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7/25/2019 Akshay Pat Ni
http://slidepdf.com/reader/full/akshay-pat-ni 1/17
Cold Heavy Oil Production
with Sand (CHOPS)
Akshay Patni
E11-0006
7/25/2019 Akshay Pat Ni
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Oil sand before oil extraction
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CHOPS
• No sand exclusion devices (screens,
liners, gravel pacs, etc!) are used• Sand is produced along with oil,
water, and gas
Co"pletio
nProcedure
#uring
Production
Separate
sand fro"oil
$nitiation ofsand in%ux
&aintenanceof sandin%ux
$"ple"entation of
"ethods
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Conditions
• 'sed only in unconsolidatedsandstone ('CSS) reservoirs (φ *+)
• Containing viscous oil ( μ - .++ cp)
• 'sed al"ost exclusively in theCanadian heavy/oil belt and inshallow (0 1++ ")
• 2ow/production/rate wells (up to 3++to 34. "*5d)
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CHOPS production rate increase
"echanis"s
• 6luid %ow rate increases if the sand "atrix isallowed to "ove because the #arcy velocityrelative to the solid "atrix increases with "atrix"ove"ent!
• 7s sand is produced fro" the reservoir, a 8one ofenhanced per"eability is generated and growsoutward, allowing a greater %uid %ux to thewellbore!
• Solids "otion in the near/wellbore environ"enteli"inates 9nes trapping, asphaltene deposition,and scale develop"ent on the for"ation "atrixoutside the casing!
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:ypical CHOPS wellbehaviour
• ;hen a new well is co"pleted, initial sand in%ux is large< 3+ to=+ of the volu"e of the (gas/free) produced li>uids and solids!
• Over a period of a few days to several "onths, the sand rategradually decays toward a steady/state in%ux rate (+!. to 3+),depending on oil viscosity!
• :he oil production rate increases to a "axi"u" several "onthsor "ore after placing the well on production and then slowlydeclines as reservoir/depletion e?ects begin to do"inate!
• 7ll CHOPS production is acco"panied by substantial gasproduction, and gas5oil ratio (@OA) values tend to re"ain
relatively consistent over "any years!• 7 successful wor/over can partly re/establish oil and sand rate
but generally not to levels as high as the 9rst cycle!
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6ield behavior
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1
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CHOPS operational and "onitoring
issues
Perforating a CHOPS well
• Cased well is perforated with large/dia"eterports, usually of 4* to 41 "" dia"eter, fullyphased, and spaced at 4B or * charges per"eter
• &ore densely spaced charges have not proved togive better results or service, but less denselyspaced charges (3* per "eter) give poorer results
• $n thin intervals (0B "), the entire interval isperforated! $n thicer intervals (- 3+ "), a B/ to 1/" 8one is perforated!
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$nitiating production and pu"ping in CHOPS wells
• 2arge sand in%ux in CHOPS wells increases well rates
• $t carries the ris that the pu"p "ay plug and awor/over "ay be re>uired
• Dringing a well onto production is a gradual process
• CHOPS wells are "aintained in an aggressivelydrawn/down condition, which increases thee?ectiveness of the foa"y/oil "echanis" indestabili8ing sand and "aintaining free %ow into the
perforations• PC pu"ps currently are widely preferred over other
pu"ps
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Conclusion
• Aate increases are associated with sand li>uefaction,per"eability increase, foa"y oil "echanis"s, and eli"inationof near/wellbore 9nes and asphaltene blocage
• 'lti"ate recovery factors have i"proved fro" 4 to B to 34to 4+ of OO$P in "any heavy oil 9elds with the use of CHOPS
• Detween 31. and 4++4, great i"prove"ents have been seenin handling sand, "aintaining wells on sand production, liftingeEciency, and other aspects of CHOPS
• CHOPS concepts are beginning to a?ect conventional oil andgas production approaches in suitable reservoirs!
• @iven the vast heavy/oil resources and the inevitabledepletion of conventional oil, technologies such as CHOPS willsteadily beco"e "ore i"portant!
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Thank you
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