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

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.

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

Fuel ◽

10.1016/j.fuel.2021.121901 ◽

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

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Applicability Analysis of Klinkenberg Slip Theory in the Measurement of Tight Core Permeability

Energies ◽

10.3390/en12122351 ◽

2019 ◽

Vol 12 (12) ◽

pp. 2351 ◽

Cited By ~ 2

Author(s):

Jirui Zou ◽

Xiangan Yue ◽

Weiqing An ◽

Jun Gu ◽

Liqi Wang

Keyword(s):

High Pressure ◽

Gas Permeability ◽

Fluid Dynamic ◽

Dynamic Parameter ◽

Low Pressure ◽

Low Permeability ◽

Apparent Permeability ◽

Tight Reservoir ◽

Gas Seepage ◽

The Relationship

The Klinkenberg slippage theory has widely been used to obtain gas permeability in low-permeability porous media. However, recent research shows that there is a deviation from the Klinkenberg slippage theory for tight reservoir cores under low-pressure conditions. In this research, a new experimental device was designed to carry out the steady-state gas permeability test with high pressure and low flowrate. The results show that, unlike regular low-permeability cores, the permeability of tight cores is not a constant value, but a variate related to a fluid-dynamic parameter (flowrate). Under high-pressure conditions, the relationship between flowrate and apparent permeability of cores with low permeability is consistent with Klinkenberg slippage theory, while the relationship between flowrate and apparent permeability of tight cores is contrary to Klinkenberg slip theory. The apparent permeability of tight core increases with increasing flowrate under high-pressure conditions, and it is significantly lower than the Klinkenberg permeability predicted by Klinkenberg slippage theory. The difference gets larger when the flowrate becomes lower (back pressure increases and pressure difference decreases). Therefore, the Klinkenberg permeability which is obtained by the Klinkenberg slippage theory by using low-pressure experimental data will cause significant overestimation of the actual gas seepage capacity in the tight reservoir. In order to evaluate the gas seepage capacity in a tight reservoir precisely, it is necessary to test the permeability of the tight cores directly at high pressure and low flowrate.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1092-1093.1361 ◽

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.

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Influence of clay minerals and cementation on pore throat of tight sandstone gas reservoir in the eastern Ordos Basin, China

Journal of Natural Gas Science and Engineering ◽

10.1016/j.jngse.2020.103762 ◽

2021 ◽

Vol 87 ◽

pp. 103762

Author(s):

Bo Jiu ◽

Wenhui Huang ◽

Yuan Li ◽

Mingqian He

Keyword(s):

Clay Minerals ◽

Ordos Basin ◽

Pore Throat ◽

Tight Sandstone ◽

Gas Reservoir

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Experimental Simulation of Gas Seepage Characteristics of a Low-Permeability Volcanic Rock Gas Reservoir Under Different Water Saturations

Chemistry and Technology of Fuels and Oils ◽

10.1007/s10553-015-0593-x ◽

2015 ◽

Vol 51 (2) ◽

pp. 199-206 ◽

Cited By ~ 3

Author(s):

Zhidi Liu ◽

Jingzhou Zhao ◽

Hongxian Liu ◽

Jian Wang

Keyword(s):

Volcanic Rock ◽

Experimental Simulation ◽

Low Permeability ◽

Gas Reservoir ◽

Gas Seepage ◽

Seepage Characteristics

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Threshold Pore Pressure Gradients in Water-Bearing Tight Sandstone Gas Reservoirs

Energies ◽

10.3390/en12234578 ◽

2019 ◽

Vol 12 (23) ◽

pp. 4578

Author(s):

Yong Wang ◽

Yunqian Long ◽

Yeheng Sun ◽

Shiming Zhang ◽

Fuquan Song ◽

...

Keyword(s):

Water Saturation ◽

High Water ◽

Linear Regression Method ◽

Tight Gas ◽

Gas Reservoirs ◽

Tight Sandstone ◽

Gas Reservoir ◽

Gas Seepage ◽

Tight Gas Reservoir ◽

Core Permeability

Tight gas reservoirs commonly occur in clastic formations having a complex pore structure and a high water saturation, which results in a threshold pressure gradient (TPG) for gas seepage. The micropore characteristics of a tight sandstone gas reservoir (Tuha oilfield, Xinjiang, China) were studied, based on X-ray diffraction, scanning electron microscopy and high pressure mercury testing. The TPG of gas in cores of the tight gas reservoir was investigated under various water saturation conditions, paying special attention to core permeability and water saturation impact on the TPG. A mathematical TPG model applied a multiple linear regression method to evaluate the influence of core permeability and water saturation. The results show that the tight sandstone gas reservoir has a high content of clay minerals, and especially a large proportion of illite–smectite mixed layers. The pore diameter is distributed below 1 micron, comprising mesopores and micropores. With a decrease of reservoir permeability, the number of micropores increases sharply. Saturated water tight cores show an obvious non-linear seepage characteristic, and the TPG of gas increases with a decrease of core permeability or an increase of water saturation. The TPG model has a high prediction accuracy and shows that permeability has a greater impact on TPG at high water saturation, while water saturation has a greater impact on TPG at low permeability.

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Influence of CO2-brine-rock Interactions on the Physical Properties of Tight Sandstone Cores via Nuclear Magnetic Resonance

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/898/1/012021 ◽

2021 ◽

Vol 898 (1) ◽

pp. 012021

Author(s):

Hanbin Liu ◽

Chengzheng Li ◽

Zhenfeng Zhao ◽

Guangtao Wang ◽

Changheng Li ◽

...

Keyword(s):

Nuclear Magnetic Resonance ◽

Physical Properties ◽

Oil Recovery ◽

Injection Pressure ◽

Low Permeability ◽

Pore Throat ◽

Tight Sandstone ◽

The Core ◽

Before And After ◽

Enhance Oil Recovery

Abstract For sandstone reservoirs with extra-low permeability, CO2 injection is regarded as a valid method to enhance oil recovery. When CO2 injection is implemented in such reservoirs, the physical properties of the formation could be altered owing to the interactions between CO2, water, and rock. In this study, the influence of CO2–brine–rock interactions on the physical properties of tight sandstone cores was analyzed by comparing the obtained T 2 spectrum before and after CO2 injection. The results revealed that the T2 spectrum after CO2 injection was significantly different from the original T2 spectrum. CO2 injection changed the pore size distribution of the core samples. When the injection pressure was low, the pore volume decreased from micropores to macropores leading to a decrease in both permeability and porosity. As the injection pressure increasing, the dissolution of CO2 in the micropores was enhanced thus improving the pore-throat connectivity; which ultimately improved the reservoir physical properties.

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Influence of Pore Throat Structure and the Multiphases Fluid Seepage on Mobility of Tight Oil Reservoir

Lithosphere ◽

10.2113/2021/5525670 ◽

2021 ◽

Vol 2021 (Special 1) ◽

Author(s):

Fan Zhang ◽

Hanmin Xiao ◽

Zhenxue Jiang ◽

Xianglu Tang ◽

Xuewei Liu ◽

...

Keyword(s):

Water Saturation ◽

Bound Water ◽

Effective Porosity ◽

Tight Oil ◽

Pore Throat ◽

Tight Sandstone ◽

Throat Radius ◽

Small Pore ◽

Fluid Seepage ◽

Phase Mobility

Abstract Mobility is the main factor restricting the production of tight oil. In order to explore the influence of pore throat structure and fluid seepage on the mobility, six tight sandstone samples are selected by high-pressure mercury intrusion, nuclear magnetic resonance, water driving oil experiments, and oil-water relative permeability experiments to discuss the influence of pore structure and multiphases on the mobility of tight oil. The results indicate that with the increase in effective porosity, more oil and water are exchanged, and the mobility of the oil phase is enhanced. The large pore is positively correlated with the mobility of tight oil while the relationship between the mobility of small pore and effective porosity remains unclear. Particularly, the mobility of the tight oil is determined by the matching relationship between the pore throat radius and the sorting of the tight reservoir. Specifically, the smaller the two-phase copermeation zone, the greater the bound water saturation; the greater the slope of the oil phase permeability curve, the less the space for the two phases to flow together; the more the oil blocked by water in the reservoir, the worse the phase mobility. The mobility of tight oil can be divided into four categories by pore throat radius, pore throat sorting coefficient, and bound water saturation.

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