s):  
Youzhi Wang ◽  
Cui Mao ◽  
Qiang Li ◽  
Wei Jin ◽  
Simiao Zhu ◽  
...  
Keyword(s):  
Pore Structure ◽  
Distribution Range ◽  
Contribution Rate ◽  
Pore Throat ◽  
Tight Sandstone ◽  
Throat Radius ◽  
Xujiahe Formation ◽  
Mercury Injection ◽  
Tight Reservoirs ◽  
Sandstone Reservoirs

Abstract The complex pore throat characteristics are significant factors that control the properties of tight sandstone reservoirs. Due to the strong heterogeneity of the pore structure in tight reservoirs, it is difficult to characterize the pore structure by single methods. To determine the pore throat, core, casting thin sections, micrographs from scanning electron microscopy, rate-controlled mercury injection, and high-pressure mercury injection were performed in member 2 of Xujiahe Formation of Yingshan gasfield, Sichuan, China. The pore throat characteristics were quantitatively characterized, and the distribution of pore throat at different scales and its controlling effect on reservoir physical properties were discussed. The results show that there are mainly residual intergranular pores, intergranular dissolved pores, ingranular dissolved pores, intergranular pores, and micro-fractures in the second member of the Xujiahe Formation tight sandstone reservoir. The distribution range of pore throat is 0.018–10 μm, and the radius of pore throat is less than 1 μm. The ranges of pore radius were between 100 and 200 μm, the peak value ranges from 160 to 180 μm, and the pore throat radius ranges from 0.1 to 0.6 μm. With the increase of permeability, the distribution range of throat radius becomes wider, and the single peak throat radius becomes larger, showing the characteristic of right skew. The large throat of the sandy conglomerate reservoir has an obvious control effect on permeability, but little influence on porosity. The contribution rate of nano-sized pore throat to permeability is small, ranging from 3.29 to 34.67%. The contribution rate of porosity was 48.86–94.28%. Therefore, pore throat characteristics are used to select high-quality reservoirs, which can guide oil and gas exploration and development of tight sandstone reservoirs.

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