Prediction of Barite Sag in Horizontal Annular Flow (original) (raw)
Related papers
Experimental Study and Modelling of Barite Sag in Annular Flow
Journal of Canadian Petroleum Technology, 2014
The phenomenon of settlement of weighting-material particles in drilling fluid is known as barite sag, which can lead to a number of drilling problems including lost circulation, well-control difficulties, poor cementing operation, and stuck pipe. This study investigates barite sag, both experimentally and numerically, in the annulus under flow conditions. Settlement of the weighting materials is generally called barite sag because barite is the most popular weight material used in drilling industry. The experimental part of the study has been conducted using a flow loop with 35-ft-long annulus test section to investigate the effects of fluid velocity in annulus, annulus eccentricity, pipe rotation, and inclination angle on barite sag. Density of the flowing fluid is measured continuously using Coriolis densitometers at the inlet and outlet of the annular test section. The simulation part of this study is based on a proposed particle- tracking method called “particle-elimination tec...
Experimental investigation on barite sag under flowing condition and drill pipe rotation
Journal of Petroleum Exploration and Production Technology
Using drilling fluids with optimum density is one of the most important approaches to stabilize the pressure of the bottom formation and prevent blowout through the drilling process. One of the common methods for this purpose is adding some additives with high specific gravity to the drilling fluid to tune its density. Among the possible chemicals, barite and hematite with the density of 4.2 and 5.2 g/cc are the most common additives. Unfortunately, although the application of these additives is advantageous, they have some drawbacks which the most important one is separation and settlement of solid phase called barite sag. The barite sag comes from barite, or other dense materials particles deposition resulted in undesired density fluctuations in drilling fluid can lead to mud loss, well control problems, poorly cementing and even pipe sticking which occurs in severe cases. With respect to these concerns, the current investigation is concentrated to obtain the relation between the ...
Modeling of Barite Sag and Fluid Flow in Drilling Fluids
Engevista, 2017
The settling of barite, or any other weighting material, causes undesirable fluctuations in the density of drilling fluids. Problems such as stuck pipe, pressure control difficulties and lost circulation are caused by the settling of barite particles. In this work, we studied a biphasic model to describe the settling and transport of barite particles in oil based drilling fluids. The model is based on the conservation equations and uses the Eulerian approach. The model studied was able to predict the settling and the formation of the particles bed, qualitatively the influence of particle size and liquid viscosity and initial solids concentration. We conducted sedimentation experiments to evaluate parameter of the model. The experimental data was analyzed in terms of the one-way ANOVA test for a 95% confidence level and showed significant reproducibility. The simulation results are qualitatively in accordance with the experimental results.
Numerical Simulation and Experiments of Barite Sag in Horizontal Annulus
Under certain drilling conditions, the weighting material particles such as barite can settle out of the drilling fluid. This phenomenon, known as barite sag, can lead to a number of drilling problems including lost circulation, well control difficulties, poor cement job, and stuck pipe. This study investigates barite sag, both experimentally and numerically, in the annulus under flow conditions. Experimental work has been conducted on a large flow loop to investigate the effects of major drilling parameters on barite sag by measuring the circulating fluid density. Results of the tests indicate that the highest sag occurs at low annular velocities and rotational speed and also at high inclination angles. It was observed that at inclination angles less than 60°, for any annular velocity, barite sag is not significant. Eccentricity of a non-rotating inner pipe did not have a significant effect on barite sag. However, effects of inner pipe rotation on barite sag for an eccentric annulus are more significant than concentric case. The simulation part of this study is based on a proposed particle tracking method called "Particle Elimination Technique". The traveling path of each solid particle is assumed to be a function of size and shape of the particle, fluid velocity and rheology. Based on the estimated traveling path of particles, density of the fluid is updated considering the number of particles whose paths lead to the bottom of the annulus and become motionless. In order to capture the complexities associated with the solid-liquid flow, a lift force is assigned to the solid particles that enable adjustment of the model with experimental results. Comparing the results of numerical simulation to the experimental study on the effects of annular velocity on barite sag in a horizontal annulus shows a good agreement. The numerical simulation was modified from laboratory scale to real wellbore dimensions for practical drilling applications. Results of the simulation show prediction of the density of the drilling fluid in the horizontal section of a wellbore with various lengths and dimensions under different annular velocities.
During drilling operations, control of sub surface pressure is of utmost importance. High density minerals such as barite and hematite are used to increase the density of drilling fluids in order to control these pressures. However, contributing factors such as gravitational force will cause the weighting material particles to settle out of the suspension. This is designated as "sag" within the drilling industry and can lead to a variety of major drilling problems including lost circulation, well control difficulties, poor cement jobs and stuck pipe. Study of this phenomenon and how to mitigate its effects has long been of interest. In this paper several methods for evaluating dynamic barite sag in oil based drilling fluids are examined in a flow loop and using a rotational viscometer modified by addition of a sag shoe (MRV). Tests using the MRV in the range of 0 -100 RPM were conducted and the effects of rotation speed on sag were correlated with flow loop tests performed by varying the inner pipe rotation speed. The combined effects of eccentricity and pipe rotation on dynamic barite sag in oil based drilling fluids are also described in this paper. Flow loop test results indicate that pipe rotation has a greater impact on reducing sag when the pipe is eccentric rather than concentric. Additionally, results in the MRV indicate a strong correlation between the test RPM and degree of measured sag.
AADE-12-FTCE-23 Hindrance Effect on Barite Sag in Non-Aqueous Drilling Fluids
2012
The phenomenon of barite sag requires better understanding, especially in non-aqueous drilling fluids (NAF) where it causes density variations leading to well stability issues. Sag is considered a dynamic phenomenon that can be severe in highly deviated and complex wells. Tackling this challenge calls for experimental/empirical methods to predict barite sag for different fluid compositions and well environments. Hindered particle settling caused by presence of nearby particles is usually a strong function of particle concentration (φ) in the suspension. Empirical methods to predict hindered settling have been well established for suspensions with Newtonian liquids as continuous phase. Here, these empirical methods for hindered settling have been extended to NAF with varied barite concentrations (mud weights). To develop the hindrance model, experimental data on sag rate U (mm/hr) in a NAF is obtained from the Dynamic High Angle Sag Tester (DST) at chosen conditions of temperature, p...
Sustainability
Drilling high-pressure high-temperature (HPHT) wells requires a special fluid formulation that is capable of controlling the high pressure and is stable under the high downhole temperature. Barite-weighted fluids are common for such purpose because of the good properties of barite, its low cost, and its availability. However, solids settlement is a major problem encountered with this type of fluids, especially at elevated downhole temperatures. This phenomenon is known as barite sag, and it is encountered in vertical and directional wells under static or dynamic conditions leading to serious well control issues. This study aims to evaluate the use of barite-ilmenite mixture as a weighting agent to prevent solids sag in oil-based muds at elevated temperatures. Sag test was conducted under static conditions (vertical and inclined) at 350 °F and under dynamic conditions at 120 °F to determine the optimum ilmenite concentration. Afterward, a complete evaluation of the drilling fluid was...
Barite Sag Measurements Using a Portable Dynamic Flow Loop
2018
Drilling fluid density is typically provided by dense, homogenously-dispersed, fine solids. Density fluctuations can occur if solids are no longer homogenously suspended. These fluctuations, commonly termed sag, can affect well integrity and increase the cost to completion. Various sag tendency prediction methods exist, but vary in their ability to provide quick and reliable measurements. This paper will focus on the performance of an innovative technology, the portable dynamic sag flow loop (PDSFL), and compare it to existing technologies and methods. Introduction Drilling fluid performance becomes increasingly critical as a well increases in depth, temperature, or angle. Operational parameters and practices, and well design may create or exacerbate fluid stability issues at critical areas. A small unwanted change in density is magnified over the length of the well and in extreme cases can lead to a loss of control. It is vital to ensure that a drilling fluid can maintain its integ...
A Combined Barite–Ilmenite Weighting Material to Prevent Barite Sag in Water-Based Drilling Fluid
Materials
Barite sag is a serious problem encountered while drilling high-pressure/high-temperature (HPHT) wells. It occurs when barite particles separate from the base fluid leading to variations in drilling fluid density that may cause a serious well control issue. However, it occurs in vertical and inclined wells under both static and dynamic conditions. This study introduces a combined barite–ilmenite weighting material to prevent the barite sag problem in water-based drilling fluid. Different drilling fluid samples were prepared by adding different percentages of ilmenite (25, 50, and 75 wt.% from the total weight of the weighting agent) to the base drilling fluid (barite-weighted). Sag tendency of the drilling fluid samples was evaluated under static and dynamic conditions to determine the optimum concentration of ilmenite which was required to prevent the sag issue. A static sag test was conducted under both vertical and inclined conditions. The effect of adding ilmenite to the drillin...
Numerical study of drilling fluids pressure drop in wellbores with pipe rotation
IOP Conference Series: Materials Science and Engineering, 2019
Determining of the pressure loss is very complicated task in the petroleum drilling industry. In the present study the effect of different drilling muds flowing inside rotating pipe and exist from an annuals investigated. The effect of rotating speed and inlet speed. The flow is turbulent, steady and 3D with non-Newtonian fluid. The governing equations (continuity and momentum) are solved numerically using CFD with fluent soft package. The results are presented as : stream line, contours, pressure drop and wall shear stress. The results show that pressure drop is decreased when pipe rotational speed increase. slight increasing in shear stress at pipe rotating speed less than 200 rpm for same inlet velocity. Moreover, remarkable shear stress increasing can be observed as the rotational speed equal to or higher than 200 rpm.