Numerical scheme for accurately capturing gas migration described by 1D multiphase drift flux model

2015 ◽  
Vol 73 ◽  
pp. 57-70 ◽  
Author(s):  
Prasanna A. Varadarajan ◽  
Paul S. Hammond
Keyword(s):  
Numerical Scheme ◽  
Gas Migration ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flux Model

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.

Dynamic Cuttings Slip Velocity Evaluation in Non-Newtonian Fluids Using a Temperature Dependent Transient Drift-Flux Model for Directional Wells

2018 ◽  
Author(s):  
Ekaterina Wiktorski ◽  
Dan Sui ◽  
Kjell Kåre Fjelde ◽  
Vebjørn Langåker
Keyword(s):  
Numerical Scheme ◽  
Slip Velocity ◽  
Newtonian Fluids ◽  
Experimental Results ◽  
Velocity Variation ◽  
Cuttings Transport ◽  
Hole Cleaning ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flux Model

The objective of drilling a well is to prepare a clean hole without obstructions for further casing and production tubing running. Cuttings transport has always been important, but challenging process, especially when drilling long directional wells. Poor hole cleaning causes severe problems, as stuck pipe, extreme torque and drag, difficulties in casing landing, cementing, etc. Extensive studies of cuttings transport, both theoretical and experimental, have been performed to estimate, for example, cuttings concentration and cuttings slip velocity to determine optimal conditions for effective hole cleaning. This paper presents a dynamic analysis of cuttings transport in non-Newtonian fluids based on a transient drift-flux model and an associated numerical scheme AUSMV (advection upstream splitting method) developed by Evje and Fjelde 2002. In this paper, the scheme is modified to simulate cuttings transport dynamically taking into account effects related to pressure, temperature and cuttings slip. During drilling, the heat is transported from the formation into the wellbore and up to the surface. In this paper, the energy balance is enhanced by introducing an analytical temperature model into the AUSMV scheme. The temperature distribution along the well is calculated at the beginning of simulation and kept constant throughout the simulation. Additionally, the AUSMV scheme is improved by considering drilling fluid’s transport- and thermal properties. Transport properties of an oil-based mud, such as viscosity and density, are obtained from experiments. The experimental results were used to determine the coefficients in a linear density model used in the study to investigate the effect of non-Newtonian behavior on the heat transfer, cuttings transport and downhole pressure. Furthermore, a model to calculate the apparent viscosity at various pressures and temperatures was developed based on the experimental results and used to evaluate the impact of viscous forces on the cuttings distribution in the well. Presented numerical scheme solves dynamic cuttings transport problems taking into account the slip velocity variation with wellbore geometry, operational (controllable) parameters and formation properties. In comparison to the traditional steady-state models, the transient cuttings transport model with integrated depth-dependent parameters gives a possibility to achieve a more realistic simulation of cuttings transport, distribution and accumulation along the wellbore through the time.

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.

Sign in / Sign up

Export Citation Format

Share Document