4D Seismic for Oil Rim Monitoring

Staples, Rob; Hague, Paul; Weisenborn, Toon; Ashton, Paul R.

doi:10.3997/2214-4609-pdb.6.a03

Cited by 2 publications

(2 citation statements)

References 6 publications

(6 reference statements)

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“…There are many examples of reservoirs in which the 4D signature is almost completely dominated by saturation changes (e.g. the Nelson Field and the Gannet Fields (Staples et al 2005)). The starting point for this work is the equation of flow for the oil phase in a 2D two-phase (oil and water) system of incompressible fluids written without well terms.…”

Section: A2 4d Seismic Signatures Controlled By Saturation Changesmentioning

confidence: 99%

Extraction of permeability from time‐lapse seismic data

MacBeth¹,

Almaskeri²

2006

Geophysical Prospecting

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A B S T R A C TTwo formulae are developed for estimating horizontal permeability directly from maps of 4D seismic signatures. The choice of the formula used depends on whether the seismic is dominated by changes of pressure or saturation. However, pressure derived from time-lapse seismic, or seismic amplitudes controlled predominantly by pressure are to be preferred for optimal 'illumination' of the reservoir. The permeability is predicted to be dependent on porosity but weighted by a 4D term related to the magnitude and spatial gradient of the 4D signature. Tests performed on model-based synthetic seismic data affirm the validity and accuracy of this approach. Application to field data from the UK continental shelf reveals a large-scale permeability variation similar to the existing simulation model, but with additional fine-scale detail. The technique thus has the potential of providing extra information with which to update the simulation model. The resultant permeability estimates have been successfully ground-truthed against the results of two well tests. As non-repeatable noise in the time-lapse seismic data diminishes with improved 4D-related acquisition, it will become increasingly possible to make robust permeability estimates using this approach. I N T R O D U C T I O NIt is now widely acknowledged that time-lapse seismic data, if interpreted appropriately with due consideration of reservoir production and injection history, can provide invaluable information with which to optimize hydrocarbon recovery. This information includes, for example, the location of hydraulically conductive faults, no flow barriers or high permeability pathways, the identification of isolated compartments possibly containing bypassed oil, the position of injected fluid fronts or contacts, and general field-wide pressure and saturation changes. To date, most of these features are commonly inferred by detecting regions of brightening or dimming on difference sections or maps, and are thus essentially semiquantitative and can provide ambiguous interpretations. This style of 4D analysis is useful for reservoir management purposes, but in general may not offer sufficient accuracy to update the flow simulation model and hence to reduce uncertainty in reservoir performance predictions. A more detailed and in-depth level * E-mail: Colin.MacBeth@pet.hw.ac.uk of quantitative analysis is required, one that delivers accurate numerical estimates of absolute permeability variations, transmissibility factors, and reservoir connectivity at a variety of scales. To address this general challenge, we start by focusing here on estimating one of these parameters, i.e. reservoir permeability, which is the key flow property that controls strategies for well completion and production.The usual starting point for determining the permeability field for the flow simulation model is the core plug or welllog data. The interwell space is then populated by extrapolating between wells using an appropriate set of geostatistics, and this final reservoir model i...

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Section: A2 4d Seismic Signatures Controlled By Saturation Changesmentioning

confidence: 99%

Extraction of permeability from time‐lapse seismic data

MacBeth¹,

Almaskeri²

2006

Geophysical Prospecting

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“…Four-dimensional (4D) seismic is a powerful tool of monitoring of subsurface reservoirs (Lumley 2010;Garcia and MacBeth 2013;Staples et al 2005;Tura et al 2005). The application of 4D seismic, with multiple 3D seismic datasets, for the monitoring of coal seams under modern coal mining conditions ) allows us to monitor the background status before coal mining,…”

Section: Introductionmentioning

confidence: 99%

An application of 4D seismic monitoring technique to modern coal mining

2016

Geophysical Prospecting

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A B S T R A C TTo study the impact of modern coal mining on the overlying formation, a full-lifecycle four-dimensional seismic monitoring study has been carried out. Four seismic data campaigns have been performed using flexi-bin geometry with square bins, with total duration of 171 days. The four seismic datasets have been processed with the same processing workflow and parameters; major problems such as statics correction, signal-to-noise ratio, resolution, and consistency processing are addressed taking into account the geological features of the research area. This guarantees that remaining four-dimensional differences between the time-lapse datasets show mostly geological factors due to the coal mining and effects such as surface subsidence. Our four-dimensional seismic monitoring of modern coal mining shows that mined and unmined areas have significant zoning characteristics; coal mining has a direct impact on the overlying formation. The mining leads to obvious event subsidence, which reflects that overlying formations undergo subsidence during the mining process. The overlying formation appears as two zones called caving zone and fractured zone. We determine the fault dip of the overlying formation at one end of the working face to be 56°or so by calculation and conversion. We also see that, during the coal mining process, over time, the overlying formation has a self-recovery capability, which gradually strengthens from the roof siltstone upward to the Aeolian sandstone near the surface. The stability of 20-m coal pillars between working faces displays a strengthening trend and remains safe during the mining process due to both coal seam supporting and formation compaction effects.

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4D Seismic for Oil Rim Monitoring

Cited by 2 publications

References 6 publications

Extraction of permeability from time‐lapse seismic data

Extraction of permeability from time‐lapse seismic data

An application of 4D seismic monitoring technique to modern coal mining

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