CasingGasCompression
CompactCompressionInc.
Calgary,Alberta,Canada
CasingGas
•  Oilinforma:onsincludesnaturalgasinsolu:on
•  Foroiltoflowintoawell,thepressureatthe
bo@omofthewellmustbelessthanthatofthe
forma:on.Asoilflowsintothewell,gaswill
comeoutofsolu:onandcollectinthecasing
•  Thisgaswastradi:onallydealtwithinoneoftwo
ways
–  Ven:ngthecasingtoatmosphere
–  Connec:ngthecasingtotheflowline
CasingPressure
Venttoatmosphere
Connecttoflowline
•  Ven:ngmethaneto
•  Canreducewell
atmosphereisbadforthe
performanceduetohigh
environment,methanehas
backpressureonforma:on
25xthegreenhouseeffect
•  Convenient,only1pipeline
ofCO2(basedon100year
required,gascanbe
globalwarmingpoten:al)
separatedfromstreamand
•  Was:ngapoten:ally
usedatba@ery
valuableandfiniteresource
•  Thisprac:ceisnowillegalin
manycountriesforthe
abovereasons
Wellconnec:ondiagram
WhyCasingGasCompression?
•  Noven:ng–delivergastoflowline
•  Canusegasasfuelorsellit
•  Reducecasingpressure,loweringthebackpressure
ontheforma:on.Thiswill:
–  Increaserateofoilproduc:on
–  Increaseoveralloilrecovery
TypicalSiteLayout
Whatdoesitdo
•  Reducepressureincasing,loweringbo@omholepressure
•  Differen:alpressurebetweentheforma:onandbo@omholeis
whatdrivestheinflowofoiltothewell
•  Maximumflowlinepressurescanreachbetween1380-2070kPa/
200-300psi
•  Acompressorcantypicallyreducecasingpressureto35-207kPa/
5-30psi,dependingonsizeandgasflow
•  Reduc:onofbackpressureagainsttheforma:onresultsinhigher
oilrecoveryrate
•  Thiseffectwillbemoresignificantonlowpressureforma:ons
–  Forma:onpressureof20700kPa(3000psi),wellis1380kPa(200psi),
dropsto207kPa(30psi),changeis6%
–  Forma:onpressureis6894kPa(1000psi),wellis1380kPa(200psi),
dropsto207kPa(30psi),changeis18%
IPRCurves
•  InflowPerformanceRela:onship
•  Indicatechangeininflowrateswithchangeof
bo@omholepressure
•  Essen:ally,thereservoir’sabilitytoflowtothewell
atarangeofbo@omholepressures
•  Dependsonreservoirstructure,permeability,
pressure,andotherfactors
•  Canbeusedasafirstindicatorofawellpoten:ally
suitedforcasinggascompression
ExampleIPRcurve
Suitabilityofawellforcasinggascompression
WellsPronetoGasLock
•  Gaslockmayoccurduetoavarietyofcondi:ons,suchashighGOR,pump
spacing,andpumplandingloca:on
•  Agaslockedpumpcancausesevereequipmentdamage
•  Onwellswherethisisaknownissue,acasinggascompressormay
aggravatetheproblem,asloweringdownholepressurewillincreasethe
rateofgasbreakout
•  Poten:alsolu:onswouldbe:
–
–
–
–
Resefngpumpspacingtomaximizepumpcompressionra:o
Addingagasanchororothergassepara:ondevicetothepump
Changetoapumpdesignedtohandlegas
Re-landingthepumpfurtherbelowtheperfora:ons
•  Ifthesedonotsolvetheproblem,thiswellmaynotbesuitableforcasing
gascompression
•  Thesolu:onmaybetoincreaseheadpressureonthepump.Thiswould
involvemaintaininggreaterfluidheightinthewell.Essen:ally,givingup
someamountofproduc:onrateinordertoavoidgaslockissues.
•  Tes:ngiscri:cal,theonlywaytoensurethatawellissuitableforcasing
gascompressionistotestinadvance
Tes:ngforsuitability
•  Trailermountedcompressorsaresimpletomovearound,saving
laborand:meovertes:ngwithaskidmountedunit
•  Screwcompressorsarequiteflexibleinperformancecanbe
adaptedtoawiderangeofopera:ngcondi:ons
•  Gasdriven,willrunoffcompressedgas,noneedforan
electriciantohookuppower
•  Atestcompressorwilldetermineexactlyhowawellwillrespond
tocasinggascompression,makingtheeconomicsofthe
applica:onacertaintyratherthanspecula:on
•  Canbeequippedwithaflowmetertopreciselydetermine
requiredsizeofcompressor
Howdowedoit
•  Varietyofcompressionelements,chosenbasedon
opera:ngcondi:ons
–  HydraulicReciproca:ng
•  Lowflow(0.1-2e3m3/dayor0.3-70mcfd)
•  Highpressure(upto3450kPa/500psi)
–  SmallFrameReciproca:ng
•  Mediumflow(0.5-6e3m3/dayor17-200mscfd)
•  Highpressure(upto2750kPa/400psi)
–  Screw
•  Highflow(6-37e3m3/dayor200-1300mscfd)
•  Mediumpressure(upto2070kPa/300psi)
HydraulicCasingGasCompressor
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•
Purposedesignforlowvolumecasinggasapplica:ons
Idealforsinglewellapplica:on
Compressorisdesignedforsweetorsourservice
Nooperatorsetuporadjustmentisrequired
Eliminatesissuescommonwithconven:onalcasinggascompressors
–
Noprocessvalvesorcoolerstobecomecontaminated
•
•
•
–
Noliquidhandlingsystem(compressorcanpumpliquidorgas)
•
•
•
•
•
•
•
•
•
•
Noinletvalve
Norecyclevalve
Nointercooler
Noseparator
Nolevelshutoff
Nolevelswitch
Noliquidpump
Ultrareliablegearpumpandelectricmotorpowersupply
Minimummovingparts
Satellitecalloutsystemno:fiesoperatorsifunitshutsdown
Noexternalleakpointsforoilorgasseals
Automa:crestartifgridpowerislost
Capacitycontrol
–
–
Compressorwilladjustcycleratetomatchflow
Upto100%turndown
HCGPerformance(USunits)
HC613CompressorwithHPP-13EPowerpack
MaximumΔP:225psi
SUCTIONPRESSURE
DISCHARGEPRESSURE
75
100
125
150
175
200
225
250
275
5
10
15
20
30
40
50
38
49
61
72
95
118
140
37
48
59
70
93
116
139
35
47
58
69
91
114
137
34
45
56
68
90
112
135
33
44
55
66
88
111
133
32
43
54
65
87
109
132
31
42
53
64
86
108
130
84
106
129
127
HC616CompressorwithHPP-13EPowerpack
MaximumΔP:350psi
SUCTIONPRESSURE
DISCHARGEPRESSURE
200
225
250
275
300
325
350
375
400
5
10
15
20
30
40
50
20
27
34
41
55
70
84
19
26
33
40
54
69
83
19
26
32
39
54
68
82
18
25
32
39
53
67
81
17
24
31
38
52
66
80
16
23
30
37
51
65
79
16
23
29
36
50
64
78
49
63
77
76
*ProjectedPerformancebasedon2500k,gasdensity.665,temp68ºFPressuresinPSIFlowRatesinMSCFD
HCGPerformance(metric)
HC613CompressorwithHPP-13EPowerpack
MaximumΔP:1550kPa
SUCTIONPRESSURE
DISCHARGEPRESSURE
35
70
100
140
200
275
345
510
1.1
1.4
1.7
2.1
2.7
3.4
4.0
690
1.1
1.4
1.7
2.0
2.7
3.3
4.0
860
1.0
1.3
1.7
2.0
2.6
3.3
3.9
1035
1.0
1.3
1.6
1.9
2.6
3.2
3.9
1200
0.9
1.3
1.6
1.9
2.5
3.2
3.8
1380
0.9
1.2
1.5
1.9
2.5
3.1
3.8
1550
0.9
1.2
1.5
1.8
2.5
3.1
3.7
1720
2.4
3.0
3.7
1900
3.6
2400
0.5
0.7
0.9
1.1
1.5
1.9
2.3
2585
0.5
0.7
0.9
1.1
1.5
1.9
2.3
2760
0.5
0.7
0.8
1.0
1.4
1.8
2.2
HC616CompressorwithHPP-13EPowerpack
MaximumΔP:2400kPa
SUCTIONPRESSURE
DISCHARGEPRESSURE
35
70
100
140
200
275
345
1380
0.6
0.8
1.0
1.2
1.6
2.0
2.5
1550
0.6
0.8
1.0
1.2
1.6
2.0
2.4
1720
0.6
0.8
1.0
1.2
1.6
2.0
2.4
1900
0.5
0.7
0.9
1.1
1.5
2.0
2.4
2070
0.5
0.7
0.9
1.1
1.5
1.9
2.3
2240
0.5
0.7
0.9
1.1
1.5
1.9
2.3
*ProjectedPerformancebasedon760m,gasdensity.665,temp20ºCPressuresinkPaFlowRatesin1000m3/day
Typicalprocessdiagram
Shutdownsandwarnings
•  ThePLCmanagesallaspectsofcompressoropera:on.Itwillprovidethe
followingalarms:
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–
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Lowsuc:onpressure
Highdischargepressure
Highdischargetemperature
Highoiltemperature
Lowoillevel
Capacityloss
•  Aswellasshutdownsforthesecondi:ons:
–
–
–
–
Oillevellow
Oilleakdetected
Motoroverload
Failuretocycle
•  Compressorwillsendamessageviasatellitetoindicateanalarmor
shutdowncondi:on
CG25Sweet-StandardCCICompressorPackage
Compact Compression Inc. CG 25
Quincy QRNG 370 2 Stage Sweet
DISCHARGE PRESSURE
Suction
2stagereciproca:ng
25hpelectric
0-205kPa/0-30psiinlet
690-2760kPa/100-400psi
discharge
•  Op:onalInletscrubberand
autodrainpump
•  Sweetnaturalgas
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•
•
•
5
10
20
30 150
85
108
155
200
83
106
153
199
250
81
104
151
197
300
79
102
149
195
350
77
100
147
193
*Performance based on Sea Level, gas density .65, temp 68 ºF
Pressures in PSI
Flow Rates in MSCFD
High Efficiency Intercooler required for flows in grey
Typicalprocessdiagram
Reciproca:ngcompressor
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Suc:onpressurefrom0-205kPa(0-30psi)
Dischargepressurefrom690-2760kPa(100-400psi)
Flowsupto5.5e3m3/day(200mscfd)
Sourcompa:blecompressorsavailable
Inletregulator
•  Whenwellisshutin,casingpressurewillincreaseto
shut-inpressure(canbe2060kPa/300+psi)
•  Compressorcannotprocessgasabove206kPa/30psi
•  Inletregulatorreducesincominggaspressuretoa
tolerablelevelforthecompressor
LowPressureRecycleRegulator
•  Compressorspeedcanneverbeperfectlymatched
togasflow
•  Recycleregulatorprovidessimpleandeffec:ve
capacitycontrol,upto100%turndown(noflowinto
compressor)
•  Maintainsspecifiedminimumpressureoncasing
(35-70kPa/5-10psi)
ShutdownSwitches
•  Suc:onpressurelow
–  Ifrecycleregulatorfails,compressorwillpullvacuum,soitwill
beshutdownatspecifiedlowpressureoninlet
•  Dischargepressurehigh
–  Ifcompressordischargeisblocked,itwillshutdownatspecified
pressuretoprotectinternalcomponents
•  Dischargetemperaturehigh
–  Compressorvalvessuscep:bletodamagefromoverhea:ng.
Compressorwillshutdownbeforetemperaturesthatmay
damagevalvesarereached
•  Compressoroilpressurelow
–  Ifcompressoroilpressureislow,compressorwillshutdownto
avoidrunningwithoutlubrica:on
InletScrubber
•  Removesliquidsthathavecondensedoutofthegas
streamcomingintothecompressor
•  Protectsthecompressorfrompossibleliquidslugs
duetodepressionsortrapsintheplumbing
•  Notalwaysnecessary–Inhotclimatestheremaybe
veryli@lecondensa:onintheline,andifthereare
noliquidtrapstherewillbenobuildupofslugs
•  Thecasingdoesmostofthejobofremovingliquids
entrainedinthegasstream
Exampleofliquidtrap
AutodrainPump
•  Removesopera:onalrequirementofdailydraining
ofinletscrubber,simplifiesdisposalofcondensate
•  Pneuma:corelectricdriven
•  Pumpsliquidsoutofscrubberandintodischarge,
willbecarriedintoflowlinewithgasdischarge
Intercooler
•  Coolingisrequiredbetweenstagesofamul:stagecompressor
•  Coolingiscri:caltomaintainacceptable
cylindertemperaturesinsecondstage
•  Highperformanceintercoolerrecommended
forhotclimatesandhighpressurera:os
AkerCooler
•  Coolsgasbeforeitleavesthecompressor
•  Onlyrequiredifthereareconcernswithelevated
temperaturesatthesurface-176°C(350°F)max
•  Hightempofgasdischargewillotherwisebe
absorbedbytheoiloftheflowline
–  2e3m3ofnaturalgas@176°C(350°F)flowinginto400
bbl/dayof30°C(86°F)crudeoil,willraisethetemperature
by0.37°C(0.67°F)
ShutdownInterlock
•  Whencompressorshutsdowncasingpressurewillrise
•  Thisleadstoadropoffininflowtothewell
•  Itispossiblethatwhilethecompressorisshutoffthe
pumpjackcouldpumpitselfoff,damagingequipment
•  Usinganinterlocksothatbothcompressorandpumpjack
shutofftogetherwillpreventthis
•  Oncertainwellsthismaynotbeneeded,asimpleauto
bypassmaybesufficienttomaintainproduc:onun:lthe
compressorcanberestarted