scholarly journals Effects of Reservoir Parameters on Separation Behaviors of the Spiral Separator for Purifying Natural Gas Hydrate

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5346
Author(s):  
Shunzuo Qiu ◽  
Guorong Wang
Keyword(s):  
Particle Size ◽  
Natural Gas ◽  
Removal Efficiency ◽  
Flow Rate ◽  
Gas Hydrate ◽  
Volume Fraction ◽  
Differential Pressure ◽  
Separation Performance ◽  
Recovery Efficiency ◽  
Natural Gas Hydrate

The spiral separator is an important tool for desanding in natural gas hydrate production, and the change of hydrate reservoir parameters has a great impact on spiral separator behavior. Mastering the influence law is helpful to improve the separation performance. Until now, there was still no detailed analysis of the effect mechanism between reservoir parameters and spiral separator behavior. In this paper, a downhole spiral separator was designed. Then, the effects of reservoir parameters (particle size, hydrate, volume fraction, and sand volume fraction) on separation performance (discrete phase distribution, separation efficiency, and differential pressure) with different flow rates were investigated by numerical simulation method Fluent 18.0. The results show that effects degree of reservoir parameters is in order from large to small: sand phase volume fraction, particle size, hydrate volume fraction. As the particle size increases, the separation performance is improved. When the sand volume fraction increases, the natural gas hydrate (NGH) recovery efficiency and differential pressure both increase, but the sand removal efficiency decreases. When the hydrate fraction increases, the separation performance change law is opposite to that when the sand volume fraction increases. In addition, with increasing the flow rate, the efficiency and differential pressure increase. Therefore, reservoir saturation and porosity can balance NGH recovery efficiency and sand removal efficiency. Furthermore, the spiral separator has good performance under the change of reservoir parameters. The performance of the NGH spiral separator can be also maintained by increasing the flow rate.

scholarly journals Study on axial-flow hydrocyclone for in-situ sand removal of natural gas hydrate in the subsea

2021 ◽  
Vol 245 ◽  
pp. 01050
Author(s):  
Haitao Lin ◽  
Yuan Huang ◽  
Hualin Wang
Keyword(s):  
Natural Gas ◽  
Flow Rate ◽  
Gas Hydrate ◽  
Separation Zone ◽  
Separation Performance ◽  
Natural Gas Hydrate ◽  
Inlet Flow ◽  
Zone Length ◽  
Inlet Flow Rate

Natural gas hydrate (NGH) has become the most potential emerging green energy known in the 21st century due to its characteristics of wide distribution, abundant reserves and clean combustion. This study designs an axial annulus in situ hydrocyclone desander (AAIHD) based on drilling instruments in order to resolve the serious problem of sand production during solid fluidization of NGH. The effect of the inlet flow rate and separation zone length on the sand removal efficiency of the AAIHD is tested through experimental research. The results indicate that AAIHD has a higher separation performance when the separation zone length is L/D=12.4 and the inlet flow rate is in the range of 10 m3/h to 25 m3/h, and the maximum separation efficiency reaches 77.4%. The purpose of this study is to achieve in-situ sand removal and the backfilling of sand slurry in addition to facilitate the advancement of solid fluidized exploration technologies.

Natural gas storage and transportation within gas hydrate of smaller particle: Size dependence of self-preservation phenomenon of natural gas hydrate

2014 ◽  
Vol 118 ◽  
pp. 208-213 ◽  
Author(s):  
Hiroko Mimachi ◽  
Satoshi Takeya ◽  
Akio Yoneyama ◽  
Kazuyuki Hyodo ◽  
Tohoru Takeda ◽  
...  
Keyword(s):  
Particle Size ◽  
Natural Gas ◽  
Gas Hydrate ◽  
Size Dependence ◽  
Gas Storage ◽  
Natural Gas Hydrate ◽  
Natural Gas Storage

Technical Analysis of Sand Production for Offshore Natural Gas Hydrate Trials in South China Sea

2021 ◽  
Author(s):  
Kun An ◽  
Lawrence Khin Leong Lau ◽  
Jian Li ◽  
Jia Liu
Keyword(s):  
Particle Size ◽  
Natural Gas ◽  
South China Sea ◽  
South China ◽  
Gas Hydrate ◽  
Clean Energy ◽  
Technical Analysis ◽  
Sand Production ◽  
Natural Gas Hydrate ◽  
China Sea

Abstract Natural gas hydrate emerges as a sustainable and alternative clean energy source. Japan (2013) and China (2017) have performed production trials on marine natural gas hydrate successfully. Sand production with associated risk is one of the main challenges for offshore natural gas hydrate production trials in Japan and China. Technical assessment related to sand production, transport and erosion is a crucial part for overall sand management strategy. This paper demonstrates the importance of flow assurance for marine natural gas hydrate production through the analysis of sand management in South China Sea ShenHu area. Multiphase modelling tool is used to investigate sand transport phenomenon, with parametric study focuses on the effects of production rates, particle bed height and sand particle size. Detailed analysis of particle flow and related erosion along production flow path is investigated by developing a 3-dimensional Computational Fluids Dynamics (CFD) model. Based on the matrix of sensitivity study, steady state operational map for continuous marine natural gas hydrate production is proposed. Such operational map provides useful risks level ranking based on actual field parameters including gas production rate, sand loading and particle size. The operator can maintain production at a lower risk based on the operational map. Through detailed technical analysis of sand production and transport, risks associated with sand blockage and erosion can be actively managed. This provides high values in terms of operational safety, asset integrity, and full compliance with related national or international HSSE standards.

scholarly journals Study on the Decomposition Mechanism of Natural Gas Hydrate Particles and Its Microscopic Agglomeration Characteristics

2018 ◽  
Vol 8 (12) ◽  
pp. 2464 ◽  
Author(s):  
Xiaofang Lv ◽  
Bohui Shi ◽  
Shidong Zhou ◽  
Shuli Wang ◽  
Weiqiu Huang ◽  
...  
Keyword(s):  
Natural Gas ◽  
Flow Rate ◽  
Gas Hydrate ◽  
Length Distribution ◽  
Chord Length ◽  
Low Flow ◽  
Natural Gas Hydrate ◽  
Reflectance Measurement ◽  
Chord Length Distribution ◽  
Water Cut

Research on hydrate dissociation mechanisms is critical to solving the issue of hydrate blockage and developing hydrate slurry transportation technology. Thus, in this paper, natural gas hydrate slurry decomposition experiments were investigated on a high-pressure hydrate experimental loop, which was equipped with two on-line particle analyzers: focused beam reflectance measurement (FBRM) and particle video microscope (PVM). First, it was observed from the PVM that different hydrate particles did not dissociate at the same time in the system, which indicated that the probability of hydrate particle dissociation depended on the particle’s shape and size. Meanwhile, data from FBRM presented a periodic oscillating trend of the particle/droplet numbers and chord length during the hydrate slurry dissociation, which further demonstrated these micro hydrate particles/droplets were in a dynamic coupling process of breakage and agglomeration under the action of flow shear during the hydrate slurry dissociation. Then, the influences of flow rate, pressure, water-cut, and additive dosage on the particles chord length distribution during the hydrate decomposition were summarized. Moreover, two kinds of particle chord length treatment methods (the average un-weighted and squared-weighted) were utilized to analyze these data onto hydrate particles’ chord length distribution. Finally, based on the above experimental data analysis, some important conclusions were obtained. The agglomeration of particles/droplets was easier under low flow rate during hydrate slurry dissociation, while high flow rate could restrain agglomeration effectively. The particle/droplet agglomerating trend and plug probability went up with the water-cut in the process of hydrate slurry decomposition. In addition, anti-agglomerates (AA) greatly prohibited those micro-particles/droplets from agglomeration during decomposition, resulting in relatively stable mean and square weighting chord length curves.

scholarly journals Effect of Gas Exchange Interval on CH4 Recovery Efficiency and Study of Mechanism of CH4 Hydrate Replacement by CO2 Mixture

2021 ◽  
Vol 9 ◽  
Author(s):  
Ya-Long Ding ◽  
Hua-Qin Wang ◽  
Tao Lv
Keyword(s):  
Gas Exchange ◽  
Natural Gas ◽  
Small Molecules ◽  
Gas Phase ◽  
Gas Hydrate ◽  
Gas Mixture ◽  
Time Interval ◽  
Recovery Efficiency ◽  
Natural Gas Hydrate ◽  
Exchange Operation

As an environment-friendly natural gas hydrate exploitation method, CO2 replacement method can not only achieve the purpose of mining natural gas hydrate, but also store the current greenhouse gas CO2 in the form of hydrate on the seabed, and maintain the stratum stability of hydrate deposit area. In order to improve the rate and efficiency of CH4-CO2 replacement reaction, researchers proposed to use CO2 contained gas mixture instead of pure CO2 to replace CH4 in natural gas hydrate. Based our previous work about CH4 hydrate recovery with 40% CO2 + 60% H2, in this study, the effect of gas concentration in gas phase on final CH4 recovery are investigated by implying different time interval of gas exchange operation. Experimental results show that The CH4 recovery efficiency is 10.41 when the gas exchange is continues through the whole replacement process, and CH4 recovery efficiency changes to 12.25, 32.24 and 28.86 when gas exchange operation is carried out every 12, 24, 36 h. Indicating that replaced CH4 needs to be discharged in time to avoid CH4 molecules being replaced to form hydrates again, and it is necessary to accurately control the time interval of gas exchange operation to avoid insufficient contact time between CO2 and H2 molecules and CH4 hydrate, which affects the final replacement efficiency. In addition, the mechanism of CO2 gas mixture containing small gas molecule such as H2, N2 are studied. The results indicate that when CO2 containing small molecules such as H2 and N2 displace CH4 hydrate, the existence of small molecules (H2, N2) can give rise to decompose the hydrate lattice and release CH4 gas. If the gas molecules (CO2, N2, H2, CH4) in the gas phase have enough driving force to enter the hydrate lattice and remain stability, CH4 hydrate will not decompose completely; If not, CH4 hydrate will be completely decomposed.

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