Mud treatments

Oil-base muds are composed of oil as the continuous phase, water as the dispersed phase, emulsifiers, wetting agents, and gellants. There are other chemicals used for oil-base mud treatment such as degellants, filtrate reducers, weighting agents, etc. 

Dispersant(s) or antifoulant(s) (sludge fluidizers, biodispersants, or mud treatments) to limit the physical adherence of insoluble salts, corrosion products, oils, fats, process contaminants, biofilms, and biomass onto heat-transfer and other water-wetted surfaces... 

Other mechanisms involve the use of mud treatments, which are normally anionic or nonionic flocculants of high molecular weight, with the objective being to flocculate the dirt into the cooling tower basin, where it can be mechanically removed (vacuum, scraper, etc.). 

Even the most modem, microprocessor-based monitoring and control systems reference only the primary chemical inhibitor with any real degree of accuracy. Methods for the monitoring and control of secondary inhibitors (such as specific polymeric dispersants) and biodispersants, biocides, antifoams, mud treatments, etc. remain imprecise to say the least. 

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The drillfloor and the derrick (drilling tower), with pipe handling systems and the flare tower on the top, are located in the centre of the platform. In this area, we find the remaining systems, for drilling and mud treatment. Subsea equipment such as valve assemblies (X-trees) and blow-out preventer (BOP) are stored and handled in the moon-pool area below the drill floor. 

Originally, mud was made from clay mixed with water, a simple system. Today the preparation and treatment of drilling fluid has reached a sophistication which requires specialist knowledge. The reason for this becomes clear if we consider the properties expected. 

Petroleum. Apart from its use ia petrochemicals manufacture, there are a number of small, scattered uses of lime ia petroleum (qv) production. These are ia making red lime (drilling) muds, calcium-based lubricating grease, neutralization of organic sulfur compounds and waste acid effluents, water treatment ia water flooding (secondary oil recovery), and use of lime and pozzolans for cementing very deep oil wells. 

CeUulosic fibers, powdered limestone, gHsonite, and asphalt are frequently added to both water and oH muds at levels of 10 to 25 kg/m (4—10 lb /bbl) when high differential pressures are encountered to control seepage losses to the formation. This treatment also is used to improve the quaHty of the mud filter cake to reduce the chance of differential pressure sticking. 

Phosphate—Polymer Control. Phosphate treatment results are improved by organic supplements. Naturally occurring organics such as lignins, tannins, and starches were the first supplements used. The organics were added to promote the formation of a fluid sludge that would settle in the mud dmm. Bottom blowdown from the mud dmm removed the sludge. 

Slight film, translucent—moderate problem, mud needs wetting agent immediately. Very light film, highly translucent—slight wetting problem, mud needs some treatment. 

Gypsum-treated muds have proved useful for drilling anhydride and gypsum, especially where these formations are interbedded with salt and shale. The treatment consists of conditioning the base mud with plaster (commercial calcium sulfate) before the anhydride or gypsum formation is penetrated. By... 

Oil-base mud maintenance involves close monitoring of the mud properties along with the mud temperature, as well as the chemical treatment (in which the order of additions must be strictly followed). The following general guidelines should be considered ... 

Sources of Toxicity. There are three contributing mechanisms of toxicity in drilling fluids, chemistry of mud mixing and treatment, storage/disposal practices, and drilled rock. The first group conventionally has been known the best because it includes products deliberately added to the system to build and maintain the rheology and stability of drilling fluids. 

The surface mud system is designed to restore the mud to the required properties before it is pumped downhole. Most of the equipment is used for solids removal only a small part of the surface mud system is designed to treat chemical contamination of the mud. There are three basic means of removing drilled solids from the mud dilution-discard, chemical treatment, and mechanical removal. 

The chemical treatment methods reduce dispersability property, of drilling fluids through the increase of size of cuttings which improves separation and prevents the buildup of colloidal solids in the mud. These methods include ionic inhibition, cuttings encapsulation, oil phase inhibition (with oil-base muds), and flocculation. The mechanical solids removal methods are based on the principles presented in Table 4-55. 

Application of Corrosion Inhibitors. There are basically two main techniques used to apply corrosion inhibitors in drilling operations. In the first method inhibitors are added to the drilling fluid system either by mixing the additives through the rig s chemical hopper or through additions into the mud pit. The treatment can be achieved in two ways, batch treatment or continuous treatment. In some cases it may be necessary to use both types of treatment simultaneously. The second technique of applying is directly coating the corrosion inhibitors on the drillpipe. 

Construction is a water-cooled wall combustion chamber connected to a steam drum at high level. The bottoms of the walls are connected to headers. Sometimes a bottom or mud drum is incorporated, but improved water treatment now available does not always necessitate this. 

These novel organic polymers were not developed solely for the CW or BW treatment market but are for much wider application. These same value-adding process additives are regularly incorporated into products for industrial and domestic cleaning, concrete, pulp and paper, metal finishing, paints and surface coatings, wastewater, seawater distillation, drilling muds, secondary oil-recovery, plastics extrusion, fibers, rubbers, and a host of other areas. 

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