Update on ESP Operation at BP Wytch Farm OilfieldBy Erwin Wahidiyat Presented at the European Artificial Lift Forum 17-18 February 2010 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 2 . Sherwood reservoir Well sites Bottom hole locations Poole Bournemouth Poole Harbour Purbeck miles 3 . Active ESP wells: 31 • Reservoirs: Sherwood. Arne.Wytch Farm Oilfield . LPG via road tanker.Location • Located in a sensitive environmental area on the southern coast of England. & Stoborough. Wareham. total active wells (producers & injectors): 65. gas by Purbeck-Sopley pipeline • 11 wellsites. • Current field production: 20+ MBDO at 93% water cut. Frome. Bridport. Kimmeridge. about 120 miles from London • Oil export via 90km 16” Purbeck-Southampton pipeline. 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.C o u ld b e m o r e p o o r ly c o n n e c t e d th a n . F Current pressure. psig CO2 % mol H2S. Zones 20. F a u lt s / f r a c t u r e s c a n b e C o n d u c tiv e a n d n o n . deg. Lower reservoir: Zones 50-100.3 357 1070 2420 Sherwood Reservoir Summary: •Triassic sandstone reservoir.Sherwood Reservoir: Summary & PVT Properties D is ta l ( f u r t h e r a w a y ) fr o m s e d im e n t s o u r c e D e n s e fa u lt s a n d fr a c tu r e s D e n s e fa u lts a n d fra c tu re s P r o x im a l ( c lo s e r t o ) s e d im e n t s o u r c e > P e r m e a b ility d is t r ib u tio n d r iv e n b y fa c ie s t y p e > B e s t q u a lity s a n d s a n d a v e r a g e s a n d s a r e i n d is t i n g u i s h a b l e o n p o r o s i t y l o g s > 6 -8 % p o ro s ity s a n d c a n h a v e g o o d p e r m e a b i l it y ( c u r r e n t p o r o s i t y c u t . % mol Value 38.c o n d u c tiv e : * F a u l t o r ie n t a t i o n * N e t: G ro s s * P r o x im it y t o f lo o d f r o n t X 0 2 A r e a – Z 7 0 is v . p o o r q u a l it y – l im it s V e r tic a l c o n n e c tiv it y Z 7 0 : p e r m e a b il it y c a n b e U p t o 4 D a r c ie s A l l z o n e s s h o w i n c r e a s e in N e t t o G r o s s in o f f s h o r e a r e a . 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) 0. SCF/STB Bubble Point Pressure.o f f fo r n e t s a n d is 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 e L o w e r N e t t o G r o s s – t h is l i m 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 ir 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 B a s e Z 1 0 a p p e a rs s a n d ie r f ie ld w id e M id Z o n e 3 0 s i lt s t o n e / s a b k h a A p p e a r s f ie l d w id e in c o r e B a s e o f Z 1 0 in b o t h w e s t A 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 tio n s 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 r t h a n b a r r i e r s t o f lu id f lo w R h i z o c r e t io n s a n d s p r e s e n t m o s t l y I n Z 5 0 ( l o c a ll y in Z 3 0 i n o f f s h o r e a r e a ) .F l u 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 . w h e r e channel sands becom e m o r e p r e v a le n t PVT Properties Oil Gravity (API) at 60 deg. 1585 m-TVDSS with a maximum 110-m column of oil bearing sand above the oil/water contact •Upper reservoir: Zones 10-40.09 0 150 1600-2200 •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. F Solution GOR. 4 . psig Initial Reservoir Pressure at datum. & 60 (muddier intervals) act as barriers •Three main oil bearing zones: Zones 30. 40. & 70 (decreasing permeability and net-to-gross in the upper zones). at datum. psig Reservoir Temperature at datum. 50.d e p o s its I n j e c t i v i t y o f u p p e r r e s e r v o ir In o n s h o re a re a h a s n o t y e t b e e n te s te d Z 5 0 / Z 7 0 s tr a n d e d A t tic T a r g e t s p o s s ib l e B a s e Z 1 0 : l o c a li s e d i s o l a t e d F l u 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 i o n a l l y in w e s t ) . with top reservoir at ca. 2 0 0 9 250 100% 90% 200 80% 70% Water Cut MBPD 150 60% 50% 100 40% 30% 50 20% 10% 0 1975 1980 1985 1990 1995 2000 2005 2010 0% 2015 Sherwood Development History & its relation to number of ESP installations: 1978 .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.Discovery of Sherwood Reservoir 1985 – 1st ESP installation (3 installations in 1985) 1990 .Role of ESP in The Development of Sherwood Reservoir S h e r w o o d R e s e r v o ir O il P r o d u c tio n : 1 9 7 8 .S he rw o o d Sherwood Reservoir Development & ESP Installations 1978-2009 1974.Average Sherwood Oil Rate: 17. 5 F ie ld O il P ro d uc tio n -S he rw o o d F ie ld W a te r C ut .5 100 Sherwood Oil Production.5 1989. MBOPD 90 80 70 60 50 40 30 20 10 0 ESP Installation Count Sherwood Field Oil Production .5 1999.2 MBOPD.Start of multi-zone. 1999 .5 1994. Cumulative ESP installation count to date: 193.5 2004.S he rw o o d F ie ld W a te r P ro d uc tio n . water cut: 93%.Production came off plateau 2009 .Start of infill drilling program – 14 ESP installations 1998 – Over 100 ESP installations to date. from 1995-1998: 13) 1997 .5 1984. vertical onshore development wells – 16 ESP installations 1993 .5 18 16 ESP Installation Count 14 12 10 8 6 4 2 0 1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 2005 2008 1979. Average ESP Installations 1999 – 2009: 8. or equal to 12 hours = 1 ** Premature failure: <. Runtime to Failure*: 805 days Installation Period Mean Time To Failure. days 1250 1000 750 500 250 0 Notes: *Per day. or equal to 3-month runtime MTTF ESP Runtime ESP Failure Failed ESP Runtime ESP Failure 6 Runtime To Failure Failure Count Premature Failure Installation Count ESP MTTF . runtime is calculated as follows: If runtime <12 hours = 0. Failure Counts & MTTF: 1985-2009 18 16 14 12 10 8 6 4 2 0 19 97 19 87 19 85 19 89 19 91 19 93 19 95 19 99 20 01 20 07 20 03 20 09 20 05 1500 ESP MTTF.Wytch Farm ESP Run-life Progression Wytch Farm ESP Run-Life Measurements: 1985-2009 1600 1400 1200 1000 Days 800 600 400 200 0 1985 1990 1995 2000 2005 200 180 160 140 120 100 80 60 40 20 0 2010 1985 – 1st ESP installation: •Three installations. Days ESP Installation Count Wytch Farm ESP Installation. Cumulative ESP Installation Count •MTTF*: 68 days. with two premature failures** •1st ESP installed had a zero run life.415 days. Days Runtime to Failure. 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. If runtime>. MLE. pigtail. splice. Motor External . surface cable. 22% Motor 44% Pump 14% Penetrators (Wellhead & Packer): Pump Seal Unknown "Cable" including main cable.Wytch Farm ESP Failures By Components* Wytch Farm ESP Failure Modes External .ESP Not at fault 4% Seal 2% Unknown 8% Penetrators (Wellhead & Packer): 6% "Cable" including main cable.ESP Not at fault * Estimated. etc. splice. etc. component failure does not translate to it being the root cause of failure 7 . pigtail. surface cable. MLE. The 1st high HP ESP motor system installed in October 1997 To date.000 BFPD The largest HP ESP motor system: 1. days 1919 1634 8 . with 28 MBD nominal pump flow rate Large HP Motor ESP System MTTF Comparison: Installation Period: 1997 . a total of 47 high HP ESP systems have been installed (27 failures.2009 All ESPs Large HP Motor ESP Systems MTTF. of which 3 were premature failures). installed in 2006). Nominal pump flow rates: 8. or equal to 800 HP). necessitated the use of high flow rate ESP with high HP motor system (defined arbitrarily as greater than.Experiences with High HP Motor ESP Systems The drilling of prolific Sherwood wells.500 – 28. particularly in the offshore area.400 HP (2 x 700 HP motors. 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. cable. Relatively benign downhole (reservoir) conditions in the Sherwood reservoir (i.g. Upgrade of ESP equipment to suit operating conditions: Change in ESP housing metallurgy along with upgrade of tubing metallurgy. T. protect ESP from deadheading situation which could arise as a result of blocked/closed surface valve. for example.. relatively low P. High water cut means less tweaking of ESP frequency to optimise production. consolidated sandstone). Onsite presence of ESP vendor support Continuous training of field operators on the day-to-day ESP operations. 9 . This system protects ESP motors from being burnt (e. 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. Upgrade & standardisation of ESP ancillary equipment (penetrator systems. Automated trip on (high) motor temperature signal. etc..) Upgrade of shaft material (higher shaft HP rating) for high HP motor ESP system Availability of downhole data for monitoring and troubleshooting purposes. It also provides additional protection for those lightly loaded motors that may not necessarily trip on current underload alone.e. This would. in no-flow conditions). 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. 2000). beginning in 2004. also led to the phasing out of smart completions (use of down hole flow control.) The relatively short run-life of the downhole instrumentations coupled with increasing ESP run-life also contributed to the phasing out of these downhole instrumentations. etc. particularly on the high PI wells without sacrificing production or without introducing excessive amount of free gas at pump intake.. flow meter. along with the desire to keep development cost down. The continued increase in water cut made it possible to move ESP setting depth up. As the field is maturing. The increase in water cut over time. 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. the depletion strategy focus shifted to being able to achieve maximum drawdown (from all laterals) for maximum liquid (both oil & water) rate at surface. minimising the number of ESP replacement workovers) Managing uncertainty in productivity in new wells 10 . address two needs at Wytch Farm: Extending well life-cycle (i.Maturing Wytch Farm Oilfield & Its Impact on ESP Completion Strategy The drilling of barefoot multilateral wells as a way to maximise well production in Wytch Farm started at around 1998.e. 000 – 28.050 KVA 11 .38” nominal OD Most ESPs set in 9-5/8” casing.000 BPD – 4.Summary of Current Wytch Farm ESPs Number of active (ESP) wells: 31 Number of Dual-ESP installations: 11 ESP Nominal Flow Rate Range: 1.75” nominal OD Average liquid production from ESP wells: 8.600 m-MD (average 2.56” to 7. and some ESPs are shrouded.400 HP (average: 550 HP) – 4.00” to 6.700 BLPD Oil production from ESPs represents over 85% of total field oil production at Wytch Farm Motor HP Range: 84 to 1. ESP Setting depths: 600 m-MD to 4.300 m-MD) VSDs: 400 KVA to 2. though some in 7” liner. 050 KVA 12 . High Water Cut Wells by Moving ESP Up – M11 Example 1998: SPE 50586 discussed ESP installation in M11.500 BPD at 95% water cut.000 BPD with 1400 HP tandem motor Production rate: 26.000 BPD with 900HP tandem motor Production rate: 18. VSD: 2. set at a depth of ca.000 BPD at 30% water cut VSD: 1. 8420 m-MD.114 m-MD – Longest well trajectory at the time Pump size: 20.Sustaining Production in High PI.050 KVA 2009: M11 ESP setting depth at 3400 m-MD Pump size: 28. Well trajectory: 10. 500 BPD with 1170HP (3x390HP) triple tandem motor Initial production rate: 15. High Water Cut Wells by Simplifying Downhole Completion – M15 Example F lo w m e te r A t W o rk o v e r: a d d 4 th P re s s u re g a u g e ? (M u ltip le x e d ) S h ro ud D is c o n n e c t 4 th c o n tro l lin e .050 KVA 2009: Production opened to both laterals (simple packered ESP completion.000 BPD at 50% water cut VSD: 1. with 5-1/2” tubing) M15 ESP setting depth: 3.500 BPD with 1170 HP (3x390HP) triple tandem motor Production rate: 18.000 BPD at 95% water cut.p re s s u re m o n ito r n o d is c h a rg e F lo w c o n tro l v a lv e s B lin d FSV 7 ” lin e r C a se d & p e rfe d ESP C o n tro l lin e f la t p a c k P h o e n ix m u lti-s e n s o r FS V packer Sum p packer B a re fo o t fo r th e 8 1 /2 ” h o le 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.050 KVA 13 . ESP setting depth: 5.Sustaining Production in High PI. VSD: 2.800 m-MD (1323 mTVD) Pump size: 21.150 m-MD (1452 m-TVD) Pump size: 21. Application of Dual-ESP Completion – Extending Well Life Cycle Retrievable Packer 9-5/8" casing 2-7/8" bypass tubing Primary system: 15000BPD (89-stg) Nominal ESP with 900-HP motor Secondary System: 15000BPD (92-stg) Nominal ESP with 900-HP motor In this example.900 m-MD (1295 m-TVD) Pump Intake Pressure: 460 psia (4. 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. remaining oil reserves is sufficient to sustain economic production rate for at least 15 years.e.2% estimated free gas volume at intake conditions) Workover frequency to replace ESP is expected to reduce over the 15-year period 14 . Liquid rate decline rate is very small (i.. 200 BPD) Retrievable Packer 9-5/8" casing 2-7/8" bypass tubing Primary system: 6000-BPD Nominal ESP with 270-HP motor 7" liner hanger Secondary System: 2600BPD Nominal ESP with 150HP motor 15 . etc). Need 2 ESPs to cover Primary ESP (3. Currently still running on the secondary ESP (1.600-3.800) ran for almost one year before switching to smaller ESP.500-7. SBHP.000 BPD the range. Gross Liquid [bpd] Initial rate estimates: 1.000-6. there was a lot of subsurface uncertainties (PI.Application of Dual-ESP Completion – Managing Productivity Uncertainty in New Wells Gross Liquids Over Time 4000 3500 3000 2500 2000 1500 1000 500 0 2007 2008 2009 When drilled. coupled with extended well life cycle (i.e.Closing Remarks As Wytch Farm oilfield continues to mature (i. especially for those wells producing from the prolific offshore Sherwood reservoir... extending the ESP run-life & the application of dual-ESP. It is expected that the conventional.e. tubing-deployed ESP systems to continue to dominate the ESP population at Wytch Farm. This involves the use of efficient ESP system. declining oil rate & increasing water cut) the need to operate ESP more efficiently becomes more important. where applicable). 16 . 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 17 . Questions? 18 .