05 Ofp Crude Field Proc

8/12/2019 05 Ofp Crude Field Proc

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Chapter 5

Field Processing of Crude Oil

INTRODUCTION

The complex nature of wellstreams is responsible for the

complex processing of the produced fluids (gas, oil, water,

and solids). The hydrocarbon portion must be separated

into products that can be stored and/or transported. Thenonhydrocarbon contaminants must be removed as much

as feasible to meet storage, transport, reinjection, and dis-

posal specifications. ltimate disposal of the various

waste streams depends on factors such as the location of

the field and the applicable environmental regulations.

The overriding criterion for product selection, construc-

tion, and operation decisions is economics.

!igure "-# is a comprehensive picture of the individual

unit operations carried out in field processing. $s stated

in %hapter #, all the various modules shown will not all

be present in every system. !urthermore, the modules

used in a given application may not be arranged in theexact se&uence shown, although the se&uence is, in gen-

eral, correct. The selection and se&uencing of modules is

determined during the design phase of field development.

'esign bases are discussed first, followed by a review

of typical processing operations. The. scope of processing

and some precautions for reducing emulsion problems

are described next. The final section deals with environ-

mental considerations.

DESIGN !SES

mportant design parameters include the feed or well-

stream composition, pressure, temperature, and flow

rate. These .properties can and do change with time in a

manner often difficult to predict, but they are neverthe-

less very important. The e&uipment selected should be

sufficiently flexible and/or ade&uately sied to operate

the well in the face of these changes in feed flow rate and

composition over the life of the field.

As stated in %hapter *, wellstreams must be sampled

and analyed with great care if the analyses are to serve as

a reliable design basis. +ven then the wellstream composi-

tion used in design must be viewed realistically. The lieli-

hood that the actual feed to the processing e&uipment will

be identical to the design-basis feed is remote. roduction

is usually from a combination of wells that may each have

differing compositions. %omposition may also vary from

one to one in a given formation. The producing pattern

(i.e., number of wells and flow rate from each) will also

probably be different from that originally envisioned.

In addition, wellstream compositions will change as

reservoir pressure declines. ressure decline with produc-

tion in reservoirs is a much studied phenomenon, which

is difficult to predict because of the nonuniforrniry and

unnown geometry of the reservoir.

$nother important factor in the field processing of

crude oil is the type of reservoir drive. The three common

types of drive are summaried in Table "-#. Table "-#

also summaries how the gas-oil ratio (GOR), water-oil

ratio (WOR), and reservoir pressure vary with time as the

formation isproduced. In addition, the oil rate will gen-

erally fall. eservoir engineers must forecast these impor-

tant production characteristics. usat (#010) points

out that under limited production rates, gas-drive fields

are usually partial water-drive. .

Artiflciallift may be used when the natural drive pres-

sure declines or is absent, such as by pumping the oil

with a deep-well pump or by gas injection into the well-

bore to provide 2gas lift.2 n the case of very viscous,

dense crude oils, steam may be injected to provide a rea-

sonable flow rate of produced oil.

It .is often advantageous to supplement the original

reservoir drive mechanism by the injection of water or

3#


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Figure 5-1 General Field-Processing Scheme

gas into the reservoir. n the past, such practice was

resorted to after pressure decline, and the procedure was

nown as secondary recovery. ore recently, the injection

process may begin very early in the life of the field,

almost from the beginning of production, in the so-

called pressure maintenance. 4olume 5 will discuss in

depth both the processes and e&uipment re&uired for

injection water treatment6 !igure "-# shows a typical

treatment se&uence involving treating vessels and pumps.

7ater-drive fields will exhibit a continuous, and, in

many cases, a dramatic increase in the water-oil ratio.

8olution-gas drive fields or gas-cap drive fields will

exhibit pressure decline and accompanying production

decline with time. 9as injection or reinjection may be

desirable to optimie fluid recovery.

Enhanced oil recovery (EOR) may be practiced to

increase the percentage of the in-place oil that is recov-

ered. any methods have been considered, but the


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main methods in use today are the injection of gas (car-

bon dioxide or nitrogen), chemicals (polymers, micellar-

polymer solutions), or steam (thermal flood). $s dis-

cussed in %hapter 1, +: practices can cause severe

Table "-* Typical 8urge !actors

8ervice !actor

!acility handling primary production from its own

emulsion problems.

ressure and flow rate changes will affect the design of

oilfield facilities including the selection of vessel and. pipe

sies and of compressor horsepower, or even the need for

compression. 'esign of e&uipment based solely on initial

production conditions can lead to inade&uate siing

and/or omission of vital e&uipment. 9eneraliations are

platform

!acility handling primary production from anotherplatform or remote well in less than #"; ft.

!acility handling primary production from another

platform or remote well in more than #"; ft.

!acility handling gas lifted production from its own

platform

!acility handling gas lifted production from another

platform or remote well

*;) can be used.

$ll of the foregoing factors are important in the field

handling of the crude oil. $nticipation of each or any of

them is important in planning the production facilities.

$nalysis of existing facilities is also re&uired6 in fact,

this tas is undertaen far more often than the original

design. The same comments previously.made with respect

to- initial design also apply e&ually well to analysis.

:%+88?9 :+$T:?8

As shown in !igure "-#, the individual phases (gas, li&uidhydrocarbon, li&uid water, and solids) should be sepa-

rated from @each other as early as practical. hase separa-

tion is discussed in detail in %hapter 3. ndividual

streams can then be treated with less technical difficulty

and more economically. Aardey and Bin Cadid (#0D0)

8ourceE $ #1+. #00#. eprinted courtesy of the $merican etroleum

nstitute

illustrate how lab and field tests performed before con-

struction can identify and minimie future production

and processing problems such as scaling, foaming, emul-

sion formation, wax deposition, and hydrate formation.

rocessing of the separated streams is now reviewed

briefly because many of the individual unit operations are

discussed in detail in subse&uent chapters.

9as rocessing

$s shown in !igure "-#, gas processing begins with treat-

ing, if necessary, to remove the acid gases-hydrogen sul-

fide and carbon dioxide. Both gases are very corrosive

when li&uid water is present and hydrogen sulfide is most

toxic. +nvironmental regulations almost always prohibit

the release of significant amounts of hydrogen sulfide to

the surroundings. %onversion to elemental sulfur is

becoming increasingly necessary.

9as sweetening usually uses a&ueous solutions of var-

ious chemicals. Therefore, sweetening will precede dehy-

dration. 'ehydration is often necessary to prevent the


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formation of gas hydrates, which may plug high-pressure

processing e&uipment or pipelines at high pressure and at

temperatures considerably higher than 5*F! (:F%).

9as that contains considerable amounts of li&uefiable

hydrocarbons (ethane or propane and heavier) can pro-

duce condensate upon compressing or cooling. The con-densate may cause difficulty in pipelining or subse&uent

processing. !ield processing to remove these natural-gas

li&uids (?9G), sometimes referred to simply as conden-

sate, may be economical or may be re&uired to meet a

hydrocarbon dew-point specification. n remote loca-

tions such processing is generally avoided if possible.

ecovered condensate may, in turn, have to be stabilied

by removing dissolved gaseous components to obtain a

transportable product.

!inal disposal of the gas stream depends on the sit-

uation. +arly in the life of a remote field, before the

availability of a pipeline, the gas may simply be flared.

It is becoming more common to conserve the gas by

compression and reinjection into the formation with a

view to its eventual recovery and sales. %onservation is

often demanded by law6 permits to flare are usually

temporary and granted only during the initial start-up

of production. +nvironmental restraints may also pre-

vent flaring especially if the gas contains any hydrogen

sulfide.

The common situation is to flow the natural gas into

a pipeline for sales. 9as pipelines have operating pressure

levels of the order of H;;-# ;;; psia to allow economical

transport in pipes of reasonably small diameter.

%ompression of the gas to pipeline inlet pressure may be

re&uired.

4olume #, %hapter " discusses field processing of nat-

ural gas in considerable detail.

:il rocessing

$fter free water removal, produced oil often contains

excessive residual emulsified water. Treating, also called

dehydration, is re&uired to reduce the water content to a

value acceptable for transportation or sales. 'ehydration

should be accomplished using the most economic com-bination of four factors or techni&ues6 namely, residence

time, chemical addition, heat, and electrostatic fields.

%hapter H discusses dehydration in detail. 'ilution water

must occasionally be added to reduce the salt content of

the residual emulsion (i.e., the sales crude oil) to a suit-

ably low level. 8uch desalting is described in %hapter D.

n the nited 8tates, desalting is usually performed in

the refinery6 overseas, desalting is sometimes performed

in the field.

Aydrogen sulfide in crude oil is limited to reduce han-

dling and transportation difficulties because of its

extreme toxicity and corrosiveness. 9as stripping or heat-

ing is usually used for hydrogen sulfide removal or sweet-

ening as is discussed in %hapter 0.

rude oil sta!ili"ation refers to lowering the vapor

pressure to a value that will allow safe handling and

transport. 4apor pressure control is obtained by stage

separation, reboiled distillation, or a combination of the

two. 'uring stabiliation some of the more volatile

hydrocarbons are removed as vapor and this gas phase

entrains hydrogen sulfide and other volatile sulfur com-

pounds from the sour crude oil. $dditional sweetening

may not be re&uired. 8tabiliation is discussed fully in

%hapter 0.

7ater rocessing

roduced water (usually saline) is a waste material, but

processing is often necessary to render the water suitable

for disposal to the surroundings. :ften additional water,

fre&uently sea water, is also processed for waterflooding.

These two separate water processing schemes are both

shown in !igure "-#.

:il removal is the first treatment for produced waters.

:il-in-water emulsions are difficult to clean up due to

the small sie of the particles, as well as the presence of

emulsifying agents. 8uspended solids may also be present

in the water. Types of e&uipment used for removing oil

and solids includeE

I :il simmer tans

I late coalescers

I $ir flotation tans

I Aydrocyclones

I !iltration units

Before reinjection, the produced water is usually fil-

tered, deaerated if necessary, and treated with biocides.

The major goal, of course, is to prevent reservoir plugging.

8eawater is by far the most commonly used in#ection

water for pressure maintenance because of its obvious

abundance. nfortunately, its poor water &uality

demands extensive treatment. As shown in !igure "-#,

seawater 8 first treated with shoc biocides to ill all

organisms and then filtered. 'issolved oxygen is


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removed either by chemical scavengers, by gas or vacuum

stripping, or by catalytic reaction with hydrogen. This

reduces the corrosivity of the water dramatically and

inhibits growth of aerobic slime-forming bacteria in the

wellbore. Then the water is sterilied either by ultraviolet

radiation or additional biocide injection to ill bacteriaand other micro-organisms. /icro-organisms can cause

corrosion, plugging oflines and reservoir formation roc,

and they can also produce A*8 in the formation

(:stroff, #0H0). 8cale inhibitors are also added before

injection into the formation.

4olume 5 will discuss field processing of both pro-

duced and injection waters. n a massive waterflood (over

1;;,;;; bwpd) , treatment of injection and produced

waters represents a major cost that often exceeds that of

treating the crude oil.

Sand Treat"ent

8and and other solid material may gather in any of the

previously mentioned e&uipment in locations where the

velocity and turbulence in the li&uid stream is low, such

as in the bottom of tans or on coalescer plates. emoval

of the sand by some type of jetting nole or similar

arrangement may be necessary. 8and removal is some-

times carried out by centrifugal cone desanders ($rnold,

#0D5). The sand itself may have adhering oil or emulsion

that re&uires washing before discharge to the surround-

ings. emoving sand from separators is discussed in

%hapter 3.

!u#iliar$ E%uip"ent

n addition to the previous operations, shown in !igure

"-#, additional e&uipment is re&uired for importantancillary functions. These are now reviewed briefly.

$est separators with appropriate gas and li&uid flowrne-

ters are often provided for periodic measurement of the

production rate from individual wells or groups of wells.

8uch testing is often a legal re&uirement. $ppropriate

flowlines, valves, and manifolds must be provided so that

the desired wellstreams can be isolated and passedthrough the test production separator. This e&uipment

can become &uite elaborate if many wells are involved.

n the nited 8tates, total oil production is usually

measured in lease automatic custody transfer (%A$) units

that measure oil production volume as well as 8J7 con-

tent. Turbine meters are sometimes used overseas. %rude

oil measurement is discussed in detail in %hapter ##. 9as

production rate is generally measured in orifice-meter

installations as is described in 4olume l.

Automatic safety systems are a necessary and integral part

of any oilfield facility. $de&uate protection must be pro-

vided against all unsafe conditions including overpressure,li&uid overflow, overheating in fired heaters, unwanted

sources of ignition, and so forth. ench et al. (#005) pre-

sent an offshore case history that illustrates safety consid-

erations. 8afety systems and other instrumentation are dis-

cussed further in %hapter #". 4ent and flare facilities are

re&uired for the safe removal and disposal of gas evolved in

both normal and emergency operation. ressure relief and

flaring are discussed in %hapter #3.

ecovery of natural gas li&uids from waste vapor is

often practiced by use of so-called vapor recovery units

(&R') , consisting of compression and cooling e&uip-

ment as is discussed in %hapter #1. +mission limitationsare maing vapor recovery mandatory in many cases.

:ther additional operations include such items as

electrical power generation, instrument air supply, as well

as fire, drining, and sanitary water supplies, and sewage

disposal.

PROCESSING 8%:+

n a given facility, the scope of processing depends on the

nature of the well fluids, the location and sie of the field,

availability of gas and electricity, the comparative salesprices for gas and crude oil.

Nature of the &ellstrea"

Key variables include the nature of the reservoir drive,

the water-oil ratio (7:) , the gas-oil ratio (9:) or

alternatively the gas-li&uid ratio (9G) , and the nature

of the crude oil (:$, pour point, etc.). $s previously

detailed, the type of drive determines how the ratios of

gas, oil, and water are expected to vary during the life of

the field. f large increases in water production are

expected, then suitable steps should be taen. This tradi-tionally involves selecting a sie safety factor.

8ie !actors. n the iddle +ast a factor as high as *

has been used because of the large flows (1;;,;;; to

H";,;;; bopd are not uncommon) and the ready avail-

ability of land. :ffshore (e.g., the ?orth 8ea) where it


6/13


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Figure 5'( Separation with Vapor Recompression (Maddox et al., 1976)

industry today. !igure "-" depicts minimum field pro-

cessing with high-vapor-pressure crude oil pipelining. $

larger pipeline is re&uired for the oil than for the pipelining

of the low-vapor-pressure crude of !igures "-3 and

"-H. These latter figures show pipelining of atmospheric

crude oil. %ondensate is recovered from the gas and is

either pipelined separately (!igure "-3) or two-phased

with the gas (!igure "-H).

+latform processing is an extreme case of remote pro-

cessing. It is safe to say that as little is done as possible on

platform because of the high cost and low allowable

weight of platform facilities. n the early days of offshoreproduction, very little processing was done on platform.

'evelopment of the ?orth 8ea area has displayed

increasingly complex offshore processing.


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!ield rocessing of %rude :il H5

screens, fittings, choes, sharp bends in the tubing and lead

lines, and other restrictions.

The turbulence can be reduced, but not prevented, by

the installation of a larger choe or by holding a higher

bac pressure on the downstream side of the choe.

Taing one large pressure drop across a single choe gen-

erates the very intense agitation that so often produces

stable emulsions. Two or three smaller pressure drops are

far superior from the emulsion viewpoint.

$ downhole choe usually causes less emulsification.

n fact, it often decreases the stability and amount of the

emulsion produced becauseE

#. There is less pressure differential across a downhole

choe.

*. 'ownhole temperatures are usually considerably

higher than surface temperatures. Aeating breas

emulsions as is described in detail in %hapter H.

5. There is straight line flow for a long distance

downstream of the choe, and correspondingly less

turbulence.

n some cases the inconvenience of a downhole choe

is offset by the economics of less emulsion treating (i.e.,

reduced usage of demulsifying chemically and/or less fuel

for heating).

9as-lift 7ells. +mulsification is caused mainly at two

places6 namely, at the point where the gas is introduced

into the flow string and at the wellhead.

7hen intermittent gas-lift is used, the emulsion usu-

ally is created at the wellhead or in the surface e&uip-

ment. 7hen continuous gas-lift is used, much of the

emulsion is formed downhole at gas injection points. n

determining the method of gas-lift that will be most

efficient, the operator should consider emulsion prob-

lems that will be encountered and how they can best be

treated.

- umping 7ells. The greatest source of emulsifica-

tion is in the pump and tubing. The following are some

causes of turbulence in pumping wellsE

#. Geaing standing valves, traveling valves, plungers,cups and other pump parts.

*. 9as production in pumping wells that causes con-

siderable turbulence in the narrow passages of the

pump.

5. ounding of the pump that causes the rods to whip

and create additional turbulence.

8ources of turbulence can be minimied by using a

good pump that has close tolerances, oversie standing

and traveling valves, and proper speed and length of

stroe. :n gas-producing pumping wells, a gas anchor

usually will reduce the turbulence.

!low Gines. rincipal sources of turbulence in mani-

folds and gathering lines are pumps, valves, and fittings

in which the flow direction changes abruptly. It seems

liely that the turbulence produced in straight sections

will often be sufficient to result in emulsion formation,

especially in the case of gas-li&uid flow.

:ther 8ources. :ther places where emulsions occur in

production e&uipment are leaing dump valves on separa-

tors, free-water nocouts, and settling tans. Aowever,

these usually can be corrected relatively easily.

+?4:?+?T$G %:?8'+$T:?8

$ vital consideration in the field processing of crude

oil in the nited 8tates is the complex nature of envi-

ronmental regulations currently in effect. The situation

is made difficult because federal and state regulations

are still evolving (oritis, #00#). 8imilar rules have

been or will be established in other nations around the

world.

The following comments are intended to summarie

important aspects of environmental regulations and not toserve as guidelines for compliance. The topic will be

reviewed under the headings of regulations, environmental-

control technology, and compliance.

egulations

The reauthoriation of %$ (esource %onservation

and ecovery $ct of #0H3) loomed as a Mpotentially diffi-

cult problem. 9enerally, oilfield wastes were listed as

exempt in the #0H3 law, placed under 8ubtitle ' for

nonhaardous substances, and remain so. 8uch a listing

may seem arbitrary, but there seems to be some justifica-tion from the standpoint of overall ris. n the nited

8tates, the petroleum industry is responsible for only

#.D*;/; of toxic releases (Kalavapudi et al., #00#). ?ot all

wastes from drilling sites are exempted (appold, #00#).

8uch items as unused fracturing fluids and acids, paint-

ing 6astes, service-company wastes, used oils, and used


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H1 !ield rocessing of %rude :il

solvents are not exempt. Audgins (#00*) reviews the uses

of production treating, gas processing, stimulation and

worover chemicals in .8. offshore operations. $cute

a&uatic toxicity and solubility data are included.

By far the largest exploration and production waste

stream is produced water (oritis, #00#). $ large portionof this water is reinjected, either for disposal, pressure

maintenance, or for enhanced recovery. The 8afe

'rining 7ater $ct (8'7$) of #0H1 and the

nderground njection %ontrol (%) established rules

for injection wells.

#. :nly approved wastes may be injected.

*. 'rining water sources must not be endangered.

5. ermitting of new wells is re&uired before con-

struction.

1. $ll wells must be tested periodically for mechanical

integrity.

?ew draft proposals by +$ for wells that inject pro-

duced brines and fluids for enhanced oil recovery are

tough6 they re&uire three layers of protection

($nonymous, #005)E

#. $ll new wells re&uired to have surface casing deep

enough to protect water sources of 5,;;; mg/G total

dissolved solids or less.

*. $ casing string cemented through the injection

interval.

5. Tubing set on a pacer.

echanical integrity testing of existing wells would be

done according to the number of layers of protectionE

:ne-test every year

Two-test every 5 years

Three-test every " years (the current regulation)

8tudy of all wells within one-&uarter mile of any injec-

tion well is re&uired to identify those that might provide

a vertical path to an underground source of drining

water. f so, remedial action would be re&uired.

:ther means of produced water disposal include

evaporation or percolation in pits, or release to surface

waters. elease to surface waters is controlled by the

?ational ollutant 'ischarge +limination 8ystem

(+-E*) under the %lean 7ater $ct. 8uch release is

generally not permitted. nlined pits for the discharge

of oil and gas waste products are being closed in the

nited 8tates, 8outhwest ($nonymous, #00*).

:perators are re&uired to submit closure plans for alter-

native systems for handling waste fluids and cleanup of

the existing installations. Testing of nearby water wells

is re&uired.

9as emissions are restricted by many regulations,

notably the #00; %lean $ir $ct $mendments (AAA).

These regulate emissions from internal-combustion

prime movers that produce volatile organic substances,

nitrogen oxides, carbon monoxide, sulfur dioxide, and

particulates. BTEX (benene, toluene, ethyl benene,

xylenes) emissions for T+9 dehydration units is of great

current concern and a classic example of how operating

practices are being changed to reduce emissions.

$nother regulated class is that of fugitive emissions.

These emissions are hydrocarbon vapors that lea from

compressor seals, valves, pumps, flanges, pressure-relief

valves, meters, storage tans, and so forth (True, #00#6

%olyer and eyer, #00#). Benene content of these

vapors is of particular concern.

easurement or estimation of fugitive emissions is

re&uired. yers and !erry (#005) discuss the applicable

laws for storage tans. 7agoner (#00;) describes open

and closed floating-roof tans and the calculation of

losses. 8mall above ground and buried tans (up to

#;,;;; gal) are subject to specific regulations

(aocynsi and Gong, #005).

$verage emission factors are available for estimating

emissions from process components (8chaich, #00#), but

oss (#005) recommends bagging and monitoring for

more accurate estimates. se of average emission factors

may grossly overestimate such losses.

$ recent concern in petroleum processing is the pres-

ence of naturally occurring radioactive materials, or

OR (9ray, #00;, #005). $s explained in %hapter *,

the source for ?: is the radioactive decay of ura-

nium *5D, which is distributed throughout the earth@s

crust. ranium *5D decays to produce radium **3 and

radon ***. ?: was first detected in %anada in

#0;1 and in ussia in the #05;s (utherford and

ichardson, #005). ecent awareness started with a-

**3 in production scale in a ?orth 8ea field in the

#0D;s and in ississippi in #0D3. Because radiation

does not affect the human senses, its presence was

detected either indirectly or by accident, as detailed by

9ray (#005).

n oil and produced water processing, the culprit is

radium which coprecipitates with barium and strontium

sulfates. :ddo and Tomson (#001) state that 5;;,;;;-

#,;;;,;;; ton/yr of ?: scale are produced. :ddo

and Tomson also discuss prediction of scaling and means


11/13

!ield rocessing of %rude :il H"

of inhibition. The concentration of produced ?: in

this scale is usually low, but it collects in e&uipment over

time. $s long as ?: is contained in processing

e&uipment, there is little danger of a health haard to

employees and the public. 7hen e&uipment is descaled

or machined, contamination of e&uipment, personnel,

and surroundings can occur. 8tate agencies are now

defining regulations for the monitoring and disposal of

pipes and e&uipment containing NORM scale.

'ecommissioned e&uipment may have to be disposed of

as radioactive waste, which is a complicated process.

ntil now, such e&uipment has not even been surveyed

for radioactivity.

n gas processing the main problem is caused by

gaseous radon that tends to collect (along with its

radioactive daughter products), especially in cryogenic

plants, and cause various difficulties. (8ee 9ray =#00;,

#005> for details.) 9ray (005) states that ?: does

not generally constitute a serious health haard if han-

dled properly.

The 9ulf of exico (GO) :ffshore %ontinental

8helf (O*) egional :ffice of the /inerals

anagement 8ervice (*) published a Getter to

Gessees and :perators (LTL) on ?ovember *;, #00;,

and another clarification GTG on 'ecember ##, #00#.

These two GTGs are intended to provide operators with

interim guidelines for the reporting, disposal, and trans-

portation of produced ?:. The +$ egion VI

final 7estern :%8 general ?ational ollutant 'ischarge

+limination 8ystem (+-E*) ermit ;#-#0-0*)

re&uires operators to test waters for a-**3, a-**B,

gross alpha radiation, and gross beta radiation on the fol-

lowing schedule.

duced sand, dec drainage, and domestic and sanitary

wastes. The rules would apply to existing and new plat-

forms.

En*iron"ental Control Technolog$

$s noted by 7ojtanowic (#005), petroleum proces-

sors have in the past relied primarily on waste-

management technology (W$). The difficulty with

7T is that it addresses a problem that is already

present and may involve extensive and expensive pro-

cessing in its remediation. 8uch difficult problems as

subsurface migration of oil and toxicants may be

involved.

7ojtanowic urges the development of environmental

control technology (E$) and gives examples. n the

chemical process industry, the techni&ue is referred to as

waste minimi"ation. n government regulatory language+%T is referred to assource reduction. The idea is to use

the ingenuity of the oil producer to battle the waste man-

agement problem before it occurs by producing less ha-

ardous waste,

7ojtanowic broadens the methodology of +%T by

describing its general techni&uesE

I 8ource reduction (waste minimiation)

I 8ource separation (removal ofpollutant)

I ecycling (confine the stream within the process)

I %onfinement (leaprevention)

I euse (after recycling and source separation)

Ais innovative approach to environmental regulations

and compliance is commendable.

o to

";; to

more than

";; bwpd

1,3;; bwpd

1,3;; bwpd

yearly

&uarterly

monthly

Co"pliance

!ognani (#00*) places the problem of compliance in

proper context.

The 'epartment of Transportation. (-O$) regulates

the transportation of radioactive materials having more

than *,;;; p%i/g radioactivity. ost :%8 produced

materials exhibit less than *,;;; p%i/g and so are not

regulated by %! arts 171-1BO. ($ Bulletin +* =#00*>discusses ?: in detail.)

$ final area to be discussed is offshore platforms. The

+$ has proposed rules to sharply reduce .8. offshore

platform discharges into the ocean ($nonymous, #00#).

tems included are oil and grease, toxics, drilling fluids

and cuttings, produced water, well-treatment fluids, pro-

9overnNental =enforcement> efforts, particularly at the

federal level, increasingly focus on opportunities to

impose criminal liability for actions that until relatively

recently would have been subject only to civil enforce-

ment and penalties.... ight or wrong, criminal enforcement is viewed as a

more effective deterrent to environmental violations

than is the traditional and somewhat controversial and

inconsistent imposition of civil penalties.

. .. n this new climate, oil and gas operators and their

personnel must tae special care to satisfy environmen-

tal re&uirements.


12/13

H3 !ield rocessing of %rude :il

!ognani reviews the general legal regulations and sug-

gests compliance strategies, especially for independent

producers. $s he states, 2%ompanies should spend their

time, resources, and efforts in operating within the envi-

ronmentallaw, not in defending themselves against crim-

inal or civil prosecutions.2

Re*ie. 0uestions

#. dentify the individual unit operations or process

modules used in the field processing of crude oil.

*. 'iscuss the correct se&uence for arranging these

modules.

5. 8tate the reasons for stabiliing, sweetening, dehy-

drating and desalting crude oil.

1. Aow do wellstream flow rate, composition, temper-

ature and pressure vary over the life of the fieldO

7hat parameters cause these changesO". Gist the important parameters or factors in designing

an oilfield crude-oil processing facility.

3. 7hat can happen if a field facility is designed solely

on the initial wellstream flow and compositionO

H. Aow does analysis of an existing facility differ from

initial design or siing of a new facilityO

B. 8uggest a suitable operating pressure for a gas

pipeline.

8upport your recommendation.

0. Gist four techni&ues for dehydrating crude oil.

#;. 8uggest a treatment scheme for a produced water

stream.8uggest suitable disposal for the produced water if it

-a dry, sweet natural gas

-a high-pressure, high-9: crude oil.

l 8, 8elect a particular production facility (e.g., +ofis).

Trace its historical development. ?otice the time

frames for discovery, exploration, initial construc-

tion, and later developments.#0. Gist the major oilfield environmental regulations.

dentify the largest production waste stream.

*;. 'efine fugitive emissions.

Aow are they controlledO

*#. 'efine ?:.

Gist the major sources of ?: in both crude oil

handling and gas processing.

**. dentify two approaches to environmental control

technology.

7hich approach do you recommendO

*5. %an .8. oilfield operators expose themselves to crim-

inalliability for violating environmental regulationsO

Pro+le"s

#. odify the process scheme shown in !igure "-* to

satisfy recent and more stringent regulations.

*. Aow would more rigorous fuel-gas specifications

affect the process scheme shown in !igure "-5O

5. 8uggest a suitable processing scheme for the follow-

ing wellstreamE

%omponent !low (brnol/hr)

is fresh and if (more liely) saline.

##. 7hat water is used most commonly for pressure

maintenanceO

Gist the advantages and disadvantages of yourselection.

8uggest a suitable treatment scheme for your

selected water.

#*. dentify the major types of auxiliary e&uipment

re&uired in the oilfield.

#5. 8uggest two methods of measuring crude oil.

#1. 7hy are test separators installed offshore in spite ofthe severe space and weight limitationsO

#". Gist the factors that must be considered in fixing the

processing scope for a particular facility.

?*

C02

%l

C2

%5

i%1

n%1

i%"

n%"

!"

H20

7ellstream pressure

7ellstream temperature

H1.1

"5.#

0,HD;."

#,;3;.3

H;3.1

0".3

*5H.5

#*0.5

*5;.*

",55D.*

1H0.5

#,;;; psig

#;;F!

#3. 'iscuss the need for sie safety factors.

Gist typical values for three different locations.

#H. 8uggest suitable processing flow diagrams forE

-a low pressure, low-9: crude oil

1. $ssume that the wellstream contains produced water.

evise !igures "-1, "-", "-3 and "-H appropriately.

". 8uggest a suitable processing scheme for the follow-

ing wellstreamE


13/13

!ield rocessing of %rude :il HH

A*;

?*

%;*

%l

%*

%5i%1

n%1

i%"

n%"

n%3

%omponent !low (lbmol/day)

##3.*

3#D.H

"0D.5

3,"**.H

*,H0".5

*,"0H.;

13H.5

#,1H".D

30D.H

D#D.H

*5*.;

%$ # esource %onservation and ecovery $ct

P ecommended ractice

scf # standard cubic feet

8'7$ P 8afe 'rining 7ater $ct

8J7 # sediment and water

T+9 # triethylene glycol (li&uid desiccant for nat-ural gas)

4 # vapor recovery unit

% # nderground njection %ontrol

7T P waste-management technology

A*8

?B #1;

?B #H"

?B **"

?B *H5

*3*.3

531."

#,35#.D

#,3"H.*

#,D0".0

7: # water-oil

References

ratio

?B 5*1

?B 5H1

#,***.1

0#1.0$nonymous (#00#), 2+$ $ims to %ut :ffshore

?B 1";

?B "";

?B 31"

?B H";

?B D0*

?B #;03

7ellstream pressure

7ellstream temperature

No"enclature

#,53*.D

#,##;.1#,;#0.D

"00.1

0H#.;

H"1.0

3; psig

H".3F!

latform 'ischarges,2 Oil J Gas /ournal, 4ol. D0, ?o.

io, p. 1D (arch #D).$nonymous (#00*), 2+$ Tightens +nforcement on

se of nlined its,2 Oil $ Gas fournal, 4ol. 0;, ?o.

1*, p. 53 (:ctober #0).

$nonymous (#005), 2+$ 'rafts Tougher njection 7ell

ules,2 Oil $ Gas/ournal, 4ol. 0#, ?o. *1, p. 11 (june #1).

$ #1+ (#00#), 2ecommended ractice for 'esign

and nstallation of :ffshore roduction latform iping

8ystems2, "th ed., $merican etroleum nstitute, #**; %.

8treet, ?.7., 7ashington, '% *;;;" (:ctober #).

$ # $merican etroleum nstitute

bopd # barrels of oil per day

BT+L # benene, toluene, ethyl benene, xylenesbwpd # barrels of water per day

%$$$ P %lean $ir $ct $mendments

':T # 'epartment of Transportation

+%T # +nvironmental %ontrol Technology

+: # enhanced oil recovery

+$ # +nvironmental rotection $gency

9G # gas-li&uid ratio

9: # 9ulf of exico

M 9: # gas-oil ratio

9:8 # gas-oil separation plant

G$%T # lease automatic custody transfer

G?9 # li&uefied natural gasGTG # Getter to Gessees and :perators

8 # inerals anagement 8ervice

?9G # natural gas li&uids (condensate)

?: # naturally occurring radioactive materials

?'+8 P ?ational ollution 'ischarge +limination

8ystem

:%8 # :uter %ontinental 8helf

05 Ofp Crude Field Proc

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