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SPE DISTINGUISHED LECTURER SERIESis funded principally
through a grant of the
SPE FOUNDATIONThe Society gratefully acknowledges
those companies that support the programby allowing their professionals
to participate as Lecturers.
And special thanks to The American Institute of Mining, Metallurgical,and Petroleum Engineers (AIME) for their contribution to the program.
Frac-pack in Ultra Deep Water: Lessons Learned from a Hundred of
Well Succeeded Operations
Carlos A. Carlos A. PedrosoPedroso
Also thanksAlso thanks to Petrobrasto Petrobras
3
OutlinesCampos Basin scenario & Sand control evolutionCampos Basin scenario & Sand control evolutionHigh productivity High productivity fracpacksfracpacks: lessons learned: lessons learned
Best practices for high productivity wells in high Best practices for high productivity wells in high permeability sandstonespermeability sandstonesSpecific deep water issuesSpecific deep water issuesChallenges in deep water, soft rock fracturing Challenges in deep water, soft rock fracturing
Importance of TSO Importance of TSO How to obtain the planned TSOHow to obtain the planned TSO
Data collectionData collectionCorrect AnalysisCorrect Analysis
Design and operational questionsDesign and operational questions
ConclusionsConclusions
4
Introduction
Campos Basin Scenario:
- Clean, high-permeability (300 to 14,000 mD) sandstones
- From poorly consolidated to unconsolidated sandstones
- Medium to heavy oil (29 to 14 API)
- Water depths ranging from 40 m (130 ft) to 2000 m (6500 ft)
5
Introduction
1988 1988 PROCAP “1000”PROCAP “1000”
19931993PROCAP 2000PROCAP 2000
20002000PROCAP 3000PROCAP 3000
6
DEPTH
COST
NEED FOR PRODUCTIVITY
7
Introduction
Deep water
High permeability
Unconsolidated Sands
ScenarioScenario PossiblePossible
SolutionsSolutionsOHHGP OHHGP –– 200 200 installationsinstallations
CHFP CHFP –– 130 130 installationsinstallations
NeedsNeeds
Sand Control
High Productivity
Durability
(( decdec 2
006)
2006
)
8
Primary option for all vertical/deviated wells, except:Primary option for all vertical/deviated wells, except:Oil/Water or Gas/Oil contact Oil/Water or Gas/Oil contact Mechanical constraints (casing, cementing,..) Mechanical constraints (casing, cementing,..)
In the past: “Can I fracpack?” In the past: “Can I fracpack?” Today: Today: ““How can I fracpack?How can I fracpack?””
Special mechanical cares: Special mechanical cares: The need of special toolsThe need of special tools
Larger volumesLarger volumesAggressive proppant rampsAggressive proppant ramps
Frac pack became…
9
Well succeeded fracpack(FRACPACK DEFINITION)
Low skin Low skin Best practicesBest practices
High conductivity fracturesHigh conductivity fractures TSO as plannedTSO as planned
No remedial acid jobs No remedial acid jobs BothBoth
No sand production No sand production Proper sand control designProper sand control design
10
Well succeeded fracpackSkin (Buildup & Falloff Test)
10
22
10
8
6
4
65
32
1
4
0
5
10
15
20
25
<0 0-1 1-2 2-3 3-4 4-5 5-10
10-15
15-20
20-30
30-40 >4
0
Skin
Num
ber o
f wel
ls
75%
From 1995 to 2005 (71 wells tested)From 1995 to 2005 (71 wells tested)
11
Best (good) practices HSC Overbalance x TCP HSC Overbalance x TCP UnderbalanceUnderbalance
Clean up flow prior to fracturingClean up flow prior to fracturing
AcidizingAcidizing prior to fracturingprior to fracturing
Riser and casing cleaningRiser and casing cleaning
Internal coated work string cleaningInternal coated work string cleaning
Brine FiltrationBrine Filtration
Gel and proppant quality Gel and proppant quality
Well k(mD)
s DR Perforating
A-1 354 1.9 1.3 Overbalanced
A-2 1516 1.6 1.1 Overbalanced
A-3 70 -1.5 0.8 Underbalanced
A-4 460 13.9 2.7 Underbalanced
A-5 860 3.9 1.6 Underbalanced
A-6 2795 10.2 6.7 Overbalanced
A-7 6600 45.2 7.0 Underbalanced
XX
12
Perforations HSC overbalance x TCP underbalance
13
Perforations
Underbalance745.26600A7-UBOverbalance6.710.22795A6-OBOverbalance1.11.61516A2-OB
Underbalance1.63.9860A5-UBUnderbalance2.713.9460A4-UBOverbalance1.31.9354A1-OB
Underbalance0.8-1.570A3-UBPerforationDRSkinK (mD)Well
Field “A”, same reservoir, equivalent operational conditions Field “A”, same reservoir, equivalent operational conditions (1997 to 1999) (1997 to 1999)
14
-10
0
10
20
30
40
50
A3-UB A1-OB A4-UB A5-UB A2-OB A6-OB A7-UB
Skin
e D
amag
e R
atio
1010
010
0010
000
Perm
eabi
lity
SkinDRK (mD)
OB OB
OB
Perforating Type x Skin & Damage Ratio
UBUB
UBUB
UBUB
UBUB
15
Acidizing prior to fracturingMain objective: clean perforationsMain objective: clean perforations
(BHP Data)
16
Workstring cleaning
Solvent and/or picklingSolvent and/or pickling
17
Casing and riser cleaning
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Stimulation boat, gel and proppant
Frac pack requires Frac pack requires specifically designed specifically designed equipmentequipmentThe proppant control must The proppant control must be automatedbe automatedHSP (Synthetic) x SandHSP (Synthetic) x Sand
Gel mixed onGel mixed on--thethe--fly using fly using sea watersea waterEnzymatic breakerEnzymatic breakerVirtually no damage related Virtually no damage related to the gel systemto the gel system
(SPE – 73722)
19
CostCostStatisticStatisticGood practiceGood practice
MEDIUMMEDIUMYESYESGel and Gel and proppantproppant quality quality MEDIUMMEDIUMNONOBrine FiltrationBrine Filtration
LOWLOWNONOInternal coated work Internal coated work string cleaningstring cleaning
LOWLOWNONORiser and casing cleaningRiser and casing cleaning
LOWLOWNONOAcidizingAcidizing prior to prior to fracturingfracturing
HIGH HIGH (*)(*)YESYESClean up flow prior to Clean up flow prior to fracturingfracturing
HIGH HIGH (*)(*)YESYESHSC Overbalance x TCP HSC Overbalance x TCP UnderbalanceUnderbalance
(*) +(*) +US$ 1,500,000/well due to OB (HSC) perforationUS$ 1,500,000/well due to OB (HSC) perforation
20
BEST (GOOD) PRACTICES
-200
300
800
1,300
1,800
2,300
2,800
C-1
E-1
A-2
G-2
A-4
M-1
E-2 F-1
F-2
G-4 J-1
F-3
A-7
C-2
C-3 J-3
H-2
B-4
B-6
G-7
B-9
P-1
B-10 I-2 N-1
A-8
B-13 G-9
Dra
w D
own
(psi
)
SPE – 73722
21
Deep Water Specific Issues
•High depths with low sediments•Low frac gradients
•Low elastic modulus
•Cooling of injected fluids (4 C @ sea bed)•Increase of frac fluid efficiency
•Breakers test temperature: -20 F to -50F
•DP rig and boats (strict and written procedures)
•Hydrates (prevention is better than remediation)
22
Design issuesDesign issuesTip Screen Out (TSOTip Screen Out (TSO) is mandatory ) is mandatory
Data collectionData collectionRock Mechanics Rock Mechanics
Calibration testCalibration test
Height growth Height growth
Well DeviationWell Deviation What is a TSO ?What is a TSO ?
23
Tip Screen Out (TSO) is mandatory
Four scenarios for fracpack:Four scenarios for fracpack:The BestThe Best: TSO happens and the fracpack is pumped as : TSO happens and the fracpack is pumped as planned, with planned net pressure gainplanned, with planned net pressure gainAcceptableAcceptable: TSO happens but it is followed by a : TSO happens but it is followed by a premature screen out, with lower premature screen out, with lower –– or higher or higher -- net pressure net pressure gaingainBad oneBad one: TSO does not happen: TSO does not happenWorst oneWorst one: TSO does not happen and a premature screen : TSO does not happen and a premature screen out occurs out occurs
SPE – 73722
24
TSO is the key factor !We can stand premature screen out after a TSO even with We can stand premature screen out after a TSO even with
little net pressure gain (low E. high little net pressure gain (low E. high νν))(No remedial acid jobs were performed when TSO was obtained)(No remedial acid jobs were performed when TSO was obtained)
2
1 4
4(1 )( ,0, ) ( , )
' net
vW x t H p x tE
QLW H pEμ
−≈ Δ
⎛ ⎞∝ ∝ Δ⎜ ⎟⎝ ⎠
26.0100ZeroNC-318.0100ZeroNB-521.967ZeroNB-44.8291100YG-14.220450YB-8-0.7100300YB-61.6551050YA-21.988370YA-1
SkinProp (%)
∆Pnet(psi)TSOWell
25
Reliable data collection Correct Analysis Skilled planning
TSO is the key factor…
……but it’s not easy !but it’s not easy !
26
Reliable data Rock Rock ppropertiespproperties
Reliable elastic Reliable elastic modulimoduliMinimum stress directionMinimum stress direction
Imaging fractureImaging fractureOriented Cores Oriented Cores
VelanVelanASRASR
Leak off dataLeak off dataCalibrationCalibration testtest
Surface pressure x BHPSurface pressure x BHPLive annulus pressureLive annulus pressureOn site analysisOn site analysis
27
Elastic Moduli
Simplified ModelSimplified Model ““More realistic” ModelMore realistic” Model
28
Usual simplifications Probable results
““Planned”Planned”FractureFracture
ObtainedObtainedFractureFracture
29
With…Inverted stress
GoodGood
Data !!!Data !!!
Elastic properties
30
Reliable data Reliable elastic Reliable elastic modulimoduliMinimum stress directionMinimum stress direction
Imaging fractureImaging fractureOriented Cores Oriented Cores
VelanVelanASRASR
CalibrationCalibration testtestSurface pressure x Surface pressure x BHPBHPLive annulus Live annulus pressurepressureOn site analysisOn site analysis
Cross Dipolar Sonic Log Cross Dipolar Sonic Log
31
Minimum stress direction•• Imaging after XLOTImaging after XLOTBefore
32
VELAN - Velocity Anisotropy0
10 2030
40
50
60
70
80
90
100
110
120
130
140150
160170180
190200210
220
230
240
250
260
270
280
290
300
310
320330
340 350
σHmax
σhmindireção de
diminuição de VPLower Lower VpVp
33
Minimum stress
Normal faults
ASRASR
VelanVelan
34
Reliable data Reliable elastic Reliable elastic modulimoduliMinimum stress directionMinimum stress direction
Imaging fractureImaging fractureOriented Cores Oriented Cores
VelanVelanASRASR
CalibrationCalibration testtest
Surface pressure x BHPSurface pressure x BHP
Live annulus pressureLive annulus pressure
On site analysisOn site analysis
35
Calibration TestCalibration tests , with in situ analysis, are a needFET, 1 or 2 Minifracs, SDT, SRTMinifrac, with BHP, is always performedSRT,
To confirm feasibility of treatment To help to restore pre-minifrac leak-off valuesAs primary evaluation of Pc
FETPrimary evaluation of Pc
SDTWell to formation connectivity
Minifrac AnalysisImportance of BHP for high permeability
3.140.10.00413.5438.90.00313.42A-37.524.40.0025.9222.70.0045.06A-4
15.78.10.0251.187.00.0180.43A-5300.06.80.0620.561.70.0930.12A-7-57.35.60.2130.6413.10.0731.23A-122.23.30.0460.202.70.0860.13A-6-59.12.70.0910.266.60.0480.90A-2
%%ft√min(min)%ft√min(min)ErrorEfCtTcEfCtTcWell
BH data Surface data (DP)
37
Live Annulus DataBHP data from live annulus is very close to BHP BHP data from live annulus is very close to BHP data from electronic gaugesdata from electronic gauges
38
Non ideal pressure declinein soft rock
Tip extensionTip extension
Pressure dependent leak offPressure dependent leak off
Height recession Height recession
39
TipExtension
40
Pressure Dependent
Leakoff
Low KLow K
High KHigh K
Low KLow K
High KHigh K
41
Height Recession
42
Temperature logs
Height growHeight grow
43
Temperature Logs
44
Thick, deviated interval Perforation: 2761Perforation: 2761--2830 (69m)2830 (69m)Inclination: 64Inclination: 64o o
Net pay: 30.5mNet pay: 30.5mLimited entry perforation prior to mf Limited entry perforation prior to mf Minifrac: 25 Minifrac: 25 bpmbpm
45
Thick, deviated interval
46
Correct analysis helped by temperature logThick, deviated interval
47
Skilled design
••Multiple intervalsMultiple intervals
••Thin intervalsThin intervals
••Highly deviated wellsHighly deviated wells
••Restricted perforationRestricted perforation
Pseudo 3D Models
48
Planned ... Obtained
49
Frac pack in thin sand with high-permeability
Thin sand, highThin sand, high--permeability:permeability:–– Low complianceLow compliance–– High leakoffHigh leakoff–– Narrow fracturesNarrow fractures
Low conductivityLow conductivityBetter results with Better results with HRWPHRWP
Well TVD (ft) Fluid DR [Prop] I-1 16.4 Gel 3.3 10
G-12 17.7 Water 1.5 1 G-13 10.5 Water 1.2 1-2 J-5 16.4 Water 1.3 1-2 M-3 19.7 Water 1.7 1-2
50
Stress anisotropy
Field MField M--22
••Completely unconsolidated Completely unconsolidated
••Permeability > 2,000 Permeability > 2,000 mDmD
••UCS < 200 UCS < 200 psipsi
••E < 400,000 E < 400,000 psipsi
StressStress
IsotropyIsotropy
ExpectedExpected
51
• 2 stacked fracpacks – 3470/3490 m (TVD – 2645/2656 m)
3435/3455 m (TVD – 2627/2637 m)
• PI – 31 (m3/d/kg/cm2)
• DR – 2.9
5 m shale (MD) - 2.6 m TVD
Deviated well – 58 Grades
52
Vertical well
• Interval -2671/2718 m
• PI – 133 (m3/d/kg/cm2)
• DR – 1.1
53
Highly deviated well
2.832.831.471.47SpecifSpecif PI PI ((m3/d/kg/cm2/mm3/d/kg/cm2/m))
2500/15002500/15001442/8831442/883ProdProd rate (rate (total/oiltotal/oil) () (m3/daym3/day))270027001430/14301430/1430ProdProd Rate (Rate (total/oiltotal/oil) () (m3/daym3/day) ) 1.11.12.92.9DRDR
1331333131PI (PI (m3/d/kg/cm2m3/d/kg/cm2))zerozero5858InclinationInclination ((grgr))474711 + 1011 + 10TVD TVD perforationperforation (m)(m)535320 + 20 20 + 20 MD MD perforationperforation (m)(m)1122FracpackFracpackVerticalVerticalDeviatedDeviated
54
Restricted PerforationRestricted Perforation
Aug/2006 12 operations well suceeded
55
Next steps
Fully 3D simulationFully 3D simulation
Green FPGreen FP
Multiple zones in one tripMultiple zones in one trip
56
Conclusions
The perforation method, OVB or UND, with or The perforation method, OVB or UND, with or without clean up flux has little importance to the without clean up flux has little importance to the final results of a well done/well designed fracpackfinal results of a well done/well designed fracpack
TSO is the key for a successful fracpack in highTSO is the key for a successful fracpack in high--permeability formations. permeability formations.
Reliable data, calibration test, BHP data and Reliable data, calibration test, BHP data and in situ in situ design is the key for high permeability fracturingdesign is the key for high permeability fracturing
Non ideal pressure decline is observed during Non ideal pressure decline is observed during minifracminifrac in soft rock formationsin soft rock formations
57
ConclusionsIn offIn off--shore shore fracpacksfracpacks, temperature log can identify , temperature log can identify fracture heightfracture height
For thin, well confined reservoirs, HRWP attain better For thin, well confined reservoirs, HRWP attain better results than fracturing with gel results than fracturing with gel
Even for completely unconsolidated sands, stress Even for completely unconsolidated sands, stress anisotropy affects fracturing results anisotropy affects fracturing results Vertical (or Vertical (or verticalizedverticalized well) is betterwell) is better
Do not perforate the entire interval to obtain TSODo not perforate the entire interval to obtain TSO
Good practices result in lower skinsGood practices result in lower skins
58
MoreMore
60
Back up & ComplementationBack up & Complementation
61
FRACPACK – Definition
Combination of the fracturing Combination of the fracturing with gravel packwith gravel pack
High permeability fracturing job High permeability fracturing job pumped with screens (GP pumped with screens (GP assembly) installedassembly) installed
62
FRACPACK – Basic concepts
Tip screen out (TSO)
Planned and controlled Screen Out at the Tip of the fracture, interrupting its propagation. The continuity of gel and proppant pumping causes the fracture width increase, which is proportional to the increment of the net pressure The TSO may happen with the arrival of the proppant at the tip of the fracture, demanding a very precise design.
63
Tip Screen Out
64
Tip Screen Out
Well Well –– Top viewTop view
65
Sand Control OptionsCased & Perforated Cased Hole Gravel
Pack Slotted Liner /
Screen in Open Hole
Open Hole Gravel Pack
Expandable Screen Cased Hole Frac Pack
After Darell Wood
66
Expandable ScreenCased & perforatedCased & perforated
O.L.O.L. Field VenezuelaField Venezuela
–– Cased & perforatedCased & perforated–– Heavy oilHeavy oil–– Swabbing for 4 hrs for Swabbing for 4 hrs for
testing testing sandingsanding–– Decided to remove Decided to remove
ExpadableExpadable ScreensScreens
–– Hot spotsHot spots
67
HotHot--SpotsSpots
Expandable Screen
68
Cased & PerforatedCased & PerforatedExpandable Screen
69
Partial ExpansionPartial Expansion
Expandable Screen
70
Expandable ScreenCased & perforatedCased & perforated
Conclusions from Service CompanyConclusions from Service Company
Fail occurred due to heavy oil flowing through Fail occurred due to heavy oil flowing through “restricted” perforations“restricted” perforations
Indication: Do not run expandable screens into cased Indication: Do not run expandable screens into cased producers wellsproducers wells
71
ExpandablesExpandables in in OffOff--ShoreShore Open Open HoleHole Horizontal Horizontal WellWell
250250250250250250150150250250250250150150
# (# (μμm)m)
PrPrPrPrPrPrPrPrInInInInInIn
TypeType
FailFailNonNon CompliantCompliant274274VV--11
FailFailCompliantCompliant620620MSMS--22
FailFailCompliantCompliant507507MSMS--11
2220022200CompliantCompliant390390MM--22
> 40000> 40000CompliantCompliant10081008MM--44
3970039700CompliantCompliant11381138MM--33
2320023200CompliantCompliant115115MM--11
Q (Q (bbl/dbbl/d))ScreenScreenL (m)L (m)WellWell
72
