A Combined Barite–Ilmenite Weighting Material to Prevent Barite Sag in Water-Based Drilling Fluid (original) (raw)
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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...
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 ...
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
Barite sag is a challenging phenomenon encountered in deep drilling with barite-weighted fluids and associated with fluid stability. It can take place in vertical and directional wells, whether in dynamic or static conditions. In this study, an anti-sagging urea-based additive was evaluated to enhance fluid stability and prevent solids sag in water-based fluids to be used in drilling, completion, and workover operations. A barite-weighted drilling fluid, with a density of 15 ppg, was used with the main drilling fluid additives. The ratio of the urea-based additive was varied in the range 0.25–3.0 vol.% of the total base fluid. The impact of this anti-sagging agent on the sag tendency was evaluated at 250 °F using vertical and inclined sag tests. The optimum concentration of the anti-sagging agent was determined for both vertical and inclined wells. The effect of the urea-additive on the drilling fluid rheology was investigated at low and high temperatures (80 °F and 250 °F). Further...
2016
This study aims to optimize the mixing ratios of barite and calcium carbonate (CaCO3) to reduce barite sag tendencies, while producing a proper equivalent circulating density (ECD). Oil based drilling fluid with various particle sizes and ratios of barite to CaCO3 were mixed in this study. These fluid samples were then tested for the sag potential by using an API modified Viscometer Sag Shoe Test (VSST). A hydraulics simulator was also used to study the effect of the fluid rheological parameters change on ECDs for a standard well geometry. The results show that using the smallest 2-micron CaCO3 particle yields the greatest barite sag mitigation when a mixing ratio between barite and CaCO3 of 70:30 was selected. In addition, mixing the largest 40-micron-CaCO3 particle yields a sag potential greater than that of 100% barite in all mixing tested ratios, but this ratio gave the lowest ECD. The effect of pH on barite sag was also investigated in this study. As the pH values of the sample...
2006
The increasing use of Through Tubing Rotary Drilling (TTRD) and Extended Reach Drilling (ERD) techniques to extend the life of maturing reservoirs has increased the stress on drilling fluids employed for those applications. Optimal hydraulic efficiency is best achieved using drilling fluids with low viscosity. However, low-viscosity fluids are unable to adequately suspend the weight material used to control formation and well bore pressures. Optimizing this conflicting rheological need for hydraulic efficiency and adequate suspension of weight material has proved difficult to reconcile as wells have become increasingly more complex in the last decade. This paper describes how a novel barite treatment process that reduces the particle size of conventional drilling-grade barite from 75 to less than 5 microns substantially improves the performance properties of both drilling and completion fluids using this novel weight material. This new drilling fluid technology allows complex extend...
Suitability of Some Nigerian Barites in Drilling Fluid Formulations
Petroleum Science and Engineering, 2019
In order to counterbalance the formation pressure, the drilling mud is weighted up using a chemical additive, usually Barite. The usability of locally sourced Nigerian Barites on the major types of drilling fluids in conventional conditions is presented. Water-Based mud, Oil-Based mud and Synthetic-Based mud formulations with locally sourced Barite were tested according to the American Petroleum Institute recommended practices. Hole cleaning capabilities of the formulations by the use of Cutting Carrying Index (CCI) and Cutting Concentration (CC) as indicators showed that Osina, Gabu and Obubra Nigerian Barites are suitable for use as drilling fluid additives; with Cutting Carrying Index in the range of 23.27 to 120.54 for Water-Based mud, 0.89 to 3.98 for Oil-Based mud and 0.45 to 1.13 for Synthetic-Based mud. The Cutting Concentration of average of 4.15 vol. % at 355gpm and 300ft/hr ROP for Water-Based mud, Oil-Based mud and Synthetic-Based mud, with MAXROP of 364ft/hr under the same conditions was recorded. Moreso, laminar flow regime in the annulus was predicted for all the mud types under the same conditions and temperatures specified, based on a MATLAB programme developed to perform the computation. Cutting Carrying Index for water based mud decreased from ambient, 120°F, 180°F to 240°F compared with API mud used as control sample.
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.
Characterization of barite reserves in Nigeria for use as weighting agent in drilling fluid
Journal of Petroleum Exploration and Production Technology
Successful drilling operations are dependent on the properties of the drilling fluid used to drill wells. Barite is used as a weighting agent during the preparation of drilling fluid. Over the years, oil and gas industry in Nigeria has been depending mainly on imported barite for drilling operations, whereas the country has huge deposits of barite. There is the need to assess the properties of the locally sourced barite for their suitability in drilling fluid formulation. This study presents the local processing methods of barite and examines the crude and on-the-site processed barite’s physio-chemical properties. These parameters were compared with American Petroleum Institute and Department of Petroleum Resources standards. XRD results show that on-the-site beneficiated barite has 87.79% BaSO4, 6.66% silica, 0.03% total soluble salt, 1.39% Fe2O3, and 1.603% heavy metals. Chemical analysis indicated that the pH, moisture content, metallic content such as Ca, Pb, Zn, Mg, Cu, and Cd ...
Stability Enhancing of Water-Based Drilling Fluid at High Pressure High Temperature
Arabian Journal for Science and Engineering, 2020
Over the years, barite (BaSO 4) as weighting agent was widely used. However, it has an issue with particles settling which is known as barite sagging, that causes a variation in drilling fluid properties and operational problems. This study introduces and investigates a novel combination of Micromax (Mn 3 O 4) and barite weighting materials to prevent the barite sagging in water-based mud under high pressure high temperature (HPHT) situations. Different amounts of Micromax, 0, 25 and 50 wt% from the total weighting material were added to the field formula. Static and dynamic sagging tests were conducted at 250°F and 120°F, respectively, to study the sagging tendency and identify the optimum combination. The mud pH and density were measured at ambient conditions. The rheological properties measurements were conducted at 120°F and 250°F. The filtration properties were evaluated using HPHT filtration test at 300 psi and 250°F. The results showed that adding 25/75 wt% Micromax/barite is enough to eliminate the sag issue in both vertical and 45°inclined position, as it enforced the sagging tendency to the safe range. The 25/75 wt% Micromax/barite has no significant effect on the rheological properties compared to the 100 wt% barite, except for the 30 min gel strength which was increased by 19% for better particles suspension while no circulation. The HPHT filtration test indicated a significant decrease in the filter cake thickness and weight with the 25/75 wt% Micromax/barite without significant change in the filtration volume compared to the 100 wt% barite.