C6 - Perforating for Stimulation

8/8/2019 C6 - Perforating for Stimulation

1/37

PerforationDesign

for

Well

Stimulation

R.D.Barree

Barree&

Associates

LLC


2/37

2009

Detonating

cord groove

point ofinitiation

Main

explosivecharge

Case or

container

Liner

Primer

charge

TypicalShapedCharge


3/37

2009

ApproximateJet

Velocitiesand

Pressures


4/37

2009

TypicalPerforationDamage

Reduced Permeability Zone

Perforation Tunnel

Plastically Compacted Zone

Pulverized Compacted Zone


5/37

2009

StressCageFormationinSandiaMineBackExperiment


6/37

2009

PoorPerforationBreakdown CausedbyStressCage


7/37

2009

CompactionDamageis

Related

to

Charge

Design BigHolechargesarefocusedtocreatelarge

diameterentry

holes

Moreradialdeformation

Morestresscageeffect

Lesspenetration

DeepPenetratingchargesarefocusedformaximum

depth

of

penetration Usuallylessradialdeformation

Smallerstresscageeffect

Lowerbreakdown

pressure


8/37

2009

ProperPerforatingTechniquesCanMinimizeDamage

0

100

200

300

400

500

600

0 20 40Perforation Charge, gm

NetBreakdownP

ressure,ps

i

4 perfs

Open

In soft rocks perforationcharge size can affect

breakdown pressure.

Perforation diameter

is more important than

penetration.

More holes are better

than deeper penetration.


9/37

2009

SteprateAnalysisforConventional

Perfs

54 holes shot, Perfd twice


10/37

2009

ImpactofPoorPerforations

onJob

Performance

3/15/200500:00 00:20 00:40 01:00 01:20 01:40 02:00 02:20 02:40 03:00

3/15/200503:20

Time

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

A

0

10

20

30

40

50

B

0

1

2

3

4

5

CCasing Pressure (psi) Slurry Rate (bpm) Surface Proppant Conc (lb/gal)A B C


11/37

2009

AvoidingPlasticCompactionand

StressCage

in

Perforating

Bulletgunsavoidplasticcompactionandmaygeneratefracturingandpermenhancement

Hydrojetting(abrasivesandjetting)cancutdeep,efficientholeswithminimalmechanical

damage Avoidjettingforlongtimesasthiscangenerate

finesandemulsions

Hydrojettingcan

provide

penetration

up

to

12

inchesormore


12/37

2009

FracturesRadiatefrom

BulletFormed

Perforation


13/37

2009

Wellhead/PlatformLeg

Removal(Lab

Test)

successful cut

unsuccessful cut


14/37

2009

StepRateAnalysisforHydroJetHoles:

Nomeasurable

DP


15/37

2009

Case1:100%ofPerfsOpenforLow

DensityPerforating

30 holes shot, 180 deg


16/37

2009

MinimumPerforationSizesforSandBridging

Perforationdiametersof6xthepropdiameterassurenobridging.

ProppantSize RecommendedPerfDiameter

(mesh) (inches)

6/12 0.80

8/16 0.56

12/20 0.40

16/30 0.28

20/40 0.20

30/50 0.14

40/70 0.10


17/37

2009

MinimumRequiredPerfDiameterDependsonConcentration

Maximum Proppant Concentration, lb/gal

Minimu

mP

erfDia

meter,in

0

0.1

0.2

0.3

0.4

0.5

0.6

0 5 10 15 20

8/12 mesh

10/20 mesh20/40 mesh

40/60 mesh

8/12

10/20

20/40

40/60


18/37

2009

FracturesRarelyInitiateatPerf

Tunnels


19/37

2009

TortuosityCausedbyPoorPerf

Orientationand

Poor

Cement

Perforation Orientation

Restricted Cement Annulus

Fluid Flows through

Annular Gap to Fracture

Annular flow restrictions cause high fluid shear,high pressure drops, and early screenouts.


20/37

2009

NearWellborePressureLoss

Stresshaloaroundperf

Flowaroundcementmicroannulus

Perforationinterference

Narrowfracturewidth

Fractureturning

and

branching(multiples)

Offverticalfractures

Pulverizedcement

debris

Chargedebris

Leakoffintodrillingandperf

inducedfracs


21/37

2009

RecommendationsforSuccessful

Perforating

for

Stimulation Perfunderbalanced,flowbackandcleanupperfs

Useaggressivecleanupprocedures

Largeenoughdiametertoacceptproppant

Sufficientnumberanddiametertoallowfluidentry

atdesired

pressure

Determineoptimumphasingtominimizeentryfriction

Dontshoot

more

holes

than

you

need

Ifascreenoutoccursconsiderreperforatingbeforerefracturing


22/37

2009

AggressivePerforationCleanupTechniquesShouldBeUsed

PerforationBreakdowns

Injectionofnondamagingfluids

Maynot

open

all

perforations

AcidorBrineBallouts

Smallperforatedintervals

Maynot

contact

all

perfs

PerforationSurgingandWashing

PerforationIsolationTools

AcidSoaks

Maintaindrawdownoveralongtimeperiod

ExtremeOverbalancePerforating

StressFrac

Treatments


23/37

2009

ConventionalPerfsAfterBallout:

Doesit

help?

72 holes shot (6 spf)


24/37

2009

UnderbalancePerforating

RemovesPerforation

Damage

Underbalanceprovidessurgeoffluidintothewellboreforcleanup.

Excessunderbalance

may

cause

collapsed

casing,

formationbreakdownanddamagefromfinesmovement.

Underbalancerequirement

is

indicated

by

field

data:

Noimprovementfromacidizingindicatescleanperforations

Underbalanceis

determined

by

reservoir

permeability

Atlowpermeability,maybeassociatedwithinsufficientflowforcleanupirrespectiveofpressuredifferential.

Underbalance


25/37

2009

Underbalance

PerforatinginOilWells

0.1

1

10

100

1000

100 1000 10000

Total Underbalance, psi

Perm

,md

?

Recommended

Underbalance

Underbalance Perforating


26/37

2009

UnderbalancePerforating

inGasWells

0.1

1

10

100

1000

100 1000 10000

Total Underbalance, psi

Perm

,md

Recommended

Underbalance

Casing collapse

Stuck Packer

Data from George King


27/37

2009

EffectofAcidonSandstone


28/37

2009

SummaryofPerforating

Recommendations OnesizedoesNOTfitall

WhatworksGREAT!Inoneareamaynotworkinanother

Find

the

optimum

strategy

for

your

reservoir

and

stress

state Ingeneralfewerholesshotmeanshigherperfefficiencyand

lessnearwelldamage Idonotfavorclusterperforating

Ido

like

low

shot

density

to

avoid

overlapping

stress

cages

Ifyoudontknowthestressfieldorientation,phasingcanbeinconclusive

Indeviatedholesandhighlyanisotropicstresses,trytoshoot

inthe

direction

of

minimum

near

well

compression

Forhighlydeviatedandhorizontalholes,thatistopandbottom

Depthofpenetrationismeaninglessinawellthatmustbefracturedtoproducecommercially

Getaholethroughthepipethatisbigenoughfortheproppant


29/37

2009

LimitedEntryFracDesigns

Forcefluidintomorethanonezone

use

perf

restriction

as

flow

orifice highshearandtreatingpressure

possiblefluiddamage

perforationerosion

concerns

maximumsustainedpressuredropisuncertain


30/37

2009

PerforationRestrictionCauses

aLarge

Pressure

Drop

Pq

C N dpsipf f

D p p

=

19752

2 2 4

.;

where

q = the total pump rate, bpm

f= the slurry density, g/cc

CD = the perforation coefficientNp = the number of open perforations

dp = the perf diameter, inches


31/37

2009

PerforationEntranceCharacteristics


32/37

2009

6 lb/gal

2.5 lb/gal

Crump & Conway, SPE

15474

Crump/ConwayStudyofPerfErosion


33/37

2009

FinalPerfGeometryin

Crump/

Conway

Study

SPE 15474

P f ti P i


34/37

2009

PerforationPin

Limited

Entry

Treatments


35/37

2009

PostFracLogs LEFracinOK

Frac 1 Frac2 Frac3 Perf Only

Post Frac Production = 29 MMCD/D


36/37

2009

PropConcentrationAfterLEFrac

Comparedto

Model


37/37

2009

FractureGeometryinMultiZone

Treatments Effectofdifferentextensionandclosure

stressesinmultiplezones

Distributionofinjectedfluid

Excessiveperferosion

Damagetofluidthroughhighshear

Effectsofproppantonmobilityandslurry

placement

Effectsofcrossflow duringclosure

Documents

C6 - Perforating for Stimulation