scholarly journals NMR Analysis Method of Gas Flow Pattern in the Process of Shale Gas Depletion Development

Geofluids ◽  
2022 ◽  
Vol 2022 ◽  
pp. 1-7
Author(s):  
Rui Shen ◽  
Zhiming Hu ◽  
Xianggang Duan ◽  
Wei Sun ◽  
Wei Xiong ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Pore Pressure ◽  
Shale Gas ◽  
Gas Flow ◽  
Continuous Medium ◽  
Slip Flow ◽  
Flow Patterns ◽  
Transitional Flow ◽  
Analysis Method ◽  
Adsorbed Gas

Shale gas reservoirs have pores of various sizes, in which gas flows in different patterns. The coexistence of multiple gas flow patterns is common. In order to quantitatively characterize the flow pattern in the process of shale gas depletion development, a physical simulation experiment of shale gas depletion development was designed, and a high-pressure on-line NMR analysis method of gas flow pattern in this process was proposed. The signal amplitudes of methane in pores of various sizes at different pressure levels were calculated according to the conversion relationship between the NMR T 2 relaxation time and pore radius, and then, the flow patterns of methane in pores of various sizes under different pore pressure conditions were analyzed as per the flow pattern determination criteria. It is found that there are three flow patterns in the process of shale gas depletion development, i.e., continuous medium flow, slip flow, and transitional flow, which account for 73.5%, 25.8%, and 0.7% of total gas flow, respectively. When the pore pressure is high, the continuous medium flow is dominant. With the gas production in shale reservoir, the pore pressure decreases, the Knudsen number increases, and the pore size range of slip flow zone and transitional flow zone expands. When the reservoir pressure is higher than the critical desorption pressure, the adsorbed gas is not desorbed intensively, and the produced gas is mainly free gas. When the reservoir pressure is lower than the critical desorption pressure, the adsorbed gas is gradually desorbed, and the proportion of desorbed gas in the produced gas gradually increases.

The Calculation of Apparent Permeability for Shale Gas Considering Adsorption and Flow Patterns

2014 ◽  
Vol 1073-1076 ◽  
pp. 2305-2309
Author(s):  
Wen Xu She ◽  
Jun Bin Chen ◽  
Jie Zhang ◽  
Bo Wei ◽  
Han Qing Wang ◽  
...  
Keyword(s):  
Pore Size ◽  
Flow Pattern ◽  
Shale Gas ◽  
Knudsen Diffusion ◽  
Slip Flow ◽  
Great Influence ◽  
Flow Patterns ◽  
Apparent Permeability ◽  
Longmaxi Formation ◽  
Shale Reservoirs

The flow pattern is unique in a certain range of pore size divided by the Knudsen number. In order to characterize permeability of nanopore in shale gas reservoir more accurately, the formulas of nanopore permeability are put forward considering the influence of adsorption gas and flow patterns. After the calculated results were compared and analyzed, the conclusions are obtained as follows: (1) Pore size is the main factor to determine the flow pattern; (2) There are three main flow pattern in the nanopore of Longmaxi formation shale reservoirs, slip flow, Fick diffusion and transition diffusion, meanwhile Darcy percolation and Knudsen diffusion do not exist; (3) Flow pattern has great influence on apparent permeability and adsorption has a greater impact in a high pressure condition (greater than 20MPa).

The Study of Exhausting Accumulated Liquid in Upward Inclined Pipe Using a Swirl Tool

2019 ◽  
Author(s):  
Zhenqiang Xie ◽  
Xuewen Cao ◽  
Fachun Liang ◽  
Jun Zhang
Keyword(s):  
Flow Pattern ◽  
Cross Section ◽  
Centrifugal Force ◽  
Annular Flow ◽  
Gas Flow ◽  
Swirling Flow ◽  
Flow Patterns ◽  
Gas Production ◽  
Gas Velocity ◽  
The Cross

Abstract The problem of accumulated liquid is very common in wet gas gathering pipelines which varies with the topography, this phenomenon is much more serious especially in upward inclined pipelines. The existence of accumulated liquid at the bottom of the pipeline would decrease the area of the cross section that gas flows through. This makes the gas velocity fluctuate unpredictably and even results in shocks and blocks in pipelines which may cause danger in the safety management of oil and gas production. Swirl tool is a kind of rigid tool which can transfer different flow patterns to a flow pattern similar to annular flow and it has been successfully used to exhaust accumulated liquid in oil fields. However, the mechanism of swirling flow generation in a swirl tool is not fully understood and few researchers have explained how the annular-similar flow decays. In this paper, the formation mechanism of swirling flow in a swirl tool is analyzed using a physical method. The flow pattern transfer procedure and distribution of gas and liquid in the cross section of the pipeline in the swirl tool is simulated with FLUENT (a commercial CFD code). Following the swirling flow formation analysis, the decay of the annular-similar flow from the outlet of the swirl tool is also simulated with FLUENT (a commercial CFD code). Also, the effects of different superficial gas velocities and different liquid rates on the decay of the annular-similar flow are studied with the swirl tool fixed at the bottom of the upward inclined pipeline. The results show that the formation of swirling flow in a swirl tool is mostly affected by the geometric structure of the swirl tool. The centrifugal force is the main force which transfers different flow patterns to a flow pattern similar to annular flow. The centrifugal force that acts on liquid is larger than that of gas since the density of the liquid is much bigger than gas. The annular-similar flow starts to take shape in the swirl tool after the first thread pitch, but the annular-similar flow is nonuniform. After about three thread pitches, the annular-similar flow becomes uniform with liquid surrounding the inner wall of the pipe and gas flowing in the core region of the pipe. The distance of the annular-similar flow sustains longer when the superficial gas velocity increases which means the decay of the swirling flow is slower. Since sufficient liquid rate is critical to maintain annular-similar flow after the tool when the gas flow rate is fixed, the distance of the annular-similar flow goes longer if there is a little increase in liquid rate.

Laboratory measurement and interpretation of nonlinear gas flow in shale

2015 ◽  
Vol 26 (06) ◽  
pp. 1550063 ◽  
Author(s):  
Yili Kang ◽  
Mingjun Chen ◽  
Xiangchen Li ◽  
Lijun You ◽  
Bin Yang
Keyword(s):  
Pore Pressure ◽  
Gas Flow ◽  
Gas Adsorption ◽  
Slip Flow ◽  
Transition Flow ◽  
Confining Stress ◽  
Slippage Effect ◽  
Longmaxi Shale ◽  
Close Relationship ◽  
Flow Mechanisms

Gas flow mechanisms in shale are urgent to clarify due to the complicated pore structure and low permeability. Core flow experiments were conducted under reservoir net confining stress with samples from the Longmaxi Shale to investigate the characteristics of nonlinear gas flow. Meanwhile, microstructure analyses and gas adsorption experiments are implemented. Experimental results indicate that non-Darcy flow in shale is remarkable and it has a close relationship with pore pressure. It is found that type of gas has a significant influence on permeability measurement and methane is chosen in this work to study the shale gas flow. Gas slippage effect and minimum threshold pressure gradient weaken with the increasing backpressure. It is demonstrated that gas flow regime would be either slip flow or transition flow with certain pore pressure and permeability. Experimental data computations and microstructure analyses confirm that hydraulic radius of flow tubes in shale are mostly less than 100 nm, indicating that there is no micron scale pore or throat which mainly contributes to flow. The results are significant for the study of gas flow in shale, and are beneficial for laboratory investigation of shale permeability.

scholarly journals Klinkenberg effect for gas permeability and its comparison to water permeability for porous sedimentary rocks

2006 ◽  
Vol 3 (4) ◽  
pp. 1315-1338 ◽  
Author(s):  
W. Tanikawa ◽  
T. Shimamoto
Keyword(s):  
Pore Pressure ◽  
Water Permeability ◽  
Gas Flow ◽  
Gas Permeability ◽  
Slip Flow ◽  
Sedimentary Rocks ◽  
Water Film ◽  
Klinkenberg Effect ◽  
Two Phase ◽  
Order Of Magnitude

Abstract. The difference between gas and water permeabilities is significant not only for solving gas-water two-phase flow problems, but also for quick measurements of permeability using gas as pore fluid. We have measured intrinsic permeability of sedimentary rocks from the Western Foothills of Taiwan, using nitrogen gas and distilled water as pore fluids, during several effective-pressure cycling tests at room temperature. The observed difference in gas and water permeabilities has been analyzed in view of the Klinkenberg effect. This effect is due to slip flow of gas at pore walls which enhances gas flow when pore sizes are very small. Experimental results show (1) that gas permeability is larger than water permeability by several times to one order of magnitude, (2) that gas permeability increases with increasing pore pressure, and (3) that water permeability slightly increases with increasing pore-pressure gradient across the specimen. The results (1) and (2) can be explained by Klinkenberg effect quantitatively with an empirical power law for Klinkenberg constant. Thus water permeability can be estimated from gas permeability. The Klinkenberg effect is important when permeability is lower than 10−18 m2 and at low differential pore pressures, and its correction is essential for estimating water permeability from the measurement of gas permeability. A simple Bingham-flow model of pore water can explain the overall trend of the result (3) above. More sophisticated models with a pore-size distribution and with realistic rheology of water film is needed to account for the observed deviation from Darcy's law.

Modelling study of flue gas flow pattern with pressure, amount and shape variation catalytic converter

2020 ◽  
Vol 1 (103) ◽  
pp. 5-17
Author(s):  
A. Ghofur ◽  
H. Isworo ◽  
R. Subagyo ◽  
M. Tamjidillah ◽  
R. Siswanto ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Gas Flow ◽  
Catalytic Converter ◽  
Flow Patterns ◽  
Gas Absorption ◽  
Exhaust Gas ◽  
Shape Variation ◽  
Turbulence Flow ◽  
Converter Design ◽  
Practical Implications

Purpose: The purpose of this study is to analyse the modelling of exhaust gas flow patterns with variations in pressure, number, and shape of filters on the catalytic converter. Design/methodology/approach: The research method used is a simulation using ANSYS, which starts by creating a converter catalytic model with pressure variations: (0.5-1.5 atm), number of filters: (2-5), and the form of filter-cut/filter-not-cut. Findings: The decrease in velocity is caused by non-uniform velocity in the exhaust gas flow that occurs when passing through a bend in the filter-cut that serves as a directional flow to create turbulence. Filter-cut type tends to have fluctuating pressure, turbulence flow pattern shape so that contact between filter and exhaust gas is more effective. Based on the analysis of flow patterns, the speed and pressure of the 5 filter-not-cut design at a pressure of 0.5 are the best, while at pressure (1-1.5 atm) the type 5 filter-cut is the best. Research limitations/implications: This study is limited to filter-not-cut and filter-cut types with variations in the number of filters: 2, 3, 4, and 5, and the inlet pressure between 0.5-1 atm. Practical implications: The practical implications of this study are to find a catalytic converter design that has advantages in the effectiveness of exhaust gas absorption. Originality/value: The results show that the filter-not-cut and filter-cut types have the best effectiveness in the number of 5 filters. Filter-not-cut at the pressure of 0.5 atm and filter-cut at pressure (1-1.5 atm).

Experimental and Model Investigations on Gas Mixing Behaviors of Spout-fluid Beds

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Wenqi Zhong ◽  
Mingyao Zhang ◽  
Baosheng Jin ◽  
Rui Xiao
Keyword(s):  
Flow Pattern ◽  
Flow Rate ◽  
Gas Flow ◽  
Flow Patterns ◽  
Gas Mixing ◽  
Gas Flow Rate ◽  
Dense Region ◽  
Tracer Gas ◽  
Gas Dispersion ◽  
Fluid Bed

Steady-state tracer gas measurements were carried out to study the gas mixing behaviors in a spout-fluid bed with a cross section of 0.3 m x 0.03 m and height of 2 m. Two different tracer gases were simultaneously injected, one was injected into the spouting gas flow and the other was injected into the fluidizing gas flow. Radial tracer gas concentrations at various bed elevations under different flow patterns were measured. The mechanism of gas mixing was discussed based on the racer gas concentrations and the flow patterns recorded by a high-resolution digital CCD camera. It was found that gas mixing in spout-fluid beds was due to both convection and dispersion. A three-region mixing model was developed to describe the gas mixing in the spout-fluid bed. The spout jet region and the boundary region were modeled with a mass transfer model; the annular region was modeled with a dispersion model. Effects of spouting gas and fluidizing gas flow rate on the gas exchange between the spout jet and the annular dense region, and the gas dispersion in the annular dense region were examined with flow patterns. The results showed that increase in spouting gas velocity and fluidizing gas flow rate could both promote the gas mixing in spout-fluid beds. The gas-solid flow pattern transited from internal jet to spouting to spout-fluidizing, and the gases were better mixed. But the gases became poorly mixed when the flow pattern transited from stable flow to instable flow.

scholarly journals Multiscale Apparent Permeability Model of Shale Nanopores Based on Fractal Theory

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3381 ◽  
Author(s):  
Qiang Wang ◽  
Yongquan Hu ◽  
Jinzhou Zhao ◽  
Lan Ren ◽  
Chaoneng Zhao ◽  
...  
Keyword(s):  
Shale Gas ◽  
Gas Flow ◽  
Gas Transport ◽  
Fractal Theory ◽  
Knudsen Diffusion ◽  
Slip Flow ◽  
Clear Understanding ◽  
Apparent Permeability ◽  
Permeability Model ◽  
Shale Gas Transport

Based on fractal geometry theory, the Hagen–Poiseuille law, and the Langmuir adsorption law, this paper established a mathematical model of gas flow in nano-pores of shale, and deduced a new shale apparent permeability model. This model considers such flow mechanisms as pore size distribution, tortuosity, slippage effect, Knudsen diffusion, and surface extension of shale matrix. This model is closely related to the pore structure and size parameters of shale, and can better reflect the distribution characteristics of nano-pores in shale. The correctness of the model is verified by comparison with the classical experimental data. Finally, the influences of pressure, temperature, integral shape dimension of pore surface and tortuous fractal dimension on apparent permeability, slip flow, Knudsen diffusion and surface diffusion of shale gas transport mechanism on shale gas transport capacity are analyzed, and gas transport behaviors and rules in multi-scale shale pores are revealed. The proposed model is conducive to a more profound and clear understanding of the flow mechanism of shale gas nanopores.

DISCRETE PARTICLE SIMULATION OF FLOW PATTERNS IN TWO-DIMENSIONAL GAS FLUIDIZED BEDS

1993 ◽  
Vol 07 (09n10) ◽  
pp. 1889-1898 ◽  
Author(s):  
T. TANAKA ◽  
T. KAWAGUCHI ◽  
Y. TSUJI
Keyword(s):  
Flow Pattern ◽  
Gas Flow ◽  
Distinct Element ◽  
Flow Patterns ◽  
Particle Simulation ◽  
Two Dimensional ◽  
Particle Mixing ◽  
Central Nozzle ◽  
Discrete Particle Simulation ◽  
Gas Fluidized Beds

The flow patterns in two-dimensional gas fluidized bed were simulated numerically by the Distinct Element Method, Gas is issued through the entire width of the base with uniform velocity. Several flow patterns, such as slugging and bubbling, are observed in the results. As the gas flow rate increases, the flow pattern changes from slugging to bubbling. It is confirmed that particle mixing is promoted by bubbling. The flow pattern of bubbling is irregular in comparison with the case of gas injection through a central nozzle which was simulated in our previous study.

scholarly journals Experimental Investigation of Two-Phase Flow Patterns in a Vertical to Horizontal Bend Pipe Using Wire-Mesh Sensor

2021 ◽  
Vol 71 (12) ◽  
pp. 18-33
Author(s):  
Lokman A. Abdulkareem ◽  
Veyan A. Musa ◽  
Raid A. Mahmood ◽  
Ezideen A. Hasso
Keyword(s):  
Flow Pattern ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Flow Rates ◽  
Tomographic Images ◽  
High Range

The air-water two-phase flow plays an important role in many applications of industry fields. Usually, a 90-degree bend is used to connect pipes for changing the direction of flow which influences the two-phase flow pattern. In this paper, the effect of 90-degree bend under different ranges of gas and liquid superficial velocities on the two-phase flow patterns in the horizontal pipe located after the bend was experimentally investigated, and then results were presented and compared in a two-phase flow pattern map. Also, tomographic images and probability density functions were used to capture the cross-section void fraction and its distribution for the two-phase flow patterns. The results revealed that at low liquid and gas flow rates, a stratified-wavy flow pattern was observed as a dominant flow pattern. While the wavy-annular and semiannular flow patterns were observed at a high range of gas flow rates in the horizontal pipe. The results also showed that at the high range of liquid flow rate, bubbly, plug, slug, stratified-wavy, and wavy-annular flow patterns were observed in the horizontal pipe when the gas flow increased. The tomographic images and probability density functions gave good agreement with the experimental observations and results.

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