Update on ESP Operation at BP Wytch Farm OilfieldBy Erwin WahidiyatPresented at the European Artificial Lift Forum 17-18 February 2010

2

Presentation Agenda

Introduction to Wytch Farm Oilfield:

Location

Sherwood Reservoir Summary

Role of ESP in Sherwood Reservoir Development

ESP Run-Life Progression: 1985 �– 2009

Summary of Run-Life Measurements

Failures by Components

High HP ESP System MTTF

Shift in Depletion Plan & Impact on ESP Strategy

Summary of Current ESP Systems

Past-Present Comparisons �– M11 & M15 Examples

Application of Dual ESP to Extend Life Cycle

Application of Dual ESP to Manage Productivity Uncertainties

Closing Remarks

3

Wytch Farm Oilfield - Location

miles

Well sitesBottom hole locations

Sherwood reservoir

BournemouthPoole

Poole Harbour

Purbeck

milesmiles

Well sitesBottom hole locations

Sherwood reservoirWell sitesBottom hole locations

Sherwood reservoir

BournemouthPoole

Poole Harbour

Purbeck

�• Located in a sensitive environmental area on the southern coast of England, about 120 miles from London

�• Oil export via 90km 16�”Purbeck-Southampton pipeline, LPG via road tanker, gas by Purbeck-Sopley pipeline

�• 11 wellsites, total active wells (producers & injectors): 65. Active ESP wells: 31

�• Reservoirs: Sherwood, Bridport, Frome, Kimmeridge, Wareham, Arne, & Stoborough.

�• Current field production: 20+ MBDO at 93% water cut.

4

Sherwood Reservoir: Summary & PVT Properties

Sherwood Reservoir Summary:

�•Triassic sandstone reservoir, with top reservoir at ca. 1585 m-TVDSS with a maximum 110-m column of oil bearing sand above the oil/water contact

�•Upper reservoir: Zones 10-40, Lower reservoir: Zones 50-100. Zones 20, 40, & 60 (muddier intervals) act as barriers

�•Three main oil bearing zones: Zones 30, 50, & 70 (decreasing permeability and net-to-gross in the upper zones). PI ranges from 1 to 100+ BPD/psi

�•The western part of the field lies onshore (below Poole harbour & surrounding area) & the eastern part of the reservoir lies offshore

�•Over half of the Sherwood reserves lies in the offshore area, which necessitated the drilling of ERD wells beginning 1993

�•Production from Sherwood reservoir accounts for 85% of total WYF production

�•Reservoir conditions relatively benign for operating ESPs (See tabulated PVT properties)

�•Normally Occurring Radioactive Material (NORM) is present with the produced fluids and causes complications when retrieving downhole completion and the handling of retrieved ESPs during teardown.

A l l z o n e s in w e s t e r n a r e a s h a v eL o w e r N e t t o G r o s s – t h is l im i t s

V e r t ic a l c o n n e c t iv i t y t o u p p e r r e s e r v o i r

X 0 2 A r e a – Z 7 0 i s v . p o o r q u a l i t y – l im i t s

V e r t i c a l c o n n e c t i v i t y

F a u l t s / f r a c t u r e s c a n b e C o n d u c t i v e a n d n o n - c o n d u c t i v e :* F a u l t o r ie n t a t i o n* N e t : G r o s s* P r o x im it y t o f lo o d f r o n t

I n je c t i v i t y o f u p p e r r e s e r v o irI n o n s h o r e a r e a h a s n o t y e t b e e n t e s t e d

B a s e o f Z 1 0 i n b o t h w e s tA n d e a s t a p p e a r s s a n d ie r

F r o m c o r e o b s e r v a t i o n s

B a s e o f Z 1 0 : is o la t e d f lu v ia l c h a n n e ls o b s e r v e d in c o r e

D is t a l ( f u r t h e r a w a y )f r o m s e d im e n t s o u r c e

D e n s e f a u l t s a n d f r a c t u r e s

D e n s e f a u l t s a n d f r a c t u r e s

R h iz o c r e t io n s a n d s p r e s e n t m o s t l yI n Z 5 0 ( l o c a l l y in Z 3 0 i n o f f s h o r e a r e a )- C o u ld b e m o r e p o o r l y c o n n e c t e d t h a n

- F lu v ia l s a n d s d u e t o m u d d ie r o v e r b a n k- d e p o s i t s

Z 5 0 / Z 7 0 s t r a n d e d A t t i cT a r g e t s p o s s ib le

B a s e Z 1 0 a p p e a r s s a n d ie r f ie ld w id e

M id Z o n e 3 0 s i l t s t o n e / s a b k h aA p p e a r s f ie l d w id e in c o r e

Z 4 0 / Z 6 0 ( a n d lo c a l l y Z 2 0 ) a r e d is c o n t i n u o u s in t h e

o f f s h o r e a r e a s o a r e b a f f le s r a t h e rt h a n b a r r i e r s t o f lu id f lo w

Z 7 0 : p e r m e a b i l i t y c a n b e U p t o 4 D a r c ie s

P r o x im a l ( c l o s e r t o )s e d im e n t s o u r c e

B a s e Z 1 0 : l o c a l i s e d i s o la t e d F lu v ia l c h a n n e ls i n e a s t e r n a r e a s

( a n d o c c a s io n a l l y in w e s t ) .

A l l z o n e s s h o w in c r e a s e in N e t t oG r o s s in o f f s h o r e a r e a , w h e r e

c h a n n e l s a n d s b e c o m e m o r e p r e v a le n t

> P e r m e a b i l i t y d i s t r ib u t io n d r iv e nb y f a c ie s t y p e

> B e s t q u a l i t y s a n d s a n d a v e r a g e s a n d sa r e in d is t in g u is h a b le o n p o r o s i t y lo g s

> 6 - 8 % p o r o s i t y s a n d c a n h a v e g o o dp e r m e a b i l i t y ( c u r r e n t p o r o s i t y c u t - o f ff o r n e t s a n d i s 1 2 % )

A l l z o n e s in w e s t e r n a r e a s h a v eL o w e r N e t t o G r o s s – t h is l im i t s

V e r t ic a l c o n n e c t iv i t y t o u p p e r r e s e r v o i r

X 0 2 A r e a – Z 7 0 i s v . p o o r q u a l i t y – l im i t s

V e r t i c a l c o n n e c t i v i t y

F a u l t s / f r a c t u r e s c a n b e C o n d u c t i v e a n d n o n - c o n d u c t i v e :* F a u l t o r ie n t a t i o n* N e t : G r o s s* P r o x im it y t o f lo o d f r o n t

I n je c t i v i t y o f u p p e r r e s e r v o irI n o n s h o r e a r e a h a s n o t y e t b e e n t e s t e d

B a s e o f Z 1 0 i n b o t h w e s tA n d e a s t a p p e a r s s a n d ie r

F r o m c o r e o b s e r v a t i o n s

B a s e o f Z 1 0 : is o la t e d f lu v ia l c h a n n e ls o b s e r v e d in c o r e

D is t a l ( f u r t h e r a w a y )f r o m s e d im e n t s o u r c e

D e n s e f a u l t s a n d f r a c t u r e sD e n s e f a u l t s a n d f r a c t u r e s

D e n s e f a u l t s a n d f r a c t u r e sD e n s e f a u l t s a n d f r a c t u r e s

R h iz o c r e t io n s a n d s p r e s e n t m o s t l yI n Z 5 0 ( l o c a l l y in Z 3 0 i n o f f s h o r e a r e a )- C o u ld b e m o r e p o o r l y c o n n e c t e d t h a n

- F lu v ia l s a n d s d u e t o m u d d ie r o v e r b a n k- d e p o s i t s

Z 5 0 / Z 7 0 s t r a n d e d A t t i cT a r g e t s p o s s ib le

B a s e Z 1 0 a p p e a r s s a n d ie r f ie ld w id e

M id Z o n e 3 0 s i l t s t o n e / s a b k h aA p p e a r s f ie l d w id e in c o r e

Z 4 0 / Z 6 0 ( a n d lo c a l l y Z 2 0 ) a r e d is c o n t i n u o u s in t h e

o f f s h o r e a r e a s o a r e b a f f le s r a t h e rt h a n b a r r i e r s t o f lu id f lo w

Z 7 0 : p e r m e a b i l i t y c a n b e U p t o 4 D a r c ie s

P r o x im a l ( c l o s e r t o )s e d im e n t s o u r c e

B a s e Z 1 0 : l o c a l i s e d i s o la t e d F lu v ia l c h a n n e ls i n e a s t e r n a r e a s

( a n d o c c a s io n a l l y in w e s t ) .

A l l z o n e s s h o w in c r e a s e in N e t t oG r o s s in o f f s h o r e a r e a , w h e r e

c h a n n e l s a n d s b e c o m e m o r e p r e v a le n t

> P e r m e a b i l i t y d i s t r ib u t io n d r iv e nb y f a c ie s t y p e

> B e s t q u a l i t y s a n d s a n d a v e r a g e s a n d sa r e in d is t in g u is h a b le o n p o r o s i t y lo g s

> 6 - 8 % p o r o s i t y s a n d c a n h a v e g o o dp e r m e a b i l i t y ( c u r r e n t p o r o s i t y c u t - o f ff o r n e t s a n d i s 1 2 % )

0H2S, % mol

0.09CO2 % mol

1600-2200Current pressure, at datum, psig

150Reservoir Temperature at datum, deg. F

2420Initial Reservoir Pressure at datum,

psig

1070Bubble Point Pressure, psig

357Solution GOR, SCF/STB

38.3Oil Gravity (API) at 60 deg. F

ValuePVT Properties

5

Role of ESP in The Development of Sherwood Reservoir

Sherwood Development History & its relation to number of ESP installations:

1978 - Discovery of Sherwood Reservoir

1985 �– 1st ESP installation (3 installations in 1985)

1990 - Start of multi-zone, vertical onshore development wells �– 16 ESP installations

1993 - Start of ERD wells (offshore Sherwood development) �– 9 ESP installations

1996 �– Field production peaked at 101+ MBOPD (average ESP installations during the field production peak, from 1995-1998: 13)

1997 - Start of infill drilling program �– 14 ESP installations

1998 �– Over 100 ESP installations to date.

1999 - Production came off plateau

2009 - Average Sherwood Oil Rate: 17.2 MBOPD, water cut: 93%. Average ESP Installations 1999 �– 2009: 8. Cumulative ESP installation count to date: 193.

S h e rw o o d Re s e r v o ir O il P ro d u c tio n : 1 9 7 8 - 2 0 0 9

0

5 0

1 0 0

1 5 0

2 0 0

2 5 0

1 9 7 5 1 9 8 0 1 9 8 5 1 9 9 0 1 9 9 5 2 0 0 0 2 0 0 5 2 0 1 0 2 0 1 5

MB

PD

0 %

1 0 %

2 0 %

3 0 %

4 0 %

5 0 %

6 0 %

7 0 %

8 0 %

9 0 %

1 0 0 %

Wat

er C

ut

F ie ld O il P ro d uc tio n -S he rwo o d F ie ld W a te r P ro d uctio n - S he rwo o dF ie ld W a te r C ut - S he rw o o d

Sherwood Reservoir Development & ESP Installations 1978-2009

0

2

4

6

8

10

12

14

16

18

1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 2005 2008

ESP

Inst

alla

tion

Cou

nt

0

10

20

30

40

50

60

70

80

90

1001974.5 1979.5 1984.5 1989.5 1994.5 1999.5 2004.5

Sher

woo

d O

il Pr

oduc

tion,

MB

OPD

ESP Installation Count Sherwood Field Oil Production

6

Wytch Farm ESP Run-life Progression

Failure ESPRuntime ESP

MTTF

Wytch Farm ESP Installation, Failure Counts & MTTF: 1985-2009

02468

1012141618

1985

1987

1989

1991

1993

1995

1997

1999

2001

2003

2005

2007

2009

0

250

500

750

1000

1250

1500

ESP

MTT

F, d

ays

Failure Count Premature Failure Installation Count ESP MTTF

1985 �– 1st ESP installation:

�•Three installations, with two premature failures**

�•1st ESP installed had a zero run life.

�•MTTF*: 68 days, Runtime to Failure*: 1 day

2009 �– As of 25th of November:

�•Total ESPs installed to date: 193

�•Total premature failures** to date: 23

�•Total failed ESPs to date: 113

�•MTTF*: 1,415 days, Runtime to Failure*: 805 days

Notes:

*Per day, runtime is calculated as follows: If runtime <12 hours = 0, If runtime>, or equal to 12 hours = 1

** Premature failure: <, or equal to 3-month runtime

Failure ESPRuntime ESP Failed

Failure To Runtime

Wytch Farm ESP Run-Life Measurements: 1985-2009

0

200

400

600

800

1000

1200

1400

1600

1985 1990 1995 2000 2005 2010

Installation Period

Day

s

020406080100120140160180200

Cum

ulat

ive

ES

P In

stal

latio

n C

ount

Mean Time To Failure, Days Runtime to Failure, Days ESP Installation Count

7

Wytch Farm ESP Failures By Components*

* Estimated, component failure does not translate to it being the root cause of failure

Wytch Farm ESP Failure Modes

Penetrators (Wellhead & Packer):

6%"Cable" including main cable, MLE, pigtail, splice, surface

cable, etc.22%

Pump14%

Motor44%

Seal2%

External - ESP Not at fault4% Unknown

8%

Penetrators (Wellhead & Packer): "Cable" including main cable, MLE, pigtail, splice, surface cable, etc.Pump Motor

Seal External - ESP Not at faultUnknown

8

Experiences with High HP Motor ESP Systems

The drilling of prolific Sherwood wells, particularly in the offshore area, necessitated the use of high flow rate ESP with high HP motor system (defined arbitrarily as greater than, or equal to 800 HP).

The 1st high HP ESP motor system installed in October 1997

To date, a total of 47 high HP ESP systems have been installed (27 failures, of which 3 were premature failures).

Nominal pump flow rates: 8,500 �– 28,000 BFPD

The largest HP ESP motor system: 1,400 HP (2 x 700 HP motors, installed in 2006), with 28 MBD nominal pump flow rate

Large HP Motor ESP System MTTF Comparison:

Installation Period: 1997 - 2009 MTTF, days

All ESPs 1919Large HP Motor ESP Systems 1634

9

Factors Contributing to Improvement in ESP Run-Life

Continuous learning from previous installations & operations (in total 25 years of ESP operation at WYF)

Abundance of local knowledge & experience: Some field operators have been around since day 1.

Onsite presence of ESP vendor support

Continuous training of field operators on the day-to-day ESP operations.

Relatively benign downhole (reservoir) conditions in the Sherwood reservoir (i.e., relatively low P, T, consolidated sandstone).

High water cut means less tweaking of ESP frequency to optimise production.

Upgrade of ESP equipment to suit operating conditions:

Change in ESP housing metallurgy along with upgrade of tubing metallurgy.

Upgrade & standardisation of ESP ancillary equipment (penetrator systems, cable, etc.)

Upgrade of shaft material (higher shaft HP rating) for high HP motor ESP system

Availability of downhole data for monitoring and troubleshooting purposes.

Very stable power supply (very few unplanned shutdowns due power supply interruptions)

Layers of automated protection system put in place:

Drive underload and overload protection

Surface (wellhead) pressure (high/low) protection system. This would, for example, protect ESP from deadheading situation which could arise as a result of blocked/closed surface valve.

Automated trip on (high) motor temperature signal. This system protects ESP motors from being burnt (e.g., in no-flow conditions). It also provides additional protection for those lightly loaded motors that may not necessarily trip on current underload alone.

10

Maturing Wytch Farm Oilfield & Its Impact on ESP Completion Strategy

The drilling of barefoot multilateral wells as a way to maximise well production in WytchFarm started at around 1998.

As the field is maturing, the depletion strategy focus shifted to being able to achieve maximum drawdown (from all laterals) for maximum liquid (both oil & water) rate at surface.

The increase in water cut over time, along with the desire to keep development cost down, also led to the phasing out of smart completions (use of down hole flow control, flow meter, etc.) The relatively short run-life of the downhole instrumentations coupled with increasing ESP run-life also contributed to the phasing out of these downholeinstrumentations.

Effect of corrosion seen as a result of increase in water cut led to the introduction of Chrome tubing and the use of corrosion resistant alloys for ESP housing (ca. 2000).

The continued increase in water cut made it possible to move ESP setting depth up, particularly on the high PI wells without sacrificing production or without introducing excessive amount of free gas at pump intake, and generally reduce the power requirement (per bbl lifted)

Larger capacity and more efficient medium voltage drives (MVD) up to 2050 KVA (200A) were introduced in 2001 to enable high rate production from the prolific Sherwood wells

The installations of Dual-ESP completions, beginning in 2004, address two needs at Wytch Farm:

Extending well life-cycle (i.e., minimising the number of ESP replacement workovers)

Managing uncertainty in productivity in new wells

11

Summary of Current Wytch Farm ESPs

Number of active (ESP) wells: 31

Number of Dual-ESP installations: 11

ESP Nominal Flow Rate Range: 1,000 �– 28,000 BPD �– 4.00�” to 6.75�” nominal OD

Average liquid production from ESP wells: 8,700 BLPD

Oil production from ESPs represents over 85% of total field oil production at Wytch Farm

Motor HP Range: 84 to 1,400 HP (average: 550 HP) �– 4.56�” to 7.38�” nominal OD

Most ESPs set in 9-5/8�” casing, though some in 7�” liner, and some ESPs are shrouded.

ESP Setting depths: 600 m-MD to 4,600 m-MD (average 2,300 m-MD)

VSDs: 400 KVA to 2,050 KVA

12

Sustaining Production in High PI, High Water Cut Wells by Moving ESP Up �– M11 Example

1998:SPE 50586 discussed ESP installation in M11, set at a depth of ca. 8420 m-MD.

Well trajectory: 10,114 m-MD �–Longest well trajectory at the time

Pump size: 20,000 BPD with 900HP tandem motor

Production rate: 18,000 BPD at 30% water cut

VSD: 1,050 KVA

2009: M11 ESP setting depth at 3400 m-MD

Pump size: 28,000 BPD with 1400 HP tandem motor

Production rate: 26,500 BPD at 95% water cut.

VSD: 2,050 KVA

13

Sustaining Production in High PI, High Water Cut Wells by Simplifying Downhole Completion �– M15 Example

1999:

SPE 62951 discussed the use of Down Hole Flow Meter to measure production rate & DHFC to facilitate selective production from the two well laterals.

ESP setting depth: 5,150 m-MD (1452 m-TVD)

Pump size: 21,500 BPD with 1170HP (3x390HP) triple tandem motor

Initial production rate: 15,000 BPD at 50% water cut

VSD: 1,050 KVA

E S P

F S V

D i s c o n n e c tD i s c o n n e c tS h r o u dB l i n d

B a r e f o o t f o r t h e 8 1 / 2 ” h o l e

7 ” l i n e rC a s e d & p e r f e d

F l o w c o n t r o l v a l v e s

C o n t r o l l i n ef l a t p a c k

F l o w m e t e r

A t W o r k o v e r : a d d 4 t h P r e s s u r e g a u g e ? ( M u l t i p l e x e d )

4 t h c o n t r o l l i n e - p r e s s u r e m o n i t o r n o d i s c h a r g e

S u m p p a c k e rP h o e n i x m u l t i - s e n s o r F S V p a c k e r

2009:

Production opened to both laterals (simple packered ESP completion, with 5-1/2�” tubing)

M15 ESP setting depth: 3,800 m-MD (1323 m-TVD)

Pump size: 21,500 BPD with 1170 HP (3x390HP) triple tandem motor

Production rate: 18,000 BPD at 95% water cut.

VSD: 2,050 KVA

14

Application of Dual-ESP Completion �– Extending Well Life Cycle

Retrievable Packer

Primary system: 15000-BPD (89-stg) Nominal ESP with 900-HP motor

Secondary System: 15000-BPD (92-stg) Nominal ESP with 900-HP motor

2-7/8" bypass tubing

9-5/8" casing

In this example, remaining oil reserves is sufficient to sustain economic production rate for at least 15 years.

Liquid rate decline rate is very small (i.e., liquid rate expected to be more or less constant over time)

Present Liquid rate: 17,600 BLPD at 95% water cut

Pump setting depth: 1,900 m-MD (1295 m-TVD)

Pump Intake Pressure: 460 psia (4.2% estimated free gas volume at intake conditions)

Workover frequency to replace ESP is expected to reduce over the 15-year period

15

Application of Dual-ESP Completion �– Managing Productivity Uncertainty in New Wells

Gross Liquids Over Time

2007 2008 200905001000150020002500300035004000

Gro

ss L

iqui

d [b

pd]

Primary system: 6000-BPD Nominal ESP with 270-HP motor

Secondary System: 2600-BPD Nominal ESP with 150-HP motor

9-5/8" casing

Retrievable Packer

2-7/8" bypass tubing

7" liner hanger

When drilled, there was a lot of subsurface uncertainties (PI, SBHP, etc).

Initial rate estimates: 1,000-6,000 BPD Need 2 ESPs to cover the range.

Primary ESP (3,500-7,800) ran for almost one year before switching to smaller ESP.

Currently still running on the secondary ESP (1,600-3,200 BPD)

16

Closing Remarks

As Wytch Farm oilfield continues to mature (i.e., declining oil rate & increasing water cut) the need to operate ESP more efficiently becomes more important.

This involves the use of efficient ESP system, coupled with extended well life cycle (i.e., extending the ESP run-life & the application of dual-ESP, where applicable).

It is expected that the conventional, tubing-deployed ESP systems to continue to dominate the ESP population at Wytch Farm, especially for those wells producing from the prolific offshore Sherwood reservoir.

17

Acknowledgments

The presenter would like to thank the following companies for making this presentation possible:

BP Exploration & Operating Co Limited

Premier Oil Exploration Limited

Summit Petroleum Dorset

Maersk Oil North Sea UK Limited

Talisman North Sea Limited

18

Questions?