Production Engineering IIMID SEM Paper

Question 2Submitted By:Akshat Saxena R010209009Apoorv Agrawal R010209015Himanshu Gupta R010209027Prateek Kumar R010209039Sameer Gupta R010209049Sandeep Khadav R010209051Sarthak Mittal R010209052Shubham Goel R010209054

EMULSIONSA suspension of tiny droplets of one liquid in

a second liquid.Contains two phases: Continuous phase Dispersed phase• It can of two types • Water in oil (oil continuous , water

dispersed)• Oil in Water(Water continuous , oil

dispersed)In oil industry water in oil types are commonly

found.

An emulsion is a mixture of two immiscible

liquids stabilized by an emulsifying agent. In

the oil field, crude oil and water are

encountered as the two immiscible phases.

They normally form water-in-oil emulsion in

which water is dispersed as fine droplets in

the bulk of oil.

OIL EMULSIONS

EMULSIONS BASIC REQUIREMENTS

Two immiscible liquids.Emulsifying agent.Sufficient agitation (to disperse discontinuous

phase into continuous phase) In oil production these conditions are met so

emulsions are obtained from wellhead choke.

EMULSION STABILITYFactors on which emulsion stability depends:

• Difference in density of water and oil phases.

• Size of dispersed water particles.

• Viscosity.

• Interfacial tension.

• Presence and concentration of emulsifying

agents.

Factors to be considered before using specific technique for demulsification:

• Tightness of the emulsion.• Specific gravity of the oil and produced water.• Corrosiveness of the crude oil, produced water,

and casing head gas.• Quantity of fluid to be treated and percent water

in the fluid.• Paraffin-forming tendencies of the crude oil.• Desirable operating pressures for equipment.• Availability of a sales outlet and value of the

casing head gas produced.

Demulsifiers are highly efficient surface active agents and act to neutralize the effect of emulsifying agents. There are four main actions performed by a demulsifier :

• Strong attraction to the oil-water interface• Flocculation• Coalescence• Solid wetting.

The manner in which the demulsifier neutralizes the emulsifier depends upon the type of emulsifiers. Their excessive use can decrease the surface tension of water droplets and actually create more stable emulsions.

DEMULSIFIERS

What is free water knock out

vessel?

The selection of a free water knockout depends on the desired performance. The design criterion developed here is based on the perception that most FWKO's are installed to remove the bulk of the water from -a high-water cut flow stream so that the oil can be dehydrated economically to salable specifications and to discharge water requiring minimal treatment before disposal.

The free water Knockout is designed to economically separate a portion of the water in a wellstream from the oil. The vessel provides a low velocity flow with a large oil / water interface area which allows the maximum amount of free water to settle out.Their primary application is to reduce the water load on a treating system where a large volume of water is present. This can greatly reduce fuel consumption, and in many cases reduce the size of the treating vessel. Free Water Knockouts also have an application where the treating system is atmospheric yet pressure is required to dump the water.

Working of Free Water Knock out VesselWhen large quantities of water are produced, it is usually desirable to separate the free water before attempting to treat the emulsion. When oil and water are agitated with moderate intensity and then allowed to settle for a period of time, three distinct phases normally will form-• A layer of essentially clean oil at the top with a small

amount of water dispersed in the oil in very small droplets,

• Relatively clean water (free water) at the bottom with a small amount of dispersed oil in very small droplets.

• An emulsion phase in between.With time, the amount of emulsion will approach zero as coalescence occurs.

The free water is the water that separates in 3 to 10 minutes. It may contain small droplets of dispersed oil that may require treatment before disposal.The fluid enters the vessel and flows against an inlet diverter. This sudden change in momentum causes an initial separation of liquid and gas, which will prevent the gas from disturbing the settling section of the vessel.The liquid-collecting section of the vessel provides sufficient time for the oil and emulsion to form a layer of oil at the top, while the free water settles to the bottom.Oil and water are usually separated more quickly and completely in an FWKO when the liquid travels through the vessel in a horizontal rather than a vertical direction. Horizontal flow permits a less restricted downward movement of the water droplets.

Describe different types of free water knock out

vessels.

Vertical

A vertical FWKO should be constructed so that the flow stream enters near the top and passes through a gas liquid separating chamber. Inside the open vessel, separation of the degassed liquid mixture begins, with the oil-continuous phase rising to the top and the water-continuous phase settling to the bottom.

Removal of water from the vessel is regulated by a dump valve that normally is controlled by an interface float. The oil/gas outlet is usually restricted only by superimposed backpressure. As with all vessels, outlets should be equipped with vortex breakers.

VERTICAL HEATER TREATER - FIRED

Horizontal

The inlet normally is located near the top of one end of the vessel, permitting gas diversion to the top with a minimum of turbulence. After gross segregation occurs, oil- and water- continuous phases flow horizontally through the vessel and are discharged through separate outlets at the opposite end.

In horizontal vessels, the rising velocity of oil droplets entrained in water and the settling velocity of water droplets entrained in oil are perpendicular to the direction of flow.

HORIZONTAL HEATER TREATER - FIRED

How to optimize heat

input to a heater

treater?

• Heater treaters are designed to break wellstream emulsions, allowing the separation of crude oil from water and other foreign materials.• The heat input and thus the fuel required for treating depend on the temperature rise, amount of water in the oil, and flow rate.• It requires about twice as much energy to heat water as it does to heat oil. • For this reason, it is beneficial to separate any free water from the emulsion to be treated with either a free-water knockout located upstream of the treater or an inlet free-water knockout system in the treater itself.•Also, the vessel is preheated to optimise the heat input to the heater treater.

Assuming that the free water has been separated from the emulsion, the water remaining is less than 10% of the oil, and the treater is insulated to minimize heat losses, the required heat input can be determined from: q=16QodT[0.5(S.G.)o+0.1] where q = heat input, Btu/hrQ0 = oil flow rate, bopddT = increase in temperature, °FS.G.0 = specific gravity of oil relative to water

Another equation to determine the required heat input is as follows: q= (350/24) dT [0.5(qoρo)+qwpw] + 0.1q where q = heat input, Btu/hrρ0 = oil density, lb/ft3

dT = increase in temperature, °Fρw = water density, lb/ft3

THANK YOU