Demulsifiers-Specialty oilfield chemicals

Demulsifiers-Specialty oilfield chemicals

Chandran Udumbasseri, Technical Consultant

Introduction

1

Definitions

• Demulsifiers are a class of specialty oilfield chemicals used to separate water in oil/oil in water emulsions.

• They are used in the processing of crude oil which contains significant amount of saline water (produce water).

• This saline water should be removed from crude oil before refining, as this saline water causes corrosion in equipments used for crude oil refining process.

2

Global Market..Oilfield chemicals

• As more petroleum crude oil wells are brought to production state around the world the demand for oilfield chemicals are expected to grow vertically.

• The global oilfield chemicals market is projected to increase at a compound annual growth rate (CAGR) of 5.7% between 2010 and 2015 as the drilling activities return and production rates are stimulated and new wells brought online. The market is expected to reach a value of $8.2 billion at the manufacturing level by 2015,

from a value of $6.2 billion in 2010.

3

Global Market..Drilling fluids

• Drilling-related chemicals accounted for 52% of the total 2009 market. It is projected that by 2015, drilling-related chemicals will increase to 55% to 56% of the oilfield chemicals market. This sector is worth an estimated $2.3 billion in 2010 and is expected to be worth $3 billion in 2015, a 5.7% compound annual growth rate (CAGR).

4

Global Market…Enhanced oil Recovery

• The largest growth rate by process application is expected in chemical-related enhanced oil recovery (EOR) applications. This sector is valued at $192 million in 2010 and is projected to reach $283 million by 2015, an 8.1% compound annual growth rate (CAGR).

5

Global Market…Demulsifiers

• Demulsifier chemicals including desalters and deoilers account for approximately 40% of the world oilfield production chemicals market. They are deployed at every crude oil processing station worldwide.

6

Oil & Gas Market..India

• Oil and gas production in India grew at a CAGR of 4.2% over the 2000-09 periods. This is expected to grow at a CAGR of 1% over the 2010-30 periods.

7

VALUE OF OILFIELD PROCESS CHEMICALS BY APPLICATION, 2010 AND 2015

($ MILLIONS)

8

Suppliers of Demulsifiers -Around the world

• AKZO-NOBEL • Baker Petrolite • BASF • Brentag • Buckman • CECA • Cochran • Clariant • Croda • Dorf Ketal • Dow • Eonchemicals Putra

• Hydrates chemical Co • Instral BV • Multichem - Halliburton • MI SWACO- Schlumberger • Nalco Champion • NCPI • REDAOilfield • Scharer & Schlaofer AG • UNIVAR • PCC EXOL (Courtesy Wikipedia)

9

Demulsifier –Main Suppliers

• Baker Petrolite

• Schlumberger

• Halliburton

• Champion (Now part of Ecolab +Nalco)

• Clariant

• Nalco (Now part of Ecolab)

10

Growth potentials for oilfield chemicals

• Horizontal drilling and hydraulic fracturing in shale oil development mainly in US &Canada

• Off-shore drilling of oilfields around the world

• Increasing oil demand in Brazil, India, Africa, China, Russia, Saudi Arabia, and a number of other Asian countries

• Well stimulation techniques - attractive option for Mexico, Argentina & Australia

• India and China looking for hydraulic fracturing of shale

11

Why crude oil Demulsification is important..?

• The stability of emulsion is very specific to each drilling wells and will vary in character as the field matures

• In addition to this emulsion there will be some free, uncombined water, the proportion of which will increase as the water content increases

• If water /oil separation is not carried then the following problems are possible: Overloading of surface separation equipment

Increased cost of pumping crude which contains significant water

High viscosity of emulsion causes pressure development at pumping

Increase vessel heating costs

Risk of corrosion

Storage tank bottoms form thick sludge, difficult to remove

High levels of basic sediments, water and salt are delivered to the refinery

Risk of catalyst poisoning

12

Emulsion & Stability

• An emulsion is a combination of two immiscible liquids that do not mix together under normal conditions.

• The dispersed phase is present in the mixture in small amount while the continuous phase is present in large proportion in the mixture.

• In water in oil emulsion the dispersed phase is water and the continuous phase is oil.

• The water may contain from trace to 70% and perhaps more but such emulsions are unstable.

• The emulsion may be tight (difficult to break) or loose (easy to break). • Industrial and domestic effluents contain oil in water emulsion. • To establish whether the emulsion is oil in-water or water in-oil, add water

or kerosene to the emulsion. • If dilution occurs on adding kerosene then the emulsion is water in-oil

emulsion and if dilution occurs on adding water then it is oil in-water emulsion.

13

w/o and o/w emulsions-Photo

14

Water in oil emulsion

Oil in water emulsion

Emulsion Classification

Class Duration (under Lab condition)

Stable-Actual Emulsion

>4 weeks

Meso Stable <3 days

Unstable Short time

Entrained water 1 day

The emulsion is classified into four, namely, stable, meso-stable, unstable and entrained water.

Their spontaneous demulsification time is tabulated as given:

15

Crude oil Classification based on density

Classification Density, kg/cu m

Light crude <825

Medium crude 825-875

Heavy crude 875-1000

Extra Heavy crude

>1000

Density range of each class of crude oil is given.

Use the following formula to convert this to API (American Petroleum Institute) gravity

API gravity = [141.5/Sp.gravity] – 131.5

16

SARA Distribution

Parameters West Africa crude

North sea

crude

Saudi crude

Problematic wells

Non-problematic

wells

Saturates,

%

47.9 48 37.5 30.3

Aromatics,

%

36.5 37.5 44.4 44.5

Resin, % 15.2 14.2 13.8 20.7

Asphaltene,

%

0.4 0.3 4.3 4.5

The classification of crude oil fraction is based on solubility, namely, saturates (heptane soluble), aromatics, resins and asphaltenes (SARA in abbreviation) present in the crude oil.

17

Agitation Effect

• Crude emulsions are formed by vigorous agitation of oil/water mix

• As crude passes through chokes, wellhead valves, etc extreme mixing conditions are experienced at the pressure gradient and new w/o interfaces are formed

• Intensity of agitation is the main factor to determine the stability of the emulsion

• More shearing action (turbulent flow) to oil-water mixture causes more water droplet division to smaller ones and thus the emulsion becomes more stable

18

Viscosity Effect

• For high viscosity crude more agitation energy is required to create the emulsion

• High viscosity oil maintain larger dispersed water droplets in suspension and smaller droplets will have more resistance to settling

• Viscous crude retards the movement of added demulsifier

• High viscosity crude forms more stable emulsion

• As the water content increases the viscosity of a stable also increases

19

Viscosity-water cut

20

Crude oil viscosity

21

Specific gravity Effect

• If there is much difference in the specific gravity of oil and water phase, then faster settling of the two phases takes place

• Heavy crude oil tends to keep water droplets in suspension longer

• Fresh water settles more slowly than salt water (salt water has higher specific gravity)

22

Stabilizing Components of Crude emulsion

• Natural surfactants: organic acids, heterocyclic nitrogen compounds reduce surface tension slightly

• Resins are absorbed at the interface

• Asphaltenes accumulate at interface

• Paraffin wax crystals precipitate and accumulate at the interface

• Inorganic fines (silt, clays, scale) which are insolubles in the crude oil accumulates at the interface

• More stable emulsions are formed by oil wettable solids like iron sulfides and oxides (corrosion products)

• Added corrosion inhibitors, biocides, scale or wax inhibitors are emulsifiers which add stability to emulsion

23

Other crude stabilizing factors

• If crude from wellheads are flowing to separator at a lower temperature emulsion will be less to break

• Long subsea pipe lines result in cooler crude

• Long chain surfactants at the interface can cause steric repulsion and retard coalescence of water droplets

• Oil wetted solids prevent destabilization of emulsion

• Presence of adsorbed surfactants create mechanical barrier to coalescence

• Ionic inorganic species generate electrostatic repulsion frces especially in oil in water emulsion

24

pH

• The pH of the produce water also plays an important role in emulsion breaking.

• pH: oil-in-water prefer a low pH (4-6) and water-in-oil prefer high pH (8-10). When pH is increased from 4 to 6 the more stable o/w emulsion is formed. But further increase to 6-8 caused less stable o/w emulsion. When the pH is increased to 8, water-in oil emulsion is formed. The water-in oil emulsion is stable at very high and at very low pH

• Most of the produce water is having pH in the range 6-7 which is not favorable for stable emulsion

25

Salt concentration

• 1.Oil-in water droplet size increase with increase of salt concentration in water while water-in oil droplet size decrease with salt concentration increase. Sea water gives emulsion of small size as it is having high concentration of salt. Such emulsion with high salt concentration water is not stable and can be broken easily. .

• 2. The inorganic salt in water of the emulsion has adverse effect on the emulsion stability. Adding salt to emulsion cause depletion force.

26

Solid Particles

• Solid particles in the emulsion stabilize the emulsion and prevent coalescence of water droplets.

• Solid particles/wax, etc, stabilize the emulsion. They get wetted by the water and oil in the emulsion. They serve as mechanical barrier to prevent coalescence of the droplets.

• When a small amount of calcium sulfate (plaster of Paris) powder is added to coconut oil-water mixture and shaken well it can be seen that the calcium sulfate powder distribute in the interface of water coconut oil emulsion formed.

27

• The emulsion formed with calcium sulfate powder, water and coconut oil is more stable as compared to emulsion without calcium sulfate powder.

• So the stability of the emulsion increases due to solid particles.

• Asphaltenes add stability to emulsion .Large sized molecules of asphaltenes are solid in nature at room temperature.

• Wax also adds stability to emulsion.

• At low temperatures wax and asphaltene start crystallizing. The stability of the emulsion increases as the solid appears at the interface.

• But as the temperature is increased to 50oC, the wax and asphaltenes dissolve and disappear from the interface. This will reduce the stability of the emulsion.

28

Ageing Effect

• A sample of crude oil emulsion collected and preserved for sometime suffer ageing

• An aged crude oil sample undergo air oxidation, photolysis, light fraction evaporation, microbial activity

• Crude emulsion containing oxygenated compounds are very difficult to break compared to fresh crude emulsion

29

Crude Oil Emulsion Destabilization

• Flocculation stage: association of large and small water droplets into clusters but without coalescence

• Creaming or dropping of water: droplet clusters separate in to phases under the influence gravity. Density difference help dropping

• Coalescence or breaking of free water: as continuous phase separates then interface film ruptures with free energy reduction

• Destabilization is enhanced by:

Increased temperature

Centrifugation

Electrical methods

Increased resonance time

Chemical treatment

30

Destabilization: heating

• Heating encourage Brownian motion and thus collision between droplets

• Viscosity of the continuous phase reduces and help better motion of water droplets

• Heating helps dissolution of emulsifying agent

• Heating is costly, increased asphaltene precipitation, and increased corrosion risk

31

Destabilization: centrifugation

• Centrifugation artificially increase G-force (gravitational force)

• Centrifugation increase concentration of dispersed phase in the creamed emulsion layer

• Centrifugation breaks the interfacial film of the emulsion

• Centrifuge and hydrocyclones are used for oil in-water emulsion

32

Destabilization: electrical methods

• Electricity was used as early as 1906 to destabilize water in oil emulsion

• High voltage electrostatic separator are used. Water permittivity is higher than oil (permittivity is, which is a measure of how easily a dielectric polarizes in response to an electric field. Permittivity relates to a material's ability to transmit (or "permit") an electric field).

• Electric grids are located at the top of the separator in the oil rich phase

• Applied field causes a dipole on water drops which are attracted to each other and destabilized by elongation (too much free water across the electric grid causes short-circuiting)

33


34

Destabilization: electrical methods GRID PLATES

35


36


• Interaction between droplets creates forces of attraction resulting aggregation and coalescence

• AC electric fields are used to produce water droplet dipoles. Droplets are not electrically charged

• Oil in water emulsions respond to dc current leading to flocculation of droplets through electrophoresis

37

Destabilization: longer residence time

• Crude emulsions are thermodynamically unstable

• If sufficient time is given the emulsion breaks

• The residence time from well head to separator are usually long and enable significant water separation making the emulsion breaking more easy

• More residence time in iron pipe lines cause corrosion risk and slug flow.

• Shorter residence time needs additional options such as using chemical demulsifiers

38

Terms explanation: well stimulation

• Well stimulation can be used to improve the flow of natural gas or crude oil into a well bore.

• Intervention techniques like increasing permeability outside the bore are used for well stimulation - clean the formation or increase perforation and fractures in the reservoir

• To clean the formation, chemicals like formic acid (acidization) is pumped in to the bore to dissolve the blockage

• Creating additional cracks and fractures in the reservoir increases the permeability

39

http://www.wisegeek.com/what-is-natural-gas.htm



Well completion

• When a well is drilled the decision is whether this well can be a producer well or be plugged and abandoned as a dry hole

• If the decision is to develop the well to produce oil, then well completion steps should be undertaken

• well completion steps transform the drilled well to a producing one

• The steps are, casing, cementing, perforating, gravel packing, and installing a production tree

40

Well completion: casing

Casing: Source: Schlumberger

41

Well completion: cementing

Cementing: Source: MPG Petroleum

42

Well completion: perforation

Perforation: Source: Halliburton

43

Well completion: gravel packing

Gravel Pack: Source: Schlumberger

44

Well completion: production tree installing

Production Tree: Source: Cameron

45

Term Explanation: horizontal drilling

• Horizontal drilling is used to gain access to pockets of oil and gas that may be missed or unreachable by traditional vertical drilling.

• A vertical hole is drilled first, and then the horizontal drilling is spurred off from there.

• The vertical part of the drill can be used for several horizontal drills in different directions and extended for over a thousand feet from the vertical hole.

• While horizontal drilling is about twice as costly to set up as traditional vertical drilling, the greater quantities of oil and gas that are returned pay for the increased investment

46

Horizontal drilling

47

Term Explanation: hydraulic fracturing

• Hydraulic fracturing is process where millions of gallons of water, sand, and chemicals are pumped underground to break apart the rock and release the gas.

• Fracking or hydraulic fracturing, is the process of extracting natural gas from shale rock layers deep within the earth

• Fracking makes it possible to produce natural gas extraction in shale rock that were once unreachable with conventional technologies

• Horizontal drilling (along with traditional vertical drilling) allows for the injection of highly pressurized fracking fluids into the shale area

48

Hydraulic fracturing

49

Terms Explanation: Shale

• Shale is a fine-grained sedimentary rock that forms from the compaction of silt and clay-size mineral particles that we commonly call "mud“

• Some shales have special properties that make them important resources. Black shales contain organic material that sometimes breaks down to form natural gas or oil

• Black organic shales are the source rock for many of the world's most important oil and natural gas deposits

50

http://geology.com/rocks/sedimentary-rocks.shtml



http://geology.com/oil-and-gas/







Shale rock

Organic-rich black shale. Natural gas and oil are sometimes trapped in the tiny pore spaces of

this type of shale.

51

Extraction of gas/oil from Shale

Conventional method Unconventional –horizontal

drilling and hydraulic fracturing

52

Enhanced Oil Recovery (EOR)

• Oil production is separated into three phases: primary, secondary and tertiary (which is also known as Enhanced Oil Recovery -EOR).

• Primary oil recovery is limited to hydrocarbons that naturally rise to the surface, or those that use artificial lift devices, such as pump jacks.

• Secondary recovery employs water and gas injection, displacing the oil and driving it to the surface

53

EOR………………

• Primary and secondary methods leave 75% of the oil in the well. By EOR methods 75% of the this oil can be recovered

• Secondary recovery uses water or gas injection, EOR uses steam/gas to change the make up of the reservoir

• Types of EOR: chemical flooding, gas injection and thermal recovery

54

Gas/chemical injection

55

Thermal recovery

• Heat is used to reduce viscosity of oil. Steam is applied for thinning oil and enhance flow

56

Chemical injection

• Chemical injection EOR helps to free trapped oil within the reservoir.

• This method introduces long-chained molecules called polymers into the reservoir to increase the efficiency of water flooding or to boost the effectiveness of surfactants,

• Surfactants help to lower surface tension that inhibits the flow of oil through the reservoir.

57

Gas injection-EOR

• Gas injection used as a tertiary method of recovery involves injecting natural gas, nitrogen or carbon dioxide into the reservoir.

• The gases can either expand and push gases through the reservoir, or mix with or dissolve within the oil, decreasing viscosity and increasing flow.

58

Gas injection

59

Chemical demulsifiers for crude oil

60

• Chemical demulsifiers are used through out the world to improve emulsion breaking processes

• First demulsifier – Sulphonated castor oil

• Today demulsifiers are prepared from surfactants of various hydrophilic/lipophilic balance values:

Non-ionic

Cationic

Anionic

61

Demulsification process

• To break crude oil emulsion the ordered structure of natural surfactant/emulsion system must be disrupted

• On adding demulsifier the following properties are modified:

Surfactant behavior at water /oil interface

Ability to flocculate dispersed phase drops

Ability to cause coalescence of dispersed phase

Wettability of solids

62

HLB values • Surfactants are classified by HLB values

• Surface active molecules with similar structures show stability maxima corresponding to w/o emulsifiers and o/w emulsifiers

• There is stability minimum where neither hydrophilic nor hydrophobic groups dominate the interfacial region

• Most demulsifiers are having HLB values in the region of this stability minimum

• Useful demulsifiers are those that adsorb or partially displace the natural surfactant, then desorb again after film rupture

• Performance characteristic of these products can be varied by molecular weight, solubility, charge reduction potential, flocculation behavior, etc.

63

Types of demulsifers

• Acid catalyzed phenol-formaldehyde resins

• Base catalyzed phenol-formaldehyde resins

• Epoxy resins

• Polyethylene amines

• Polyamines

• Di-epoxides

• Polyols

• EO/PO Block polymers

• The above are usually ethoxylated (and/or propoxylated) to provide the desired degree of water/oil solubility. The addition of Ethylene oxide increases water solubility, Propylene oxide decreases it.

64

http://en.wikipedia.org/wiki/Ethylene_oxide



http://en.wikipedia.org/wiki/Propylene_oxide



EO/PO Block polymers

• Non-ionic EO/PO Block polymers are good for flocculating small sized water droplets

• They are called treaters

• They flocculate tiny individual water droplets in w/o emulsion

• Molecular weight range is 1000-10000

65

Ethoxylated alkylphenol resins

• Ethoxylated resins are good for water dropping and coalescence

• Performance of these resins can be modified by:

o Varying the alkyl group

o Degree of ethoxylation/propoxylation

o Cyclic formations

• Acid catalyzed resins are effective for water dropping and coalescence, but good residence time is required for good water quality

• Higher Mol Weight products show wetting capability

• Mol weight range 500-2000 shows good dropping ability

66

Di-epoxides

• Di-epoxides are excellent emulsion breakers, they separate water if used singly, but show good performance in blends with resins and/or polyamines

• They are oil cleaners giving low BS&W and salt content

• Polyethylene glycols of different mol weight are reacted with bisphenol A to give products with varying HLB values

67

Polyamines

• Polyamine are similar to di-epoxides and give low BS&W and very good desalting

• They blend with resins and give faster water separation

• Disadvantage is that they need considerable initial mixing and long contact time

68

Polymerized Polyols

• Polymerized polyols show rapid penetration through oil phase reaching emulsified water.

• This penetration is vividly demonstrated by the rapid blackening of cream-colored emulsions and the quick brightening of water-hazed emulsions.

• They are extremely oil soluble in nature and exhibit great tenacity for finishing the dehydration of crudes where more water-soluble compounds can “wash out” with the water phase of a partially resolved emulsion.

• Polymerized polyols typically require blending with other emulsion breaker intermediates to achieve complete treatment of water-in-oil emulsion.

69

Polyol Esters

• Polyol esters are a reaction product of a polyalkylene oxide block polymer and a polyfunctional organic acid. Polyol esters are particularly effective on fresh-water emulsions and tend not to cause emulsion inversion or oil-in-water emulsions.

• Polyol esters act, as do most emulsion breakers, by counteracting the effect of naturally occurring emulsifiers.

• Polyol esters are an effective emulsion breaker when used separately or in blends with oxyalkylated phenolic resins. This high molecular weight chemical is non-ionic in character.

70

Resin Esters

• Resin ester intermediates are reaction products of an oxyalkylated phenolic resin and an organic carboxylic acid.

• Resin esters are unusually effective when used as a detergent or as a wetting agent in emulsion breaker formulations.

• Despite resin ester’s high detergency, they do not cause inversion to oil-in-water emulsion. Resin esters have also been used in limited applications as a desalting chemical and in treating slop oils.

71

Polyalkylene glycols

• Polyalkylene glycols are non-ionic in character. They work by counteracting naturally occurring emulsifiers.

• These Polyols have been found to be particularly effective when used in low salt water brine or in fresh water emulsions.

• In these cases, polyols are often formulated with sulfonates or used as is.

• Polyols exhibit exceptional ability to lower interfacial tension and, as a result, have a high degree of wetting activity. For this reason, polyols can effectively disperse or deflocculate solids.

• Polyalkylene glycols can be used with effectiveness in synergistic blends with oxyalkylated phenolic resins

72

Sulfonates

• Sulfonates have outstanding characteristics that include low cost and a resistance to “burning” or “overtreating” when used in formulations to treat crude oil emulsions of the water-in oil type.

• Sulfonates aid in emulsion breaking by counteracting naturally occurring emulsifiers and are extremely effective in resolving loose water emulsions stabilized by solids. Sulfonates are often used in treating refinery “slop” emulsions as well as tank bottoms

• Sulfonate intermediates are generally used in conjunction with oxyalkylated phenolic resins and with polyglycols.

73

Compounds with demulsifying activity

• Polyethylene imine alkoxylate & Mono or oligo-amine alkoxylate.

• Alkoxylated alkylphenol formaldehyde resin.

• Alkoxylated amine modified alkyl phenol formaldehyde resin.

• Co or ter polymers of alkoxylated acrylates or methacrylates with vinyl compounds.

• Condensates of mono- or oligo- amine alkoxylates, dicarboxylic acids and alkylene oxide block polymers (may be quaternized at nitrogen).

• Cross linked products of all above

74

Compounds acting as demulsifying assistant

• Poly alkylene glycol ethers

General Formula, [R’(OA1)a ..OH]n , R’ = C7 to C20 alkyl group, phenyl group, alkyl phenyl group: A1,A2,A3 = 1,2 alkylene group with 2 to 4 carbon atoms, phenyl ethyl group ( there should be one 1,2 alkylene group with 4 carbon atoms); a = 1 to 50; n = 1 to 10.

• General Formula H-(OA1)b-(OA2) c-(OA3) d-OH (where b, c and d each has value from 0 to 50 and b+c+d is >3).

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Classification –water droppers

• Water droppers coalesce water droplets in the crude oil and release free water.

• Predominant type is based on alkyl phenol formaldehyde resins with low levels of addition of ethylene oxide or propylene oxide.

• These demulsifiers also show excellent desalting properties.

76

Treaters

• The primary function of these compounds is to flocculate the large number of submicron water droplets dispersed in the crude oil. Water droplets are thus concentrated at the base of the oil column prior to coalescence and the crude is dehydrated above the settling level of the flocs.

• This can be noticed by the brightening of the top oil in contrast to its dull appearance when the water dispersion existed.

• The predominant type is based on high molecular poly propylene glycol molecules with hydrophilic ‘tips’ which solvate into the water droplets and facilitate gathering.

77

Hybrids

• These compounds incorporate a balance of molecular design features such that both ‘dropping’ and ‘treating’ characteristics are exhibited.

• Hybrids are more cost effective than blends of droppers and treaters.

78

Desalters

• The emulsions coming along the crude to the desalting stage have low amounts of water and are less stable. Some of the naturally occurring emulsion stabilizers have been removed at the 1st stage demulsification process. The droplet size is not very small. High potential electric field applied coalesce these polar salt water droplets.

• A good desalter demulsifier would achieve rapid water separation at low level addition rates.

79

Wetting agents • Some ethoxylates, sulfonates, amine ethoxylates are

extremely useful for treating emulsions stabilized by inorganic solids

• They selectively wet the surfaces of inorganic solids like, clay, sulfides, iron hydroxides

• Organic solids such as paraffins can be effectively re-solublised to the organic phase by using wetting agents

• Sulfonated oils exhibit good wetting ability.

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Gas Oil Separating Plant (GOSP)

D1 HPPT

D201 HPPT

D2 LPPT

D211 DehydratorD212 Desalter

Shipment line

Production Header

Sample Point

81

GOSP-Saudi Aramco • The flow chart given above is a typical gas oil separating plant

in Saudi Aramco. Almost all GOSPs have the same flow chart except a few

• The crude is collected at Production header through pipes from different production wells

• Production header is pipes of 36” diameter size. Demulsifier, corrosion inhibitor, scale inhibitor and biocide are injected in this order to this header

• Crude oil samples for “bottle testing” are collected from the header before the injection point of demulsifier

82

Crude processing in GOSP • The crude oil gets mixed with demulsifier and other

additives through turbulent flow inside the pipe

• Wet Crude enter the first separator, which is called High Pressure Production Trap (HPPT – D1 & D201 in the flow chart). Here the separation of gas-oil-water takes place

• Water gets collected at one side of divider baffle and oil overflows from the top to the outlet. Water flows out from the bottom. Gas escapes through the vent to gas collection tanks.

83

Crude processing …2 • The oil from outlet flows to Low Pressure Production Trap

(LPPT, D2 in the flow chart). As the pressure is reduced all gas gets removed from crude

• Almost 70% water in crude oil is separated in HPPT while no water is separated at LPPT separator.

• Gas freed oil flows to Dehydrator (D211 in the flow chart). Dehydrator is electrostatic grid with aid water separation electro statically (Slide 27,28,29).

• Water separated is removed through bottom of dehydrator. Almost all the remaining water (30%) is separated from this vessel.

84

Crude processing…..3 • The oil from the outlet of dehydrator should be dry with </=

0.2% water content

• Oil from the outlet of dehydrator is mixed on-line with wash water (vary from 10-15% by volume of crude). This water is added to remove any crystallized salt in the dried crude from dehydrator

• Wash water mixed crude is fed to desalter (D212, in the flow chart). Here also the water is removed electro statically.

• The dried and desalted crude oil from desalter should meet the specification of Saudi Aramco

• Oil specification, Salt content = < 8PTB; BS&W = < 0.2%

85

Vendor Registration-Saudi Aramco

• Vendors are registered to Saudi Aramco after approval for prequalification. Supplier Relations Management Unit (SRMU) of Saudi Aramco is managing the vendor approval.

• http://www.saudiaramco.com/content/mobile/en/home/doing-business-with-us/materials-suppliers/registering-as-a-materials-supplier.html

• Vendor portal is used by the supplier for submitting their products

• For overseas vendors like India the following agency is looking into such matters

86

http://www.saudiaramco.com/content/mobile/en/home/doing-business-with-us/materials-suppliers/registering-as-a-materials-supplier.html


















Aramco Overseas Agency

87

Manufacturers &

Suppliers

Registration

India and Malaysia,

Singapore,

Indonesia,

Thailand, Vietnam,

Cambodia, & The

Philippines

Aramco Overseas Company B.V. India

Branch Office

Unit 610, Level-6, Time Tower Building

MG Road, Gurgaon,-122002, Haryana., India

Tel: +91 (0) 1244983900

Fax: +91 (0)124 498 3909

Email: [email protected]

Website: http://www.aramcooverseas.com/

The above nations can use Aramco Overseas

Agency for submitting their registrations

Oil producers in Middle east area

• Saudi Arabia – Saudi Aramco

• Kuwait – KOC

• Abu Dhabi – ADNOC

• Bahrain – Bapco

• Qatar – QP

• Oman – Petroleum Development Oman (PDO)

• Syria-Syrian Petroleum (Al Furat, de Ezour, Sino)

• Iran-NIOC

• Algeria –Sonatrach

• Libya - LNOC

88

GOSP-Demulsifier consumption

89

Demulsifier dosage-histogram

90

120112

180

165

180

140

95

160

70 7065 65

57 6065

55 55

90

70

90

150

125125

160

140

113

100

7570

92

0

20

40

60

80

100

120

140

160

180

200

3/2/

2009

7/2/

2009

24/2

/200

9

28/2

/200

9

7/3/

2009

15/3

/200

9

24/3

/200

9

29/3

/200

9

6/7/

2009

16/7

/200

9

1/8/

2009

9/8/

2009

29/8

/200

9

7/9/

2009

29/9

/200

9

10/1

0/20

09

17/1

0/20

09

31/1

0/20

09

14/1

1/20

09

21/1

1/20

09

2/12

/200

9

6/12

/200

9

14/1

2/20

09

21/1

2/20

09

28/1

2/20

09

4/1/

2010

11/1

/201

0

18/1

/201

0

1/2/

2010

16/2

/201

0

GPD

Date/Time/Period

GPD (S 4 Demulsifier dosage)

Dosage pattern

• Above data were from actual results

• The patterns of dosage show high value from months November to April while it is minimum from months May to October

• There are two dosage rates winter and summer rates. Winter rates high and summer rates low

• The pipe lines, through which oil is delivered from wells, are effected by temperature variation of winter (-5C to 15C) and summer (40C to 60C)

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Yearly consumption of demulsifiers

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Yearly anticipated consumption in all 28 GOSPs, US Gallons per year

GOSPs which go bottle test bidding separately (not included here)

Shaibah, Kurais, Khursaniyah, Safaniyah, Zuluf, Tanajib, Qatif, Khafji, Hout, Manifa

GOSP Consumption /year, GPY GOSP Consumption /year, GPY

ABQaiq-2 4460 Uthmaniyah 4 121730




Aindar 1 70300 Uthmaniyah 10 35160

Aindar-2 51400 Uthmaniyah 11 70330

Aindar 3 51400 Uthmainyah 12 62220

Aindar 4 48690 Uthmaniyah 13 29700

Aindar 6 43280 Hawaiyah 2 100090

SHadgm 1 59500 Hawaiyah 3 175800

SHadgm 3 108210 Hawaiyah 4 119030

SHadgm 4 86560 Harad 1 175800

SHadgm 5 119030 Harad 2 75740

SHadgm 6 43280 Harad 3 54100

Total,gallons 705800 1154850

Grand total, gallons 1,860,650

Demulsifier formulations

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More bases in formulation • Demulsifiers are not always single component, but formulated

with more than one and sometimes with 4 or more bases.

• Demulsifier reduces interfacial tension between water and crude oil

• For better demulsification natural gas should be removed from crude

• Demulsifier is injected at the wellhead giving adequate time before crude reaches the separator.

• Demulsifier should reach the targeted interface to function effectively. It should have right solubility. It is attracted to the target through difference in polarity.

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• The stability of emulsion vary from well to well. So it is necessary to develop demulsifier blends to specific targeted crude oil.

• They are selected based on their performance in bottle tests and centrifuge tests.

• These tests help to identify products that produce maximum water dropping with cleanest oil phase

• The sample should be tested for fastest water drop, sludge, quality of interface, quality of water

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Bottle Test Report

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Relative Solubility Number (RSN) • The RSN value assigned to each demulsifier components

indicates its relative solubility in water (RSN is an empirical value)

• As the numerical value increases the solubility of the polymer in water increases

• Practically the product having RSN<13 are insoluble in water

• RSN 13-17 are dispersible in water at low concentration and form gel at high concentration

• RSN>17 are completely water soluble

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Guidelines for RSN

• For a crude oil emulsion, a demulsifier formulation should have RSN between 6 and 15. The RSN value can be added algebraically.

• A 50-50 blend of two bases with RSN of 10 and 20 will yield blend RSN as 15 (10+20 = 30/2=15)

• Synergism between intermediates make demulsifier blend better than single component system

• Demulsifiers with very low and very high RSN are not used individually

• Due to synergism, blends of intermediates from different chemical groups make better demulsifiers, than blends using intermediates from same family of compounds

98

• Some demulsifiers have special properties that give them very good blending characteristics

This is the case with highly oil soluble (low RSN) polyglycols. When blended with oxyalkylated resin give excellent demulsifier formulation. Other blends are resin with polyols, diepoxides, polyacrylates based molecules

• To get dried oil, water droppers and oil driers are used. Water droppers work very quickly due to flocculation of large droplets, the base sediment will be greater than 1%

• Drying demulsifiers reduce water content fully via coalescence but takes longer time.

99

Synergism in formulation

100

Synergism • In the above graph conductivity is plotted against

temperature

• As emulsion breaks the water droplets coalesce and the conductivity increases due to salinity of water.

• As the temperature increases more emulsion breaks.

• Thus conductivity proportional to amount of

emulsion broken.

• The rate of emulsion breaking with temperature is different for components 1,2,&3 and amount of breaking also less in the temperature range 30C-50C

101

• The plot of DF Formulation ( ) is of formulated demulsifier from components 1, 2 & 3.

• Compared to individual plots, the plot of blend suddenly shoots up to the maximum showing large amount of emulsion breaking.

• This is the synergic effect of blends

102

Effectiveness of demulsifier • Capable of treating a wide range of emulsions under the most

demanding field conditions - including short residence times, high turbulence, high solids loading and water content.

• Should possess different types of property:

1.Flocculant or treater

2.Coalescer or dropper

3.Wetting Agent (wetter/dispersant)

4.Booster for special crudes (asphaltene / wax additives)

5.Solvent system (usually hydrocarbon based)

• The emulsion from a group of wells change with time. Composition of a crude oil will change within time as well usually the amount of water will increase during production

103

• If the demulsifier formulation is poor then:

– Poor water separation

– Emulsion build up at the oil/water interface

– High water cut in the treated oil

– Oily water

– “Sludging”, usually at the interface but can occur throughout the oil layer. The “sludge” is a new emulsion.

– “Bad oil” production then contaminates clean oil in storage

104

• Good demulsifier formulation depends on the following:

– evaluate the system,

– plan the test,

– obtain a representative sample,

– carry out a ratio test,

– screen the individual actives,

– develop and screen potential formulations,

– then follow with a final evaluation and selection

105

• For good formulation, the sample should be:

– Representative of the production system

– Composite

– Consistent with current production

– Chemical free (absence of normally injected field chemicals)

– Contaminant free

– Fresh

– Consistently available

106

• Parameters noted in bottle tests are:

– Speed and amount of water drop

– Top oil treatment

– BS - sludge formation

– Interface quality

– Clarity of water

– Colour of oil

– Nature of centrifuge cut

107

HLB values • The Hydrophilic-lipophilic balance of a non-ionic surfactant is

a measure of the degree to which it is hydrophilic or lipophilic

• HLB may be theoretically calculated using the formula:

– HLB = Weight % Hydrophile/5

– Example: lauryl ethoxylate (1:4)

– Mol Weight of ethoxylate part = 176

– Mol Weight of lauryl alcohol = 186

– Weight% = [176/(176+186)]*100 = 48.6%

– HLB= 48.6/5 = 9.7

• HLB value below 9 is taken as lipophilic and HLB above 11 is taken as hydrophilic. HLB between 9-11 is intermediate

• HLB values are used for emulsifiers

108

HLB of blends • When two or more emulsifiers are blended

the resulting HLB can be calculated:

– Example: Blend of 70%Tween 80 (HLB, 15) and 30% Span 80 (HLB, 4.3)

– Tween 80=0.7x15 = 10.5

– Span 80 = 0.3x4.3 =1.3

– Sum value = 11.8 is the calculated HLB for the blend

109

HLB Value &Classification of chemicals

110

Chemicals can be classified using HLB values.

Table shows the classification into groups:

Required HLB calculation

111

• Table below shows how the required HLBs

can be calculated. Here Tween 60 (HLB=4.7)

& Span 60 (HLB=14.9) are used

HLB vs RSN

• Relative solubility number (RSN) provides a practical alternative to the HLB method of assessing hydrophilic-lipophilic balance of surfactants.

• It is a different possibility to characterize demulsifiers in the Oilfield area.

• Raw materials for demulsifiers are mainly non-ionic surfactants and can be characterized by the RSN number

• It was found that, within the same surfactant family, RSN values determined at certain molar concentration showed a

good linear relationship with classic HLB values.

112

HLB vs RSN • The surfactant concentration in RSN titration,

solvent affected the RSN values;

• The effect of salt concentration in the titration water was negligible.

• A generalized regression model was used to correlate RSN values with the structure parameters of surfactants such as carbon number in hydrophobic groups, C-O number and free OH number.

113

RSN & Mol Weight relation

• Research shows that there is no overall correlation between demulsification performance and RSN value.

• But within a given surfactant family, such as polymerized polyols, oxyalkylated alkylphenol formadehyde resins, and oxyalkylated alkyl resins, the degree of demulsification was found to correlate with the RSN value.

• A maximum of dewatering performance was observed in a specific RSN range for two surfactant families. Molecular weight also showed a significant effect on demulsification performance.

114

RSN & Mol Weight correlation

• Surfactants with low molecular weight (<4000) did not break the emulsion in dosages of 300-400 ppm regardless of RSN value.

• For the water-in-bitumen emulsion studied in this research work, the most effective demulsifiers are those with RSN values between 7.5 and 12.5 and molecular weights between 7500 and 15000

115

RSN, Water dropping, desalting

• Bottle test results of Saudi Aramco crude showed the following correlation:

– Higher RSN causes higher water dropping up to RSN 21.5 then decreases as RSN increases

– Low RSN (<10) showed very low salt content in dry crude layer

– Better results were observed if the demulsifier bases were from the same chemical family of the same manufacturer

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End

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Documents

Demulsifiers-Specialty oilfield chemicals