Akshay Pat Ni

7/25/2019 Akshay Pat Ni

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Cold Heavy Oil Production

with Sand (CHOPS)

Akshay Patni

E11-0006



Oil sand before oil extraction



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



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)









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!





: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!



6ield behavior



1



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!





$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



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!



Thank you

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Akshay Pat Ni