wet crude processing

8/10/2019 Wet Crude Processing

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Wet crudeprocessing


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OIL DEHYDRATION


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1. INTRODUCTION


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Rarely is clean oil (produced from an oilwell ( ready for sale.

Generally, what comes out of the well is

a mixture of:

Oil, Water, Gas, and Sand or solid materiel


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Foreign material, such as

water and sand

must e separated from the oil and gasefore they can e sold.

!his process is "nown as:

Oil !reating or Oil#ehydration


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!he amount of this foreign material is

referred to as $S%W

($asic Sediment and Water, content of

the oil&

'ormally, the $S%W contentmust e

less than .) * +ol.$efore the oil will e acceptale for saleinto a pipeline


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Oil treating reuires a "nowledge

of emulsions.water-in-oil emulsionOil-in-water emulsion

WaterinOil

/mulsion

Oilin

Water

Separated

Oil % Water


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2. EMULSIONS


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Water produced with oil in the form of:

Free waterand2or /mulsion(water mixed

oil&

0n an emulsion:One of the liuids is spread out or

dispersed (discontinuous phase&throughout the other (continuousphase& in the form of small (tiny&droplets.


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0n most oil 3eld emulsions arewaterin

oil emulsion.

When the opposite happens, oilinwater emulsion is formed in case of

high water cut.

/mulsions may e:

!ight (di4cult to rea"&or

5oose (easy to rea"&

#epending on the type and amount ofemulsifying agent present.


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necessary o a+e:

!wo mutually immiscile liuid 6n emulsifying agent 0n the form

of Wor"o+er 7uids Resins #rilling muds Organic

acids Solid particles Organicases

8ara4ns 9etallic

salts 6sphaltenes olloidal

salts

Su4cient agitation to disperse


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su4cient agitation always occurs as7uid ma"es its way into the

Well ore(down hole pump or gas lift

+al+es&;p the tuing(restrictions& !hrough the surface cho"e

(pressure drop&

!he degree of agitationand the natureand amount of emulsifying agentdetermine the staility of the emulsion


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Oil Bearing Formation

Well bore area -

perforations

Chokes/Valves

Bends in

pipework Pumps

Flow

Regime

Potential Shear

o!rce


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3.E"!lionTer"inolo#$


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. ;nstale or 5oose /mulsionwater droplets are relati+ely large insi?e.

@. Stale or !ight /mulsionwater droplets are small si?e.


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%. EMULSI&'IN()(ENTS


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/.6 is a sustance has a surfaceacti+e

eha+ior that:8romotes the formation, andStaility of emulsion.

/.6 are collecting on the surface ofwater droplets and forming a tough 3lmwhich "eeps the droplets from Aoining.

6n emulsi3er will tend to e insolulein one of the liuid phases, it thusconcentrates at the interface.


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!here are se+eral ways emulsi3ers wor"to change a dispersion phase into an

emulsion.


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>. !he emulsi3ers may e polar

molecules (which align themsel+es insuch manner as to cause an electricalcharge on the surface of thedroplets&


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Stabilit$ o* the e"!lion

!he following factors are aBecting inemulsion formation and staility:

. !he speed of migration of the

emulsifying agent to the oil waterinterface, and

@. !he eha+ior in terms of the strength


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0n order to rea" an emulsion, the 3lmmust e neutrali?ed or destroyed y

using treatment methods.

!reating is usually done in the 3eldusing:

Carious types of euipment. 1eater treaters.@. /lectrostatic treaters.

6dding chemicals immediatelyafter oil is produced.


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+. DEMULSI&IERS


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#emulsi3ersact to neutrali?e the eBectof emulsifying agentsand are:

surfaceacti+e agents

!heir excessi+e use:

an decrease the surface tension ofwater droplets and actually createmore stale emulsion.

!end to promote oilinwateremulsions.

Sold under +arious trade names such as

!retolite, Cisco, $ra"sit,etc.


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!here are four important actions

reuired of a demulsi3er:

Strong attraction to the oil2waterinterface,

Flocculation,oalescence, andSolid wetting.

When these actions are present theypromote the separation of oil and water.


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Stron# attraction to the oil,-aterinter*ace

!he demulsi3er mustha+e the aility tomigrate rapidlythrough the oil phasetothe droplet interface, where it must

compete with the more concentratedemulsifying agent.

!he demulsi3er mustha+e an attraction

for droplets with a similar condition.

0n this way, large clusters of dropletsgather which, under a microscope,

appear li"eunches of 3sh eggs.


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Oil 8hase Oil 8hase

Water#roplet

Water#roplet

Water#roplet

Water#roplet

Without #emulsi3er !reatment the8liale Film 6round the Water

#roplet Remains 0ntact whena ollision Occurs

With #emulsi3er !reatment the

Film $ecomes $rittle and Ruptures whena ollision Occurs

#emulsi3er hemicals


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&locc!lation

6t this point, the emulsi3er 3lm is still

continuous.

0f the emulsi3er is wea", the 7occulationforce may e enough to causecoalescence.

!he demulsi3er must therefore:

'eutrali?e the emulsi3er, and 8romote a rupture of the dropletinterface 3lm.


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#roplets ha+e

strong attraction foreach other

ontact is made F5O;56!0O'

Resultant larger water drop

$arrier is ro"en O65/S/'/ta"es place

he 8rocess of Flocculation andoalescence


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Coalecence

With the emulsion in a 7occulatedcondition, the 3lm rupture results andcauses coalescence in rapid growth of

water drop si?e.


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Soli -ettin#

!he manner in which the demulsi3er

neutrali?es the emulsi3er depends uponthe type of emulsi3ers.

0ron sul3des, clays and drilling mudDs

can e waterwet causing them to lea+ethe interface and e diBused into thewater droplet.

8ara4ns and asphaltenes could edissol+ed or altered to ma"e their 3lmsless +iscous so they will made oilwet

and will e dispersed in the oil.


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0t would e unusual if one

chemical structure could produceall four desirale actions.

6lend of compoundsis thereforeused to achie+e the right alanceof acti+ity.


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De"!li/er Selection

!he demulsi3ers selection should e

made with the process system in mind.

0f the treating process is a settling tan",a relati+ely slowacting compound cane applied with good results.

0f the system is an electrochemical

process where some of the 7occulationand coalescing action is accomplishedy the electric 3eld, there is need for auic"acting compound.


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De"!li/er Chan#e

6s 3eld conditions change,0f the process is modi3ed,

Seasonal changes ring para4ninduced emulsion prolems,

Wor"o+ers contriute to solid, and6cid2ase contents which alters

emulsion staility.

0t can not e assumed that thedemulsi3er will always e satisfactoryo+er the life of the 3eld.


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0. &)CTORS )&&ECTIN(EMULSION RE)DO3N


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6.1Di4erential Denit$

0.2 5icoit$0.6 Inter*acial Tenion0.% 3ater Dro7 Si8e

0.+ Salinit$ o* the 3ater0.0 5ol!"e Percent o* the 3ater0.9 E"!li*$in# )#ent0. )#e o* E"!lion0.; )#itation


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!he di4culty of separating the

emulsi3ed water from the oildepends on the staility of theemulsion, and

!he staility of the emulsion, inturn, is dependent on se+eralfactors.

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