Time-lapse seismic programme at Gullfaks: value and the road ahead

Najjar, N.F.; Strønen, L. K.; Alsos, T.

doi:10.1144/1354-079302-516

Cited by 9 publications

(3 citation statements)

References 2 publications

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Section: Discussionmentioning

confidence: 99%

“…Finally, a current point that limits possible widespread use of the method is the requirement for at least two repeat surveys. It is thus applicable to fields where a comprehensive 4D programme has been established such as the Gullfaks Field (Najjar, Stronen and Alsos 2003) and the Andrew Field (Parr et al 2003). However, with the future emphasis of industry being on permanent installations and more frequently acquired surveys (see, for example, the Valhall Field: Barkved et al 2003), appropriate data for our technique should become readily available and the number of surveys required is not envisaged as a difficulty.…”

Section: Discussion a N D C O N C L U S I O N Smentioning

confidence: 99%

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Going quantitative with 4D seismic analysis

MacBeth

Floricich

Soldo

2006

Geophysical Prospecting

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It is demonstrated that time‐lapse seismic signatures can be directly calibrated with historical data from producing and injecting wells via a reservoir simulator, material balance calculation or simply using the hard data. When this procedure is applied to a field over which two or more repeat surveys have been shot at different calendar times, the correlation coefficients that link the seismic difference signatures to the reservoir's pressure and saturation variations are determined. By utilizing several seismic attributes that respond differently to reservoir perturbations, pressure and saturation changes are then independently estimated. The approach is tested on synthetic data and then on data from the Schiehallion Field on the UK continental shelf, with favourable results.

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Section: Discussionmentioning

confidence: 99%

Section: Discussion a N D C O N C L U S I O N Smentioning

confidence: 99%

Going quantitative with 4D seismic analysis

MacBeth

Floricich

Soldo

2006

Geophysical Prospecting

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“…The use of time-lapse seismic data in conjunction with reservoir simulation models and production data allows the creation of an internally consistent subsurface model. Published field examples of such integrated case studies include Lena, Gulf of Mexico (Johnston et al 2000), Gullfaks, North Sea (Najjar et al 2003), Jotun, North Sea (Gouveia et al 2004), Girassol and Jasmin, West Africa (Gonzalez-Carballo et al 2006), Gannet C (Staples et al 2006) and Marlim (Thedy et al 2007). More recently, the impact of reservoir compaction on time-lapse seismic data has been studied in more detail (Guilbot & Smith 2002;Hatchell et al 2003) and reservoir geomechanical models are included into workflows that integrate time-lapse seismic data with subsurface flow and geomechanical models (Barkved & Kristiansen 2005;Staples et al 2006;De Gennaro et al 2008).…”

Section: Time-lapse Seismic Data: Acquisition Processing and Inversionmentioning

confidence: 99%

Applying time-lapse seismic methods to reservoir management and field development planning at South Arne, Danish North Sea

Herwanger¹,

Schiøtt²,

Frederiksen³

et al. 2010

PGC

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At South Arne a highly repeatable time-lapse seismic survey (normalized root-mean-square error or NRMS of less than 0.1) allowed us to reliably monitor reservoir production processes during five years of reservoir depletion. Time-lapse AVO (amplitude v. offset) inversion and rock-physics analysis enables accurate monitoring of fluid pathways. On the crest of the field, water injection results in a heterogeneous sweep of the reservoir, whereby the majority of the injected water intrudes into a highly porous body. This is in contrast to a pre-existing reservoir simulation model predicting a homogeneous sweep. On the SW flank, time-lapse AVO inversion to changes in water saturation DS w reveals that the drainage pattern is fault controlled. Time-lapse seismic data furthermore explain the lack of production from the far end of a horizontal producer (as observed by production logging), by showing that the injected water does not result in the expected pressure support. On the highly porous crest of the reservoir compaction occurs. Time-lapse time shifts in the overburden are used as a measure for compaction and are compared with predictions of reservoir compaction from reservoir geomechanical modelling. In areas where compaction observations and predictions disagree, time-lapse seismic data give the necessary insight to validate, calibrate and update the reservoir geomechanical model. The information contained in time-lapse seismic data can only be fully extracted and used when the reservoir simulation model, the reservoir geomechanical model and the time-lapse seismic inversion models are co-visualized and available in the same software application with one set of coordinates. This allows for easy and reliable investigation of reservoir depletion and gives deeper insight than using reservoir simulation or time-lapse seismic individually.

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Limitations in qualitative and quantitative analysis of time-lapse data due to fluid flow uncertainties

Furtney

Woods

2006

J. Geophys. Eng.

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We address some limitations in qualitative and quantitative analysis of time-lapse data due to underlying uncertainties in the flow of reservoir fluids. We explore how seismic signals may evolve over time by developing synthetic time-lapse data based on a variety of flow scenarios including radial flow, multi-phase flow and flows with unstable mobility ratios. Model predictions of water saturation and effective stress are used to construct synthetic impedance profiles. Using an idealized model of water-flood type production we show that qualitative analysis can be limited by the signal complexities resulting from flows in which both water saturation and effective stress change gradually, such as may occur when the injected water and the displaced oil are not separated by a sharp interface. A two-layer reservoir flow model is developed with which the limitations of quantitative analysis are explored. If a quantitative inversion technique is error free the resolution limits and signal noise in the seismic data allow only spatially averaged reservoir properties to be known. In some reservoirs undergoing water flood, volumetrically significant movement of the injected water may occur on length scales below that of the resolution and noise threshold the seismic data allows. In such a reservoir the inversion technique gives good quality information about the average location of the injected water but does not provide information about how all the injected water is moving. Specifically the possibility of thin high permeability layering carrying a significant fraction of the injected water cannot be eliminated. We show that this can introduce great uncertainty in estimates of reservoir performance.

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Time-lapse seismic programme at Gullfaks: value and the road ahead

Cited by 9 publications

References 2 publications

Going quantitative with 4D seismic analysis

Going quantitative with 4D seismic analysis

Applying time-lapse seismic methods to reservoir management and field development planning at South Arne, Danish North Sea

Limitations in qualitative and quantitative analysis of time-lapse data due to fluid flow uncertainties

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