A Model of Multiphase Flow Dynamics Considering the Hydrated Bubble Behaviors and Its Application to Deepwater Kick Simulation

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Xiaohui Sun ◽  
Baojiang Sun ◽  
Yonghai Gao ◽  
Zhiyuan Wang
Keyword(s):  
Heat Transfer ◽  
Multiphase Flow ◽  
Void Fraction ◽  
Mass Transfer Rate ◽  
Hydrate Formation ◽  
Flow Dynamics ◽  
Fluid Temperature ◽  
Hydrate Shell ◽  
Free Gas ◽  
Mass And Heat Transfer

The interaction between hydrated bubble growth and multiphase flow dynamics is important in deepwater wellbore/pipeline flow. In this study, we derived a hydrate shell growth model considering the intrinsic kinetics, mass and heat transfer, and hydrodynamics mechanisms in which a partly coverage assumption is introduced for elucidating the synergy of bubble hydrodynamics and hydrate morphology. Moreover, a hydro-thermo-hydrate model is developed considering the intercoupling effects including interphase mass and heat transfer, and the slippage of hydrate-coated bubble. Through comparison with experimental data, the performance of proposed model is validated and evaluated. The model is applied to analyze the wellbore dynamics process of kick evolution during deepwater drilling. The simulation results show that the hydrate formation region is mainly near the seafloor affected by the fluid temperature and pressure distributions along the wellbore. The volume change and the mass transfer rate of a hydrated bubble vary complicatedly, because of hydrate formation, hydrate decomposition, and bubble dissolution (both gas and hydrate). Moreover, hydrate phase transition can significantly alter the void fraction and migration velocity of free gas in two aspects: (1) when gas enters the hydrate stability field (HSF), a solid hydrate shell will form on the gas bubble surface, and thereby, the velocity and void fraction of free gas can be considerably decreased; (2) the free gas will separate from solid hydrate and expand rapidly near the sea surface (outside the HSF), which can lead to an abrupt hydrostatic pressure loss and explosive development of the gas kick.

Wellbore Dynamics of Kick Evolution Considering Hydrate Phase Transition on Gas Bubbles Surface During Deepwater Drilling

2017 ◽  
Author(s):  
Xiaohui Sun ◽  
Baojiang Sun ◽  
Zhiyuan Wang
Keyword(s):  
Phase Transition ◽  
Mass Transfer ◽  
Void Fraction ◽  
Hydrate Formation ◽  
Stability Field ◽  
Fluid Temperature ◽  
Hydrate Shell ◽  
Free Gas ◽  
Hydrate Phase ◽  
Hydrate Stability

It is of high potential and risk to form gas hydrate along the wellbore in deepwater drilled-kick scenarios. Considering the transient mass transfer process that appears as the hydrate shell renewal at gas-liquid interface, we build a fully coupled hydrodynamic-hydrate model to describe the interaction of hydrate phase transition characteristics and wellbore multiphase flow behaviors. Through comparison with experimental data, the performance of proposed model is validated and evaluated. The simulation results show that the hydrate formation region is mainly near the seafloor affected by the fluid temperature and pressure distributions along the wellbore. The volume change and mass transfer over a hydrate coated moving bubble, vary complicatedly, because of the hydrate formation, hydrate decomposition and bubble dissolution (both gas and hydrate). Overall, hydrate phase transition can significantly alter the void fraction and migration velocity of free gas in two aspects: (1) when gas enters the hydrate stability field, a solid hydrate shell will form around the gas bubble, and thereby the velocity and void fraction of free gas can be considerably decreased; (2) the free gas will separate from solid hydrate and expand rapidly near the sea surface (out of hydrate stability field), which can lead to an abrupt hydrostatic pressure loss and explosive development of kick accident. These two phenomena generated by hydrate phase transition can make deepwater gas kick to be “hidden” and “abrupt” successively, and present challenges to early kick detection and wellbore pressure management.

Modelling of hydrate dissociation in multiphase flow considering particle behaviors, mass and heat transfer

Fuel ◽  
2021 ◽  
Vol 306 ◽  
pp. 121655
Author(s):  
Xuewen Cao ◽  
Kairan Yang ◽  
Hongchao Wang ◽  
Jiang Bian
Keyword(s):  
Heat Transfer ◽  
Multiphase Flow ◽  
Hydrate Dissociation ◽  
Mass And Heat Transfer

New Simulator for Gas–Hydrate Slurry Stratified Flow Based on the Hydrate Kinetic Growth Model

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Bohui Shi ◽  
Yang Liu ◽  
Lin Ding ◽  
Xiaofang Lv ◽  
Jing Gong
Keyword(s):  
Heat Transfer ◽  
Shell Model ◽  
Gas Hydrate ◽  
Hydrodynamic Model ◽  
Formation Rate ◽  
Hydrate Formation ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Two Phase ◽  
Mass And Heat Transfer

A new simulator for gas–hydrate slurry stratified flow is presented, which can simulate the flow characteristics, including gas/liquid velocity, liquid holdup, and pressure drop. The simulator includes an inward and outward hydrate growth shell model and two-phase flow hydrodynamic model. The hydrate growth model systematically considers the kinetics and limitations of hydrate formation, namely, the mass– and heat–transfer. The two-phase flow hydrodynamic model is composed of mass and momentum equations for each phase as well as energy balance equations considering the heat generation related to hydrate formation. Thereafter, an inclined pipeline case is simulated using the simulator. The results demonstrate that, once the kinetic requirements for hydrate crystallization are satisfied, hydrates form rapidly during the initial stage and the hydrate formation rate then decreases owing to the limitation of the mass– and heat–transfer. Meanwhile, the hydrate states (formation onset time, formation rate, and volume fraction) as well as flow characteristics of a multiphase system are obtained, providing acceptable results for engineers in the field. Sensitivity analyses of the key hydrate growth shell model parameters are implemented, and the results indicate that the influences of diffusivity and initial water droplet size on the hydrate formation rate are greater than the of the porous parameter.

Two-Dimensional Effects on the Response of Packed Bed Regenerators

1989 ◽  
Vol 111 (2) ◽  
pp. 328-336 ◽  
Author(s):  
J. A. Khan ◽  
D. E. Beasley
Keyword(s):  
Heat Transfer ◽  
Void Fraction ◽  
Transient Response ◽  
Packed Bed ◽  
Wall Effect ◽  
Heat Transfer Fluid ◽  
Fluid Temperature ◽  
Two Dimensional ◽  
Dimensional Effects ◽  
Wide Range

Packed beds have a wide range of applications as heat transfer and energy storage devices. Employed as a regenerator, a packed bed is subject to the flow of a heat transfer fluid, which alternately stores and recovers energy from a packing of discrete particles. The flow direction reverses during the addition and removal of energy. The nature of a packing of discrete particles in a container is such that variations in the resistance to flow and in the void fraction occur across the cross section of the packing. Particularly, the region of the bed near the boundary of the container has a markedly reduced resistance to flow. In addition, the wall effect on the packing geometry changes the void fraction in the near-wall region. The purpose of the present study is to quantify the two-dimensional effects of nonuniform void fraction, velocity, and temperature distributions in a packed bed regenerator on the dynamic and steady periodic behavior. A two-dimensional numerical model of the transient response of a packed bed subject to the flow of a heat transfer fluid has been developed and verified through comparison with measured responses. The model includes the effects of nonuniform velocity and porosity in the bed, and the effects of axial and radial thermal dispersion. The results of the present computations are compared with one-dimensional transient periodic results to demonstrate the two-dimensional effects on the transient response of a packed bed regenerator to a step change in fluid temperature. The classical dimensionless parameters, such as reduced length and reduced time, are not sufficient to characterize the two-dimensional transient nature of a packed bed regenerator. This study identifies the range of bed-to-particle-diameter ratios over which the transient response is significantly influenced by the wall effect on void fraction and flow.

Improved Thermal Model for Hydrate Formation Drilling Considering Multiple Hydrate Decomposition Effects

2020 ◽  
Author(s):  
Youqiang Liao ◽  
Xiaohui Sun ◽  
Zhiyuan Wang ◽  
Baojiang Sun
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Multiphase Flow ◽  
Thermal Model ◽  
Hydrate Formation ◽  
Wellbore Stability ◽  
Drilling Process ◽  
Hydrate Layer ◽  
Hydrate Decomposition ◽  
Gas Hydrate Formation

Abstract Hydrate is ice-like solid non-stoichiometric crystalline compound, which is stable at favorable low temperature and high-pressure conditions. The predominant gas component stored in naturally-occurring hydrate bearing sediment is CH4 and is estimated about 3000–20000 trillion cubic meter worldwide. Thus, it has attracted significant research interests as an energy source from both academic and industry for the past two decades. Ensuring drilling safety is much important to realize efficient exploitation of hydrate source. Additionally, accurate prediction of wellbore temperature field is of great significance to the design of drilling fluid and cement slurry and the analysis of wellbore stability. However, the heat transfer process in wellbore and hydrate layer during drilling through hydrate formation is a complex phenomenon. The calculation method used in the conventional formation cannot be fully applied to hydrate reservoir drilling, largely due to the complex interactions between the hydrate decomposition, multiphase flow and heat transfer behaviors. In this study, an improved thermal model of wellbore for hydrate layer drilling process is presented by coupling the dynamic decomposition of hydrate, the transportation of hydrate particles in cuttings and heat transfer behaviors in multiphase flow. The distribution of temperature field and rules of hydrate decomposition both in wellbore and hydrate layers are thoroughly analyzed with case study, which is very helpful for the designing drilling parameters, avoiding the gas kick accidents. As well as making a detailed guidance of wellbore stability analysis. This proposed mathematical model is a more in-depth extension of the conventional temperature field prediction model of wellbore, it can present some important implications for drilling through gas–hydrate formation for practical projects.

scholarly journals Mass and Heat Transfer of Thermochemical Fluids in a Fractured Porous Medium

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4179
Author(s):  
Murtada Saleh Aljawad ◽  
Mohamed Mahmoud ◽  
Sidqi A Abu-Khamsin
Keyword(s):  
Heat Transfer ◽  
Hydraulic Fracture ◽  
Reactive Transport ◽  
Heat Propagation ◽  
Design Parameters ◽  
Hydraulic Fractures ◽  
Fluid Temperature ◽  
Heat Of Reaction ◽  
Penetration Length ◽  
Mass And Heat Transfer

The desire to improve hydraulic fracture complexity has encouraged the use of thermochemical additives with fracturing fluids. These chemicals generate tremendous heat and pressure pulses upon reaction. This study developed a model of thermochemical fluids’ advection-reactive transport in hydraulic fractures to better understand thermochemical fluids’ penetration length and heat propagation distance along the fracture and into the surrounding porous media. These results will help optimize the design of this type of treatment. The model consists of an integrated wellbore, fracture, and reservoir mass and heat transfer models. The wellbore model estimated the fracture fluid temperature at the subsurface injection interval. The integrated model showed that in most cases the thermochemical fluids were consumed within a short distance from the wellbore. However, the heat of reaction propagated a much deeper distance along the hydraulic fracture. In most scenarios, the thermochemical fluids were consumed within 15 ft from the fracture inlet. Among other design parameters, the thermochemical fluid concentration is the most significant in controlling the penetration length, temperature, and pressure response. The model showed that a temperature increase from 280 to 600 °F is possible by increasing the thermochemical concentration. Additionally, acid can be used to trigger the reaction but results in a shorter penetration length and higher temperature response.

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