The threshold pressure gradient effect in the tight sandstone gas reservoirs with high water saturation

Tian, Weibing; Li, Aifen; Ren, Xiaoxia; Josephine, Yapcheptoyek

doi:10.1016/j.fuel.2018.03.192

Cited by 76 publications

(41 citation statements)

References 36 publications

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“…The TPG increases with lower permeability and smaller pores and throats 23), 24) . Investigation of the effect of TPG on gas flow in the tight sandstone gas reservoir found that the biggest pores and throats of cores start to contribute to gas flow at TPG, similar to the physical phenomenon of entry pressure, and more pores and throats contribute to the flow forming a concave curve by increasing the pressure gradient 23) . After the concave curve, the increasing ratio of airflow rate against the pressure gradient became constant, and the extrapolation line intersects the horizontal axis (flow rate 0) at a pressure gradient of 5.8 kPa/cm, which is called as the pseudo threshold pressure gradient (PTPG) as shown in Fig.…”

Section: Blocking Performance Of In-situ S _ C-gelmentioning

confidence: 88%

Evaluation of In-situ Reservoir Blocking by Sodium Carbonate Gel Formed from Sodium Metasilicate Solution and Injected CO2 for CO2 Sequestration

Samneang

Sasaki

Nguele

et al. 2019

J. Jpn. Petrol. Inst.

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Preventing channeling flows during enhanced oil recovery targeting heterogeneous or fracture type reservoirs and leakage flows from saline aquifers containing CO2 remains a challenge. This study evaluated the potential of in-situ gelation as a blocking agent in a heterogeneous reservoir using the reaction between aqueous solution of sodium metasilicate (Na2SiO3 9H2O; S _ MS) and dissolved carbon dioxide (CO2). Both Raman and scanning electron microscopy/energy dispersive X-ray (SEM-EDS) spectroscopy revealed that the gel was a sodium carbonate type (S _ C-gel). Physical characterization of the S _ C-gel including the gelation time, gel strength and stability, were investigated in respect of S _ MS concentration, temperature, salinity (NaCl), divalent ion concentration (calcium, Ca 2) as well as CO2 injection pressure. Gelation time after CO2 gas injection was around 1 to 24 h depending on temperature and pressure. Gel strength increased with higher S _ MS concentration (≤ 10 wt%) and CO2 gas pressure (≤ 5.5 MPa). Threshold pressure gradient (TPG) and gas permeability of the sandstone core filled with in-situ gel increased by 2.6 times and decreased about 1/10, respectively, compared with the water saturated core. These promising findings herein could be extended to CO2 sequestration.

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Section: Blocking Performance Of In-situ S _ C-gelmentioning

confidence: 88%

Evaluation of In-situ Reservoir Blocking by Sodium Carbonate Gel Formed from Sodium Metasilicate Solution and Injected CO2 for CO2 Sequestration

Samneang

Sasaki

Nguele

et al. 2019

J. Jpn. Petrol. Inst.

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“…According to the roadmap on natural gas development in China, the total production of natural gas will reach 4.5 -5 × 10 12 m 3 in 2020 and the proportion of unconventional gas will then exceed 30% of the total gas production [2]. Due to the low permeability, high water saturation, and complex pore structure of shale gas reservoirs, the gas flow in a low-pressure gradient zone is always slow and non-Darcy [3][4][5][6]. This low-velocity non-Darcy flow has been emphasized in low-permeability reservoirs for the following two issues [3,7,8], which are still unsolved:…”

Section: Introductionmentioning

confidence: 99%

Multi-Scale Insights on the Threshold Pressure Gradient in Low-Permeability Porous Media

Wang

et al. 2020

Symmetry

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Low-permeability porous medium usually has asymmetric distributions of pore sizes and pore-throat tortuosity, thus has a non-linear flow behavior with an initial pressure gradient observed in experiments. A threshold pressure gradient (TPG) has been proposed as a crucial parameter to describe this non-linear flow behavior. However, the determination of this TPG is still unclear. This study provides multi-scale insights on the TPG in low-permeability porous media. First, a semi-empirical formula of TPG was proposed based on a macroscopic relationship with permeability, water saturation, and pore pressure, and verified by three sets of experimental data. Second, a fractal model of capillary tubes was developed to link this TPG formula with structural parameters of porous media (pore-size distribution fractal dimension and tortuosity fractal dimension), residual water saturation, and capillary pressure. The effect of pore structure complexity on the TPG is explicitly derived. It is found that the effects of water saturation and pore pressure on the TPG follow an exponential function and the TPG is a linear function of yield stress. These effects are also spatially asymmetric. Complex pore structures significantly affect the TPG only in the range of low porosity, but water saturation and yield stress have effects on a wider range of porosity. These results are meaningful to the understanding of non-linear flow mechanism in low-permeability reservoirs.

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“…Such tight sandstone consists mainly of nanopores, which are the main passageway for fluid flow . The most common mining technique is depletion; however, tight sandstone gas reservoirs always have high water saturation, so the resistance to gas transport is considerably high, which reduces the gas recovery. Moreover, tight porous media have a complex microstructure; the microchannels and nanochannels reduce intermolecular collisions and enhance molecule‐rock surface collisions, and the surface of clay materials is usually negatively charged.…”

Section: Introductionmentioning

confidence: 99%

Three‐dimensional Lattice Boltzmann simulation of gas‐water transport in tight sandstone porous media: Influence of microscopic surface forces

Wang

Liu

et al. 2020

Energy Science & Engineering

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A three-dimensional two-phase Lattice Boltzmann model was developed and validated for the fundamental phenomena of gas-water transport in tight porous media considering microscopic forces, namely, the electrostatic and solid-liquid intermolecular forces. The thickness of the water film adhering to the porous media surface was calculated based on the principle of thermodynamic equilibrium and the gas-water electrostatic potential energy. The Lattice Boltzmann model simulations focused on the effects of the microscopic forces and water film thickness on the gas-water transport in tight porous media. The fluid flow in the porous media was simulated under different conditions for the characteristic length, interfacial tension, and displacement pressure gradient. The results confirmed that the gas-water transport is strongly affected by the microscopic forces in tight porous media and that the transport process is accompanied by a high seepage resistance. The seepage resistance is more pronounced in the case of smaller pores because the adhering water film is thicker and more stable. During the transport process, the water film may disintegrate under certain conditions, which would enhance the gas flow in the porous media. However, it is difficult to effectively improve the gas flow by increasing the displacement pressure gradient under microscopic forces; this can be attributed to the accumulation of water or increased seepage resistance dictated by the interfacial tension, which occurs more frequently with smaller pores. This paper provides a promising new perspective for efficiently improving the Lattice Boltzmann model for transport trends considering microscopic forces. K E Y W O R D S bounded water film, gas-water two-phase transport, Lattice Boltzmann model, microscopic surface force, tight sandstone gas reservoir | 1925 HU et al. egge (s) The position of the gas leading edge (x/L) The interfacial tension: 0.020 N/m The interfacial tension: 0.025 N/m The interfacial tension: 0.030 N/m The interfacial tension: 0.035 N/m The interfacial tension: 0.040 N/m 0 5 10 15 20 0 0 .2 0.4 0 .6 0.8 1 The breakthrough time of the leading edge (s) The position of the gas leading edge (x/L) The interfacial tension: 0.020 N/m The interfacial tension: 0.025 N/m The interfacial tension: 0.030 N/m The interfacail tension: 0.035 N/m The interfacial tension: 0.040 N/m

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The threshold pressure gradient effect in the tight sandstone gas reservoirs with high water saturation

Cited by 76 publications

References 36 publications

Evaluation of <i>In-situ</i> Reservoir Blocking by Sodium Carbonate Gel Formed from Sodium Metasilicate Solution and Injected CO<sub>2</sub> for CO<sub>2</sub> Sequestration

Evaluation of <i>In-situ</i> Reservoir Blocking by Sodium Carbonate Gel Formed from Sodium Metasilicate Solution and Injected CO<sub>2</sub> for CO<sub>2</sub> Sequestration

Multi-Scale Insights on the Threshold Pressure Gradient in Low-Permeability Porous Media

Three‐dimensional Lattice Boltzmann simulation of gas‐water transport in tight sandstone porous media: Influence of microscopic surface forces

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