Barite Sag Measurements Using a Portable Dynamic Flow Loop (original) (raw)
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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...
Experimental investigation on barite sag under flowing condition and drill pipe rotation
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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 ...
Prediction of Barite Sag in Horizontal Annular Flow
SPE Annual Technical Conference and Exhibition, 2012
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 annulu...
2012 IFAC Workshop on Automatic Control in Offshore Oil and Gas Production, 2012
This paper introduces a method to enable automatic updates of the density, compressibility and frictional effects of the drilling fluid during a drilling operation. By placing pressure sensors along the circulation path from the mud pump to the connection to the drillstring, the fluid dynamics can be examined more thoroughly at various flow rates and pressures. This will help filling the gap of reliable data on drilling fluid properties, which is of great importance in automated drilling operations.
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.
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.
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...
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...
Simultaneous Continuous Monitoring of the Drilling-Fluid Friction Factor and Density
SPE Drilling & Completion, 2013
Summary This paper introduces a method to enable continuous automatic online updates of the density and frictional effects of the drilling fluid during drilling operations. The placement of differential-pressure sensors along the circulation path from the rig pump to the connection to the drillstring enables the fluid properties to be examined more thoroughly at various flow rates, pressures, and temperatures. The paper presents results from a full-scale test in which different fluids were examined. The results show that the method may give reliable data on the main drilling-fluid properties, which are important in all drilling operations, and especially in automatic modes.
A Comprehensive Approach to Barite Sag Analysis on Field Muds
Barite or weight material sag remains a poorly understood problem for drilling fluids, and prevention efforts related to drilling fluid properties or drilling practices seem inadequate. This paper presents the analysis of drilling fluid field samples that were in current use by major operators. These samples were tested for barite sag behaviour using the Dynamic High Angle Sag Tester (DHAST™) tool and a sequence of rheology tests. DHAST tool was used to measure the sag rate of drilling fluids under different non-conventional shear rate conditions chosen to closely match sag-prone shearing conditions in the field. All drilling fluids were compared at the selected low shear rates. Results from this analysis compared well with observations made in the field, in terms of sag potential, at specified shear rate conditions. Rheological tests (flow curve analysis, gel strength, oscillatory amplitude, frequency and time sweeps tests) were also performed to understand the structure building/b...