Time lapse seismic monitoring of the Draugen field

Gabriels, Pieter; Horvei, Nils Aksel; Koster, J.K.; Onstein, Arne; Geo, Aker; Staples, Rob

doi:10.1190/1.1820970

Cited by 14 publications

(7 citation statements)

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“…The basic tool in such studies has been velocity analysis. In the Magnus 4-D study (Watts et al, 1996), the main seismic changes were attributed to pore-pressure changes, while in the Gullfaks and the Draugen (Gabriels et al, 1999) 4-D seismic studies, most of the seismic changes were interpreted as fluid related. However, for most reservoirs, pressure changes in combination with fluid-saturation changes create abnormal seismic responses.…”

Section: Introductionmentioning

confidence: 98%

Discrimination between pressure and fluid saturation changes from time‐lapse seismic data

2001

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Explicit expressions for computing saturation-and pressure-related changes from time-lapse seismic data have been derived and tested on a real time-lapse seismic data set. Necessary input is near-and far-offset stacks for the baseline seismic survey and the repeat survey. The method has been tested successfully in a segment where pressure measurements in two wells verify a porepressure increase of 5 to 6 MPa between the baseline survey and the monitor survey. Estimated pressure changes using the proposed relationships fit very well with observations. Between the baseline and monitor seismic surveys, 27% of the estimated recoverable hydrocarbon reserves were produced from this segment. The estimated saturation changes also agree well with observed changes, apart from some areas in the water zone that are mapped as being exposed to saturation changes (which is unlikely). Saturation changes in other segments close to the original oil-water contact and the top reservoir interface are also estimated and confirmed by observations in various wells. SATURATION AND PRESSURE VERSUS SEISMIC PARAMETERSDistinguishing between fluid-saturation and pore-pressure changes from seismic data requires knowing how seismic parameters are influenced by such changes. In the Gullfaks 4-D project a rock physics model calibrated with well-log measurements was used to predict the seismic effect of substituting oil with water. The basic equation in the rock physics model is the Gassmann equation (Gassmann, 1951). Repeated logging in wells typically shows a change in 836

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Section: Introductionmentioning

confidence: 98%

Discrimination between pressure and fluid saturation changes from time‐lapse seismic data

2001

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“…In general, neglecting compaction or subsidence effects, time-lapse variations of seismic attributes are the combined expression of changes both in saturation and in pressure (Landrø 2001;Trani et al 2011). We focused on waterflooding field cases, where changes are predominantly ascribed to changes in saturation (e.g., Gabriels et al 1999). Other potential applications are related to CO 2 -injection experiments such as those at Sleipner (Arts et al 2009) for which the main changes in seismic attributes are predominantly caused by saturation changes.…”

Section: Discussionmentioning

confidence: 99%

“…In particular, the example of the Draugen field (e.g., Gabriels et al 1999) is representative of the type of reservoir that will be investigated in this study. The same technique could probably be applied for CO 2 storage in aquifers as well, where similar fronts could be discerned.…”

Section: Introductionmentioning

confidence: 99%

Seismic History Matching of Fluid Fronts Using the Ensemble Kalman Filter

Trani

Arts²,

Leeuwenburgh³

2012

SPE Journal

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Time-lapse seismic data provide information on the dynamics of multiphase reservoir fluid flow in places where no production data from wells are available. This information, in principle, could be used to estimate unknown reservoir properties. However, the amount, resolution, and character of the data have long posed significant challenges for quantitative use in assisted-historymatching workflows. Previous studies, therefore, have generally investigated methods for updating single models with reduced parameter-uncertainty space. Recent developments in ensemblebased history-matching methods have shown the feasibility of multimodel history and matching of production data while maintaining a full uncertainty description. Here, we introduce a robust and flexible reparameterization for interpreted fluid fronts or seismic attribute isolines that extends these developments to seismic history matching. The seismic data set is reparameterized, in terms of arrival times, at observed front positions, thereby significantly reducing the number of data while retaining essential information. A simple 1D example is used to introduce the concepts of the approach. A synthetic 3D example, with spatial complexity that is typical for many waterfloods, is examined in detail. History-matching cases based on both separate and combined use of production and seismic data are examined. It is shown that consistent multimodel history matches can be obtained without the need for reduction of the parameter space or for localization of the impact of observations. The quality of forecasts based on the history-matched models is evaluated by simulating both expected production and saturation changes throughout the field for a fixed operating strategy. It is shown that bias and uncertainty in the forecasts of production both at existing wells and in the flooded area are reduced considerably when both production and seismic data are incorporated. The proposed workflow, therefore, enables better decisions on field developments that require optimal placement of infill wells.

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“…Information about effective pressure could be used to decide on optimal well design to reduce risks of blow-outs and damage to production equipment. * E-mail: hhve@statoil.com Time-lapse seismic differences can be attributed to being either dominantly pressure related (e.g., the Magnus Field, Watts et al 1996), or dominantly saturation related (e.g., the Gullfaks Field, Landrø et al 1999, and the Draugen Field, Gabriels et al 1999). In some cases, however, it is difficult to separate the effects of saturation and pressure from one set of stacked seismic data, since these effects can be of the same order of magnitude.…”

Section: Introductionmentioning

confidence: 99%

Stochastic inversion of pressure and saturation changes from time‐lapse multi component data

Veire

Borgos

Landrø

2007

Geophysical Prospecting

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A B S T R A C TKnowledge about saturation and pressure distributions in a reservoir can help in determining an optimal drainage pattern, and in deciding on optimal well designs to reduce risks of blow-outs and damage to production equipment. By analyzing time-lapse PP AVO or time-lapse multicomponent seismic data, it is possible to separate the effects of production related saturation and pressure changes on seismic data. To be able to utilize information about saturation and pressure distributions in reservoir model building and simulation, information about uncertainty in the estimates is useful. In this paper we present a method to estimate changes in saturation and pressure from time-lapse multicomponent seismic data using a Bayesian estimation technique. Results of the estimations will be probability density functions (pdfs), giving immediate information about both parameter values and uncertainties. Linearized rock physical models are linked to the changes in saturation and pressure in the prior probability distribution. The relationship between the elastic parameters and the measured seismic data is described in the likelihood model. By assuming Gaussian distributed prior uncertainties the posterior distribution of the saturation and pressure changes can be calculated analytically. Results from tests on synthetic seismic data show that this method produces more precise estimates of changes in effective pressure than a similar methodology based on only PP AVO time-lapse seismic data. This indicates that additional information about S-waves obtained from converted-wave seismic data is useful for obtaining reliable information about the pressure change distribution. I N T R O D U C T I O NInformation about saturation and pressure distributions in the reservoir, and changes in these properties over time, is of great value in the reservoir development process. In the production phase, knowledge about changes in saturation over time will help in determining optimal drainage patterns. Information about effective pressure could be used to decide on optimal well design to reduce risks of blow-outs and damage to production equipment. *

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Time lapse seismic monitoring of the Draugen field

Cited by 14 publications

References 0 publications

Discrimination between pressure and fluid saturation changes from time‐lapse seismic data

Discrimination between pressure and fluid saturation changes from time‐lapse seismic data

Seismic History Matching of Fluid Fronts Using the Ensemble Kalman Filter

Stochastic inversion of pressure and saturation changes from time‐lapse multi component data

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