Subsea MPFM & Sampling

Paul EggelingJune 2008

2

Subsea MPFM & Sampling - Introduction

• What we will be covering:

− Subsea MPFM

− Subsea sampling

− How used

− The Good, the Bad & the Ugly

− Based primarily on ETAP experience

3

Subsea MPFM – ETAP Overview

• Eastern Trough Area Project is an integrated development of 9 different reservoirs with differing ownership and operatorship

• 240km east of Aberdeen

• First production 1998

• Satellites 2002

• Export via FPS & CATS

• Water depth 85m

4

Subsea MPFM – Machar Overview

• Machar is an oil accumulation in a fractured chalk reservoir requiring WI support

− Ownership 100% BP

− 35km subsea tie-back (test line not viable)

− 9 prod (daisy chained) + 2 WI wells

− 1 Phasewatcher Vx on manifold (retrofit)

− TCI link to Framo PC

− Data link onshore (Processnet)

5

Subsea MPFM – How used ?

• Subsea MPFM used continuously for well optimisation (eg high GOR, water cut)

− One well stream routed through MPFM at all times

− Cycle round all wells

− Typically 48hrs well monitoring

− Eliminate topsides issues (looking for stable 8hrs data)

W127 & W123 performance

• Also monitor for (expected) changes

− Workover, water breakthrough, verify if achieved expected performance

− New well, instability, GL optimisation

6

Subsea MPFM – Good news & Issues

• The Good

− Well monitoring & optimistation

− Good correlation with topsides slugcatcherrates (10%)

− No impact on production

− Previous MPFM suffered from early design faults (sealing, HV supply)…significant improvement with Phasewatcher Vx

• The Bad & the Ugly

− On failure, replace with spare but in meantime reliant on slugcatcher rates, takes much longer & need good stability (eg. production impact)

− Daisy-chain wells (eg. production impact)

− Changes in production chemistry affecting performance (eg. salinity)

− Comms, loss of PTx

Machar Slugcatcher Salinity as Na and Cl Ions

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

100000

5/9/2005 14/12/2005 24/3/2006 2/7/2006 10/10/2006 18/1/2007 28/4/2007 6/8/2007 14/11/2007 22/2/2008 1/6/2008 9/9/2008

mg/

l

Na (mg/l) Cl (mg/l)

7

Subsea MPFM – Comparisons

• Farragon – 1st production 2006

− 1 MPFM on towhead

− Used for field flow allocation

− Well testing issue with stability/slugging & prod impact

− Comms - no TCI link

− Px faultMeasurement discrepancy (PVT)

• G.Plutonio - 1st production 2007

− MPFM on each manifold (8-off)

− Daily testing each well (every 8 hrs)

− Comms - smart tool

− MPFM & rig well data correlate well (10%)

− Tx faultWater cut reading affected by sulphur

8

Subsea Sampling – How used ?

• Subsea MPFM with sample point• Subsea panel with docking points, isolation valves and stab point.• Flow particular wellstream to steady state (2-3 hrs), draw sample • Typically up to six samples per trip

• ROV Sampling

− Workclass ROV with TDU for valves and stab ops

− Sampling skid carried below with 2 sample bottles (change-out offshore)

• Diver Sampling

− Work basket c/w valves and 6 sample bottles

− Used during parallel pigging operations at manifold

9

Subsea Sampling – How used ?

• Reservoir Surveillance

− Data acquisition, jigsaw puzzle (down-hole, well work, slugcatcher, MPFM)

− Fractional reservoir, requires WI support, issues with water breakthrough, leaving oil behind

− Understanding water-cut, reservoir water vsseawater eg. W127

− Monitor tracers to understand WI support eg. Machar East

Solution triangle

1000

10000

100 1000 10000

Detector puls frequency at energy level # 1

Det

ecto

r pul

s fr

eque

ncy

at e

nerg

y le

vel #

2

Gas

OilWater

Constant GVFConstant WLR

s95/mpfm/daniel/document/triangel.xls

• Production Chemistry

− Composition of water, susceptibility to scaling

• Subsea MPFM calibration

− Fluid property changes eg. new wells, salinity

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Subsea Sampling – Good news & Issues

• The Good− Reservoir surveillance from individual

wells (dedicated test line not viable: cost, wax & hydrates, commingled topsides)

− WI optimisation− Opportunistic sampling in parallel eg.

pigging operations• The Bad & the Ugly

− Previously sampled regularly (legislation) but thereafter less regular, more appetite now, need to commit over long-term

− Daisy-chain wells (eg. production impact)

− Limited awareness (eg. subsurface, chemist)

Laboratory Report 07-005376-0-ABDN Page 2 of 7

Sample No. 002-00

Field Machar Location

LEASE/UNIT WELL DEPTH FORMATION RATE B/DW128

TYPE OF WATER SAMPLING POINT DATE SAMPLED14/6/2007

SAMPLE APPEARANCE Clear No Cloudy Yes Coloured Yes

AFTER FILTRATIONSuspended Solids Yes Oil Present No Odour Yes

Remarks:

Na Cl

Ca HCO3

Mg SO4

Fe CO3

CATIONS mg/l meq/lSodium, Na(Calc.) 45400 1975 pH @ 20°C 7.3Potassium, K 889 23 Specific Gravity @ 20°C 1.0854Calcium, Ca 3230 162 Resistivity @ 25°C (ohm.meter) 0.0704Magnesium, Mg 852 70Barium, Ba 4.5 <1 Additional Elements (mg/l)Strontium, Sr 327 7Iron, Fe 3 <1 Lithium Li 13.8

Manganese Mn 1ANIONS Silicon Si 21.0Chloride, Cl 78496 2211 Phosphorus P <2Sulphate, SO4 854 18 Boron B 129Carbonate, CO3 0 <1 Aluminium Al <1Bicarbonate, HCO3 443 7 Zinc Zn <0.3Hydroxide, OH 0 <1

11

Subsea Sampling – Comparisons

• G.Plutonio

− Liquid sampler onshore for sampling water cut wells for salinity and tracers

− Expect to take 2-3 samples from each well over lifetime (salinity)

• Farragon

− No sampler

− Strong aquifer, no need for WI support

12

Subsea MPFM & Sampling – Conclusion

• Reliability

− MPFM retofit is significant improvement

− some issues to address

• Quality control

− configuration files,

− solution triangle

− PVT data

• Design decisions

− Production impact

− Data comms

− SamplingSubsea MPFM & Sampling

troubleshooters…