Recommendations for mixing SULFEX® (clay inhibitor)
The solubility of SULFEX® additive (clay inhibitor) largely depends on the temperature and duration of washing. The higher the fluid temperature the faster SULFEX® additive is incorporated into the solution. If the solution is very cold it may be better to refrain from addition until it can be warmed up. A dilution volume may also be required on initial addition. The continuous addition of SULFEX® is required to maintain its sufficient concentration in the system if losses occur during the drilling process. SULFEX® additive is consumed upon sedimentation on drilled solids and wells. It is recommended to use 50 % more additive a day after the initial addition to ensure the required concentration. If the chlorides do not exceed 60,000 ppm, use a conventional funnel. On addition to systems with high mineralization, the best results can be achieved by preliminary moistening of SULFEX® additive with fresh water and adding it using a chemical barrel or a premixing tank.
PRELIMINARY MIXING of SULFEX® additive (clay inhibitor)
Bituminous materials (including the SULFEX® additive (clay inhibitor) may be subject to preliminary losses on the shaker. Preventive measures may be required to eliminate or reduce this possibility. Premixing is recommended even if the product does not pass through shakers, as highest possible dissolution prior to mixing with the general drilling fluid results in an increase of wellbore stability. If SULFEX® additive cannot be directly added to the system through the hopper, it can be added to the system using a chemical barrel or a premixing tank. Add 40-50 ppb (100-150 kg/m3) of SULFEX® additive either to the base lubricating oil or to the initial drilling fluid, and then pump it into the active system. Mixing, shaking or circulation in a premix tank or a chemical drum may be required to prevent excessive settling. Premixing in fresh water is recommended as an optimal method even on addition to a hydrocarbon-based drilling fluid. Such salts as calcium chloride can be added during premixing, but it is usually not required, as the amount of fresh water added to the system along with the concentrated premixed solutions is negligible.
PREMIXING of SULFEX® (clay inhibitor)IN FRESH WATER
Mixing in fresh water can be the simplest and the least costly solution. Mix 40-50 ppb (100-150 kg/m3) of SULFEX® additive with fresh water in a tank for slug preparation. A certain amount of foam may be formed, so if required for the mixing system a defoamer may be added to prevent the formation of foam on the surface.
PREMIXING IN SOLUTIONS WITH HIGH SALT CONTENT AT DRILLING SITES
SULFEX® additive (clay inhibitor) can be generally used without any issues in drilling fluids with a high salt content (60,000 ppm of chlorides and higher) and increased density, provided that certain additional measures are taken. If there is enough time, both products can be gradually added over the course of several days to the existing system with the provision of time, temperature and shear force of the bit to disperse the product. The gradual addition of the product reduces shaker losses which could be expected under these conditions. However, if well conditions require rapid introduction of large amounts of SULFEX® additive preliminary moistening of SULFEX® additive with fresh water in a separate mixing tank is recommended. In fresh water, large amounts of the product up to 200 ppb (500-600 kg) can be mixed to create slurry which can be added directly to the drilling fluid without large shaker losses.
PREMIXING IN SOLUTIONS WITH HIGH SALT CONTENT IN DRILLING FLUID MIXING UNITS
Mixing of drilling fluids containing 60,000 ppm of chlorides and higher in drilling fluid mixing units requires introduction of SULFEX® product prior to the addition of salt. Attempts to add SULFEX® after adding salt in low temperature conditions will result in floating of SULFEX® additive on the surface. In order to prevent this, SULFEX® additive is not excluded from the process but is mixed at the drilling site after a certain time. There will be losses on the shaker in such conditions. The use of premixed salt solutions requires introduction of SULFEX® products at the drilling site instead of using a drilling fluid mixing unit. The introduction of SULFEX® products after moistening with fresh water can resolve the aforesaid issues in mixing units.
PREMIXING IN HYDROCARBON-BASED SOLUTIONS
Alternatively SULFEX® additive can be dissolved in a base lubricating oil. If this option is more preferable than the fresh water option, highest efficiency is achieved by mixing 40-50 ppb (100-150 kg) in a minimal amount of base oil prior to pumping into the active system. Use of diesel oils is prohibited in most sea areas. It can be easily determined by analytical methods, and if they are detected, the solution should not be discharged into the sea. However, for onshore operations, when permitted, a small amount of diesel oil can be used to premix SULFEX® additive. If used sparingly, it becomes difficult to determine after introduction into the system. Naturally, SULFEX® additive can be premixed with other hydrocarbons, such as mineral and synthetic oils.
