Inhibitors batch treatment

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. 

Batch Treatment. This treatment is accomplished by pumping manufacturer s recommended volume (with concentration up to 10,000 ppm or according to the manufacturer s recommendations for prevailing conditions) to batch down the drillpipe initially. Once the film is formed, the inhibitor concentration can be lowered for batch treatment at regular predetermined intervals. 

Continuous injection of corrosion inhibitors is practiced in once-through systems where slugs or batch treatment cannot be distributed evenly through the fluid. This method is used for water supplies, oil field injection water, once-through cooling water, open annulus oil or gas weUs, and gas lift wells. Liquid inhibitors are injected with a chanical injection pump. These pumps are extremely reliable and require little maintenance. Most chemical injection pumps can be adjusted to deliver at the desire injection rate (Chen et al. 2010). 

The most familiar example of batch treatment is the antomobile cooling system. A qnantity of inhibitor is added at one time to provide protection for an extended period. Additional inhibitor may be added periodically, or the fluid may be drained and replaced with a new supply. In most aerated, closed-loop cooling systems, it is important that the inhibitor concentration be measnred occasionally to ensure that a safe level is maintained (Li et al. 2011). 

Batch treatment is also used in treating oil and gas wells. An inhibitor is diluted with an appropriate solvent and injected into the annuals of open-hole wells or into the tubing of gas wells that have a packer. In this application, it is important that the inhibitor contacts all surfaces and that it has good persistence. Most wells require treatment about every 2 weeks. 

This is a periodic treatment in which a large quantity of chemicals is used for an extended period of time. It is commonly used to treat flowing oil wells. Batch treatment is also called slug treatment For batch treating, the tube displacement method is employed. Several barrels of inhibitor are pumped into the tubing at the top. The inhibitor is displaced to the bottom of the tubing with the fluids in the oil well. The well is closed for a specific period before operation. The batch is used mciinly to treat water with biocides and not to supply inhibitors or scavengers. 

Batch treatment Addition of an inhibitor at one time to provide protection for an extended period of time. Additional quantities may be added later depending on the need. 

This type of batch treatment is usually based on the rule of thumb 5.7 L (1.5 gallons) of inhibitor-oil mixture for each 304 m (1000 feet) of drill pipe in the hole. Spray equipment has been designed to treat the drill pipe while making trips. This technique is preferred for coating the outside of the drill string. 

Protection of production tubing requires that the inhibitor be squeezed, added continuously, or have film persistency so that batch treatment is feasible. Shear stresses impose the same requirements on inhibitors to withstand velocity effects. The tubing will be wetted more completely on the low side... 

If a chemical string is not feasible, batch treatments using persistent film inhibitors may be used. The inhibitor is designed to form a tough film that is not too soluble in the production stream so it will last for a sufficient time between treatments. The batch may be displaced with liquids, gas, or nitrogen. Squeeze inhibitors must be designed to be stable in the formation, and not cause severe emulsion problems. The adsorption characteristics should be controlled for proper feedback of the inhibitor. Pumped wells, can be treated by continuous addition or batching down the annulus. 

Inhibitors for batch treatment or tubing displacement in gas wells are returned to the surface cut with water and distillate. The inhibitor concentration is high, and at high concentrations some inhibitors behave as good emulsifiers for water and oil. For this reason the inhibitors reconunended for gas wells contain emulsion breakers to prevent emulsions that cause trouble in separators. 

Long or extended period batch treatments are occasionally performed on wells producing low water cut fluids (0 to 25% water). Oil-soluble or nearly oil-soluble inhibitors may be batched into the annulus. Usually half to one drum of chemical is used. The well fluids are circulated for two to four hours to mix the inhibitor into the annulus oil. The wells are then produced for a period of time (one month), when 37.8 to 56.7 liters (10 to 15 gallons) are again batched and the well circulated for two to four hours. With high fluid level wells this treatment has lasted for up to three months per batch. This procedure is a general guideline and the exact procedure should be supplied by tbe manufacturer. 

Continuous injection is used after clean-up and batch treatment has heen accomplished. In dry gas systems handling condensate, the same programs apply. Condensate should always he considered to contain some water. In dry gas systems that handle no hquids, clean-up and hatch treatments are recommended. Continuous injection is not desirable because there is nothing to help carry the inhibitor down the hne. Pipeline programs have to be designed for each system separately. 

Inhibitor concentrations vary from a few parts per million in continuous injection applications, to several thousand parts per million in closed systems, to batch treatments of the neat or undiluted inhibitor. Concentrations used influence test conditions and often determine whether or not... 

The wheel test, however, measures only the acmal effectiveness of the inhibitor in minimizing corrosion. Persistency (long-term effectiveness by a strongly adsorbed film in an uninhibited environment) and solubility determinations are supplementary tests used to evaluate desirable properties for the batch treatment method. 

In certain cases, such as in batch treatment of oil wells, dispersibility of an oil-soluble inhibitor into an aqueous phase is necessary merely to carry the inhibitor throughout the system. Efispersihility is also necessary for the same reason when using the relatively insoluble inhihitors for long-term persistency in batchwise treatment. 

Chem. Descrip. Surfactant blend Uses Corrosion inhibitor for batch treatment in gas systems Features Does not contain chlorides and halides, which can affect refinery works incompat. with anionics... 

Direct Treatment. Although batch and continuous treatment are both quite effective, there is a problem with inhibitor waste. When corrosion inhibitors contact the circulating drilling fluid, they are likely to coat the solids in the fluid system (cuttings or other solids). By applying the corrosion inhibitor directly to drillstem components before they are run in the hole, the corrosion inhibitor is the first thing that contacts the exposed metal surface. There are two methods for this type of corrosion inhibitor treatment. 

The common method of treating rod-pumped wells is to periodically batch inhibitor into them. The treatment period for a given well is selected using empirical rules based on well production volumes. A successful and economic corrosion inhibition program must carefully control the inhibitor concentration in the well fluids. Environmental aspects and efficacious inhibitor usage necessitate the measurement of very low corrosion inhibitor concentrations. Inhibitor concentrations as low as one part per million are significant, thus... 

The product is applied for the treatment of Parkinsonism that is caused by a lack of l-dopamine and its receptors in the brain. L-Dopamine is synthesized in organisms by decarboxylation of L-3,4-dihydroxyphenylalanine (L-dopa). Since L-dopamine cannot pass the blood-brain barrier L-dopa is applied in combination with dopadecarbox-ylase-inhibitors to avoid formation of L-dopamine outside the brain. Ajinomoto produces L-dopa by this lyase-biotransformation with suspended whole cells in a fed batch reactor on a scale of 250 t a-1. Much earlier, Monsanto has successfully scaled up the chemical synthesis of L-dopa (Fig. 19-38). 

Sometimes a short batch is forced down with a nitrogen displacement or compressed gas to speed up the fall rate and reduce shut-in time. An inhibitor squeeze is sometimes used to try to get a longer return time and simulate a continuous treatment. However, there is always the concern of formation damage with squeezes and with tubing displacements. 

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