22 Sand Control

Copyright 2007, , All rights reserved

Sand Control


Completions Type

Slotted Liner

Fracpack

ExternalGravelpack

ChemicalConsolidation

InternalGravelpack

Screen/open hole

CementedCasing/liner

Barefoot(Openhole)

CompletionType


SAND PRODUCTION PROBLEMS AND

PRODUCTIVITY EFFECTS

Copyright 2007, , All rights reserved 4

Sandstone Reservoir

natural cementingCaCO3

mineral grainQuartz, SiO2


SAND PRODUCTION MECHANISM

As fluids flow through a porous material, drag forces are created along the path of flow. Depending on the degree of natural intergranular cementation, compaction, intergranular friction, and cohesion of particles making up the porous material, flowing fluid may carry with it considerable quantities of loose and friable sand grains.

SAND PRODUCTION CONTROL AND PRODUCTIVITY EFFECTS


Sand Production

Once the destabilizing forces overcome the formation strength, the rock will fail.

Sand production will follow if sand can be transported.


Sand and Fines

Fines – solids with 44 microns Fines are most probably produced in every well. Fines are not controlled. They can be dissolved. Sand can not be dissolved. Needs to be controlled.


PRODUCTIVITY EFFECTS

• Erosion damage of surface and subsurface production equipment (eg.Casing/liner failures)

• Plugging of well and surface production facilities

• Sand Disposal



Sand production during a four-rate test

0 1 2 3 4 5 6 7

PRODUCTION TIME, MONTHS

OIL

RAT

E

CRITICAL OIL RATE

SAND

OIL

“TOLERABLE”FINES


SAND RATE


FACTORS INCREASING SAND PRODUCTION

• Decline of reservoir presssure (increase of overburden pressure)

• Cementing Material, Degree of Consolidation

• Fluid Viscosity, Production Velocity, Drag Forces

• Increasing water production (destroys intergranular cementing material)

• Formation damage (increases drawdown)


Causes of Sand Production (I)

Time Dependence– decreasing reservoir pressure increases the effective stress on

the grains (overburden is constant) Fluid Flow

– fluid velocity and viscosity contributes to the pressure drop near the wellbore (drag force)

– production induces stress on the formation sand– induced stress > formation stress sand production


Causes of Sand Production (II)

Geological Factors– tertiary age reservoirs, usually shallow depths

Þunconsolidated Impairment on Natural Consolidation

– high compressive strength– internal pore pressure supports the overburden

P-'


Causes of Sand Production (III)

Mutiphase Flow Water production may dissolve natural cementing materials

weakening the intergranular bonds; Water production may mobilize fines resulting in plugging of

the pore structure.


Prediction of Sand Production

ExperienceAnalogySpecial Well TestCore Inspection and Testing

MeasurementsLog InterpretationCorrelations


MEASURES TO CONTROL SAND PRODUCTION

1. Reduce producing oil and gas rates below the critical rate for sand production.

2. Prevent sand production mechanically by screen or gravel pack.

3. Chemically consolidate the formation sand near the wellbore using resinous material.

4. Inject resin-coated gravel into the perforations to pack and stabilize the perforations.


FLOW RATE, Q

BOTT

OM

HO

LE F

LOW

ING

PRE

SSUR

E, P

wf

Pr

00

CRITICAL SAND FREE OIL RATE

OUTFLOW(CONTROLLED)INFLOW

CONTROLLING PRODUCTION RATES

CRITICALDRAW-DOWN

MEASURES TO CONTROL SAND PRODUCTION


Methods for Sand Control

Screnless

With Screen


Screenless Methods for Sand Control

In-situ consolidation Use of resins to consolidate formations.

Resin-Coated Gravel Injection of pre-coated gravel.


Methods for Sand Control using Screen

Gravel Pack Natural Sand Pack (NSP) Frac & Pack (Frac-n-Pack, Frac-Pack, StimPAC*)

* - mark of Schlumberger


MECHANISMS OF MECHANICAL RETENTION

GRAVEL

SAND

GRAVEL

SAND

BRIDGING FILTER-SIZE RETENTION

THE WHOLE IDEA BEHIND GRAVEL PACKING IS THAT THE GRAVEL MAY BE SIZED TO EFFECTIVELYRETAIN THE FORMATION SAND AND THE SCREEN MAY BE SIZED TO RETAIN THE GRAVEL

MEASURES TO CONTROL SAND PRODUCTION(GRAVEL PACK)


MECHANICAL SAND RETENTIONMEASURES TO CONTROL SAND PRODUCTION

INSIDE CASINGGRAVEL PACK

OPEN HOLEGRAVEL PACK

UNDERREAMEDOPEN HOLE

GRAVEL PACK

UNDERREAMED CASING

GRAVEL PACKSCREEN LINERIN OPEN HOLE


PERMEABILITY REDUCTION AS A FUNCTION OF RATIO OF GRAVEL SIZETO FORMATION GRAIN SIZE (After Saucier)

dG50/dR50

K/Ki

0.2

0.4

0

0.6

0.8

1.0

14121086420 1816 20

dG50(optimum) = 5 or 6dR50

RULE

OF

THUM

B


Gravel Pack

Sand - Gravel - Screen


FORMATION GRAIN SIZE STATISTICAL DISTRIBUTION(Sieve Analysis)

0.01 0.001 0.00010

20

40

PARTICLE SIZE, INCHES

RETA

INED

WEI

GHT

, PER

CENT

AGE

10

30


FORMATION GRAIN SIZE DISTRIBUTION(Sieve Analysis Results)

1.0 0.1 0.01 0.001 0.0001

100

2030405060708090

100

GRAIN DIAMETER, INCHES

CUM

ULAT

IVE

PERC

ENTA

GE

BY W

EIG

HT

DR50

DG50(optimum) = 5DR50


OPTIMUM GRAVEL SIZE DIAMETER AND OPTIMUM SCREEN SIZE

DG50(optimum) = 5DR50

1.0 0.1 0.01 0.001 0.0001

100

2030405060708090

100

GRAIN DIAMETER, INCHES

CUM

ULAT

IVE

PERC

ENTA

GE

BY W

EIG

HT

DR50

RESERVOIR

COMMERCIALGRAVEL

DG50

DGmin

DLINER SLOT = 0.5DGmin(*)

(*) FOR SCREEN LINER IN OPEN HOLE DLINER SLOT = 2xDR10 FOR NONUNIFORM SANDAND = DR10 FOR UNIFORM SAND


MEASURES TO ACHIEVE PROPER INSIDE CASING GRAVEL PACK

1. PROPERLY SIZED GRAVEL AND SCREEN LINER.

2. SHOOTING LARGE DIAMETER PERFORATIONS TO ALLOW EFFECTIVE PLACEMENT OF GRAVEL.

3. CLEANING AND WASHING THE PERFORATIONS TO REMOVE DEBRIS FROM THE PERFORATIONS.

4. EFFECTIVE TRANSPORT AND PLACEMENT OF THE GRAVEL IN THE PERFORATIONS.

5. PRESSURIZING AND SQUEEZING GRAVEL IN THE PERFORATIONS.

6. MAINTAINING CLEAN WELLBORE FLUIDS THROUGHOUT THE GRAVEL PACKING OPERATION.


COMMERCIAL GRAVEL DATA

____________________________________________________________________________________________________Aprox. βG=bkG

-a

Sand/Gravel US Mesh Median Porosity Permeability ________________________Size(in.) Size Dia.(in.) (%) (mD) a b____________________________________________________________________________________________________0.006 ----- 0.017 40/100 0.0120.008 0.017 40/70 0.0130.010 0.017 40/60 0.014 32-39 1.2x105-1.7x105 1.6 2.12x1012

0.017 0.033 20/40 0.025 35-40 1.54 2.12x1012

0.023 0.047 16/30 0.0350.033 0.066 12/20 0.0500.039 0.066 12/18 0.0530.043 0.079 10/20 0.056 32-40 5x105-6.5x105 1.34 8.4x1011

0.047 0.079 10/16 0.063 35-40 17x105-20x105

0.066 0.094 8/12 0.080 36-40 17x105- 1.24 5.31x1011

0.079 0.132 6/16 0.106 -42____________________________________________________________________________________________________

By convention, 20-40 mesh commercial gravel passes through a 20 mesh sieve and is retained by a 40 mesh sieve


PROCEDURES TO COLLECT SAMPLES OF FORMATION SAND

1. RUBBER-SLEEVES CORES

2. CONVENTIONAL CORES

3. SIDEWALL CORES

4. PRODUCED SAND FROM THE SEPARATOR OR SAND TRAP

5. SAND BAILERSNot recommended


Sampling

per layer– critical for gravel size determination

full core samples are best– bail samples are not representative because of loss of – high and low ends of particle distribution

sidewall cores are acceptable– frequent sampling

• heterogeneous formation - 1 ft• uniform formations - 5, 10, 20 ft spacing

shale-shaker– representative, if collection is accurate


Sample collection

size

%

size (log)%

cum

ulat

ive

bail sample (high end)core samplebail sample (low end)


GRAVEL PACK PLACEMENT

(Washpipe raised)


GRAVEL PACK EVALUATION


EXERCISE

solution

_________________________________________________________________U.S.sieve Grain Weight

CumulativeNumber diameter retained Weight weight(mesh) (in.) (gm) percent percent_________________________________________________________________8 0.093012 0.066116 0.046920 0.033130 0.0232 0.25 1.4 1.4

40 0.016550 0.0117 0.79 4.3 5.7100 0.0059 2.81 15.4 21.1

140 0.0041 3.25 17.8 38.9200 0.0029 4.10 22.5 61.4270 0.0021325 0.0017 4.52 24.8 86.2Pan 2.52 13.8 100.0

Totals 18.24_________________________________________________________________

Well X4 is to be gravel packed. A sidewall sample was available and a sieve analysis was made.Results of the analysis are shown in the following table:

Suggest gravel and screen for gravel pack design for the well.


First Selections

1st: select fluid system– least damaging, economical, efficient

2nd: select gravel and screen or slotted liner– size and type

3rd: NODAL analysis:– evaluate effect on well productivity

4th: Re-select fluids and gravel– if necessary


Gravel Pack Preparation

Always In OH, clean mud cake prior running screen In CH, ensure that all perforations are open and clean Clean tubing prior to any pumping


Internal gravel pack

Reliable drilling and completion methodologies

Requires efficient perforation system

Easier workover compared to EGP

Isolate production from undesirable zones

Poor perforation pack may lead to low productivity

Cased Hole Considerations


External gravel pack

Open Hole Considerations

Can be Underreamed, increasing wellbore area

No damage due to poor perforation pack efficiency

Hole stability is a concern while drilling and completion

Water production control may become impractical


Circulation system - IGP

Fluid may leak to the formation, may be circulate back to the surface or both.

When pumping slurry, gravel will be placed inside perforation tunnels and annular casing-screen.


Circulation system - EGP

Fluid may leak to the formation, may be circulate back to the surface or both.

When pumping slurry, gravel will be placed in the annular formation-screen.

Accessories : Lower and Upper Telltale.


Squeeze system - IGP

Fluid may leak only to the formation.

Fluid may travel through inside the screen.

When pumping slurry, gravel will be placed inside perforation tunnels and annular casing-screen.


Formation Analysis

Lithology, definition of fluids Granulometry, selection of gravel size


Fluids Compatibility

potential damage by fines migration (clays) formation cores are often unavailable inference from lab studies on similar formations requires comprehensive clays analysis of the samples


Clay Chemistry

Montmorillonite– swelling clays– sensitive to fluids with low NaCl content

Kaolinite, illite and chlorite– dispersed by fluid movement– NaCl increases the sensitivity of the clays– CaCl2 is normally used instead of NaCl


Clays

In Gravel Packing, potential clay problems merits serious consideration when clay content equals or exceeds 5%.

As a prevention, a clay stabilizer should be add to the carrier fluid.


Acid clean-up prior to gravel pack

HCl – dissolves calcium scale and improves injectivity Fluoboric Acid - controls swelling and movement of clays and

fines (dissolves most and stabilizes the remain) Maximum operational flexibility Increased leak-off rate during GP Do not overflow the well after treatment


Filtration

All fluids must be filtered– preferably at well site; avoid contamination in tanks and

transports Brines must be filtered at 2 μ Gels must be filtered at 10 μ

– 15/64 in to 3/8 in choke at 500 psi – estimate 10% reduction in viscosity


Damage caused by solids

A (2.5 ppm)

C (94 ppm)

D (436 ppm)

Per

mea

bili

ty (

md)

Volume Injected (gal/perf)

500

100

50

100 0.02 0.04 0.06 0.08 0.10

(A) Bay Water FilteredThrough 2um Cotton Filer

(B) Bay Water Through 5um Cotton Filter

(C) Produced Water Untreated

(D) Bay Water Untreated

B (26 ppm)


Sizing Criteria

Saucier Method: median grain for gravel is 5 or 6 times median grain size for sand formation

(D50)g = 5 or 6 x (D50)f

Coberly Method: uniform sands. Gravel too large to prevent fines.

Stein Method: uniform sand. Schwartz Method: reduces probability of fines


Screen, blank pipe & wash pipe

Screen length: 5 ft above and 5 ft below perforationsScreen OD: gap of 1-in per sideWash pipe OD: very close to screen IDBlank pipe OD: slightly less than screenBlank pipe ID: same as screen

1-in

wash-pipescreen minimum gap

blank pipe

screen


Liners or Screens ?

primary control onlyslots erosion

welding might corrodepressure loss across slots

cost can be highsmall fluid area

large flow areaun-restricted flow

robustenhanced control low cost

Wire Wrapped Screens

Slotted Liners


The ideal gravel pack

Complete packing with a properly sized high-permeability gravel.Clear interface between the formation sand and gravel.No invasion of the matrix with damaging material.No reduced-permeability section between the formation sand and the gravel pack.No residuals from the carrier fluid and/or fluid-loss pills.


Poor gravel pack placement

PerforationPotential for

production lossOpen Hole

Potential for production loss and/or screen failure (erosion)


Poor interface Gravel / Sand

Reduced pack permeabilityPotential for production

loss


Matrix damage

Invasion of the matrix by treatment/completion fluids

Potential for production loss


Damage zone

Perforation Crushed ZonePotential for

production lossOpen Hole Filter Cake

Potential for production loss


Gravel pack damage

Residuals from the treatment fluidPotential for production

loss


Multi-zone treatment

12840

12860

12880

12900

12920

12940

12960

12980

13000

13020

0 5 10 15 20

12840

12860

12880

12900

12920

12940

12960

12980

13000

13020

1 10 100 1000

0100020003000400050006000700080009000

10000

0 10 20 30 40 50 60

Time (minutes) P

ress

ure

(psi

)

0

2

4

6

8

10

12

14

16

Rate or C

onc. (bpm or ppa)

Surface Pressure

Rate

Conc.

4500

5000

5500

6000

6500

7000

7500

8000

0 10 20 30 40 50 60

Time (minutes)

P

ress

ure

(psi

)

130

140

150

160

170

180

190

Temperature (D

eg F) BHP Upper and Lower

Temp. Upper Gauge

Temp. Lower Gauge


Multi-zone treatment

Benefits– Interval between zones 6 feet– Single trip in hole– Single pump stage– Simple

Completions– Gravel Pack-Frac / Pack

• 15 jobs to date for PRISA• 1 job with 3 zones (2 x MZ)


Two zones (lower wet)

1 0360

1 0380

1 0400

1 0420

1 0440

1 0460

1 0480

1 0500

1 0520

1 0540

0 50 1 00 1 50

10360

10380

10400

10420

10440

10460

10480

10500

10520

10540

0.1 1 1 0 1 00

Wet Sand

0

1000

2000

3000

4000

5000

6000

0 20 40 60

Time (min)W

ell P

ress

ure

(psi

)

0

5

10

15

20

25

30

Rate (bpm) Conc (ppa)


Multi-zones results

Complete Packs of All Zones Significant Completion Cost

Savings Elimination of Kill Pills Better Production

27 f t

0.7 in.

140 lbs/ f t

Documents

22 Sand Control