London 2013, 75th eage conference en exhibition incorporating SPE Europec, 2013
ABSTRACT We have introduced a method for probabilistic calculation of the Vp/Vs2 ratio from the i... more ABSTRACT We have introduced a method for probabilistic calculation of the Vp/Vs2 ratio from the intercept, PP-reflection coefficient at a given angle and assumed Vp/Vs1 ratio. The method opens up the possibility to create uncertainty maps, such as a standard deviation and Shannon’s information entropy maps. By a quick scanning over the maps, we can quickly identify zones where the calculations give unstable or erroneous results. Another novelty of the approach is avoiding extraction of the gradient from uncalibrated seismic data. Instead, we find (only) one scaler by dividing the uncalibrated intercept by the intercept from synthetic seismogram and apply it to each gather at the target zone. We tested the methodology on a gas discovery in the Barents Sea.
We present a methodology for estimating uncertainties and mapping probabilities of occurrence of ... more We present a methodology for estimating uncertainties and mapping probabilities of occurrence of different lithofacies and pore fluids from seismic amplitudes, and apply it to a North Sea turbidite system. The methodology combines well log facies analysis, statistical rock physics, and prestack seismic inversion. The probability maps can be used as input data in exploration risk assessment and as constraints in reservoir modeling and performance forecasting. First, we define seismic‐scale sedimentary units which we refer to as seismic lithofacies. These facies represent populations of data (clusters) that have characteristic geologic and seismic properties. In the North Sea field presented in this paper, we find that unconsolidated thick‐bedded clean sands with water, plane laminated thick‐bedded sands with oil, and pure shales have very similar acoustic impedance distributions. However, the [Formula: see text] ratio helps resolve these ambiguities. We establish a statistically repr...
London 2013, 75th eage conference en exhibition incorporating SPE Europec, 2013
ABSTRACT We have introduced a method for probabilistic calculation of the Vp/Vs2 ratio from the i... more ABSTRACT We have introduced a method for probabilistic calculation of the Vp/Vs2 ratio from the intercept, PP-reflection coefficient at a given angle and assumed Vp/Vs1 ratio. The method opens up the possibility to create uncertainty maps, such as a standard deviation and Shannon’s information entropy maps. By a quick scanning over the maps, we can quickly identify zones where the calculations give unstable or erroneous results. Another novelty of the approach is avoiding extraction of the gradient from uncalibrated seismic data. Instead, we find (only) one scaler by dividing the uncalibrated intercept by the intercept from synthetic seismogram and apply it to each gather at the target zone. We tested the methodology on a gas discovery in the Barents Sea.
We present a methodology for estimating uncertainties and mapping probabilities of occurrence of ... more We present a methodology for estimating uncertainties and mapping probabilities of occurrence of different lithofacies and pore fluids from seismic amplitudes, and apply it to a North Sea turbidite system. The methodology combines well log facies analysis, statistical rock physics, and prestack seismic inversion. The probability maps can be used as input data in exploration risk assessment and as constraints in reservoir modeling and performance forecasting. First, we define seismic‐scale sedimentary units which we refer to as seismic lithofacies. These facies represent populations of data (clusters) that have characteristic geologic and seismic properties. In the North Sea field presented in this paper, we find that unconsolidated thick‐bedded clean sands with water, plane laminated thick‐bedded sands with oil, and pure shales have very similar acoustic impedance distributions. However, the [Formula: see text] ratio helps resolve these ambiguities. We establish a statistically repr...
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