time lapse seismic, a journey trough 20 years of seismic ... · the case study fields are...

Time lapse Seismic, a journey Trough 20 years of seismic challenges Cyril Saint-Andre*, Benoit Blanco, Yann Montico, Patrick Charron, Emmanuelle Brechet Total SA Time-lapse seismic data have now proved to be very valuable for monitoring production and fluid injection in reservoirs. Overcoming the 4D acquisition and processing challenges in both quality and timing is still a key task for operators as 4D data deliverables must conform to challenging production and development deadlines. This paper will review several case studies showing examples of 4D experiments with a wide range of technical difficulties and contexts . The case study fields are characterized by very different geological settings and development maturities We shall start in the early 1990s with a naive 2D-on-2D trial from the North sea, and continue with a look at the precise and repeated monitoring of water injection and production for reservoir management and field development in the Gulf of Guinea turbidite reservoirs a decade later. Following these early successes we will describe the actions taken to industrialize time lapse processing and thus drastically reduce the processing turnaround and costs. In order to cope with the increase in processing challenges we developed efficient and innovative QCs that allow faster and more straightforward assessment of the 4D signal quality after each processing step. The next step up in difficulty came with the use of 4D technology to monitor production phenomena in carbonates fields. Time-lapse seismic has been acquired on a field in Eastern Asia affected by significant subsidence effects which significantly complexify the 4D processing workflow. However the rise in the Gas Water Contact (GWC) was clearly observed, which allowed us to anticipate future water breakthroughs in the field.

More recently, Time lapse processing techniques applied to the overburden have enabled us to characterize very subtle geomechanical effects above heavily depleted reservoirs.

Looking ahead, we are now aiming to routinely apply 4D techniques in Middle east carbonate fields suffering from heavy multiple contamination; Land 4D will offer another set of challenges, the first of which being to achieve acceptable acquisition repeatability, where using permanent sources and receivers may be a major part of the solution. Last but not least 4D in Sub Salt contexts adds imaging challenges to the difficulties of preserving the reliable and repeatable amplitudes needed for quantitative time lapse results assessment.

p.1 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges

Cyril Saint-Andre*, Benoit Blanco, Yann Montico, Patrick Charron, Emmanuelle Brechet Total SA

Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges


The « early days » of 4D - 1990’s Toward 4D Workflow Optimization - 2008 Focus on dedicated QCs - 2011 The « carbonate » Challenges - 2012 The overburden Bonus - 2014 The Leaps forward - 2016 and Beyond !

OUTLINE


The « early days » of 4D Toward 4D Workflow Optimization Focus on dedicated QCs The « carbonate » Challenges The overburden Bonus The Leaps forward

OUTLINE

p.4 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges 4D: What is it for?

4D = Images / Pictures of a reservoir taken at different Period of time 4D gives you the unique spatial monitoring image It contributes to the dynamic knowledge of the field: > Fluid communications > Reservoir heterogeneities (geological & dynamic barriers) > Fault sealing behaviour > Water/gas injection efficiency > GWC or WOC rise ups > Production efficiency: drained versus undrained areas > Monitoring of pressure and/or geomechanical effect

Gas ex-solution linked to depletion Water injection in oil pool Aquifer rise

p.5 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges What is 4D?: The “African Sunset” “4D” Experiment

BASE

MONITOR

p.6 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges What is 4D?: The “Sunset “4D” Experiment”

• « 4D » is a term defining successive 3D experiments • The quality of a 4D result is strictly related to the quality of the baseline survey • As any other physical measure, 4D is subject to errors, carried by every 3D contributor • The way we restitute data is at least as important as how we acquire it • A 4D effect, in general, generates a number changes in the surrounding environment


7

- Références, date, lieu

4D is used in a field life in a short and in a long term processus Short term using a fast track:

3 months after 4D acquisition

4D is used in a qualitative way

Long term using a full processing:

6 months/1 year after 4D acquisition

4D is used in a quantitative way

Objectives: •Field developement • Positionning infill wells •Reservoir management • Understanding of global communications and dynamic behaviours of the field

Objectives: • Integration of 4D interpretation inside reservoirs models • Imporovement of reservoir model to be more predictive by changing AE, facies, NTG, permeabilities, fault transmissibilities to perform better HM

Processing & post processing: • Fast track full offset cube • Warping

Processing & post processing: Full processing with substacks Warping 4D inversion

4D Interpretation: • Boundaries &/or geobodies on dV/V attributes and/or amplitude cubes

4D Interpretation & integration: •Geobodies on dV/V and/or dIP/IP • Upscaling inside reservoir models • Comparison with geological models, eclipse simulations, seismic modellings • Update of AE, facies, NTG, K, Fmult …

Proximity between 4D processing teams and warping teams enhanced the speedness of 4D inversion cubes delivery


The « early days » of 4D Toward 4D Workflow Optimization Focus on dedicated QCs The « carbonate » Challenges The overburden Bonus

The Leaps forward

OUTLINE


9

Minimize timing for delivery of final 4D volumes after the end of acquisition; No more Fast-track for repeated monitors! (2 months for processing turnaround)

Cope with sharply increasing 4D activity (Nb of projects / Acquisition cycle)

Reduce costs

OBJECTIVES

Long term contract => anticipation

Fixed Processing sequence

Process incremental monitor only!

Secure same resources for repeats

Synergies with Development team for 4D interpretation &

integration with reservoir monitoring and models

MEANS

4D processing Dedicated team – Objective & Motivation

Ofon

In progress or under examination

operatedDone or decided

Non operated

Done or decided

In progress or under examination

4D activity in TOTAL

p.10 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges 4D: Girassol Example / History

=> Increasing turnaround

=> Increasing complexity

2002

2004

2008


Lean, stable and standardized single monitor processing sequence

No fast -track route; only full integrity dataset delivered within the same turnaround

Testing phase limitation to the strict necessary

More time devoluted to QC’s

Getting more out of 4D by Processing Turnaround reduction

Innovative Solutions

4D Processing Turnaround Reduction by 4D Single Monitor Processing (SMP)


WHAT : Do not reprocess all vintages for each new monitor

Reduce lost time in procurement phase

Capitalize on previous 4D experiences

Replace FT & Full scenario by optimized Full processing only

2 months turnaround target for new monitor

BENEFITS :

Mimimize testing

Take full advantage or Vintages already processed (Base and Mx)

Implement automated QCs

Strip down costs $ $ $ $

⇒Turnaround Reduction (RTT)

4D stabilized « lean » processing sequences

X X X

p.13 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges Getting more out of 4D by Processing Turnaround reduction

No Compromise on quality

Preserving 4D signal

Lean & Frozen sequence per project

Seamless production ( // QC @ Milestones)

Capitalize on previous 4D experiences


The « early days » of 4D Toward 4D Workflow Optimization Focus on dedicated QCs The « carbonate » Challenges The overburden Bonus The Leaps forward

OUTLINE


SDR: Signal Distortion Ratio,

NCCP, Noise Characterization Cross Plot

RPTSC, Relative Phase Time Shift Cube

NRMS Band Pass

SDR vs NRMS cross plot.

4D R&D interaction & innovative QCs

Innovative QCs

p.17 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges Dedicated proprietary QC Integration in SISMAGE



The Leaps forward

OUTLINE

p.19 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges STORY OF THE DAY… comes from yesterday

2012 Acquisition of the new 3D acquisition first 4D Monitor

yesterday

Today

1993 1995

1998

2012

Start of production of Gas Field • Geological context: Miocene Carbonate Platform • 1998 first gas • Production with 13 gas producer wells

First 3D development acquisition performed in 1993… followed by a second one in 1995.

Processing, Interpretation and analysis of the 4D

p.20 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges MAIN Challenges

• 2 inhomogeneous vintages • Base = two different old seismic from 1993 & 1995 • Monitor = “modern” New Acquisition 2012

• Subsidence observed at Water Bottom • It introduces a time shift and make 4D processing very

tricky

Base 1995

Base 1993

Monitor 2012

Production platform area

during monitor acquisition

Rig area during base acquisition

Subsidence Area

Challenge for both acquisition & processing

Challenge for both processing & interpretation


SUBSIDENCE Subsidence is an “aging” effect that must be

preserved

Subsidence is a “production” effect that

must be preserved

Overburden

Reservoir

Attenuation of the 4D footprint with subsidence phenomena

http://chipiedream.c.h.pic.centerblog.net/cfd4d8bc.gif

p.23 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges 4D time & amplitude de-striping (base only)

3D time de-strippingOne per vintage (new

one for Base)

New full global matching for Base merge (93 & 95)

Global MatchingPseudo surface

consistent residual time statics

4D Binning 12.5x25m4D time & amplitude de-

stripping applied on Base (to fit Monitor)

3D regularization 12.5x25m

Inline interpolation 12.5x12.5m

3D Kirchhoff Pre Stack Time Migration using

new PSTM velocity fieldRMO correction

Angle mute & stacking

Residual Global Matching

Local Matching

4D F

ull P

roce

ssin

g

Raw Time Shift map is smoothed (1250 x 1250m) Low Frequency = Subsidence map

Raw Time Shift Map

0 +6ms -6ms

Subsidence Map

p.24 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges 4D time & amplitude de-striping (base only)

3D time de-strippingOne per vintage (new

one for Base)

New full global matching for Base merge (93 & 95)

Global MatchingPseudo surface

consistent residual time statics

4D Binning 12.5x25m4D time & amplitude de-

stripping applied on Base (to fit Monitor)

3D regularization 12.5x25m

Inline interpolation 12.5x12.5m

3D Kirchhoff Pre Stack Time Migration using

new PSTM velocity fieldRMO correction

Angle mute & stacking

Residual Global Matching

Local Matching

4D F

ull P

roce

ssin

g

De-striped Time Shift Map

Time Shift Map – No Subsidence

After 4D De-striping application

Good de-striping & Subsidence preserved


Pessimistic Res. Mod.

-15 m

30m

Porosity & Permeability over-

estimated in Reservoir model

Porosity & Permeability

under-estimated in Reservoir

model

Optimistic Res. Mod.

GWC: 4D vs. Simulated

Efficient acquisition + Processing led to relevant reservoir and overburden information 4D interpretation highlights some significant differences

compared to reservoir simulation. Reservoir model can be improved to optimize the production. Subsidence related to Reservoir Carbonates Compaction

can be assessed

dV/V

4D GWC (2012)

Simulated GWC (2012)

Original GWC

INTERPRETATION

p.26 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges Vintage 2009 3D Processing of 1996 data

26

p.27 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges 2014 4D Processing of 1996 data

Improved SNR Less multiples More continuity.

27

p.29 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges Time Shift Panorama Reservoir – Mishrif-SB6

1. Denoise 2. Shallow Water Demultiple 3. Cold Water Statics 4. 4D Destriping

5. 4D Binning & Reg 6. PreSTM 4D SRME + Undershoot Matching

7. Final Mute + Global Matching

Fast Track PoSTM + 4D SRME

29

p.30 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges NRMS Panorama Reservoir – Mishrif-SB6

1. Denoise 2. Shallow Water Demultiple 3. Cold Water Statics 4. 4D Destriping

5. 4D Binning & Reg 6. PreSTM 4D SRME + Undershoot Matching

7. Final Mute + Global Matching

Fast Track PoSTM + 4D SRME

30


4D Destriping methodology allows to reveal the 4D signal 4D SRME allows to apply a SRME without any 4D artefacts

Demultiple of this 4D project is better than vintage 3D processing

Time Shift 4D Signal is below 1ms in the overburden / 2ms in the reservoir

About 60 segy output for internal 4D QCs

11% NRMS at reservoir level ;



The Leaps forward

OUTLINE

p.33 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges Dalia M14 overburden 4D PROCESSING

4D Destriping theory, used to reveal a potential 4D signal in the overburden.

p.34 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges Dalia M14 overburden 4D PROCESSING

Time Shift section over the producing fields allows seeing the slight arching effect. The deghosted section is visible by transparency. Water bottom difference converted in depth.

The subsidence is very slight but appears clear on this particularly repeatable 4D seismic

p.35 Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges Results in sections: 4D qc attributes (xl 3582)

Overall increase in 4D signature from M12 to M14, as expected.



The Leaps forward

OUTLINE


4D processing is not only a good combination of good 3D processing 4D processing require accuracy to match Base and Monitor

Cross functionality / Integration with the research team, reservoir interpreters and experts. Knowledge building and development of dedicated innovative workflows. Internal development of innovative QCs. Cost / Workload / Procurement effort reduction

Conclusions


Looking ahead, we are now aiming to routinely apply 4D techniques in carbonate fields suffering from heavy multiple contamination

Land 4D will offer another set of challenges, the first of which being to achieve acceptable acquisition repeatability

Last but not least 4D in Sub Salt contexts adds imaging challenges to the difficulties of preserving the reliable and repeatable amplitudes needed for quantitative time lapse results assessment.

The Leaps forward


Cyril Saint-Andre*, Benoit Blanco, Yann Montico, Patrick Charron, Emmanuelle Brechet Total SA

THANK YOU !

4D_Story_AAPG_2500_v2_pw4D_AAPG Cancun_CSA_TOTAL_finalTime lapse Seismic, a Journey Trough 20 Years of Seismic ChallengesOUTLINEOUTLINE4D: What is it for?What is 4D?: The “African Sunset” “4D” ExperimentWhat is 4D?: The “Sunset “4D” Experiment”Diapositive numéro 7OUTLINE4D processing Dedicated team – Objective & Motivation4D: Girassol Example / HistoryGetting more out of 4D by Processing Turnaround reductionDiapositive numéro 12Getting more out of 4D by Processing Turnaround reductionOUTLINE4D R&D interaction & innovative QCs Diapositive numéro 17OUTLINESTORY OF THE DAY… comes from yesterdayMAIN ChallengesAttenuation of the 4D footprint with subsidence phenomena� 4D time & amplitude de-striping (base only)� 4D time & amplitude de-striping (base only)Diapositive numéro 25Vintage 2009 3D Processing of 1996 data�2014 4D Processing of 1996 data�Time Shift Panorama Reservoir – Mishrif-SB6NRMS Panorama Reservoir – Mishrif-SB6Diapositive numéro 31OUTLINEDalia M14 overburden 4D PROCESSING�Dalia M14 overburden 4D PROCESSING�Results in sections: 4D qc attributes (xl 3582)OUTLINEConclusionsThe Leaps forwardTHANK YOU !

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