Mud filtrate loss

Damage from mud filtrate loss to the formation includes permeability-reducing effects, such as the following ... 

Mud filtrate invasion is normally restricted to within a few inches into the formation, after which the build up of mudcake prevents further filtrate loss. If resistivity tools with different depths of investigation (in the invaded and non-invaded zones) are used to... 

SANDS Low pressure. Water or mud blocking. Loss of crude or diesel oil used as completion fluid. Minimum filtration rate water-base muds. Minimum filtration rate water-base emulsions. Miminum filtration rate oU-base emulsions. Oil-base muds. Inhibited muds. Minimum weight muds. Crude oil or diesel oil. Add oil-soluble lost circulation material. 

Laboratory experiments have been conducted with a chromium lignite-chromium lignosulfonate mud system both without and with solid lubricants. These studies include filtration loss, cake quality, and their impact on the formation. A comparative evaluation has led to the conclusion that Gilsonite is a better additive compared with sulfonated asphalt as it results in less filtration... 

Loss of confinement resulting from the creation of a borehole can lead to wellbore failure. The weight of the drilling fluid provides some of the support (for the wellbore) which was originally provided by the drilled out material. However, when drilling under an overbalance condition in shales without an effective flow barrier present at the wellbore wall, invasion of the mud filtrate into the formation may occur. Due to the saturation and low permeability of shales, a small volume of mud filtrate penetrating the formation will result in a considerable increase in pore pressure near the wellbore wall. The increase in pore pressure reduces the effective mud support and can lead to a less stable wellbore condition. 

Fluid loss controlling agents filtrate or fluid loss reducers serve to decrease fluid loss. The drilling mud fluid loss property is a measure of the liquid phase tendency to pass through the filter cake. Examples of this type include names such as polyacrylates, starch, and carboxymethyl starch. 

Caustic soda is removed from the carbonate—bicarbonate solution by treating with a slight excess of hard-burned quicklime (or slaked lime) at 85—90°C in a stirred reactor. The regenerated caustic soda is separated from the calcium carbonate precipitate (lime mud) by centrifuging or rotary vacuum filtration. The lime mud retains 30—35% Hquid and, to avoid loss of caustic soda, must be weU-washed on the filter or centrifuge. Finally, the recovered caustic solution is adjusted to the 10% level for recycle by the addition of 40% makeup caustic soda. 

Filtration. The API filtration test for oil-base muds usually gives an all-oil filtrate. The test may not indicate downhole filtration, especially in viscous oils. The alternative high-temperature-high-pressure (HT-HP) filtration test will generally indicate a pending mud problem by amount of fluid loss or water in the filtrate. 

A modified saturated saltwater mud is prepared with bentonite clay by a special technique. First, bentonite is hydrated in freshwater, then treated with lignosulfonate and caustic soda. This premix is then mixed with saltwater (one-part premix to three-part saltwater). The mixture builds up a satisfactory viscosity and develops filtration control. Thinning of the mud is accomplished by saltwater dilutions additional premix is required for viscosity and water loss control. 

Filtration control additives are added to cements for the same reason they are used in drilling fluids. Untreated cement slurries, however, have much greater filtration rates than do untreated drilling muds. Therefore it is very important to limit the loss of water from a slurry into a permeable formation. This is... 

Iron oxide, clays, and most other impurities do not dissolve under alumina digestion conditions and are quite finely divided (1-10 p,m). By adding wash water to decrease the viscosity, it is possible to decant the still hot sodium aluminate solution from the slowly precipitating red muds. These muds that are red from the high iron content are then washed with water to minimize losses of alumina and sodium hydroxide on disposal of the muds. By using this wash water for dilution of the next digester output, alumina and base are not lost from the Bayer circuit. Newer facilities use pressure filtration for both removal and washing of red muds. 

Itabirite mud system exhibited higher cumulative fluid loss volumes than barite mud system. It was observed that 0..5 Ibm/bbI concentration of DS or KXCD polymer for a large particle size of itabirite (between 74 and 125 microns), and 0.75 Ibm/bbI for small particle size of Itabirite (between 34-44 microns) were adequate to improve the filtration properties. 

Derivatives of EMA resins are useful in both the oil field and as additives for fuel oils or lubricants. As additives for oil well drilling muds, the derivatives help reduce water loss due to filtration and perform as viscosity control agents. Long-chain alkyl amine derivatives are useful as antistatic additives for fuel oils. Antistatic coatings are also readily available for many other applications. Aqueous solutions of EMA resins are claimed to be useful in foam systems for dust control. For example, aqueous solutions of the resins can be used to trap 90-95% of the airborne dust generated in a coal cutting laboratory. ... 

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