A Simplified Two-Phase Flow Model for Riser Gas Management With Non-Aqueous Drilling Fluids

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Nnamdi Nwaka ◽  
Chen Wei ◽  
Yuanhang Chen
Keyword(s):  
Drilling Fluids ◽  
Gas Migration ◽  
Dissolved Gas ◽  
Two Phase ◽  
Simplified Approach ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Gas Kick ◽  
Flux Model ◽  
Using Data

Abstract Gas-in-riser events can lead to rapid unloading if not timely controlled in a proper manner. When gas influx enters a wellbore with non-aqueous muds (NAMs), the ability of gas being dissolved in NAMs increases the difficulty in gas kick detection and significantly alters gas migration and unloading behavior from the predictions based on water-based muds (WBMs) assumptions. In this study, a new mathematical model for riser gas management in NAMs is developed. In this model, the desorption of dissolved gas influx from NAMs is accounted for as an instantaneous process using a solubility-based mass transfer submodel. The effects of surface backpressures and circulation rates on the unloading behavior in both WBMs and NAMs were studied. This model was validated using data obtained from a drift-flux model (DFM) based simulator. Results show that with the same amount of free gas in the risers at the mudline level, the severity of unloading is significantly more severe in the cases of NAMs. Applied backpressure can effectively control the desorption of the gas influx from the mud, and the unloading occurs later and at shallower depth with higher backpressure. The behavior of unloading tends to be independent on the time when backpressures are applied but highly dependent on the magnitude of the backpressure and the circulation rates. The new two-phase model can accurately simulate riser gas kick events utilizing a simplified approach with improved numerical stability, making it more applicable for real-time riser gas management.

Use of a Transient Model for Studying Kick Migration Velocities and Build-Up Pressures in a Closed Well

2021 ◽  
Author(s):  
Thea Hang Ngoc Tat ◽  
Dalila Gomes ◽  
Kjell Kåre Fjelde
Keyword(s):  
Flow Model ◽  
Transient Flow ◽  
Flow Patterns ◽  
Drilling Fluids ◽  
Transient Model ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Gas Kick ◽  
Flux Model ◽  
Migration Velocities

Abstract The objective of the paper is to show that using pressure build-up curves for estimating kick migration velocities can be unreliable. This will be demonstrated by using a transient flow model where different flow patterns including suspended gas are considered. Suspended gas will occur in Non-Newtonian drilling fluids. This can also be the reason why there is reported large discrepancies in literature about what the gas kick migration velocities can be. A transient flow model based on the drift flux model supplemented with a gas slip relation will be used. The model will be solved by an explicit numerical scheme where numerical diffusion has been reduced. Different flow patterns are included i.e. suspended gas, bubble flow, slug flow and transition to one-phase gas. Kick migration in a closed well will be studied to study how pressure build-ups evolve. A sensitivity analysis will be performed varying kick sizes, suspension limits and changing the transition intervals between the flow patterns. It is seen in literature that the slope of the pressure build-up for a migrating kick in a closed well has been used for estimating what the kick velocity is. It has been reported earlier that this can be an unreliable approach. In the simulation study, it is clearly demonstrated that the suspension effect will have a significant impact of reducing the slopes of the pressure build-ups from the start of the kick onset. In some severe cases, the pressure builds up but then it reaches a stable pressure quite early. In these cases, the kick has stopped migrating in the well. However, in the cases where the kicks are still migrating, it seems that the bulk of the kick moves at the same velocity even though the degree of suspension is varied and gives different slopes for the pressure build-up. Hence, it seems impossible to deduce a unique gas velocity from different pressure build-up slopes. However, abrupt changes in the slope of the pressure build-up indicate flow pattern transitions.

Interfacial Structures and Regime Transition in Co-Current Downward Bubbly Flow

2004 ◽  
Vol 126 (4) ◽  
pp. 528-538 ◽  
Author(s):  
S. Kim ◽  
S. S. Paranjape ◽  
M. Ishii ◽  
J. Kelly
Keyword(s):  
Two Phase Flow ◽  
Bubbly Flow ◽  
Superficial Velocity ◽  
Phase Flow ◽  
Two Phase ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flow Parameters ◽  
Interfacial Structures ◽  
Flux Model

The vertical co-current downward air-water two-phase flow was studied under adiabatic condition in round tube test sections of 25.4-mm and 50.8-mm ID. In flow regime identification, a new approach was employed to minimize the subjective judgment. It was found that the flow regimes in the co-current downward flow strongly depend on the channel size. In addition, various local two-phase flow parameters were acquired by the multi-sensor miniaturized conductivity probe in bubbly flow. Furthermore, the area-averaged data acquired by the impedance void meter were analyzed using the drift flux model. Three different distributions parameters were developed for different ranges of non-dimensional superficial velocity, defined by the ration of total superficial velocity to the drift velocity.

One-dimensional drift-flux model for two-phase flow in pool rod bundle systems

2012 ◽  
Vol 40 ◽  
pp. 166-177 ◽  
Author(s):  
Shao-Wen Chen ◽  
Yang Liu ◽  
Takashi Hibiki ◽  
Mamoru Ishii ◽  
Yoshitaka Yoshida ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
One Dimensional ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Rod Bundle ◽  
Flux Model

scholarly journals A Hydraulic Model for Multiphase Flow Based on the Drift Flux Model in Managed Pressure Drilling

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3930 ◽  
Author(s):  
Fang ◽  
Meng ◽  
Wei ◽  
Xu ◽  
Li
Keyword(s):  
Multiphase Flow ◽  
Oil And Gas ◽  
Splitting Method ◽  
Field Application ◽  
Effective Control ◽  
Two Phase ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Managed Pressure Drilling ◽  
Flux Model

Managed pressure drilling (MPD) is a drilling technique used to address the narrow density window under complex geological environments. It has widespread applications in the exploration and exploitation of oil and gas, both onshore and offshore. In this study, to achieve effective control of the downhole pressure to ensure safety, a gas–liquid two-phase flow model based on the drift flux model is developed to describe the characteristics of transient multiphase flow in the wellbore. The advection upwind splitting method (AUSM) numerical scheme is used to assist with calculation and analysis, and the monotonic upwind scheme for conservation laws (MUSCLs) technique with second-order precision is adopted in combination with the Van Leer slope limiter to improve precision. Relevant data sourced from prior literature are used to validate the suggested model, the results of which reveal an excellent statistical consistency. Further, the influences of various parameters in a field application, including backpressure, density, and mass flow, are analyzed. Over the course of later-stage drilling, a combination of wellhead backpressure and displacement is recommended to exercise control.

Wax appearance and prevention in two-phase flow using the multi-solid and drift-flux model

2019 ◽  
Vol 177 ◽  
pp. 374-383
Author(s):  
Maria Rosa R.T. Góes ◽  
Rodrigo G.D. Teixeira ◽  
Frederico W. Tavares ◽  
Argimiro R. Secchi
Keyword(s):  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flux Model
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