Simulation of cuttings transport with foam in deviated wellbores using computational fluid dynamics
J Petrol Explor Prod Technol
Simulation of cuttings transport with foam in deviated wellbores using computational fluid dynamics
Reza Rooki 0 1
Faramarz Doulati Ardejani 0 1
Ali Moradzadeh 0 1
Mahmood Norouzi 0 1
0 M. Norouzi Faculty of Mechanics, Shahrood University of Technology , Shahrood , Iran
1 R. Rooki (&) F. Doulati Ardejani A. Moradzadeh Faculty of Mining, Petroleum and Geophysics, Shahrood University of Technology , Shahrood , Iran
Foam is non-Newtonian pseudo-plastic fluid, which is used for drilling, well intervention, and stimulation. Predicting the cutting transport efficiency of foam in the wellbore annulus is very important to optimize the drilling process. In this paper, the cuttings transport process with foam is numerically simulated using an Eulerian twophase model in inclined wellbores. A computational fluid dynamics (CFD) software package called FLUENT was used for this goal. The effect of foam quality, foam velocity, drill pipe rotation, and wellbore inclination on cuttings transport phenomena in both concentric and eccentric annulus was investigated. The simulation results are compared to the experimental data from previous studies, with a relative error less than 8 %. This study shows the reliability of the CFD simulation in replicating the actual physical process.
Cuttings transport; CFD simulation; Foam drilling; Deviated wellbores
Introduction
Foam is often used for underbalanced drilling. Foam fluids
generally consist of 5–25 % of the liquid phase and 75–95 %
of the gaseous phase. The liquid phase could be fresh water
or brines. The gaseous phase is usually an inert gas. A
surfactant is used as a stabilizer and it comprises about 5 % of
the liquid phase. The liquid phase can be weighted up using
heavy brines or barites. The advantages of foam drilling over
conventional mud drilling include high penetration rates, a
high cuttings transport ratio, and less formation damage. For
the drilling with low bottom-hole pressures, the use of a
lighter fluid, such as foam, is required
(Zhu et al. 1995;
Teichrob and Manuel 1997; Foster and Steiner 2007;
Ramalho 2006; Chen 2005; Wang et al. 2009b)
. In drilling
operation, the fluid is pumped through the drill pipe down to
the hole. Then the fluid with cuttings is circulated back up to
the surface through the annular space between the drill pipe
and the hole. Cuttings transport as a multiphase flow, is
important to successful drilling operation, which can affect
the operation cost, the time, and the quality of well drilling
and completion. Inadequate hole cleaning can result in many
costly problems, such as pipe stuck, lost circulation,
premature bit wear, slow penetration rate, poor cement jobs,
formation fracturing, high torque and high drag. Cuttings
transport is controlled by many variables, such as the well
deviation angle, hole diameter, drill pipe diameter, drill pipe
rotation, drill pipe eccentricity, rate of penetration (ROP),
cuttings characteristics (including the size, shape and
porosity of bed), fluid velocity, fluid type, and the complex
non-Newtonian fluid rheology. A comprehensive review of
the cuttings transport was given by
Nazari et al. (2010)
.
Much research has been carried out on cuttings transport
with conventional drilling fluids in horizontal and
directional wells. In addition, some empirical and mechanistic
models have been developed for cuttings transport
(Clark
and Bickham 1994; Larsen et al. 1997; Nguyen and Rahman
1998; Kelessidis and Bandelis 2004; Loureiro et al. 2010;
Piroozian et al. 2012)
. Foam as a non-Newtonian
pseudoplastic fluid has high viscosity. Its viscosity is greater than
either its liquid or gaseous components. Its density is usually
less than one-half that of water. Therefore, foam could
promote efficient cuttings transport. Its low density allows
for underbalanced conditions, an increased ROP, and
minimal formation damage. Foams are also stable at high
temperatures and pressures
(Ozbayoglu 2002; Ozbayoglu et al.
2005; Chen 2005; Duan 2007)
.The rheological properties
and hydraulic of foam have been studied much less than
conventional (incompressible) drilling fluids. Even less is
known about the cuttings transport capabilities of foam.
Determining how to effectively remove cuttings with foam is
critical to the drilling process. The cuttings particles with the
foam drilling fluid could create problems similar to those
with conventional drilling fluid. The solids particles can also
change foam properties, which may completely alter the plan
for controlling down-hole pressure. The majority of research
related to cuttings transport with foam describes operators’
experiences, field practices, and one-dimensional numerical
simulations of the cuttings transport process
(Machado and
Ikoku 1982; Owayed 1997; Saintpere et al. 2000; Martins
et al. 2001; Ozbayoglu 2002; Ahmed et al. 2003; Li and Kuru
2003; Chen 2005; Capo et al. 2006; Chen et al. 2007; Osunde
and Kuru 2008; Wang et al. 2009b; (...truncated)