Application of NMR Technology on Test of Movable Fluid Saturation of Tight Sandstone Gas Reservoir

2015 ◽  
Vol 1092-1093 ◽  
pp. 1361-1365
Author(s):  
Hong Xia Ming ◽  
Wei Sun ◽  
Ping Wu
Keyword(s):  
Pore Structure ◽  
Transverse Relaxation Time ◽  
Single Peak ◽  
Pore Throat ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Fluid Saturation ◽  
Structure Heterogeneity ◽  
Spectrum Distribution ◽  
The Difference

The difference of movable fluid saturation of tight sandstone gas reservoir is researched, with transverse relaxation time (T2) distribution derived from nuclear magnetic resonance technique (NMR). This article newly calculate T2 cutoff value and elaborate the influence of pore structure on the occurrence characteristics of movable fluid. The study had revealed T2 spectrum distribution includes the following types: (1) wide and flat single peak; (2) left single peak; (3) high left peak with low right peak. Movable fluid saturation is low, with class IV and class V movable fluid mainly. Pore structure control properties and percolation ability of rock reservoir and whether oil could be driven out depends on throat parameters of interconnected pores. Movable fluid saturation is low with bigger pore throat ratio, narrower pore throat distribution and higer pore structure heterogeneity.

Effect of pore-throat structure on gas-water seepage behaviour in a tight sandstone gas reservoir

Fuel ◽  
2021 ◽  
pp. 121901
Author(s):  
Guangfeng Liu ◽  
Shuaiting Xie ◽  
Wei Tian ◽  
Juntao Wang ◽  
Siying Li ◽  
...  
Keyword(s):  
Pore Throat ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Water Seepage

Experimental Simulation on Imbibition of the Residual Fracturing Fluid in Tight Sandstone Reservoirs

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Xiaoxia Ren ◽  
Aifen Li ◽  
Asadullah Memon ◽  
Shuaishi Fu ◽  
Guijuan Wang ◽  
...  
Keyword(s):  
Interfacial Tension ◽  
Oil Recovery ◽  
Experimental Simulation ◽  
Fluid Distribution ◽  
Oil Viscosity ◽  
Pore Throat ◽  
Fracturing Fluid ◽  
Tight Sandstone ◽  
The Difference ◽  
Displacement Processes

Fracturing is a fundamental technique for enhancing oil recovery of tight sandstone reservoir. The pores in tight reservoirs generally have small radii and generate tremendous capillary force; accordingly, the imbibition effect can significantly affect retention and absorption of the fracturing fluid. In this study, the imbibition behaviors of the fracturing fluid were experimentally investigated, and the effects of interfacial tension, (IFT) permeability, oil viscosity, and the salinity of the imbibition fluid were determined. In addition, combining with nuclear magnetic resonance (NMR)-based core analysis, fluid distribution, and the related variations in imbibition and displacement processes were analyzed. Finally, some key influencing factors of imbibition of the residual fracturing fluid, the difference and correlation between imbibition and displacement, as well as the contribution of imbibition to displacement were explored so as to provide optimization suggestions for guiding the application of oil-displacing fracturing fluid in exploration. Results show that imbibition recovery increased with time, but the imbibition rate gradually dropped. There exists an optimal interfacial tension that corresponds to maximum imbibition recovery. In addition, imbibition recovery increased as permeability and salinity increases and oil viscosity decreases. Furthermore, it was found that extracted oil from the movable pore throat space was almost equal to that from the irreducible pore throat space during imbibition and their contribution in the irreducible pore throat space was greater than in the movable pore throat space in the displacement process. Hence, imbibition plays a more important role during the displacement process in the reservoirs with finer porous structure than previously thought.

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.

Gas Seepage Law in Condition of Bound Water of Low Permeability and Tight Sandstone Gas Reservoir

2015 ◽  
Vol 1094 ◽  
pp. 385-388
Author(s):  
Qi Li ◽  
Li You Ye ◽  
Wei Guo An
Keyword(s):  
Bound Water ◽  
Low Permeability ◽  
Pore Throat ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Tight Reservoir ◽  
Gas Seepage ◽  
Pressure Region ◽  
Non Linear ◽  
Seepage Law

In condition of bound water, bound water is distributed on surface of pore throat in the form of water film in low permeability and tight sandstone gas reservoir, so bound water reduces the seepage space of the gas and makes gas to occur Special seepage law. This article design physical simulation research experiment about gas seepage law in containing water reservoir. Experimental results explain: Gas seepage curve existed obvious non-linear seepage region in low permeability reservoir, gas slippage effect happens in the low-pressure region, and high-speed non-Darcy seepage happens in the high-pressure region. With the limit of water and pore throat in tight reservoir, gas hardly occurs specific non-linear seepage phenomenon. The critical water saturation which causes gas effective permeability sudden changing is around 30% in low permeability and tight reservoir. The research result has important theoretical significance on establishing corresponding percolation model of single well productivity and efficient development of low permeability and tight sandstone gas reservoir.

scholarly journals The Impacts of Nano-Micrometer Pore Structure on the Gas Migration and Accumulation in Tight Sandstone Gas Reservoirs

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4102
Author(s):  
Juncheng Qiao ◽  
Xianzheng Zhao ◽  
Jianhui Zeng ◽  
Guomeng Han ◽  
Shu Jiang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Gas Flow ◽  
Physical Simulation ◽  
Effective Porosity ◽  
Gas Migration ◽  
Pore Throat ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Linear Flow ◽  
Small Pore

The uncertainties between reservoir quality and gas migration and accumulation in tight sandstone gas reservoirs are intrinsically attributed to complex microscopic pore structures. Integrated analysis including the physical simulation experiment of gas migration and accumulation, X-ray computed tomography (X-CT), and casting thin section (CTS) were conducted on core plug samples collected from the Upper Paleozoic Permian Lower Shihezi and Shanxi tight sandstone of the Daniudi area in the Ordos Basin to investigate the impacts of pore structure on the gas migration and accumulation. Physical simulation suggested that the gas flows in migration in tight sandstone reservoirs were characterized by deviated-Darcy linear flow and non-linear flow regimes. Minimum and stable migration pressure square gradients determined by application of apparent permeability were employed as key parameters to describe gas flow. Pore structure characterization revealed that the tight sandstone reservoir was characterized by wide pore and throat size distributions and poor pore-throat connectivity. The pore–throat combinations could be divided into three types, including the macropore and coarse throat dominant reservoir, full-pore and full-throat form, and meso-small pore and fine throat dominant form. Comparative analyses indicated that pore and throat radii determined the gas flow regimes by controlling the minimum and stable migration pressure gradients. Gas accumulation capacity was dominated by the connected effective porosity, and the gas accumulation process was controlled by the cumulative effective porosity contribution from macropores to micropores. Variations in pore structures resulted in differences in gas migration and accumulation of tight sandstone reservoirs. The macropore and coarse throat-dominant and the full-pore and full-throat reservoirs exhibited greater gas migration and accumulation potentials than the small pore and fine throat dominate form.

scholarly journals Difference of Microfeatures among Diagenetic Facies in Tight Sandstone Reservoirs of the Triassic Yanchang Formation in the Midwestern Region, Ordos Basin

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Jian Shi ◽  
Xiaolong Wan ◽  
Qichao Xie ◽  
Shuxun Zhou ◽  
Yan Zhou ◽  
...  
Keyword(s):  
Pore Space ◽  
Ordos Basin ◽  
Water Flooding ◽  
Pore Throat ◽  
Tight Sandstone ◽  
Throat Radius ◽  
Yanchang Formation ◽  
Fluid Saturation ◽  
Sandstone Reservoirs ◽  
Diagenetic Facies

Based on the background of sedimentary characteristics, a large amount of core and thin section analysis, taking Chang 6 reservoir of Yanchang Formation in the central and western Ordos Basin as an example, through the application of scanning electron microscopy, high-pressure mercury injection, nuclear magnetic resonance and microscopic water drive oil model, and other experimental test methods, the diagenetic facies types and microscopic pore structure characteristics of tight sandstone reservoirs are discussed and analyzed in depth. The results show that the average porosity loss rate caused by early diagenesis compaction in the study area is 50.62%, which is the main reason for reservoir compactness. The cementation further causes porosity loss, and the later dissolution increases the reservoir space in the study area to a certain extent. Different diagenetic facies reservoirs not only have obvious differences in porosity evolution characteristics but also have significant differences in pore throat radius distribution characteristics, movable fluid occurrence characteristics, and water drive oil characteristics. The pore throat distribution with radius greater than R50∼R60 determines the permeability. The difference in movable fluid saturation mainly depends on the connectivity of the relative large pore space corresponding to the relaxation time greater than the cut-off value of T2. The size of pore throat radius has a good control effect on water flooding efficiency.

scholarly journals Insight into the Pore Structures and Its Impacts on Movable Fluid in Tight Sandstones

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Dazhong Ren ◽  
Fu Yang ◽  
Rongxi Li ◽  
Desheng Zhou ◽  
Dengke Liu ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Pore Structure ◽  
Water Film ◽  
Gas Content ◽  
Pore Throat ◽  
Gas Field ◽  
Fluid Saturation ◽  
Western Area ◽  
Flow Features ◽  
Insight Into

Both the characteristics of pore structure and movable fluid are significant properties in controlling the flow regularity in pores in tight sandstones. However, the governing factors that affect the fluid flow features will still be a myth. In our research, the western area of the Sulige gas field was chosen as the research region, and various kinds of experiments were conducted. Three reservoir groups, including intergranular-dissolved pore type, dissolved-intercrystalline pore type, and pore plus microcracks type were identified on the basis of pore development features. The results suggest that the intergranular-dissolved pore type has a more prominent influence on the high movable fluid saturation and larger pores. Both large throat sizes and homogeneous pore-throat degree demonstrate high movable fluid saturation. The increment of the thickness of water-film resulted from hydrophilic enhancement, indicating that an increased hydrophilic will decrease the movable fluid saturation and block the throats. The reservoirs of different pore combination types are closely related to the gas content of the reservoir.

scholarly journals Investigation effect of wettability and heterogeneity in water flooding and on microscopic residual oil distribution in tight sandstone cores with NMR technique

Open Physics ◽  
2017 ◽  
Vol 15 (1) ◽  
pp. 544-550 ◽  
Author(s):  
Pufu Xiao ◽  
Xiaoyong Leng ◽  
Hanmin Xiao ◽  
Linghui Sun ◽  
Haiqin Zhang ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Physical Simulation ◽  
Spontaneous Imbibition ◽  
Recovery Factor ◽  
Water Flooding ◽  
Pore Throat ◽  
Tight Sandstone ◽  
Large Pore ◽  
Oil Distribution ◽  
The Difference

AbstractIn order to explore the effect of wettability and pore throat heterogeneity on oil recovery efficiency in porous media, physical simulation experiment and nuclear magnetic resonance (NMR) measurements were conducted to investigate how crude oil residing in different sized pores are recovered by water flooding. Experimental results indicate that the recovery factor of water flooding is governed by spontaneous imbibition and also pore throat heterogeneity. It is found that intermediate wetting cores lead to the highest final recovery factor in comparison with water wet cores and weak oil wet cores, and the recovery oil difference in clay micro pore is mainly because of the wettability, the difference in medium pore and large pore is affected by pore throat heterogeneity. Water wet core has a lower recovery factor in medium and large pore due to its poor heterogeneity, in spite of the spontaneous imbibition effect is very satisfying. Intermediate wetting cores has significant result in different sized pore and throat, the difference in medium pore and large pore is affected by pore throat heterogeneity.

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