One of the most widely used materials in drilling mud is Barite. The main function of Barite in drilling mud is its weighting agent properties, which is widely used in water-based mud and oil-based muds.
Barite mines are mainly located in China, USA, India, Russia and Iran. The amount of extraction of this mineral is closely related to the process of oil & crude gas exploration. The consumption of Barite is mainly in drilling mud but a small portion of the produced barite is used in industries such as chemicals, paper, plastics, glass ceramics and pharmaceuticals.
Barium Sulfate is mineral which is used to produce Barite required in the drilling industry. Barium Sulfate ore may contain other by-products. Due to the presence of these minerals, the color of the ore may change from white and milky to yellow, gray or red.
Barite does not dissolve in water and therefore remains as suspended particles in the mud without changing its chemical properties. One of the important features of Barite is its high density, when added to drilling mud, it occupies a smaller volume of mud compared to other particles. As a result, it can increase the density and weight of drilling mud. Increasing the density of mud is suitable for immersing rock particles. Under these conditions, a larger volume of muds remains in liquid phase, as the result the flow of mud will be smoother.
Barite literally means heavy and has Greek roots. The specific gravity of this mineral is about 4.2 to 4.6. Barite hardness varies in the range of 2.5 to 3.5. This mineral is used with different density and hardness to meet requirements of various drilling formations. The amount of alkaline earth metals soluble in water should be less than 250 mg/kg. In addition, Barite used in offshore drilling rigs must meet environmental regulations in terms of the amount of mercury and cadmium content.
Advantages of using Barite in drilling mud
Drilling in high pressure wells is very challenging due to the need for formulation and precise design of drilling mud. One of the advantages of using Barite in drilling mud is the ability to increase the final weight of the mud. Typically, various weighting agents such as Hematite, Calcium Carbonate and Micromax are used in drilling operations. Barite increases the hydrostatic pressure of the drilling mud and thus controls the high-pressure areas under operation. It can be used in drilling deep wells to carry cuttings to the surface.
No abrasion
Barite powder does not wear pipes and drilling bits due to its softness. The high weight of drilling fluids increases the pressure on pipes and drilling bit, in this case hard minerals can cause more abrasion in drilling pipes.
Barite also acts as a lubricant due to its softness. By improving the flow of drilling fluid, it causes lubrication and cooling of the bit.
Neutral properties
Barite does not react with other chemicals used in drilling mud due to its neutrality. furthermore, because of not being corrosive, it does not damage pipes and drilling equipment.
Magnetic properties
Due to non-magnetic properties, it does not interfere with magnetic measurements made in deep wells.
Reasonable price
The reasonable price of Barite compared to other weighting fluids has increased its popularity. Increasing the demand along with its compatible properties compared to similar materials has led to an increase in the price of this mineral, but still the price is reasonable.
Barite specification for drilling
The American Petroleum Institute (API) has defined the Barite specification used in drilling industry. These characteristics mainly take into account the relative density, particle size and maximum amount of impurities. Barite should have a relative density of 4.2 grams per cubic centimeter and should be crushed into a powder with at least 97% passing through a 200-mesh sieve. The amount of alkaline earth metals soluble in water should be less than the recommended amount of 250 mg / kg. In addition to the specifications set by the American Petroleum Institute, the Barite used in the offshore drilling rig must also meet the mercury and cadmium content of environmental regulations.
In which type of drilling mud Barite can be used?
To perform drilling operations in deep wells various types of drilling fluids are used accordingly. Drilling muds are usually divided into two categories; water-based muds and oil-based muds. Water-based muds contain clay, weighting agents and specialty chemicals in an aqueous phase. Oil-based muds, on the other hand, contain a hydrocarbon phase and a brine phase with clay along with weighting agents. Barite can be used in both water and oil-based muds.
Reduction of Barite reserves and its compensation solution
High consumption of Barite in various industries, especially drilling, has reduced its reserves. The main reason behind the high consumption of Barite is due to its low cost and compatible characteristics in drilling. One of the solutions proposed to compensate for the reduction of Barite reserves, has been the implementation of new standards set by API. In the new standards of API 13A, the specific gravity of Barite for use in drilling has changed from 4.2sg to 4.1sg. This standard recommends that contractors use this type of Barite to increase the weight of drilling fluids. The difference between this type of Barite and conventional Barite is in reducing the percentage of purity. Since this decrease in purity of the drilling mud rheology does not change, it can also be used in drilling. By using Barite with a lower percentage of purity and lower specific gravity, it is hoped that Barite reserves will decrease at a slower rate.
Due to the fact that more than 90% of Barite is used in drilling, after drilling operations, a significant amount of Barite along with drilling logs and other fluids is generated as waste. The amount of Barite consumption in different wells depends on factors such as well depth, formation pressure/temperature, and the amount of drilling fluids consumed.
The presence of Barite in drilling mud has created waste which needs to undergo costly crushing operations, and so it can sometimes be economically viable to recover this material from drilling waste.
Environmental issues of Barite consumption
Pure Barite has a specific gravity of 4.5sg but in industrial applications weight of 4.2sg is used. This low specific gravity is due to the presence of impurities in the Barite ore. These impurities include Mercury and Cadmium. Therefore, the issue of Barite-containing waste recovery is important from two aspects; the preventing of the reduction of Barite reserves, the need to find new resources, as well as the reducing environmental issue.
Sama Karimi is chemical engineer, drilling fluids specialist and product manager. She’s is involved in technical aspect of chemical export project at TEAM. Her effective communication skills made her to be our contact person for many reigns.
She is chemical engineer, and drilling fluids specialist at TEAM. Before that she was a drilling fluid engineer for 3 years. In this role, she was responsible to work on new type of drilling fluids additives and specialty chemicals along with managing a team of two drilling fluids production expert. Her efforts and success in this role helped to reduce waste and general costs of mud production projects.
She is graduated from Farzangan High School and entered the chemical field at Iran University of Sciences and Technology.
Drilling mud can be considered as the most important factor in the drilling process. Any problem in the production of drilling mud or mud circulation system will stop drilling operations and result in heavy fines. Proper selection of mud circulation system is effective in preventing possible breakdowns and reducing downtime. This systems are made of different parts, which will be introduced in the following.
Drilling mud problems may be due to mud composition or the mud circulating system selection. The composition of added materials to the mud is determined depending on the drilling conditions, formation structure, drilling depth etc. For example, Hematite is added to the drilling mud composition in high pressure wells to control the pressure caused by the formation. It is clear that the selection of materials to be add to the mud requires special expertise. But in this article, without considering the composition of drilling mud, the systems used to circulate the mud in drilling are examined.
Lost circulation is an occurrence in Formation when drilling fluids is lost into cracks during drilling or cementing operations. Lost circulation in drilling is always examined in two parts: prevention and remedial of loss. Prevention is to take all measures to prevent loss during drilling. This stage is usually done by technically examining the condition of the earth’s layers (geology) and recognizing the geographical area. Lost circulation treatment is also done by using additives appropriate to the structure of the earth’s layers and depending on the geological conditions, different materials and additives are used.
Preventing and controlling lost circulation reduces costs, reduces drilling time and facilitates the drilling process.
For drilling in different areas with different geological structure, the capabilities of drilling methods should be examined. Studies show that most of Iran’s oil reservoirs are tougher in comparison to many countries and the formations have many cracks. For this reason, due to the lost circulation of mud in these cracks, there is always the risk of financial cost and damages.
The main priority in drilling such formations is the use of Under Balanced Drilling (UBD) method. Also in resources that are sensitive to the penetration of fluids and solids and UBD method should be used. In formations with shale fracture cracks, due to high mud lost circulation, the use of conventional drilling methods causes lots of damage in drilling operations. In these cases, the best type of drilling is to use UBD drilling with fluids such as foam. High drilling speed is an influential factor in drilling operations in these areas. However, in formations which the well wall has low strength and stability (increasing the probability of well collapse) as well as formations that swell and reduce the diameter of the well or watery formations, UBD drilling is not recommended.
Gilsonite usage in drilling fluid is as high-temperature, high-pressure filtration control additives in drilling mud. This mineral can be used in all oil based mud and all temperatures. Also, mixed Gilsonite is used effectively in water-based mud systems.
Gilsonite powder reduce API and HPHT fluid loss in all oil-base muds. It has the ability to stabilize drilling mud and thus prevent erosion of pit. It helps improve the overall emulsion stability, Thermal stability and suspension characteristics of most oil-base formulations. Gilsonite also increase viscosity, especially at lower temperatures due to its partial solubility and reduces torque and drag.
Mud with Gilsonite creates a narrow and strong wall inside the wells. It is also used to control lost circulation in drilling formations.
The purpose of using Gilsonite in cementing oil wells is mainly to lighten the slurry and increase its volume. Gilsonite is a solid hydrocarbon that belongs to the category of asphalts. The type of this mineral used in cementing wells has fine and coarse black grains. Gilsonite used in cementing oil wells is a mixture of fine and coarse black grains. This mixture should be such that it does not block the grout channels and at the same time, it should not be too small that it cannot fill the seams and gaps of the formations. Gilsonite grain size is in range of 200-325Mesh, because these grains have low shear strength, they break under high pressure.
